 Section 9 of Grey's Anatomy, Part 5 This is a Librovox recording. All Librovox recordings are in the public domain. For more information or to volunteer, please visit Librovox.org, recording by Ellie, a anatomy of the human body, Part 5, by Henry Grey, the mouse, Part 2. The Permanent Tees Dentists Permanentes Densizers, dentists in Cissiri, incisive for cutting teeth, are so named from their presenting a sharp cutting edge, adapted for biting the foot. They are 18 numbers and form the forefront teeth in each dental arch. The ground is directed vertically and is sizzle shaped, being barreled at the expense of its lingual surface, so as to present a sharp horizontal cutting edge, which before being subjected to attrition, presents three small prominent points, separated by two slight notches. It is convex, smooth and highly polished on its libial surface, concave on its lingual surface, where in the teeth of the upper arch, it is frequently marked by an inverted V-shaped eminence, situated near the gum. This is known as the basal ridge, a singulum. The neck is constricted. The root is long, single, conical, transversely flattened, sickle in front and behind, and slightly curved on either side in the longitudinal direction. The upper incisors are larger and stronger than the lower, and are directed obliquely downward and forward. The central ones are larger than the lateral, and the roots are more rounded. The lower incisors are smaller than the upper. The central ones are smaller than the lateral, and are the smallest of all the incisors. They are placed vertically and are somewhat barreled in front, where they have been worn down by contact with the overlapping edge of the upper teeth. The singulum is absent. The canine teeth, dentis canini, a fine number, two in the upper and two in the lower arch, one being placed laterally to each lateral incisor. They are larger and stronger than the incisors, and their roots sink deeply into the bones, and cause well marked prominences upon the surface. The crown is large and conical, where it convex on its lingual surface, a little hollowed and uneven on its lingual surface, and tapered to a planted point or cusp, which projects beyond the level of the other teeth. The root is single, but longer and thicker than that of the incisors. Conical in form, compressed laterally and marked by a single groove on each side. The upper canine teeth, popularly called ITs, are larger and longer than the lower, and usually present a distinct basal ridge. The lower canine teeth, popularly called stomach teeth, are placed nearer the middle line than the upper, so that their summits correspond to the intervals between the upper canines and the lateral incisors. The primolars, or bricuspid teeth, than the sprimularis, are eight in number, four in each arch. They are situated lateral to and behind the canine teeth, and are smaller and shorter than they. The crown is compressed interposteriorly, and summounted by two pyramidal immenences or cusps, a labial and a lingual, separated by a groove, hence the name bicuspid. Of the two cusps, the labial is larger and more prominent. The neck is oval. The root is generally single, compressed and present in front and behind the deep groove, which indicates a tendency in the root to become double. The apex is generally bifid. The upper primolars are larger and present a greater tendency to division of their roots than the lower. This is especially the case in the first upper primolars. The molar teeth, then the smaller are the largest of the permanent set, and the broad crowns are adapted for grinding and pounding the foot. They are twelve in number, six in each arch. Three being placed posterior to each of the second primolars. The crown of each is nearly cubical in form, convex on its buccal and lingual surfaces, and flattened on its surfaces of contact. It is summounted by four or five tubercles or cusps, separated from each other by a crucial depression. Hence the molars are sometimes termed bicuspids. The neck is distinct, large and rounded. Upper molars. As they rule the first is the largest and the third the smallest of the upper molars. The crown of the first is usually four tubercles, that of the second three or four, that of the third three. Each upper molar has three roots, and of these two a buccal and nearly parallel to one another. The third is lingual and diverges from the others as it runs upward. The roots of the third molar, then the serotonous wisdom tooth are more or less fused together. Lower molars. The lower molars are larger than the upper. On the crown of the first, they are usually five tubercles. On those of the second and third four or five, each lower molar has two roots, an anterior, nearly vertical, and the posterior, directed obliquely backward. Both roots are growth longitudinally, indicating a tendency to division. The two roots of the third molar, then the serotonous wisdom tooth are more or less united. The deciduous teeth. The intesticidory, temporary or milk teeth. The deciduous are smaller than, but generally speaking, resembling form, the teeth which bear the same names in the permanent set. The hind of the two molars is the largest of all the deciduous teeth. It is succeeded by the second premolar. The first upper molar has only three casps, two labial and one lingual. The second upper molar has four casps. The first lower molar has four casps. The second lower molar has five. The roots of the deciduous molars are smaller and more divergent than those of the permanent molars. But in other respects, be a stronger resemblance to them. Structure of the teeth. On making a vertical section of the tooth, a cavity will be found in the interior of the crown and the center of each root. It opens by a minute or if you set the extremity of the letter. It is called the pulp cavity and contains a dental pulp, a loose connective tissue which is applied with vessels and nerves, which enter the cavity through the small aperture at the point of each tooth. Some of the cells of the pulp are arranged as a layer on the wall of the pulp cavity. They are named the odontoblasts of Valdaya and during the development of the tooth are columnar in shape. But later on when the dentine is fully formed, they become flattened and resemble osteoblasts. Each has two fine processes, the outer one passing into the dental canniculas and the inner being continuous with the processes of the connective tissue cells of the pulp matrix. The solid portion of the tooth consists of the ivory or dentine, which forms the bark of the tooth, the enamel which covers the exposed part of the crown, and the thin layer of bone, a cement or crust of petrosa, which is disposed on the surface of the root. The dentine, substantia buonia, ivory, forms the principal mass of the tooth. It is a modification of Osia's tissue, from which it differs however in structure. On microscopic examination, it is seen to consist of a number of menute wavy and branching cubes, the dental canniculi, embedded in a dense homogenous substance, the matrix. The dental canniculi, the tinnial tubules, are placed parallel with one another and augment the inner ends into the pulp cavity. In their cores to the periphery, they present two or three curves and are twisted on themselves in a spiral direction. These canniculi vary in direction, thus in the tooth of the mandible, they are vertically in the upper portion of the crown, becoming oblique and then horizontal in the neck and upper part of the root, while toward the lower part of the root, they are inclined downward. In their cores, they divide and subdivide ecodominously, and especially in the root, give off manure branches, which join together in loops in their matrix or end blindly. Near the periphery of the dentine, the finer ramifications of the canniculi terminate imperceptibly by three ends. The dental canniculi have definite walls consisting of an elastic homogenous membrane, the tinnial sheath of Neumann, which resists the action of acids. They contain slender cylindrical prolongations of the odontoplasts, first described by tomes and named tomes fibers or dentinal fibers. The matrix, intertubular dentin, is translucent and contains the chief part of the earthy matter of the dentin. In it are a number of fine fibers, which are continuous with the fibers of the dental bulb. After the earthy matter has been removed by steeping a tooth in weak acid, the animal bases remaining may be torn into laminae, which run parallel with the pulp cavity across the direct shafted tubes. A section of tridentin often displays a series of somewhat parallel lines, the incremental lines of solder. These lines are composed of imperfectly calcified dentin arranged in layers, in consequence of the imperfection of the calcifying process, little irregular cavities are left, termed interglobulular spaces. Normally a series of these spaces is found toward the outer surface of the dentin, where the formal layer, which is sometimes known as the granular layer, they have received a name from the fact that they are surrounded by minute neutrals, or globulules of dentin. Other curved lines may be seen parallel to the surface. These are the lines of Schreger and are due to the optical effect of simultaneous curvature of the dental fibers. Chemical composition. According to Basilios and from Bipra, dentin consists of 28 parts of animal and 72 parts of earthy matter. The animal matter is converted by boiling into gelatin. The earthy matter consists of phosphate of lime, carbonate of lime, a trace of fluoride of calcium, phosphate of magnesium and other salts. The animal substance here, the mantina, is the hardest and most compact part of the tools and forms a thin crust over the exposed part of the crown, as far as the commandment of the root. It is thickest on the grinding surface of the crown until one away by adhesion and becomes thinner toward the neck. It consists of my new taxagonal rods in columns termed animal fibers or animal prisms, prismata, the mantina. They lie parallel with one another, resting by one extremity upon the dentin, which presents a number of minute depressions for the reception and forming the free surface of the crown by the other extremity. The columns are directed vertically on the summit of the crown horizontally at the sides. They are about four million diameters and pursue a more or less wavy course. In each column is a six-sided prism and presents numerous dark transverse shadings. These shadings are probably due to the matter in which the columns are developed in successive stages, producing shallow contritions as will be subsequently explained. Another series of lines having a brown appearance, the parallel strip, or color lines of rite seos, is seen on section. According to Ebner, they are produced by air in the interprismatic spaces. Others believe that they are the result of tropicmentation. Numerous minute interstices intervene between the animal fibers and the dentinal ends. A provision calculated to allow for the permenation of fluids from the dental canically into the substance of the animal. Chemical composition. According to Van Bipra, animal consists of 96.5% of earthy matter and 3.5% of animal matter. The earthy matter consists of phosphate of lime with traces of fluoride of calcium, carbonate of lime, phosphate of magnesium and other salts. According to Tomes, the animal contains the merest rays of organic matter. The Krusta Petrosa Assument, substance here asia, is disposed as a thin layer on the roots of the teeth, from the termination of the animal to the apex of each root, where it is usually very sick, and the structure in chemical composition resembles bone. It contains spherently the lacuna and canically, which characterize true bone. The lacuna placed at the surface, receives the canically radiating from the side of the lacuna throughout the periodontal membrane, and those multiple blades join with the adjacent dental canically. In the secret portions of the Krusta Petrosa, the lamella or haversia and canal speculia to bone are also found. As age advances, the cement increases in thickness, and gives rise to those bone in Krusta exostosis to come in the teeth of the aged. The pulp cavity also becomes partially filled up by a hard substance, intermediating structure between dentin and bone, osteodentin, Owen, secondary dentin, Tomes. It appears to be formed by a slow conversion of the dental pulp, which shrinks or even disappears. End of Section 9, Recording by Ellie, January 2010 Section 10 of Grey's Anatomy Part 5 This is a liprovox recording. All liprovox recordings are in the public domain. For more information or to volunteer, please visit liprovox.org. Recording by Ellie. Anatomy of the human body Part 5, by Henry Grey The mouse, Part 3 Development of the teeth In describing the development of the teeth, the mode of formation of the dcds teeth was first be considered, and then that of the permanent series. Development of the dcds teeth The development of the dcds teeth begins about the sixth week of fetal life as the thickening of the bicellium along the line of the future chore, the thickening being due to a rapid multiplication of the more deeply situated bicellial cells. As the cells multiply, they extend into the adjacent mesoderm and thus form a retro-strand of cells embedded in mesoderm. About the seventh week, along the toenail splitting, a cleavage of this strand of cells takes place, and it becomes divided into two strands. The separation begins in front and extends laterally. The process occupying four or five weeks. Of the two strands, thus formed, the labial forms the labiodental lamina, while the other, the lingual, is the ridge of cells in connection with which the teeth, both deciduous and permanent, are developed. Hence it is known as the dental lamina, or common dental germ. It forms a flat band of cells, which grows into the substance of the embryonic chore, at first horizontally inverting then as the teeth develop vertically, i.e. upward in the upward chore, and downward in the lower chore, while still maintaining a horizontal direction test two edges. An attached edge continues with the bicellium lining the mouse, in the free edge, projecting inward and embedded in the mesodermal tissue of the embryonic chore. Along its line of attachment to the buccal epicellium is a shallow groove, the dental furrow. About the ninth week, the dental lamina begins to develop enlargements along its free border. These are 10 in number in each chore, and each corresponds with the future deciduous tools. They consist of masses of epithelial cells, and the cells of the deeper part that is the part farthest from the margin of the chore increase rapidly and spread out in all directions. Each mastas comes to assume a club shape, connected with the general epithelial lining of the mouse by a narrow neck, embraced by mesoderm. They are now known as special dental germs, after a time the lower expanded portion inclines outward, so as to form an angle with the superficial constricted portion, which is sometimes known as the neck of the special dental germ. About the tenth week, the mesodermal tissue beneath the special dental germs becomes differentiated into papillae. This chore upwards and come in contact with the epithelial cells of the special dental germs, which become folded over them like a hood or cap. There is then at this stage a papilla or papillae, which has already begun to assume somewhat the shape of the crown of the future tools, and from which the dentin and pulp of the tooth are formed, surmounted by a domar cap of epithelial cells, from which the animal is derived. In the meantime, while these changes have been going on, the dental laminar has been extending backward behind the special dental germ, corresponding with the second the city has smaller tools, and at about the seventeenth week it presents an enlargement, the special dental germ for the first permanent molar, soon followed by the formation of a pillar in the mesodermal tissue for the same tools. This is followed about the six months of the birth where further extension backward of the dental laminar is the formation of another enlargement in this corresponding papilla for the second molar, and finally the process is repeated for a third time, its papilla appearing about the fifth year of life. After the formation of the special dental germs, the dental laminar undergoes atrophic changes and becomes grip reform, except on the lingual and lateral aspects of each of the special dental germs. After the formation of the special dental germs, the dental laminar undergoes atrophic changes and becomes grip reform, except on the lingual and lateral aspects of each of the special germs of the temporarities, where it undergoes a local sickening following the special dental germ of each of the successional permanent teeth, the ten anterior ones in each jaw. Here the same process goes on as has been described in connection with those of the deciduous teeth, that is the recede into the substance of the gum behind the germs of the deciduous teeth, as the recede they become club shaped, form expansions at the distal extremities and finally meet papilla, which have been formed in the mesoderm just in the same manner as was the case in the deciduous teeth. The apex of each papilla indents the dental germ which encloses it, and forming a cap for it becomes converted into animal, where the papilla forms the dentin and pulp of the permanent tooth. The special dental germs consist at first of rounded or polyhedral epicyclic cells. After the formation of the papilla, these cells undergo differentiation into three layers, those which are in immediate contact with the papilla become elongated and form a layer of well marked columnar epicyclic encoding the papilla. They are the cells which form the animal fibers and therefore termed animal cells or adamantoblasts. The cells of the outer layer of the special dental germs, which are in contact with the inner surface of the dental sac, presently to be described a much shorter cubical form in the name of the external animal epicyclium. All the intermediate round cells of the dental germ between these two layers undergo peculiar change. They become stellate in shape and develop processes which unite to form a network into which fluid is secreted. This has the appearance of a jelly and to it the name animal pulp is given. This transformed special dental germ is now known under the name of animal organ. While these changes are going on, a sac is formed around each animal organ from the surrounding mesodermal tissue. This is known as the dental sac and is a vascular membrane of connective tissue. It grows up from below and thus encloses the whole tooth's germ. As it grows, it causes the neck of the animal organ to atrophy and disappear, so that all communication between the animal organ and the superficial epicyclium is cut off. At this stage, the vascular papilla surmount the backpacks of epicyclial cells, the whole being surrounded by membranous sacs. Formation of the animal The animal is formed exclusively from the animal's cells or the mandoblasts of the special dental germs, either by direct calcification of the columnar cells, which become elongated into hexagonal rods of the animal, or it is more generally believed that the secretion from the mandoblasts is in which calciferous matter is subsequently deposited. The process begins at the apex of each cusp, at the ends of the animal's cells in contact with the dental papilla. Here a fine globular deposit takes place, being apparently shed from the end of the mandoblasts. It is known by the name of animal droplet and resembles keratin in its resistance to the action of mineral acids. This droplet then becomes fibrous in calcifies and forms the first layer of the animal. A second droplet now appears in calcifies and so on. Successive droplets of keratin-like material shed from the adamantoblasts and form successive layers of animal. The adamantoblasts gradually receding as each layer is produced, until the determination of the process, they have almost disappeared. The intermediate cells of the animal pulp atrophiant disappear, so that the newly formed calcified material in the external animal bacillium come into a position. This latter layer however soon disappears in the emergence of the tooth beyond the gum. After its disappearance the crown of the tooth is still covered by a distinct membrane, which persists for some time. This is known as the cuticuladentis, anasmus membrane, and is believed to be the last formed layer of animal derived from the adamantoblasts, which has not yet become calcified. It forms a honey layer, which may be separated from the subjacent calcified mass by the action of strong acids. It is marked by the hexagonal impressions of the animal prisms, and when seen by nitrate of silver, shows the characteristic appearance of the bacillium. Formation of dentin. While these changes are taking place in the bacillium to form the animal, contemporary changes occurring in the differentiated mesoderm of the dental papillae result in the formation of the dentin. As before stated, the first germs of the dentin are the papillae, corresponding in number to the teeth, formed from the soft mesodermal tissue, which bonds the depressions containing the special animal germs. The papillae grow upward into the animal germs and become covered by them, both being enclosed in a vesicular connective tissue, the dental sac, in the matter above described. Each papilla then constitutes the formative pulp, from which the dentin and permanent pulp are developed. It consists of rounded cells in this very vesicular, and soon begins to assume the shape of future tooth. The next step is the appearance of the odontoblasts, which have a relation to the development of the teeth similar to that of the osteoblasts to the formation of the bone. They are formed from the cells of the periphery of the papillae. This is so safe from the cells in immediate contact with the odontoblasts of the special dental germ. These cells become elongated, one end of the elongated cell resting against the bicellium of the special dental germs, the other being tapered and often branched. By the direct transformation of the peripheral ends of these cells, or by a secretion from them, a layer of unclassified matrix pro-dentin is formed, which keeps the cusp or cusps, if they are more than one, of the papillae. This matrix becomes fibrillated, and the inlet islets of calcification make the appearance, and coalescing gives rise to a continuous layer of calcified material, which covers each cusp and constitutes the first layer of dentin. The odontoblasts, having thus formed the first layer, retire toward the scent of the papillae, and as they do so, produce successive layers of dentin from the peripheral extremities. That is to say, they form the dental matrix in which calcification subsequently takes place. As the tasks recede from the periphery of the papillae, they leave behind them filamentous processes of cell protoplasm, provided with finer site processes. These are surrounded by calcified material, and thus form the dental canniculi, and by the site branches and instruments in canniculi, the processes of protoplasm contained within them constitute the dental fibres, tomes fibres. In this way the entire thickness of the dentin is developed, each cannicula is being completed throughout its whole length by a single odontoblast. The central part of the papillae does not undergo calcification, but persists as the pipe of the tooth. In this process of formation of dentin, it has been shown that an uncalcified matrix is first developed, and that in this matrix islets of calcifications appear, which subsequently blend together to form a cap to each cusp. In like manner successive layers are produced, which ultimately become blended with each other. In certain places this blending is not complete. Portions of matrix remain uncalcified, between the successive layers. This gives rise to little spaces, which are the inter globular spaces alluded to above. Formation of the cement. The root of the tooth begins to be formed shortly before the crown emerges through the gum, but is not completed until some time afterward. It is produced by a down-gross of the bicellium of the dental germ, which extends almost as far as the situation of the apex of the future root, and determines the form of this portion of the tooth. This fold of the bicellium is known as the epicillial sheath, and on its papillary surface odontoblasts appear, which in turn form dentin, so that the dentin formation is identical in the crown and root of the tooth. After the dentin of the root has been developed, the vascular tissues of the dental sec begin to break, so the epicillial sheath and spread of the surface of the root is a layer of bone-forming material. In this osteoblasts make the appearance, and the process of ossification goes on in identically the same manner as in the ordinary intramembranous ossification of bone. In this way the cement is formed. It consists of ordinary bone containing cannicula and lacuna. Formation of the alveoli. About the 14th week of embryonic life, the dental lamina becomes enclosed in a shrugger groove of mesodermal tissue, which is at first coming to all the dental germs, but subsequently becomes divided by bone accept into loculi. Each loculi is containing a special dental germ of the decidius tooth and its corresponding permanent tooth. After birth, each cavity becomes subdivided, so as to form separate loculi, the future alveoli, for the decidius tooth and its corresponding permanent tooth. Although at one time the hole of the growing tooth is contained in the cavity of the alveolus, the latter never completely encloses it, since there is always an aperture over the top of the ground filled by soft tissue by which the dental sac is connected with the surface of the gum, in which the permanent tooth is called the gubernaculum dentis. Development of the permanent teeth. The permanent teeth is regarded as a development maybe divided into two sets. First, those which replace the decidius teeth, and which, like them, are 10 in number in each jaw. These are the successional permanent teeth, and second, those which have no decidius predecessors, but are superedited distal to temporary dental series. These are three in number on either side of each jaw, in the term superedited permanent teeth. They are the three molars of the permanent set, the molars of the decidius set being replaced by the primolars of the permanent set. The development of the successional permanent teeth, the 10 anterior ones in either jaw, has already been indicated. During the development, the permanent teeth enclosed in their sacs come to place on the lingual side of the decidius teeth, and more distant from the margin of the future gum, and, as already stated, are separated from them by bony partitions. As the ground of the permanent tooth grows, absorption of these bony partitions with the root of the decidius tooth takes place, through an agency of osteoclasts, which appeared this time, and finally nothing but the ground of the decidius tooth remains. This is shadow removed, and the permanent tooth takes its place. The superedited permanent teeth are developed in the manner already described by extension spec one of the posterior part of the dental lamina in each jaw. Erruption of the teeth When the calcification of the different tissues of each tooth is sufficiently advanced to enable it to feel the pressure to which it will be afterwards subjected, eruption takes place, the tooth making its way through the gum. The gum is absorbed by the pressure of the ground of the tooth against it, which is itself pressed up by the increasing size of the root, at the same time deceptor between the dental sex ossify and constitute the alveoli. This firmly embraces the necks of the teeth, and before them a solid basis of support, the eruption of the decidius teeth commences about the seven months after birth, and is completed about the end of the second year, the teeth of the lower jaw preceding those of the upper. The following, according to searist tomes, are the most usual times of eruption. Lower central incisors, 6 to 9 months. Upper incisors, 8 to 10 months. Lower lateral incisors and first molars, 15 to 21 months. Canines, 16 to 20 months. Second molars, 20 to 24 months. There are, however, considerable variations in these times, thus according to hold. At the age of 1 year, a child should have 6 teeth. At the age of 2 and a half years, a child should have 12 teeth. At the age of 2 years, a child should have 16 teeth. At the age of 2 and a half years, a child should have 20 teeth. Calcification of the permanent teeth proceeds in the following order in the lower jaw. In the upper jaw, it takes place a little later, the first molar, sooner after birth. The central and lateral incisors and the canine, about 6 months after birth. The premolars at the second year, were a little later. The second molar, about the end of the second year. The third molar, about the 12th year. The eruption of the permanent teeth takes place in the following periods. The teeth of the lower jaw preceding those of the upper or short intervals. First molars, 6 years. Two central incisors, 7 years. Two lateral incisors, 8 years. First premolars, 9 years. Second premolars, 10 years. Canines, 11 to 12 years. Second molars, 12 to 13 years. Serb molars, 17 to 25th year. Toward the 6th year, before the shedding of the deciduous teeth begins, there are 24 teeth in each jaw, the 10 deciduous teeth in the grounds of all permanent teeth, except the Serb molars. End of section 10, recording by Ellie, February, 2010. Section 11 of Gracie Netomi, part 5. This is a liprovox recording. All liprovox recordings are in the public domain. For more information or to volunteer, please visit liprovox.org, recording by Ellie. A anatomy of the human body, part 5, by Henry Gray. The mouse, part 4. The tongue, lingua. The tongue is the principal organ of the sense of taste and an important organ of speech. It also assists in domestication and declutination of the food. It is situated in the floor of the mouse, within the curve the body of the mandible. Its root, radix linguae base, is directed backward and connected with the hyoid bone by the hyoclossi and guineoclossi muscles and the hyoclossal membrane, with the epiglottis by three folds. Clossoepiglottic, of mucus membrane, with the soft pellet by the closopellet and arches, and with the pharynx by the constrictoris pharynx superioris and the mucus membrane. Its apex, apex linguae tip, sine and narrow is directed forward against the lingual surfaces of the lower incisor teeth. Its inferior surface, fazius inferior linguae, on the surface, is connected with the mandible by the guineoclossi. The mucus membrane is reflected from it to the lingual surface of the gum and on the floor of the mouse, where in the middle line it is elevated into a distinct vertical fold, the phrenulum linguae. On either side lateral to the phrenulum is a slight fold of the mucus membrane, the plica fibrillata, the free edge of which occasionally exhibits a series of fringe-like processes. The apex of the tongue, the inferior surface, the sides and dorsum are free. The dorsum of the tongue, dorsum linguae, is convex and marked by median sulcus, which divides it into symmetrical halves. This sulcus ends behind about 2.5 centimeters from the root of the organ in a depression. The forearm and ceicum, from which a shallow groove, the sulcus terminalis, ends lateral, warden forward on either side to the margin of the tongue. The part of the dorsum of the tongue in front of its groove, forming about two thirds of its surface, looks upward, in this rough and covered with papillae. The posterior assert looks backward and is smoother and contains numerous muciperas clens and lumpful nickels, lingual tonsil. The forearm and ceicum is the remains of the upper part of the surioclossal duct, a diverticulum from which the thyroid gland is developed. The pyramidal lobe of the thyroid gland indicates the position of the lower part of the duct. The papillae of the tongue are projections of the corium, they are sickly distributed over the anterior two thirds of its dorsum, giving to this surface its characteristic roughness. The varieties of papillae medvis are the papillae valate, papillae fungiformis, papilla filiformis and papillae simplicis. The papillae valate, circumvele papillae, are of a large size and vary from 8 to 12 in number. They are situated at the dorsum of the tongue immediately in front of the forymen ceicum and suricus terminalis, forming a row on either side. The two rows run backward and medialward and meet in the middle line, like the limbs of the letter V inverted. Each papillae consists of a projection of mucous membrane from 1 to 2 mm wide, attached to the bottom of a circular depression of the mucous membrane. The margin of the depression is elevated from a wall, volume, and between this and the papillae is a circular sulcus, termed the fossa. The papillae is shaped like a truncated cone, the smaller end being directed downward and attached to the tongue, the broader part of base projecting a little above the surface of the tongue and being started with numerous small secondary papillae and covered with stratified squamous epicyllium. The papillae fungiformis, fungiform papillae, manumora stendipresiding, are found chiefly at the sides of the apex. They are scattered irregularly and sparingly over the dorsum. They are easily recognized among the other papillae by their large size, rounded eminences and deep red color. They are narrow at the entrenchment of the tongue, but broad and rounded at the free extremities and covered with secondary papillae. The papillae filiformis, filiform or conical papillae cover the interior two-thirds of the dorsum. They are very minute, filiform in shape, and arranged in lines parallel with the two rows of the papillae velate, excepting at the apex of the organ, where the direction is transverse, projecting from the apices on numerous filamentous processes. A secondary papillae, these are the whitest hint owing to the thickness and density of the epicillium, of which they are composed, which has here undergone a peculiar modification, the cells having become quantified and elongated into dense, implicated brush-leg processes. They contain also a number of elastic fibers, which render them far more elastic than the papillae of mucus membrane generally. The larger and longer papillae of this group are sometimes termed papillaeconice. The papillae simplicis are similar to those of the skin, and cover the whole of the mucus membrane of the tongue, as well as the larger papillae. They consist of closely set microscopic elevations of the corneum, each containing a capillary loop, covered by a layer of epicillium. Muscles of the tongue. The tongue is divided into lateral halves by a medium fibrous septum, which extends throughout its entire length and is fixed below to the hyoid bone. In either half there are two sets of muscles, extrinsic and intrinsic. The former having the origin outside the tongue. The latter are contained entirely within it. The extrinsic muscles are genioclossus, hyoclossus, controglossus, stiloclossus, glosopalatinos, footnote 160. The glosopalatinos, platoclossus, although one of the muscles of the tongue is more closely associated with the soft palate bone situation and function. It has consequently been described as the muscles of the structure. End of footnote. The genioclossus. Genioclossus is a flat triangular muscle close to and parallel with the medium plane. Its epics corresponding with its point of origin from the mandible. It spaces its insertion into the tongue and hyoid bone. It derises by a sort of tendon from the superior mental spine on the inner surface of the synphysis mentee, immediately above the genioclossus, and from this point spreads out in a fennelike form. The inferior fibres extend backward to be attached by syneponorosis to the upper part of the body of the hyoid bone, a few passing between the hyoclossus and controglossus to blend with the constrictoris faringis. The middle fibres pass backward and the superior ones upward and forward to enter the whole length of the under surface of the tongue from the root to the apex. The muscles of opposite sides are separated at the insertions by the median fibra septum of the tongue. In front they are more or less blended owning to the dequisition of fasciculi in the medium plane. The hyoclossus, synun quadralateral, arises from the side of the body and from the whole length of the greater corno of the hyoid bone and passes almost vertically upward to enter the side of the tongue between the stiloclossus and longitudinalis inferior. The fibres arising from the body of the hyoid bone overlap those of the greater corno. The controglossus is sometimes described as part of the hyoclossus, but they are separated from it by fibres of the genioclossus, which passes through the side of the pharynx. It is about two centimeters long and arises from the medial side and base of the lesser corno in contiguous portion of the body of the hyoid bone and passes directly upward to blend with the intrinsic muscular fibres of the tongue between the hyoclossus and genioclossus. A small slip of muscular fibres is occasionally found, arising from the cartilagodretesia and the lateral hyocyroid ligament and entering the tongue is the hindermost fibres of the hyoclossus. The stiloclossus, the shortest and smallest of the three stiloid muscles, arises from the interior and lateral surfaces of the stiloid process, near its apex and from the stilomendipolar ligament. Passing downward and forward between the internal and external carotid arteries, it divides upon the side of the tongue near its dorsal surface, blending with the fibres of the longitudinalis inferior in front of the hyoclossus. The other oblique overlaps the hyoclossus and the castes to its fibres. The intrinsic muscles are longitudinalis superior transversus, longitudinalis inferior verticalis. The longitudinalis lingeris superior superior lingualis is a synestratum of oblique and longitudinal fibres immediately underlying the mucous membrane and the dorsum of the tongue. It arises from the mucous fibres layer close to the epiglottis and from the median fibres septum and runs forward to the edges of the tongue. The longitudinalis lingualis inferior inferior lingualis is a narrow bend situated on the under surface of the tongue between the genioclossus and hyoclossus. It extends from the root to the apex of the tongue. Behind, some of its fibres are connected with the body of the hyoid bone, in front it blends with the fibres of the stiloclossus. The transversus lingualis consists of fibres which arise from the median fibros septum and pass lateral ward to be inserted into the submucous fibros tissue at the sides of the tongue. The verticalis lingualis is found only at the borders of the four parts of the tongue. Its fibres extend from the upper to the under surface of the organ. The median fibros septum of the tongue is very complete, so that the anastomosis between the two lingual arteries is not very free. Nerves, the muscles of the tongue describe the bath as applied by the hyoclossal nerve. Actions, the movements of the tongue, although numerous and complicated, may be understood be carefully considering the direction of the fibres of its muscles. The genioclossus by means of the posterior fibres draw the root of the tongue forward and protrude the apex from the mouse. The anterior fibres draw the tongue back into the mouse. The two muscles acting in their entirety draw the tongue downward, so as to make its superior surface concave from side to side. Forming a canal along which fluids may pass toward the pharynx, as in sucking. The hyoclossy depress the tongue and draw down its sides. The stiloclossy draw the tongue upward and backward. The glossopalatini draw the root of the tongue upward. The intrinsic muscles are mainly concerned in alternating the shape of the tongue. Whereby become shortened, narrowed or curved in different portions, thus the longitudinal superior and inferior tend to shorten the tongue. But the form in addition turns the tip and sides upward, so as to render the dorsum concave. While the latter pull the tip downward and render the dorsum convex. The transversus narrows in the illung against the tongue, and the vertical is flattened and broadens it. The complex arrangement of the muscular fibres of the tongue and the various directions in which the run give this organ the power of assuming the forms necessary for the enunciation of the different, continental sounds. And McKellister states, there is reason to believe the musculature of the tongue varies in different races, owning to the hereditary practice and the pitual use of certain motions required for enunciating the several vernacular languages. Structure of the tongue The tongue is partly invested by mucous membrane, the sub mucous fibres layer, the mucous membrane, tonic and mucosa lingui. Differently from parts, that covering the under surface of the original sense must an identical instructor with that, lining the rest of the oral cavity. The mucous membrane of the dorsum of the tongue, behind the forearm and ceicum and sulcus terminalis is thick and freely movable over the subjacent parts. It contains a large number of lymphoid follicles, which together constitute what is sometimes termed the lingual tonsil. Each follicle forms a rounded eminence, the center of which is perforated by a minute orifice leading into a final shaped cavity of races. Around these races are grouped numerous, oval rounded nodules of lymphoid tissue, each enveloped by a capsule derived from the sub mucosa, while opening into the bottom of the races are also seen the ducts of mucous glands. The mucous membrane on the anterior part of the dorsum of the tongue is thin. Immediately it turns to the muscular tissue, and presents numerous minute surface eminences, the papilla of the tongue. It consists of a layer of connective tissue, the corneum of the mucosa, covered with a bicellium. The bicellium is of the stratophyte's cramous variety, similar to but much thinner than that of the skin, and each papilla has a separate investment from root to summit. The deepest cells must sometimes be attached to the separate layer, corresponding to the red mucosum, but they never contain coloring matter. The corneum consists of a dense feltwork of fibros connective tissue, with numerous elastic fibers, firmly connected with the fibros tissue, forming the septal between the muscular bundles of the tongue. It contains the ramifications of the numerous vessels and nerves from which the papilla is applied, large plexuses of lymphatic vessels, and the clans of the tongue. Structure of the papilla The papilla apparently resembles the structure of the kutis, consisting of cone-shaped projections of connective tissue, covered with a thick layer of stratophyte's cramous bicellium, and containing one or more crepillary loops, among which nerves are distributed in great abundance. If the bicellium be removed, it will be found that there are no simpler elevations like the papilla of the skin. For the surface of each is studied with a minute conical process, which forms secondary papillae. In the papillae valate, the nerves are numerous and of a large size. In the papillae fungiformis, they are also numerous, in the end in the plexiform network, from which brush-like branches proceed. In the papillae filiformis, the mode of termination is ensured. Clans of the tongue The tongue is provided with mucus and serous clans. The mucus clans are similar in structure to the labial and buccal clans. They are found especially at the back part behind the valate papilla, but they are also present at the apex in marginal parts. In this connection, the terelingual clans, blended or known, require special notice. They are situated on the under-surface of the apex of the tongue, when on either side of the phrenolum, when they are covered by fasciculars of muscular fibers derived from the stiloclosus and longitudinalis inferior. They are from 12 to 25 millimeters long and about 8 millimeters broad in each open spesary of adducts and the under-surface of the apex. The serous clans occur only in the back of the tongue in the neighborhood of the taste buds. The ducts opening for the most part into the fossa of the valate papilla. These clans are agmos, the duct of each branching into several minute ducts, which end in alveoli, lined by a single layer of more or less column albicillium. The secretion is of a watery nature and probably assists in the distribution of the substance to be tasted over the taste area, ebna. Deceptum Deceptum consists of a vertical layer of fibrous tissue, extending throughout the entire length of the medium plane of the tongue, donor quite reaching the torso. It is thicker behind than in front and locational contains a small fibrocatellage about 6 millimeters in length. It is well displayed by making a vertical section across the organ. The hyoclosal membrane is a strong fibrous laminar which connects the under-surface of the root of the tongue to the body of the hyoc bone. This membrane receives in front some of the fibers of the genioclossi. Taste buds, the end organs of the custodiori scents, as scattered on the mucous membrane of the mouse and tongue with irregular intervals. They occur especially in the sides of the velle papille. In the rebites the localized area at the side of the base of the tongue, the papille folliata, in which the eye is specially abandoned, they are described under the organs of the scences. Wessels and nerfs The main artery of the tongue is the lingual branch of the external carotid, but the external maxillary and descending pharyngeal also give branches to it. The veins open into the internal chocular. The lymphatics of the tongue have been described on page 696. The sensory nerfs of the tongue are 1. The lingual branch of the mandibular, which is distributed to the papille at the four part and sides of the tongue informs the nerve for auditory sensibility for its interior two thirds. 2. The quadrotemporal branch of the facial which runs in the sheets of the lingual and is generally regarded as the nerve of taste for the interior two thirds. This nerve is a continuation of the sensory root of the facial, nervous intermedius. 3. The lingual branch of the glossopharyngeal, which is distributed to the mucous membrane at the base and sides of the tongue, and to the papille volate, in which supplies both gustatory filaments and fibers of general sensation to this region. 4. The superior lingual, which sends some fine branches to the root-need epiclottis. End of section 11, recording by Ellie, February 2010. Section 12, of Grace Anatomy Part 5. This is Ellie provox recording. Only provox recordings are in the public domain. For more information or to volunteer, please visit lipovox.org, recording by Ellie. Anatomy of the human body part 5, by Henry Gray. The mouse, part 5. 5. The salivary glands. Three large pairs of salivary glands communicate with the mouse and put the secretion into its cavity. They are the parotid sub-axillary and sublingual. Parotid gland, clandolaporotes. The parotid gland, the largest of the three, varies in weight from 14 to 28 grams. It lies upon the side of the face, immediately below and in front of the external ear. The main portion of the gland is superficial, somewhat flattened and quadrilateral in form and displaced between the ramus of the mandible in front and the mastoid process and sanocleidomastodios behind, overlapping her ever-post boundaries. Above it is broad and reaches nearly to the psychomatic arch, below it tapers somewhat to about the level of the line joining to the tip of the mastoid process to the angle of the mandible. The remainder of the gland is irregularly wet-shaped and extends deeply inward to the varyngeal wall. The gland is enclosed within the capsule, continuous with the deep cervical fascia. The layer covering the superficial surface is dense and closely returned to the gland. A portion of the fascia attached to the stilioid process and the angle of the mandible is signified to form the stilio-mandibular ligament, which intervenes between the perotid and the subaxillary glands. The anterior surface of the gland is molded on the posterior part of the ramus of the mandible, closed by the pterogridius internus and maseta. The inner lip of the groove dips for a short distance between the two pterogrid muscles, while the outer lip extends for some distance or the superficial surface of the maseta. A small portion of this lip, immediately below the psychomatic arch, is usually detached and is named the accessory part. Socia perotidis of the gland. The posterior surface is grooved longitudinally in the but against the external acoustic miatus, the mastery process and the anterior part of the sternocleidomastideus. The superficial surface, slightly lobulated, is covered by entanglement. The superficial fascia are containing the facial branches of the great auricular nerve and some small lymph glands, and the fascia which forms the capsule of the gland. The deep surface extends inward by means of two processes, one of which lies under the gastricus, stulloid process and the stulloid group of muscles and projects under the mastoid process and sternocleidomastideus. The other is situated in front of the stulloid process and sometimes passes into the posterior part of the mandibular fossa behind the temporal mandibular joint. The deep surface is in contact with the internal and external carotid arteries, the internal jugular vein and the vagus enclose the pharyngeal nerves. The gland is separated from the pharyngeal wall by some loose connective tissue. Structures within the gland, the external carotid artery lies at first on the deep surface and then in the substance of the gland. The artery gives off its posterior auricular branch, which emerges from the gland behind. It then divides into its terminal branches, the internal maxillary and the superficial temporal. The former runs forward deep to the neck of the mandible. The latter runs upward across the zygomatic arch and gives off its transverse facial branch, which emerges from the front of the gland. Superficial to the arteries are the superficial temporal and internal maxillary veins, uniting to form the posterior facial vein. In the lower part of the gland, this vein splits into anterior and posterior divisions. The anterior division emerges from the gland and unites with the anterior facial to form the common facial vein. The posterior unites in the gland with the posterior auricular to form the external jugular vein. On a still more superficial plane is the facial nerve, the branches of which emerge from the bodies of the gland. Branches of the great auricular nerve pierce the gland to join the facial, while the auricular temporal nerve is used from the upper part of the gland. The parotid duct, ductus parotidius, stands unstucked. It's about seven centimeters long. It begins with numerous branches from the anterior part of the gland, crosses the masseta, and at the anterior part of this muscle turns inward nearly at the right angle, passes through the corpus at the bosom of the cheek and pierces the buccinator. It then runs for a short distance obliqually, far out between the buccinator and mucus membrane of the mouse, and opens upon the oral surface of the cheek by a small orifice, opposite the second upper molar tooth. While crossing the masseta, it receives the duct of the accessory portion. In this position it lies between the branches of the facial nerve, the accessory part of the gland and the transverse facial artery albafit. Structure. The parotid duct is dense. It's warping of considerable thickness. Its canal is about the size of a grogwell, but at its orifice on the oral surface of the cheek, its lumen is greatly reduced in size. It consists of a thick external fibroscote, which contains contractile fibres, and of an internal lumbucous coat, lined with a short columnar bicellium. Vessels and nerves. The artery is supplying the parotid gland that derived from the external carotid, and from the branches given off by that vessel, in or near substance. The veins empty themselves into the external jugular, through some of its tributaries. The lymphatics end in the superficial and deep cervical lymph glands, passing in their cores through two or three glands, placed on the surface and in the substance of the parotid. The nerves are derived from the plexus of the sympathetic and the external carotid artery. The facial, the auricular temporal, integrate auricular nerves. It is probable that the branch from the auricular temporal nerve is derived from the claustropharyngeal through the ottic ganglion. At all events, in some of the lower animals, this has been proved experimentally to be the case. Submaxillary gland. Glandula submaxillaris. The submaxillary gland is irregular in form about the size of a walnut. A considerable part of it is situated in the submaxillary triangle, reaching forward to the anterior belly of the digastricus and backward to the stilomandipular ligament, which intervenes between it and the parotid gland. Above, it extends under the cover of the body of the mandible. Below, it usually relapses the intermediate tendons of the digastricus and the insertion of the stilohydrius, while from its deep surface, a tongue-like deep process extends forward above the stilohydrius muscle. Its superficial surface consists of an upper and a lower part. The upper part is directed outward and lies partly against the submaxillary depression on the inner surface of the body of the mandible and partly on the pterigodrius internus. The lower part is directed downward and outward and is covered by the skin, superficial fascia, platysma, and deep cervical fascia. It is crossed by the anterior facial vein and by filaments of the facial nerve in contact with it near the mandible at its maxillary lymph glands. The deep surface is in relation to the mulleriodius hyoclosus, stiloclosus, stiloriodius, and posterior belly of the digastricus. In contact with it are the mullerhyoid nerve, the mullerhyoid, and submental vessels, the external maxillary artery is embedded in a groove in the posterior part of the gland. The deep process of the gland extends forward between the mulleriodius below and externally and the hyoclosus and stiloclosus internally. The bathroom is the lingual nerve and submaxillary ganglion, below it the hyoclosal nerve and its accompanying vein. The submaxillary duct, ductus submaxilaris, wardens duct, is about five centimeters long and its wall is much thinner than that of the periodic duct. It begins with numerous branches from the deep surface of the gland and runs forward between the mulleriodius and hyoclosus and genioclosus, then between the sublingual gland and the genioclosus and opens by narrow orifice on the summit of a small papilla at the side of the phrenulum lingui. On the hyoclosus it lies between the lingual and hyoclosal nerves, but at the anterior part of the muscle it is crossed laterally by the lingual nerve. The terminal branches of the lingual nerve is sent on its medial side. Vessels and nerves. The arteries supplying the submaxillary gland are branches of the external maxillary and lingual. Its veins follow the cause of the arteries. The nerves are derived from the submaxillary ganglion, through which it receives filaments from the quadrotemporary of the facial nerve and the lingual branch of the mandipular, sometimes from the mulleriod branch of the inferior alveolar and from the sympathetic. Sublingual gland. Glandola sublingualis. The sublingual gland is the smallest of the three clans. It is situated beneath the mucus membrane of the floor of the mouse at the side of the phrenulum lingui in contact with the sublingual depression on the inner surface of the mandible, close to the symphysis. It is narrow, flattened, shaped somewhat like an ailment and weights only two grams. It is in relation above with the mucus membrane below with the mulleriodius behind with the deep part of the submaxillary gland. Laterally with the mandible and medially with the genioclosus from which it is separated by the lingual nerve and the submaxillary duct. The excretory ducts are from 8 to 20 number of the smallest of lingual ducts, ducts of rivinus, some joined the submaxillary duct. Others open separately into the mouse and the elevated crest of the mucus membrane, plica sublingualis, crossed by the projection of the gland on either side of the phrenulum lingui, one or more joined from the larger sublingual duct, duct of basulin, which opens into the submaxillary duct. Vessels and nerves. The sublingual gland is supplied with blood from the sublingual and submental arteries. Its nerves are derived from the lingual, the quadrotemperny and the sympathetic. Structure of the cellivary glands. The cellivary glands are compound resmus glands, consisting of numerous lobes, which are made up of smaller lobules, connected together by dense erola tissue, vessels and ducts. Each lobule consists of the ramifications of a single duct. The branches ending in the elated ends, or alveoli, in which the capillaries are distributed. The alveoli are enclosed by a basement membrane, which is continuous with the membranopropria of the duct and consists of a network of branched and flattened nucleated cells. The alveoli of the cellivary glands are of two kinds, which differ in appearance of the secreting cells in their size and in the nature of the secretion. One, the mucous variety secretes a viscid fluid, which contains mucin. Two, the cirrhose variety secretes a thinner and more watery fluid. The sublingual gland consists of mucous, the parotid of cirrhose alveoli. The submaxillary contains both mucous and cirrhose alveoli, the latter however preponderating. The cells in the mucous alveoli are column 9 shape, in the fresh condition that contain large granules of mucinogen. In hardened preparations a delicate protoblasmic network is seen and the cells are clear and transparent. The nucleus is usually situated near the basement membrane and is flattened. In some alveoli are seen peculiar crescentic bodies lying between the cells in the membranopropria. They are termed the crescents of Shannoussi or the demilion of head and hand and are composed of polyhedral granular cells, which head and hand regard as young epicyclic cells destined to supply the place of those cellular cells which have undergone disintegration. This view however is not accepted by clan. Fan can only creep us between the mucous secreting cells to reach the demilion and even penetrate the cells forming these structures. In the cirrhose alveoli the cells almost completely fill the cavity so that there is hardly any lumen perceptible. They contain secretory granules embedded in a closely reticulated protoblasm. The cells are more cubical than those of the mucous type. The nucleus of each is spherical and placed near the center of the cell, the granules are smaller. Both mucous and cirrhose cells vary in appearance according to whether the gland is in resting condition or has recently been active. In the pharma case the cells are large and contain many secretory granules. In the letter case they are shrunken and contain few granules, chiefly collected at the inner ends of the cells. The granules are best seen in fresh preparations. The ducts are lined at the origins by bicellium which differs little from the pavement form. As the ducts enlarge the bicellular cells change to the columnar shape and the part of the cell next to the basement membrane is finally straight. The lobules of the cellular glands are rich in supplied with blood vessels which form a dense network in the inter-alveolar spaces. Fine plexuses of nerves are also found in the inter-alveolar tissue. The nerve fibers pierce the basement membrane of the alveoli and end in branched varicose filaments between the secreting cells. In the heels of the sugemexillary gland there's a collection of nerve cells termed Langley's ganglion. Excessory glands. Besides the cellular glands proper numerous other glands are found in the mouse. Many of these glands are found in the posterior part of the dorsum of the tongue behind the valid papillae and also along its margin is far forward as the apex. Others lie around and in the pellet and tonsil between its crops and large numbers are present in the soft pellet the lips and cheeks. These glands are of the same structure as the larger cellular glands and they are of a mucosamix type. End of section 12 Recording by Ellie, February 2010 Section 13 of Grey's Anatomy, Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by Leanne Howlett Anatomy of the Human Body, Part 5 by Henry Gray The Fausseys 2b the Fausseys The aperture by which the mouth communicates with the pharynx is called the Isthmus Fausseum. It is bounded above by the soft pellet below by the dorsum of the tongue and on either side by the glossopalatine arch. The glossopalatine arch, Arcus glossopalatinus anterior pillar of Fausseys on either side runs downward, lateral word, and forward to the side of the base of the tongue and is formed by the projection of the glossopalatinus with its covering mucous membrane. The pharyngopalatine arch, Arcus pharyngopalatinus posterior pillar of Fausseys is larger and projects farther toward the middle line than the anterior. It runs downward, lateral word, and backward to the side of the pharynx and is formed by the projection of the pharyngopalatinus covered by mucous membrane. On either side the two arches are separated below by a triangular interval in which the palatine tonsil is lodged. The palatine tonsils, tonsillipalatini tonsil, are two prominent masses situated one on either side between the glossopalatine and pharyngopalatine arches. Each tonsil consists fundamentally of an aggregation of lymphoid tissue underlying the mucous membrane between the palatine arches. The lymphoid mass, however, does not completely fill the interval between the two arches so that a small depression, the supratonsil or Fausseys exists at the upper part of the interval. Further, the tonsil extends for a variable distance under cover of the glossopalatine arch and is here covered by a reduplication of mucous membrane. The upper part of this fold reaches across the supratonsil or Fausseys between the two arches as a thin fold sometimes termed the pleica semilunaris. The remainder of the fold is called the pleica triangularis. Between the pleica triangularis and the surface of the tonsil is a space known as the tonsil or sinus. In many cases, however, this sinus is obliterated by its walls becoming adherent. From this description, it will be apparent that a portion of the tonsil is below the level of the surrounding mucous membrane, i.e., is embedded, while the remainder projects as the visible tonsil. In the child, the tonsils are relatively and frequently absolutely larger than in the adult and about one-third of the tonsil is embedded. After puberty, the embedded portion diminishes considerably in size and the tonsil assumes a disc-like form, flattened from side to side. The shape and size of the tonsil, however, vary considerably in different individuals. The medial surface of the tonsil is free except anteriorly, where it is covered by the pleica triangularis. It presents from 12 to 15 orifices, leading into small crips or recesses from which numerous follicles branch out into the tonsil or substance. The lateral or deep surface is adherent to a fibrous capsule, which is continued into the pleica triangularis. It is separated from the inner surface of the constrictor pharyngeis superior, usually by some loose connective tissue. This muscle intervenes between the tonsil and the external maxillary artery with its tonsillar and ascending palatine branches. The internal carotid artery lies behind and lateral to the tonsil, at a distance of 20 to 25 millimeters from it. The tonsils form part of a circular band of adenoid tissue, which guards the opening into the digestive and respiratory tubes. The anterior part of the ring is formed by the submucous adenoid collections, lingual tonsil, on the posterior part of the tongue. The lateral portions consist of the palatine tonsils and the adenoid collections in the vicinity of the auditory tubes, while the ring is completed behind the pharyngeal tonsil on the posterior wall of the pharynx. In the intervals between these main masses are smaller collections of adenoid tissue. Structure The follicles of the tonsil are lined by a continuation of the mucous membrane of the pharynx, covered with stratified squamous epithelium. Around each follicle is a layer of closed capsules consisting of lymphoid tissue embedded in the submucous tissue. Lymph corpuscles are found in large numbers invading the stratified epithelium. It is probable that they pass into the mouth and form the so-called salivary corpuscles. Surrounding each follicle is a close plexus of lymphatics, from which the lymphatic vessels pass to the deep cervical glands in the neighborhood of the greater corneal of the hyoid bone behind and below the angle of the mandible. Vessels and nerves The arteries supplying the tonsil are the dorsalis lingui from the lingual, the ascending palatine and tonsilor from the external maxillary, the ascending pharyngeal from the external carotid, the descending palatine branch of the internal maxillary, and a twig from the small meningeal. The veins end in the tonsilor plexus on the lateral side of the tonsil. The nerves are derived from the sphenopalatine ganglion and from the glossopharyngeal. Palatine aponeurosis Attached to the posterior border of the hard palate is a thin, firm fibrous lamella which supports the muscles and gives strength to the soft palate. It is thicker above than below, where it becomes very thin and difficult to define. Laterally, it is continuous with the pharyngeal aponeurosis. Muscles of the palate The muscles of the palate are levator vilae palatinei, tensor vilae palatinei, musculus uvele, glossopalatinus, pharyngo palatinus. The levator vilae palatinei, levator palatinei is a thick rounded muscle situated lateral to the coani. It arises from the under surface of the apex of the petrus part of the temporal bone and from the medial lamina of the cartilage of the auditory tube. After passing above the upper concave margin of the constrictor pharyngea superior, it spreads out in the palatine velum, its fibers extending obliquely downward and medialward to the middle line where they blend with those of the opposite side. The tensor vilae palatinei, tensor palatinei, is a broad, thin, ribbon-like muscle placed lateral to the levator vilae palatinei. It arises by a flat lamella from the scaphoid fossa at the base of the medial pteragoid plate from the spina angularus of the sphenoid and from the lateral wall of the cartilage of the auditory tube. Descending vertically between the medial pteragoid plate and the pteragoidius internus, it ends in a tendon which winds around the pteragoid hamulus, being retained in this situation by some of the fibers of origin of the pteragoidius internus. Between the tendon and the hamulus is a small bursa. The tendon then passes medialward and is inserted into the palatine aponeurosis and into the surface behind the transverse ridge on the horizontal part of the palatine bone. The musculus uvele, azygose uvele, arises from the posterior nasal spine of the palatine bones and from the palatine aponeurosis. It descends to be inserted into the uvella. The glossopalatinus, palatoglossus, is a small, fleshy, fasciculus, narrower in the middle than at either end, forming, with the mucous membrane covering its surface, the glossopalatine arch. It arises from the anterior surface of the soft palate, where it is continuous with the muscle of the opposite side and passing downward, forward, and lateral word in front of the palatine tonsil is inserted into the side of the tongue, some of its fibers spreading over the dorsum, and others passing deeply into the substance of the organ to intermingle with the transversus lingui. The pharyngopalatinus, palatopharyngeus, is a long, fleshy fasciculus, narrower in the middle than at either end, forming, with the mucous membrane covering its surface, the pharyngopalatine arch. It is separated from the glossopalatinus by an angular interval in which the palatine tonsil is lodged. It arises from the soft palate, where it is divided into two fasciculi by the levator-veli palatinei and musculus uvele. The posterior fasciculus lies in contact with the mucous membrane and joins with that of the opposite muscle in the middle line. The anterior fasciculus, the thicker, lies in the soft palate between the levator and tensor and joins in the middle line the corresponding part of the opposite muscle. Passing lateralward and downward behind the palatine tonsil, the pharyngopalatinus joins the stylo pharyngeus and is inserted with that muscle into the posterior border of the thyroid cartilage, some of its fibers being lost on the side of the pharynx, and others passing across the middle line posteriorly to decosate with the muscle of the opposite side. Nerves. The tensor veli palatinei is supplied by a branch from the otic ganglion. The remaining muscles of this group are in all probability supplied by the accessory nerve to the pharyngeal plexus. Actions. During the first stage of deglutition, the bolus of food is driven back into the faussis by the pressure of the tongue against the hard palate. The base of the tongue being, at the same time, retracted, and the larynx raised with the pharynx. During the second stage, the entrance to the larynx is closed by the drawing forward of the erotinoid cartilages toward the cushion of the epiglottis, a movement produced by the contraction of the thyroid erotinoidei, the erotinoidei, and the erotino epiglottidii. After leaving the tongue, the bolus passes on to the posterior or laryngeal cirrhosis, or laryngeal surface of the epiglottis, and glides along this for a certain distance. Then the glossopalatine eye, the constrictors of the faussis, contract behind it. The palatine velem is slightly raised by the levator veli palatine eye, and made tense by the tensor veli palatine eye, and the pharyngo palatine eye by their contraction, pull the pharynx upward over the bolus, and come nearly together, the uvula filling up the slight interval between them. By these means, the food is prevented from passing into the nasal part of the pharynx. At the same time, the pharyngo palatine eye form an inclined plane, directed obliquely downward and backward along the undersurface of which the bolus descends into the lower part of the pharynx. The salpingo pharyngei raise the upper and lateral parts of the pharynx, i.e. those parts which are above the points where the stylo pharyngei are attached to the pharynx. Mucus membrane. The mucus membrane of the soft palate is thin, and covered with stratified squamous epithelium on both surfaces, accepting near the pharyngeal ostium of the auditory tube where it is columnar insiliated. According to Klein, the mucus membrane on the nasal surface of the soft palate in the fetus is covered throughout by columnar ciliated epithelium, which subsequently becomes squamous. Some anatomists state that it is covered with columnar ciliated epithelium except at its free margin throughout life. Beneath the mucus membrane on the oral surface of the soft palate is a considerable amount of adenoid tissue. The palatine glands form a continuous layer on its posterior surface and around the uvula. Vessels and nerves. The arteries supplying the palate are the descending palatine branch of the internal maxillary, the ascending palatine branch of the external maxillary, and the palatine branch of the ascending pharyngeal. The veins end chiefly in the pteragoid and tonsillar plexuses. The lymphatic vessels pass to the deep cervical glands. The sensory nerves are derived from the palatine and nasopalatine nerves and from the glossopharyngeal. End of Section 13. Recording by Leanne Howlett. Section 14 of Grey's Anatomy, Part 5. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Leanne Howlett. Anatomy of the Human Body, Part 5 by Henry Gray. The pharynx. 2c. The pharynx. The pharynx is that part of the digestive tube which is placed behind the nasal cavities, mouth, and larynx. It is a musculosmembranous tube, somewhat conical in form, with the base upward and the apex downward extending from the under surface of the skull to the level of the tricoid cartilage in front and that of the sixth cervical vertebra behind. The cavity of the pharynx is about 12.5 centimeters long and broader in the transverse than in the antero-posterior diameter. Its greatest breadth is immediately below the base of the skull where it projects on either side behind the pharyngeal osteum of the auditory tube as the pharyngeal recess fossa of Rosenmüller. Its narrowest point is at its termination in the esophagus. It is limited above by the body of the sphenoid and basilar part of the occipital bone. Below it is continuous with the esophagus. Posteriorly it is connected by loose aryler tissue with the cervical portion of the vertebral column and the prevertebral fascia covering the longest coli and longest capitis muscles. Anteriorly it is incomplete and is attached in succession to the medial pterogoid plate, pterogomendicular rhaefi, mandible, tongue, hyoid bone, and thyroid and cricoid cartilages. Laterally it is connected to the styloid processes and their muscles and is in contact with the common and internal carotid arteries, the internal jugular veins, the glossovaryngeal, vagus and hypoglossal nerves, and the sympathetic trunks and above with small parts of the pterogoidii internii. Seven cavities communicate with it vis the two nasal cavities, the two tympanic cavities, the mouth, the larynx, and the esophagus. The cavity of the pharynx may be subdivided from above downward into three parts, nasal, oral, and laryngeal. The nasal part of the pharynx, pars nasalis faringus, nasopharynx, lies behind the nose and above the level of the soft palate. It differs from the oral and laryngeal parts of the pharynx in that its cavity always remains patent. In front it communicates through the koana with the nasal cavities. On its lateral wall is the pharyngeal osteum of the auditory tube, somewhat triangular in shape and bounded behind by a firm prominence, the torus or cushion caused by the medial end of the cartilage of the tube which elevates the mucous membrane. A vertical fold of mucous membrane, the salpingo-pharyngeal fold stretches from the lower part of the torus. It contains a salpingo-pharyngeus muscle. A second and smaller fold, the salpingo-palatine fold, stretches from the upper part of the torus to the palate. Behind the osteum of the auditory tube is a deep recess, the pharyngeal recess, fossa of Rosenmüller. On the posterior wall is a prominence, best marked in childhood, produced by a mass of lymphoid tissue which is known as the pharyngeal tonsil. Above the pharyngeal tonsil, in the middle line, an irregular flask-shaped depression of the mucous membrane sometimes extends up as far as the basilar process of the occipital bone. It is known as the pharyngeal bursa. The oral part of the pharynx, pars-orealis pharyngeus, reaches from the soft palate to the level of the hyoid bone. It opens anteriorly through the ismas spasium into the mouth, while in its lateral wall between the two palatine arches is the palatine tonsil. The laryngeal part of the pharynx, pars-laryngia pharyngeus, reaches from the hyoid bone to the lower part of the cricoid cartilage where it is continuous with the esophagus. In front it presents the triangular entrance of the larynx, the base of which is directed forward and is formed by the epiglottis, while its lateral boundaries are constituted by the areoepiglottic folds. On either side of the laryngeal orifice is a recess termed the sinus piriformis, which is bounded medially by the areoepiglottic fold, laterally by the thyroid cartilage and hyothyroid membrane. Muscles of the pharynx. The muscles of the pharynx are constrictor inferior, constrictor medius, constrictor superior, stylo pharyngeus, salpingo pharyngeus, pharyngo palatinus, note the pharyngo palatinus is described with the muscles of the palate. End of note. The constrictor pharyngeus inferior, inferior constrictor, the thickest of the three constrictors, arises from the sides of the cricoid and thyroid cartilage. From the cricoid cartilage it arises in the interval between the cricothyroidius in front and the articular facet for the inferior corneal of the thyroid cartilage behind. On the thyroid cartilage it arises from the oblique line on the side of the lamina, from the surface behind this nearly as far as the posterior border and from the inferior corneal. From these origins the fibers spread backward and medial word to be inserted with the muscle of the opposite side into the fibrous raffae in the posterior median line of the pharynx. The inferior fibers are horizontal and continuous with the circular fibers of the esophagus. The rest ascend increasing in obliquity and overlap the constrictor medius. The constrictor pharyngeus medius, middle constrictor, is a fan-shaped muscle smaller than the preceding. It arises from the whole length of the upper border of the greater corneal of the hyoid bone, from the lesser corneal and from the stylohyoid ligament. The fibers diverge from their origin. The lower ones descend beneath the constrictor inferior, the middle fibers pass transversely, and the upper fibers ascend and overlap the constrictor superior. It is inserted into the posterior median fibrous raffae, blending in the middle line with the muscle of the opposite side. The constrictor pharyngeus superior, superior constrictor, is a quadrilateral muscle thinner and paler than the other two. It arises from the lower third of the posterior margin of the medial pterygoid plate and its hamilus, from the pterygomandigular raffae, from the alveolar process of the mandible above the posterior end of the mylohyoid line, and by a few fibers from the side of the tongue. The fibers curve backward to be inserted into the median raffae, being also prolonged by means of an aponeurosis to the pharyngeal spine on the basilar part of the occipital bone. The superior fibers arch beneath the levator veli palatinii and the auditory tube. The interval between the upper border of the muscle and the base of the skull is closed by the pharyngeal aponeurosis and is known as the sinus of morgani. The stylopharyngeus is a long slender muscle cylindrical above flattened below. It arises from the medial side of the base of the styloid process, passes downward along the side of the pharynx between the constrictor's superior and medius, and spreads out beneath the mucus membrane. Some of its fibers are lost in the constrictor muscles, while others, joining with the pharyngopalatinus, are inserted into the posterior border of the thyroid cartilage. The glossopharyngeal nerve runs on the lateral side of this muscle and crosses over it to reach the tongue. The salpingo pharyngeus arises from the inferior part of the auditory tube near its orifice. It passes downward and blends with the posterior fasciculus of the pharyngopalatinus. Nerves. The constrictors and salpingo pharyngeus are supplied by branches from the pharyngeal plexus. The constrictor inferior by additional branches from the external laryngeal and recurrent nerves, and the stylopharyngeus by the glossopharyngeal nerve. Actions. When deglutition is about to be performed, the pharynx is drawn upward and dilated in different directions to receive the food propelled into it from the mouth. The stylopharyngei, which are much farther removed from one another at their origin than at their insertion, draw the sides of the pharynx upward and lateral word, and so increase its transverse diameter. Its breadth in the antero-posterior direction is increased by the larynx and tongue being carried forward in their ascent. As soon as the bolus of food is received in the pharynx, the elevator muscles relax, the pharynx descends, and the constrictors contract upon the bolus and convey it downward into the esophagus. Structure. The pharynx is composed of three coats, mucous, fibrous, and muscular. The pharyngeal aponeurosis, or fibrous coat, is situated between the mucous and muscular layers. It is thick above where the muscular fibers are wanting and is firmly connected to the basilar portion of the occipital and the petrus portions of the temporal bones. As it descends, it diminishes in thickness and is gradually lost. It is strengthened posteriorly by a strong fibrous band, which is attached above to the pharyngeal spine on the under surface of the basilar portion of the occipital bone and passes downward, forming a median raffae, which gives attachment to the constrictors pharyngus. The mucous coat is continuous with that lining the auditory tubes, the nasal cavities, the mouth, and the larynx. In the nasal part of the pharynx, it is covered by columnar, ciliated epithelium. In the oral and laryngeal portions, the epithelium is stratified squamous. Beneath the mucous membrane are found rachyma-smucous glands. They are especially numerous at the upper part of the pharynx around the orifices of the auditory tubes. End of section 14. Recording by Leanne Howlett. Section 15 of Gray's Anatomy Part 5. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Anatomy of the Human Body Part 5 by Henry Gray. The esophagus. The esophagus, or gullet, is a muscular canal about 23 to 25 centimeters long, extending from the pharynx to the stomach. It begins in the neck at the lower border of the cricoid cartilage, opposite the sixth cervical vertebra. Descends along the front of the vertebral column through the superior and posterior mediastina, passes through the diaphragm, and entering the abdomen ends at the cardiac orifice of the stomach, opposite the 11th thoracic vertebra. The general direction of the esophagus is vertical, but it presents two slight curves in its course. At its commencement, it is placed in the middle line, but it inclines to the left side as far as the root of the neck, gradually passes to the middle line again at the level of the fifth thoracic vertebra, and finally deviates to the left as it passes forward to the esophageal hiatus in the diaphragm. The esophagus also presents anterior posterior flexures, corresponding to the curvatures of the cervical and thoracic portions of the vertebral column. It is the narrowest part of the digestive tube, and is most contracted at its commencement and at the point where it passes through the diaphragm. Relations. The cervical portion of the esophagus is in relation in front with the trachea, and at the lower part of the neck where it projects the left side with the thyroid gland. Behind it rests upon the vertebral column and longest coli muscles. On either side, it is in relation with the common carotid artery, especially the left as it inclines to that side, and parts of the lobes of the thyroid gland. The recurrent nerves ascend between it and the trachea to its left side is the thoracic duct. The thoracic portion of the esophagus is at first situated in the superior mediastinum between the trachea and the vertebral column, a little to the left of the median line. It then passes behind and to the right of the aortic arch, and descends in the posterior mediastinum along the right side of the descending aorta, then runs in front and a little to the left of the aorta and enters the abdomen through the diaphragm at the level of the 10th thoracic vertebra. Just before it perforates the diaphragm, it presents a distinct dilation. It is in relation in front with the trachea, the left bronchus, the pericardium, and the diaphragm. Behind it rests upon the vertebral column, the longest coli muscles, the right aortic intercostal arteries, the thoracic duct, and the heme azygos veins, and below, near the diaphragm, upon the front of the aorta. On its left side in the superior mediastinum are the terminal part of the aortic arch, the left subclavian artery, the thoracic duct, and the left pleura. While running upward in the angle between it and the trachea is the left recurrent nerve. Below it is in relation with the descending thoracic aorta. On its right side are the right pleura and the azygos vein, which it overlaps. Below the roots of the lungs, the vagae descend in close contact with it, the right nerve passing down behind, and the left nerve in front of it, the two nerves uniting to form a plexus around the tube. In the lower part of the posterior mediastinum, the thoracic duct lies to the right side of the esophagus, higher up it is placed behind it, and crossing about the level of the fourth thoracic vertebra is continued upward on its left side. The abdominal portion of the esophagus lies in the esophageal groove on the posterior surface of the left lobe of the liver. It measures about 1.25 cm in length, and only its front and left aspects are covered by peritoneum. It is somewhat conical with its base applied to the upper orifice of the stomach and is known as the antromcardiacum. Structure The esophagus has four coats, an external or fibrous, a muscular, a submucous or areolar, and an internal or mucous coat. The muscular coat, tunica muscularis, is composed of two planes of considerable thickness, an external of longitudinal and an internal of circular fibers. The longitudinal fibers are arranged at the commencement of the tube in three fasciculi, one in front which is attached to the vertical ridge on the posterior surface of the lamina of the tricoid cartilage and one at either side which is continuous with the muscular fibers of the pharynx. As they descend they blend together and form a uniform layer which covers the outer surface of the tube. Accessory slips of muscular fibers pass between the esophagus and the left pleura where the ladder covers the thoracic aorta or the root of the left bronchus or the back of the pericardium. The circular fibers are continuous above with the constrictor pharyngeus inferior, their direction is transverse at the upper and lower parts of the tube but oblique in the intermediate part. The muscular fibers in the upper part of the esophagus are of a red color and consist chiefly of the striped variety but below they consist for the most part of involuntary fibers. The areolar or submucous coat telosubmucosa connects loosely the mucous and muscular coats. It contains blood vessels, nerves and mucous glands. The mucous coat tunica mucosa is thick of a reddish color above and pale below. It is disposed in longitudinal folds which disappear on distension of the tube. Its surface is studded with minute papuli and it is covered throughout with a thick layer of stratified squamous epithelium. Beneath the mucous membrane between it and the areolar coat is a layer of longitudinally arranged non-striped muscular fibers. This is the muscularis mucosi. At the commencement of the esophagus it is absent or only represented by a few scattered bundles. Lower down it forms a considerable stratum. The esophageal glands glangeli esophagee are small compound rassimus glands of the mucous type. They are lodged in the submucous tissue and each opens upon the surface by a long excretory duct. Vessels and nerves. The artery supplying the esophagus are derived from the inferior thyroid branch of the thyroservicle trunk from the descending thoracic aorta from the left gastric branch of the celiac artery and from the left inferior phrenic of the abdominal aorta. They have for the most part a longitudinal direction. The nerves are derived from the vagae and from the sympathetic trunks. They form a plexus in which are groups of ganglion cells between the two layers of the muscular coats and also a second plexus in the submucous tissue. End of section 15. Section 16 of Gray's Anatomy Part 5. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Anne Boulay. Anatomy of the Human Body Part 5 by Henry Gray. The Abdomen Part 1. The abdomen is the largest cavity in the body. It is of an oval shape. The extremities of the oval being directed upward and downward. The upper extremity is formed by the diaphragm, which extends as a dome over the abdomen so that the cavity extends high into the bony thorax, reaching on the right side in the mammary line to the upper border of the fifth rib. On the left side, it falls below this level by 2.5 centimeters. The lower extremity is formed by the structures which clothe the inner surface of the bony pelvis, principally the levitator ante, and the ocoxagias on either side. These muscles are sometimes termed the diaphragm of the pelvis. The cavity is wider above than below and measures more in the vertical than in the transverse diameter. In order to facilitate description, it is artificially divided into two parts. An upper and larger part, the abdomen proper, and the lower and smaller part, the pelvis. These two cavities are not separated from each other, but the limit between them is marked by the superior aperture of the lesser pelvis. The abdomen proper differs from the other great cavities of the body and being bounded for the most part by muscles and fascia, so that it can vary in capacity and shape according to the condition of the viscera which it contains. But in addition to this, the abdomen varies in form and extent with age and sex. In the adult male, with moderate distention of the viscera, it is oval in shape, but at the same time flatten from before backward. In the adult female, with a fully developed pelvis, it is ovoid with a narrower pole upward, and in young children it is also ovoid, but with the narrower pole downward. Boundaries. It is bounded in front and at the sides by the abdominal muscles and the iliacus muscles, behind by the vertebral column, and the psoces and quadratus laborum muscles, above by the diaphragm, below by the plane of the superior aperture of the lesser pelvis. The muscles forming the boundaries of the cavity are lined upon their inner surfaces by a layer of fascia. The abdomen contains the greater part of the digestive tube. Some of the accessory organs to digestion, these, the liver and pancreas, the spleen, the kidneys, and the suprarenal glands. Most of these structures, as well as the wall of the cavity in which they are contained, are more or less covered by an extensive and complicated serous membrane, the peritoneum. The apertures in the walls of the abdomen. The apertures in the walls of the abdomen for the transmission of structures to and from it are, in front, the umbilical in the fetus, for the transmission of the umbilical vessels, the allantois and vitiline duct, above the vena cava opening for transmission of the inferior vena cava, the aortic hiatus for the passage of the aorta, azagos vein and thoracic duct and the esophageal hiatus for the esophagus and vagae. Below, there are two apertures on either side, one for the passage of the femoral vessels and the lumboenguineal nerve and the other for the transmission of the spermatic cord in the male and the round ligament of the uterus in the female. Regions. For convenience of description of the viscera, as well as a reference to the morbid conditions of the contained parts, the abdomen is artificially divided into nine regions by imaginary planes, two horizontal and two sagittal, passing through the cavity, the edges of the planes being indicated by lines drawn on the surface of the body. Of the horizontal planes, the upper or transpiloric is indicated by a line in circling the body at the level of a point midway between the jugular notch and the symphus pubis. The lower by a line carried around the trunk at the level of a point midway between the transpiloric and the symphus pubis. The latter is practically the intertubular plane of Cunningham, who pointed out that its level corresponds with the prominent and easily defined tubercle on the iliac crest, about five centimeters behind the anterior superior iliac spine. By means of these imaginary planes, the abdomen is divided into three zones, which are named from above downward, the subcoastal, the umbilical and hypogastric zones. Each of these is further subdivided into three regions by the two sagittal planes, which are indicated on the surface by lines drawn vertically through points halfway between the anterior superior iliac spines and the symphus pubis. The middle region of the upper zone is called the epigastric and the two lateral regions, the right and left hypochondriac. The central region of the middle zone is the umbilical and the two lateral regions, the right and left lumbar. The middle region of the lower zone is the hypogastric or pubic region and the lateral regions are the right and left iliac or inguinal. The pelvis is the portion of the abdominal cavity which lies below and behind a plane passing through the promontory of the sacrum, lineae terminalis of the hip bones and the pubic crests. It is bounded behind by the sacrum, coxide, piriformis and the sacrosfinis and sacrotuberous ligaments, in front and laterally by the pubis and ischia and obitura torus internii. Above it communicates with the abdomen proper. Below it is closed by the levatoris ani and the coxigii and the urogenital diaphragm. The pelvis contains the urinary bladder, the sigmoic colon and rectum, a few coils of the small intestine and some of the generative organs. When the anterior abdominal wall is removed, the viscera are partly exposed as follows. Above and to the right side is the liver, situated chiefly under the shelter of the right ribs and their cartilages, but extending across the middle line and reaching for some distance below the level of the xiphoid process. To the left of the liver is the stomach, from the lower border of which an apron-like fold of the peritoneum, the greater omentum, descends for a varying distance and obscures to a greater or lesser extent the other viscera. Below it however, some of the coils of the small intestine can generally be seen, while in the right and left iliac regions respectively, the cecum and the iliac colon are partly exposed. The bladder occupies the anterior part of the pelvis, and if distended, will project above the symphus pubis. The rectum lies in the concavity of the sacrum, but is usually obscured by the coils of the small intestine. The sigmoic colon lies between the rectum and the bladder. When the stomach is followed from left to right, it is seen to be continuous with the first part of the small intestine, or duodenum, the point of continuity being marked by a thickened ring which indicates the position of the pyloric valve. The duodenum passes toward the undersurface of the liver, and then, curving downward, is lost to sight. If however, the greater omentum be thrown upward over the chest, the inferior part of the duodenum will be observed passing across the vertebral column towards the left side, where it becomes continuous with the coils of the duodenum and ilium. These measure some six meters in length, and if followed downward, the ilium will be seen to end in the right iliac fossa by opening into the cecum, the commencement of the large intestine. From the cecum, the large intestine takes an arched course, passing at first upward on the right side, then across the middle line, and downward on the left side, and forming respectively the ascending, transverse, and descending parts of the colon. In the pelvis, it assumes the form of a loop, the sigmoid colon, and ends in the rectum. The spleen lies behind the stomach in a left hypochondriac region, and may be in part exposed by pulling the stomach over toward the right side. The glistening appearance of the deep surface of the abdominal wall and of the surface of the exposed viscera is due to the fact that the former is lined, and the latter are more or less completely covered by a cirrus membrane, the peritoneum. The peritoneum, tunica cirrosa. The peritoneum is the largest cirrus membrane in the body, and consists in the male of a closed sac, part of which is applied against the abdominal parietes, while the remainder is reflected over the contained viscera. In the female, the peritoneum is not a closed sac, since the free ends of the uterine tubes open directly into the peritoneal cavity. The part which lines the parietes is named the parietal portion of the peritoneum. That which is reflected over the contained viscera constitutes the visceral portion of the peritoneum. The free surface of the membrane is smooth, covered by a layer of fat and mesothelium, and lubricated by a small quantity of cirrus fluid. Hence, the viscera can slide freely against the wall of the cavity, or upon one another with the least possible amount of friction. The attached surface is rough, being connected to the viscera and inner surface of the parietes by means of areolar tissue, termed the sub-cirrus areolar tissue. The parietal portion is loosely connected with the facial lining of the abdomen and pelvis, but is more closely adherent to the under surface of the diaphragm, and also in the middle line of the abdomen. The space between the parietal and visceral layers of the peritoneum is named the peritoneal cavity, but under normal conditions this cavity is merely a potential one, since the parietal and visceral layers are in contact. The peritoneal cavity gives off a large diverticulum, the omental bursa, which is situated behind the stomach and adjoining structures. The neck of communication between the cavity and the bursa is termed the epiplotic foramen, foramen of Winslow. Formerly the main portion of the cavity was described as the greater, and the omental bursa the lesser sac. The peritoneum differs from the other cirrus membranes of the body in presenting a much more complex arrangement, and one that can be clearly understood only by following the changes which take place in the digestive tube during its development. To trace the membrane from one viscous to another, and from the viscera to the parietes, it is necessary to follow its continuity in the vertical and horizontal directions, and it will be found simpler to describe the main portion of the cavity and the omental bursa separately. Vertical disposition of the main peritoneal cavity, greater sac. It is convenient to trace this from the back of the abdominal wall at the level of the umbilicus. In following the peritoneum upward from this level, it is seen to be reflected around a fibrous cord. The ligamentum teres, obliterated umbilical vein, which reaches from the umbilicus to the under surface of the liver. This reflection forms a somewhat triangular fold, the falsiform ligament of the liver, attaching the upper and anterior surfaces of the liver to the diaphragm and abdominal wall. With the exception of the line of attachment of this ligament, the peritoneum covers the whole of the under surface of the anterior part of the diaphragm, and is continued from it onto the upper surface of the right lobe of the liver as the superior layer of the coronary ligament, and onto the upper surface of the left lobe as the superior layer of the left triangular ligament of the liver. Covering the upper and anterior surfaces of the liver, it is continued around its sharp margin onto the under surface, where it presents the following relations. A. It covers the under surface of the right lobe, and is reflected from the back part of this onto the right suprarenal gland and the upper extremity of the right kidney, forming in this situation the inferior layer of the coronary ligament. A special fold, the hepatorenal ligament, is frequently present between the inferior surface of the liver and the front of the kidney. From the kidney, it is carried downward to the duodenum and the right colic flexure, and medial ward in front of the inferior vena cava, where it is continuous with the posterior wall of the omental bursa. Between the two layers of the coronary ligament, there is a large triangular surface of the liver devoid of peritoneal covering. This is named the bare area of the liver, and is attached to the diaphragm by areolar tissue. Toward the right margin of the liver, the two layers of the coronary ligament gradually approach each other, and ultimately fuse to form a small triangular fold connecting the right lobe of the liver to the diaphragm, and name the right triangular ligament of the liver. The apex of the triangular bare area corresponds with the point of meeting of the two layers of the coronary ligament. It is based with the fossa for the inferior vena cava. B, it covers the lower surface of the quadrat lobe, the under and lateral surfaces of the gallbladder, and the under surface and posterior border of the left lobe. It is then reflected from the upper surface of the left lobe to the diaphragm as the inferior layer of the left triangular ligament, and from the porta of the liver and the fossa for the ductus venosis to the lesser curvature of the stomach, and the first 2.5 centimeters of the duodenum as the anterior layer of the hepato gastric and the hepato duodenal ligaments, which together constitute the lesser omentum. If this layer of the lesser omentum be followed to the right, it will be found to turn around the hepatic artery, bile duct, and portal vein, and become continuous with the anterior wall of the omental bursa, forming a free folded edge of the peritoneum. Traced downward, it covers the anterior superior surface of the stomach and the commencement of the duodenum, and is carried down into a large free fold known as the gastrocolic ligament, or greater omentum. Reaching the free margin of this fold, it is reflected upward to cover the under and posterior surfaces of the transverse colon, and thence to the posterior abdominal wall as the inferior layer of the transverse mesocolon. It reaches the abdominal wall at the head and anterior border of the pancreas, is then carried down over the lower part of the head and over the inferior surface of the pancreas on the superior mesenteric vessels, and thence to the small intestine as the anterior layer of the mesentery. It encircles the intestine and subsequently may be traced as the posterior layer of the mesentery, upward and backward to the abdominal wall. From this it sweeps down over the aorta into the pelvis, where it invests the sigmoid colon, its re-duplication forming the sigmoid mesocolon. Leaving first the sides and then the front of the rectum, it is reflected onto the seminal vesicles and the fundus of the urinary bladder and, after covering the upper surface of this viscous, is carried along the medial and lateral umbilical ligaments onto the back of the abdominal wall to the level from which a start was made. Between the rectum and the bladder it forms, in the male, a pouch, the recto-vesicle excavation, the bottom of which is slightly below the level of the upper ends of the vesicleae seminelles, i.e. about 7.5 centimeters from the orifice of the anus. When the bladder is distended, the peritoneum is carried up with the expanded viscous so that a considerable part of the anterior surface of the bladder lies directly against the abdominal wall without the intervention of the peritoneal membrane, pre-vesicle space of retzias. In the female, the peritoneum is reflected from the rectum over the posterior vaginal fornix to the cervix and body of the uterus, forming the rectouterine excavation, pouch of Douglas. It is continued over the intestinal surface and fundus of the uterus on its vesicle surface, which it covers as far as the junction of the body and cervix uteri, and then to the bladder, forming here a second but shallower pouch, the vesicleuterine excavation. It is also reflected from the sides of the uterus to the lateral walls of the pelvis as two expanded folds, the broad ligaments of the uterus, in the free margin of each of which is the uterine tube. Vertical disposition of the omencel bursa, lesser peritoneal sac. A start may be made in this case on the posterior abdominal wall at the anterior border of the pancreas. From this region, the peritoneum may be followed upward over the pancreas onto the inferior surface of the diaphragm, and thence onto the caudate lobe and the caudate process of the liver to the fossa from the ductus venosis and the porta of the liver. Traced to the right, it is continuous over the inferior vena cava with the posterior wall of the main cavity. From the liver, it is carried downward to the lesser curvature of the stomach and the commencement of the duodenum as the posterior layer of the lesser omentum, and is continuous on the right around the hepatic artery, bile duct, and portal vein, with the anterior layer of this omentum. The posterior layer of the lesser omentum is carried down as a covering for the posterior surfaces of the stomach and the commencement of the duodenum, and is continued downward as the deep layer of the gastrocolic ligament or greater omentum. From the free margin of this fold, it is reflected upward on itself to the anterior and superior surfaces of the transverse colon, and thence as the superior layer of the transverse mesocolon to the anterior border of the pancreas, the level from which a start was made. It will be seen that the loop formed by the wall of the omental bursa below the transverse colon follows, and is closely applied to, the deep surface of that formed by the peritoneum of the main cavity, and that the greater omentum or large fold of the peritoneum which hangs in front of the small intestine therefore consists of four layers, two anterior and two posterior separated by the potential cavity of the omental bursa. End of section 16.