 CHAPTER 11 SPLANKNOLOGY Section 3D, The Female Genital Organs Part 6, The Mammai Mammary glands, breast The mammai secrete milk and are accessory glands of the generative system. They exist in the male as well as in the female, but in the former only in the rudimentary state, unless their growth is excited by peculiar circumstances. In the female there are two large hemispherical eminences lying within the superficial fascia and situated on the front and sides of the chest. Each extends from the second rib above to the sixth rib below and from the side of the sternum to near the mid-axillary line. Their weight and dimensions differ at different periods of life and in different individuals. Before puberty they are of small size, but enlarge as the genitive organs become more completely developed. They increase during pregnancy and especially after delivery and become atrophied in old age. The left mammai is generally a little larger than the right. The deep surface of each is nearly circular, flattened, or slightly concave and has its long diameter directed upward and lateralward toward the axilla. It is separated from the fascia covering the pectoralis major, serratus anterior and obliquus externus abdominis by loose connective tissue. The subcutaneous surface of the mammai is convex and presents just below the center a small conical prominence, the papilla. The mammary papilla or nipple, papilla mammai is a cylindrical or conical eminence situated above the level of the force in a coastal space. It is capable of undergoing a sort of erection from mechanical excitement, a change mainly due to the contractions of its muscular fibers. It is of a pink or brightish hue with surface wrinkled and provided with secondary papillae and it is perforated by from 15 to 20 orifices, the apertures of the lactiferous ducts. The base of the mammary papilla is surrounded by an areola. In the virgin the areola is of a delicate rosy hue. About the second month after impregnation it enlarges and acquires a darker tinge and as pregnancy advances it may assume a dark brown or even black color. This color diminishes as soon as lactation is over but is never entirely lost throughout life. These changes in the color of the areola are of importance in forming a conclusion in a case of suspected first pregnancy. Near the base of the papilla and upon the surface of the areola are numerous large sebaceous glands, the areolar glands, which become much enlarged during lactation and present the appearance of small tubercles beneath the skin. These glands secrete a peculiar fatty substance which serves as a protection to the integument of the papilla during the act of sucking. The mammary papilla consists of numerous vessels intermixed with plain muscular fibers which are principally arranged in a circular manner around the base, some few fibers radiating from base to apex. Development The mamm is developed partly from mesoderm and partly from ectoderm. Its blood vessels and connective tissues being derived from the former, its cellular elements from the latter. Its first rudiment is seen about the third month in the form of a number of small inward projections of the ectoderm, which invade the mesoderm. From these secondary tracts of cellular elements radiate and subsequently give rise to the epithelium of the glandular follicles and ducts. The development of the follicles however remains imperfect except in the paris female. Structure The mamm consist of gland tissue, a fibers tissue connecting its lobes and a fatty tissue in the interfills between the lobes. The gland tissue when freed from fibers tissue and fat is of a pale reddish color, firm in texture, flattened from before backward and thicker in the center than in the circumference. The subcutaneous surface of the mamm presents numerous irregular processes which project toward the skin and are joined to it by bands of connective tissue. It consists of numerous lobes and these are composed of lobules and ducts. The smallest lobules consist of a cluster of rounded alveoli which open into the smallest branches of the lactiferous ducts. These ducts unite to form larger ducts and these end in a single canal corresponding with one of the chief subdivisions of the gland. The number of excretory ducts varies from 15 to 20. They are termed the tubuli lactifory. They converge toward the areola beneath which they form dilations which serve as reservoirs for the milk and, in the base of the papuli, become contracted and pursue a straight course to its summit perforating it by separate orifices considerably narrower than the ducts themselves. These ducts are composed of areolar tissue containing longitudinal and transverse elastic fibers. Muscular fibers are entirely absent. They are lined by columnar epithelium resting on a basement membrane. The epithelium of the mammite differs according to the state of activity of the organ. In the gland of a woman who is not pregnant or suckling the alveoli are very small and solid, being filled with a massive granular polyhedral cells. During pregnancy the alveoli change and the cells undergo rapid multiplication as the commencement of lactation. The cells in the center of the alveolus undergo fatty degeneration and are eliminated in the first milk as colostrum corpuscles. The peripheral cells of the alveolus remains and form a single layer of granular short columnar cells with spherical nuclei lining the basement membrane. The cells during the state of activity of the gland are capable of forming in their interior oil globules which are then ejected into the lumen of the alveolus and constitute the milk globules. When the acene are distended by the accumulation of the secretion, the lining epithelium becomes flattened. The fibers tissue invests the entire surface of the mamma and sends down septa between its slopes connecting them together. The fatty tissue covers the surface of the gland and occupies the interval between its slopes. It usually exists in considerable abundance and determines the form and size of the gland. There is no fat immediately beneath the areola and papilla. Vessels and nerves The arteries supplying the mamma are derived from the thoracic branches of the axillary, the intercostals and the internal mammary. The veins described an anastomatic circle around the base of the papillae called by Haller the circulus penosis. From this large branches transmits the blood to the circumference of the gland and in the axillary and internal mammary veins. The lymphatics are described on page 715. The nerves are derived from the anterior and lateral cutaneous branches of the fourth, fifth and sixth thoracic nerves. End of Chapter 11 Splanknology, Section 3D The Female Genital Organs, Part 6 The Mammae, Recording by Jeannie Whitfield Section 42 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 Recorded by Larry Ann Walden Anatomy of the Human Body, Part 5 by Henry Gray The Ductless Glands There are certain organs which are very similar to secreting glands but differ from them in one essential particular. That is they do not possess any ducts by which their secretion is discharged. These organs are known as ductless glands. They are capable of internal secretion, that is to say of forming from materials brought to them in the blood, substances which have a certain influence upon the nutritive and other changes going on in the body. This secretion is carried into the bloodstream either directly by the veins or indirectly through the medium of the lymphatics. These glands include the thyroid, the parathyroids and the thymus, the pituitary body and the pineal body, the chromophil and cortical systems to which belong the suprarenals, the paraganglia and aortic glands, the glomus caroticum and perhaps the glomus coxidium. The spleen is usually included in this list and sometimes the lymph and hemolymph nodes, described with the lymphatic system. Other glands, as the liver, pancreas and sexual glands, give off internal secretions, as do the gastric and intestinal mucous membranes. The thyroid gland, glandular thyroidia, thyroid body. The thyroid gland is a highly vascular organ situated at the front and sides of the neck. It consists of right and left lobes connected across the middle line by a narrow section, the ismus. Its weight is somewhat variable, but is usually about 30 grams. It is slightly heavier in the female, in whom it becomes enlarged during menstruation and pregnancy. The lobes, libuli, glanduli, thyroidiae, are conical in shape, the apex of each being directed upward and lateralward, as far as the junction of the middle with the lower third of the thyroid cartilage. The base looks downward and is on a level with the fifth or sixth tracheal ring. Each lobe is about 5 centimeters long. Its greatest width is about 3 centimeters, and its thickness about 2 centimeters. The lateral or superficial surface is convex, and covered by the skin, the superficial and deep fascia, the sternocleidomastoidius, the superior belly of the omohiodias, the sternohiodius and sternothyroidius, and beneath the last muscle, by the pre tracheal layer of the deep fascia, which forms a capsule for the gland. The deep or medial surface is molded over the underlying structures. These are the thyroid and cricoid cartilages, the trachea, the constrictor pharyngeus inferior and posterior part of the cricothyroidius, the esophagus, particularly on the left side of the neck, the superior and inferior thyroid arteries, and the recurrent nerves. The anterior border is thin and inclines obliquely from above downward toward the middle line of the neck. While the posterior border is thick and overlaps the common carotid artery, and, as a rule, the parathyroids. The ismus, ismus glandular thyroidia, connects together the lower thirds of the lobes. It measures about 1.25 cm in breadth, and the same in depth, and usually covers the second and third rings of the trachea. Its situation and size present, however, many variations. In the middle line of the neck, it is covered by the skin and fascia, and close to the middle line, on either side, by the sternothyroidius. Across its upper border runs an anastomotic branch uniting the two superior thyroid arteries. At its lower border are the inferior thyroid veins. Sometimes the ismus is altogether wanting. A third lobe of conical shape, called the pyramidal lobe, frequently arises from the upper part of the ismus, or from the adjacent portion of either lobe, but most commonly the left, and the right is the left. It is sometimes as far as the hyoid bone. It is occasionally quite detached, or maybe divided into two or more parts. A fibrous or muscular band is sometimes found attached above to the body of the hyoid bone, and below to the ismus of the gland, or its pyramidal lobe. When muscular, it is termed the levator glandular thyroidiae. Small detached portions of thyroid tissue are sometimes found in the vicinity of the lateral lobes, or the ismus. They are called accessory thyroid glands, glandular thyroidiae accessory. Development. The thyroid gland is developed from a median diverticulum, which appears about the fourth week on the summit of the tuberculum impar, but later is found in the furrow immediately behind the tuberculum. It grows downward and backward as a tubular duct, which bifurcates and subsequently subdivides into a series of cellular cords from which the ismus thyroid gland are developed. The ultimo-branchial bodies from the fifth pharyngeal pouches are enveloped by the lateral lobes of the thyroid gland. They undergo atrophy and do not form true thyroid tissue. The connection of the diverticulum with the pharynx is termed the thyroglossal duct. Its continuity is subsequently interrupted, and it undergoes degeneration, its upper end being represented by the foramen cecum of the tongue, and its lower by the pyramidal lobe of the thyroid gland. Structure. The thyroid gland is invested by a thin capsule of connective tissue, which projects into its substance and imperfectly divides it into masses of irregular form and size. When the organ is cut into, it is of a brownish-red color, and is seen to be made up of a number of closed vesicles containing a yellow-glary fluid, and separated from each other by intermediate connective tissue. The vesicles of the thyroid of the adult animal are generally closed spherical sacs, but in some young animals, for example young dogs, the vesicles are more or less tubular and branched. This appearance is supposed to be due to the mode of growth of the gland, and merely indicates that an increase in the number of vesicles is taking place. Each vesicle is lined by a single layer of cubicle epithelium. There does not appear to be a basement membrane so that the epithelial cells are in direct contact with the connective tissue reticulum which supports the asini. The vesicles are of various sizes and shapes and contain as a normal product a viscid, homogenous, semi-fluid, slightly yellowish colloid material. Red corpuscles are found in it in various stages of disintegration and decolorization. The yellow tinge being probably due to the hemoglobin, which is thus set free from the colored corpuscles. The colloid material contains an iodine compound, iodothyron, and is readily stained by eosin. According to Binsley, the thyroid gland prepares and secretes into the vascular channels a substance formed under normal conditions in the outer pole of the cell and excreted from it directly without passing by the indirect root through the follicular cavity. In addition to this direct mode of secretion, there is an indirect mode which consists in the condensation of the secretion into the form of droplets, having high content of solids, and the extension of these droplets into the follicular cavity. These droplets are formed in the same zone of the cell as that in which the primary or direct secretion is formed. This internal secretion of the thyroid is supposed to contain a specific hormone which acts as a chemical stimulus to other tissues, increasing their metabolism. Vessels and nerves. The artery supplying the thyroid gland are the superior and inferior thyroids, and sometimes an additional branch, thyroidia ima, from the inominate artery or the arch of the aorta which ascends upon the front of the trachea. The arteries are remarkable for their large size and frequent anastomoses. The veins form a plexus on the surface of the gland and on the front of the trachea. From this plexus, the superior, middle, and inferior thyroid veins arise. The superior and middle end in the internal jugular, the inferior in the inominate vein. The capillary blood vessels form a dense plexus in the connective tissue around the vesicles between the epithelium of the vesicles and the endothelium of the lymphatics which surround a greater or smaller part of the circumference of the vesicle. The lymphatic vessels run in the inter lobular connective tissue, not uncommonly surrounding the arteries which they accompany, and communicate with the network in the capsule of the gland. They may contain colloid material. They end in the thoracic and right lymphatic trunks. The nerves are derived from the middle and inferior cervical ganglia of the sympathetic. The parathyroid glands. The parathyroid glands are small, brownish-red bodies situated as a rule between the posterior borders of the lateral lobes of the thyroid gland and its capsule. They differ from an instructor being composed of masses of cells changed in a more or less columnar fashion with numerous intervening capillaries. They measure, on an average, about six millimeters in length and from three to four millimeters in breadth and usually present the appearance of flattened oval discs. They are divided according to their situation into superior and inferior. The superior, usually two in number, are the more constant in position and are situated one on either side at the level of the lower border of the cricoid cartilage behind the junction of the pharynx and esophagus. The inferior, also usually two in number, may be applied to the lower edge of the lateral lobes or placed at some little distance below the thyroid glands or found in relation to one of the inferior thyroid veins. In man, they number four as a rule. Fewer than four were found in less than one percent of over a thousand persons per peri, but more than four and over 33 percent of 122 bodies examined by Civaleri. In addition, numerous minute islands of parathyroid tissue may be found scattered in the connective tissue and fat of the neck around the parathyroid glands proper and quite distinct from them. Development. The parathyroid bodies are developed as outgrowths from the third and fourth brachial pouches. A pair of diverticular arise from the fifth brachial pouch and formed what are termed the ultimo brachial bodies. These fuse with the thyroid gland, but probably contribute no true thyroid tissue. Structure. Microscopically, the parathyroids consist of intercommunicating columns of cells supported by connective tissue containing a rich supply of blood capillaries. Most of the cells are clear, but some, larger in size, contain oxafil granules. Vessicles containing colloid have been described as occurring in the parathyroid, but the observation has not been confirmed. No doubt the parathyroid glands produce an internal secretion essential to the well-being of the human economy, but it is still a matter of dispute what symptoms of disease are produced by their removal and suppression of their secretion. Paperry believes that they show signs of exceptional activity during pregnancy and that parathyroid insufficiency is a main factor in the production of tetany in infants and adults, of eclampsia and of certain sorts of fits. It is probable that the tetany following parathyroid ectomy is due to the accumulation of ammonium carbonate and Kindle has suggested that the function of the parathyroid is to convert ammonium carbonate into urea. End of section 42. Section 43 of Grey's Anatomy Part 5. This is a liverbox recording. All liverbox recordings are in the public domain. For more information or to volunteer, please visit liverbox.org. Recording by Jeanne Whitfield. Anatomy of the Human Body Part 5 by Henry Gray. Section 43, The Thymus. Four C. The Thymus. The Thymus is a temporary organ attaining its largest size as a time of puberty. Hamar. When it ceases to grow gradually duendals and almost disappears. If examined when its growth is most active it will be found to consist of two lateral lobes placed in close contact along the middle line situated partly in the thorax, partly in the neck and extending from the fourth costal cartilage upward as high as the lower border of the thyroid gland. It is covered by the sternum and by the origins of the sternohyoidae and the sternothyrodiae. Below it rests upon the pericardium being separated from the aortic arch and great vessels by a layer of fascia. In the neck it lies on the front and sides of the trachea being the sternohyoidae and sternothyrodiae. The two lobes generally differ in size. They are occasionally united so as to form a single mass and sometimes separated by an intermediate lobe. The thymus is of a pinkish-gray color solved and lobulated on its surfaces. It is about five centimeters in length and about six millimeters in breadth below and about six millimeters in thickness. At birth it weighs about 15 grams. At puberty its weight is about 35 grams. After this it gradually decreases to 25 grams at 25 years and less than 15 grams at 60 and about 6 grams at 70 years. Development. The thymus appears in the form of two flasks shaped intodermal diverticula which arise one on either side from the third brachial pouch and extend lateral word and backward into the surrounding mesoderm in front of the ventral aortae. Here they meet and become joined to one another by connective tissue. But there is never any fusion of the thymus tissue proper. The pharyngeal opening of each diverticulum is soon obliterated but the neck of the flask persists for some time as a cellular cord. By further proliferation of the cells lining the flask buds of cells are formed which becomes surrounded and isolated by invading mesoderm. In the latter numerous lymphoid cells make their appearance and are aggregated to form lymphoid follicles. These lymphoid cells are probably derivatives of the intodermal cells which line original diverticula and their subdivisions. Additional portion of thymus tissues are sometimes developed from the fourth brachial pouches. Thymus continues to grow until the time of puberty and then begins to atrophy. Structure Each lateral lobe is composed of numerous lobules held together by delicate areolar tissue. The entire gland being enclosed in an investing capsule of similar but denser structure. Primary lobules vary in size from that of a pin's head to that of a small pea and are made up of a number of small nodules or follicles which are irregular in shape and are more or less fused together especially toward the interior of the gland. Each follicle is from 1 to 2 mm in diameter and consists of a medullary and a cortical portion. These different mini-essential particulars from each other, the cortical portion is mainly composed of lymphoid cells supported by a network of finely branched cells which is continuous with a similar network in the medullary portion. The network forms an advencia to the blood vessels. In the medullary portion the reticulum is coarser than the cortex. The lymphoid cells are relatively fewer in number and there are found peculiar nest-like bodies, the concentric course puzzles of hassle. These concentric core puzzles are composed of a central mass consisting of one or more lanular cells and of a capsule which is formed of epithelioid cells. They are the remains of the epithelial tubes which grow out from the third branchial pouches of the embryo to form the thymus. Each follicle is surrounded by a vascular plexus from which vessels pass into the interior and radiate from the periphery to the center forming a second zone just within the margin of the medullary portion. In the center of the medullary portion there are very few vessels and they are of minute size. Watney has made the important observation that hemoglobin is found in the thymus either in cysts or in cells situated near to or forming part of the concentric core puzzles. This hemoglobin occurs as granules or as circular masses exactly resembling colored blood core puzzles. He has also discovered in the lymph issuing from the thymus similar cells to those found in the gland and like them containing hemoglobin in the form of either granules or masses. From these facts he arrives as a conclusion that the gland is one source of the colored blood core puzzles where recently Shaper has observed actual nucleated red blood core puzzles in the thymus. The function of the thymus is obscure. It seems to furnish during the period of growth an internal secretion concerned with some phases of body metabolism especially that of the sexual glands. Vessels and nerves the arteries supplying the thymus are derived from the internal memory and from the superior inferior thyroid. The veins end in the left in nominate vein and in the thyroid veins. The lymphatics are described on page 698. The nerves are exceedingly minute they are derived from the vagae and sympathetic. Branches of the descendants hypoglossy and phrenic reach the investing capsule but do not penetrate into the substance of the gland. End of section 43 Recording by Jeannie Whitfield Recorded by Laurie Ann Walden Anatomy of the Human Body Part 5 by Henry Gray The Hypothesis Cerebri The Hypothesis pituitary body is a small reddish gray body about 1 cm in diameter attached to the end of the infinibulum of the brain and resting in the hypophysiophosa. The Hypothesis consists of an anterior and a posterior lobe which differ from one another in their mode of development and in their structure. The anterior lobe is the larger and is somewhat kidney shaped the concavity being directed backward and embracing the posterior lobe. It consists of a par's anterior and a par's intermedia separated from each other by a narrow cleft the remnant of the pouch or diverticulum. The par's anterior is extremely vascular and consists of epithelial cells of varying size and shape arranged in cord-like trabeculae or alveoli and separated by large thin walled blood vessels. The par's intermedia is a thin lamina closely applied to the body and neck of the posterior lobe and extending onto the neighboring parts of the brain. It contains few blood vessels and consists of finely granular cells between which are small masses of colloid material. The par's intermedia in spite of the fact that it arises in common with the par's anterior form of the primitive buccal cavity is often considered as a part of the posterior lobe which arises from the floor of the third ventricle of the brain. Although of nervous origin, the posterior lobe contains no nerve cells or fibers. It consists of neuroglia cells and fibers and is invaded by columns which grow into it from the par's intermedia. Embedded in it are large quantities of a colloid substance histologically similar to that found in the thyroid gland. In certain of the lower vertebrates, for example, fishes, nervous structures are present and the lobe is of large size. From the par's intermedia, a substance no doubt an internal secretion causes constriction of the blood vessels with rise of arterial blood pressure. This substance seems to have a stimulating effect on most of the smooth muscles acting directly upon the muscle causing contraction. It also increases the secretion of the urine, of the mammary gland when in functional activity and of the cerebrospinal fluid. Extracts of this lobe also influence the general metabolism of the carbohydrates by accelerating the process of glycogenalysis in the liver. The par's anterior exercises a stimulating effect on the growth of the skeleton and probably on connective tissues in general. Enlargement of the hypothesis and of the cavity of the cell atursica are found in the rare disease acromegaly which is characterized by gradual enlargement of the face, hands and feet with headache and often a peculiar type of blindness. This blindness is due to the pressure of the enlarging hypothesis on the optic chiasma. Development of the hypothesis cerebri This in the adult consists of a large anterior consisting of the par's anterior and the par's intermedia and a small posterior lobe. The former is derived from the ectoderm of the stomadium. The latter from the floor of the forebrain. About the fourth week there appears a pouch-like diverticulum of the ectodermal lining of the roof of the stomadium. This diverticulum pouch of rathke is the rudiment of the anterior lobe of the hypothesis. It extends upward in front of the cephalic end of the notochord and the remnant of the buccal pharyngeal membrane and comes into contact with the under surface membrane. It is then constricted off to form a closed vesicle, but remains for a time connected to the ectoderm of the stomadium by a solid cord of cells. Masses of epithelial cells form on either side and in the front wall of the vesicle and by the growth between these of a stroma from the mesoderm, the development of the anterior lobe is completed. The upwardly directed hypofecyl involution becomes applied to the anterolateral aspect of the downwardly directed diverticulum from the base of the forebrain. This diverticulum constitutes the future infundibulum in the floor of the third ventricle while its inferior extremity becomes modified to form the posterior lobe of the hypothesis. In some of the lower animals, the posterior lobe contains nerve cells and nerve fibers, but in man and the higher vertebrates these are replaced by connective tissue. A canal, craniofaryngeal canal is sometimes found extending from the anterior part of the fossa hypofecius of the sphenoid bone to the under surface of the skull and marks the original position of Rathke's pouch. While at the junction of the septum of the nose with the palate, traces of the stomadial end are occasionally present. Frasier. The pineal body. The pineal body, epithesis is a small reddish gray body about eight millimeters in length which lies in the depression between the superior folliculae. It is attached to the roof of the third ventricle near its junction with the midbrain. It develops as an outgrowth from the third ventricle of the brain. In early life it has a glandular structure which reaches its greatest development at about the seventh year. Later, especially after puberty, the glandular tissue gradually disappears and is replaced by connective tissue. Structure. The pineal body is destitute of nervous substance and consists of follicles lined by epithelium and enveloped by connective tissue. These follicles contain a variable quantity of gritty material composed of phosphate and carbonate of calcium, phosphate of magnesium and ammonia, and a little animal matter. It contains a substance which, if injected intravenously, causes fall of blood pressure. It seems probable that the gland furnishes an internal secretion in children that inhibits the development of the reproductive glands since the invasion of the gland in children by pathological growths which practically destroy the glandular tissue results in accelerated development of the sexual organs, increased growth of the skeleton, and precocious mentality. End of section 44 Section 45 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 Recorded by Larry Ann Walden. Anatomy of the Human Body Part 5 by Henry Gray. The Chromophil and Cortical Systems Chromophil or chromophine cells so-called because they stain yellow or brownish with chromium salts are associated with the ganglia of the sympathetic nervous system. Development They arise in common with the sympathetic cells from the neural crest and are therefore ectodermal in origin. The chromophil and sympathetic cells are indistinguishable from one another at the time of their migration from the spinal ganglia to the regions occupied in the adult. Differentiation of chromophil cells begins in embryos about 18mm in length, but is not complete until about birth. The chromophiloblasts increase in size more than the sympathoblasts and stain less intensely with ordinary dyes. Later the chrome reaction develops. The aortic bodies differentiate first and are prominent in 20mm embryos. The paraganglia of the sympathetic plexuses differentiate next and last of all the paraganglia of the sympathetic trunk. The carotid body is completely differentiated in 30mm embryos. After birth the chromophil organs degenerate but the paraganglia can be recognized with the microscope and sites ordinarily occupied by them. The paraganglia are small groups of chromophil cells connected with the ganglia of the sympathetic trunk and the ganglia of the celiac renal, supra renal, aortic and hypogastric plexuses. They are sometimes found in connection with the ganglia of other sympathetic plexuses. None have been found with the sympathetic ganglia associated with the branches of the trigeminal nerve. The aortic glands or bodies are the largest of these groups of chromophil cells and measure in the newborn about 1 cm in length. They lie one on either side of the aorta in the region of the inferior mesenteric artery. They decrease in size with age and after puberty are only visible with the microscope. About 40 they disappear entirely. Other groups of chromophil cells have been found associated with the sympathetic plexuses of the abdomen independently The medullary portions of the supra renal glands and the glomus caroticum belong to the chromophil system. The supra renal gland glanduli supra renalis adrenal capsule. The supra renal glands are two small, flattened bodies of a yellowish color situated at the back part of the abdomen behind the peritoneum and immediately above and in front of the upper end of each kidney hence their name. The right one is somewhat triangular in shape, varying a resemblance to a cocked hat. The left is more similunar, usually larger, and placed at a higher level than the right. They vary in size in different individuals, being sometimes so small as to be scarcely detected. Their usual size is from 3 to 5 cm in length, rather less in width, and from 4 to 6 mm in thickness. Their average weight is from 1.5 to 2.5 g each. Development. Each supra renal gland consists of a cortical portion derived from the salomic epithelium and a medullary portion originally composed of sympathochromophen tissue. The cortical portion is first recognizable about the beginning of the fourth week as a series of buds from the salomic cells at the root of the mesentery. Later it becomes completely separated from the salomic epithelium and forms a supra renal ridge connecting into the selum between the mesonephros and the root of the mesentery. Into this cortical portion cells from the neighboring masses of sympathochromophen tissue migrate along the line of its central vein to reach and form the medullary portion of the gland. Relations. The relations of the supra renal gland differ on the two sides of the body. The right supra renal is situated behind the inferior vena cava and right lobe of the liver and in front of the diaphragm and upper end of the right kidney. It is roughly triangular in shape. Its base, directed downward, is in contact with the medial and anterior aspects of the upper end of the right kidney. It presents two surfaces for examination an anterior and a posterior. The anterior surface looks forward and lateral and has two areas a medial, narrow and nonperitoneal which lies behind the inferior vena cava and a lateral somewhat triangular in contact with the liver. The upper part of the lateral surface is devoid of peritoneum and is in relation with the bare area of the liver near its lower and medial angle while its inferior portion is covered by peritoneum, reflected onto it from the inferior layer of the coronary ligament. Occasionally the duodenum overlaps the inferior portion. A little below the apex and near the anterior border of the gland is a short furrow termed the helum from which the super renal vein emerges to join the inferior vena cava. The posterior surface is divided into upper and lower parts by a curved ridge. The upper, slightly convex rests upon the diaphragm. The lower, concave is in contact with the upper end and the adjacent part of the anterior surface of the kidney. The left super renal slightly larger than the right is crescentic in shape, its concavity being adapted to the medial border of the upper part of the left kidney. It presents a medial border which is convex and a lateral which is concave. Its upper end is narrow and it's lower rounded. Its anterior surface has two areas, an upper one covered by the peritoneum of the omental bursa which separates it from the cardiac end of the stomach sometimes from the superior extremity of the spleen. And a lower one which is in contact with the pancreas and leanyl artery and is therefore not covered by the peritoneum. On the anterior surface near its lower end is a furrow or helum directed downward and forward from which the super renal vein emerges. Its posterior surface presents a vertical ridge which divides it into two areas. The lateral area rests on the kidney, the medial and smaller on the left cross of the diaphragm. The surface of the super renal gland is surrounded by areolar tissue containing much fat and closely invested by a thin fibrous capsule which is difficult to remove on account of the numerous fibrous processes and vessels entering the organ through the furrows on its anterior surface in base. Small accessory super renals glandularly super renalies accessorier are to be found in the connective tissue around the super renails. The smaller of these on section show a uniform surface but in some of the larger a distinct medulla can be made out. Structure On section the super renal gland is seen to consist of two portions an external or cortical and an internal or medullary. The former constitutes the chief part of the organ and is of a deep yellow color. The medullary substance is soft, pulpy and of a dark red or brown color. The cortical portion substantial corticalis consists of a fine connective tissue network in which is embedded the glandular epithelium. The epithelial cells are polyhedral in shape and possess rounded nuclei. Many of the cells contain coarse granules, others lipoid globules. Owing to differences in the arrangement of the cells three distinct zones can be made out. One the zona glomerulosa situated beneath the capsule consists of cells arranged in rounded groups with here and there indications of an alveolar structure. The cells of this zone are very granular and stain deeply. Two the zona fasciculata continuous with the zona glomerulosa is composed of columns of cells arranged in a radial manner. The cells contain finer granules and in many instances globules of lipoid material. Three the zona reticularis in contact with the medulla consists of cylindrical masses of cells irregularly arranged. These cells often contain pigment granules which give this zone a darker appearance than the rest of the cortex. The medullary portion substantial medularis is extremely vascular of large chromophil cells arranged in a network. The irregular polyhedral cells have a finely granular cytoplasm that are probably concerned with the secretion of adrenaline. In the meshes of the cellular network are large anastomosing venous sinuses sinusoid which are in close relationship with the chromophil or medullary cells. In many places the endothelial lining of the blood sinuses is in direct contact with the medullary cells. Some authors consider the endothelium absent in places and here the medullary cells are directly bathed by the blood. This intimate relationship between the chromophil cells and the bloodstream undoubtedly facilitates the discharge of the internal secretion into the blood. There is a loose mesh work of supporting connective tissue containing non-striped muscle fibers. This portion of the gland is richly supplied with non-medulated nerve fibers and here and there sympathetic ganglia are found. Vessels and nerves The arteries supplying the superrenal glands are numerous and of comparatively large size. They are derived from the aorta, the inferior phenic, and the renal. They subdivide into non-youth branches previous to entering the cortical part of the gland where they break up into capillaries which end in the venous plexus of the medullary portion. The superrenal vein returns the blood from the medullary venous plexus and receives several branches from the cortical substance. It emerges from the helium of the gland and on the right side opens into the inferior vena cava on the left into the renal vein. The lymphatics end in the lumbar glands. The nerves are exceedingly numerous and are derived from the celiac and renal plexuses and according to Bergman from the phrenic and vegas nerves. They enter the lower and medial part of the capsule, traverse the cortex, and end around the cells of the medulla. They have numerous small ganglia developed upon them in the medullary portion of the gland. In connection with the development of the medulla from the sympathochromophon tissue, it is to be noted that this portion of the gland secretes a substance, adrenaline, which has a powerful influence on those muscular tissues which are supplied by sympathetic fibers. Glomus caroticum, carotid glands, carotid bodies. The carotid bodies, two in number, are situated one on either side of the neck, behind the common carotid artery at its point of bifurcation into the external and internal carotid chunks. They are reddish-brown in color and oval in shape, the long diameter measuring about five millimeters. Each is invested by a fibrous capsule and consists largely of spherical or irregular masses of cells, the masses being more or less isolated from one another by septa, which extend inward from the deep surface of the capsule. The cells are polyhedral in shape and each contains a large nucleus embedded in finely granular protoplasm, which is stained yellow by chromic salts. Numerous nerve fibers derived from the sympathetic plexus on the carotid artery are distributed throughout the organ and a network of large sinusoidal capillaries ramifies among the cells. Glomus coxidium, coxigial gland or body, lusca's gland. The glomus coxidium is placed in front of or immediately below the tip of the coccyx. It is about 2.5 millimeters in diameter and is irregularly oval in shape. Several smaller nodules are found around or near the main mass. It consists of irregular masses of round or polyhedral cells, the cells of each mass being grouped around a dilated sinusoidal capillary vessel. Each cell contains a large round or oval nucleus, the protoplasm surrounding which is clear and is not stained by chromic salts. End of Section 45 Section 46 of Anatomy of the Human Body 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 Spleen The Spleen is situated principally in the left hypochondriac region but its superior extremity extends into the epigastric region. It lies between the fundus of the stomach and the diaphragm. It is the largest of the ductless glands and is of an oblong flattened form, soft a very friable consistent, highly vascular and of a dark purplish color. Development. The Spleen appears about the fifth week as a localized thickening of the mesoderm in the dorsal mesogastrium above the tail of the pancreas. With the change in position of the stomach the Spleen is carried to the left and comes to lie behind the stomach and in contact with the left kidney. The part of the dorsal mesogastrium which intervened between the Spleen and the greater curvature of the stomach forms the gastrosplenic ligament. Relations. The diaphragmatic surface feces diaphragmatica external or phrenic surface is convex, smooth and is directed upward, backward and to the left except at its upper end where it is directed slightly medial word. It is in relation with the under surface of the diaphragm which separates it from the ninth, tenth and eleventh ribs on the left side and the intervening lower border of the left lung and pleura. The visceral surface is divided by a ridge into an anterior or gastric and a posterior or renal portion. The gastric surface feces gastrica which is directed forward, upward and medial word is broad and concave and is in contact with the posterior wall of the stomach and below this with the tail of the pancreas. It presents near its medial border a long fissure termed the heilum. This is pierced by several irregular apertures for the entrance and exit of vessels and nerves. The renal surface, faces renalis is directed medial word and downward. It is somewhat flattened is considerably narrower than the gastric surface and is in relation with the upper part of the anterior surface of the left kidney and occasionally with the left super renal gland. The superior extremity, extremitis superior is directed toward the vertebral column where it lies on a level with the 11th thoracic vertebra. The lower extremity or colic surface, extremitis inferior is flat, triangular in shape and rests upon the left flexure of the colon and the phrenicocolic ligament and is generally in contact with the tail of the pancreas. The anterior border, margot interior is free, sharp and thin and is often notched especially below. It separates the diaphragmatic from the gastric surface. The posterior border, margot posterior, more rounded and blunter than the anterior separates the renal from the diaphragmatic surface. It corresponds to the lower border of the 11th rib and lies between the diaphragm and the left kidney. The intermediate margin is the ridge which separates the renal and gastric surfaces. The inferior border, internal border, separates the diaphragmatic from the colic surface. The spleen is almost entirely surrounded by peritoneum which is firmly adherent to its capsule. It is held in position by two folds of this membrane. One, the fritico-lienal ligament is derived from the peritoneum where the wall of the general peritoneal cavity comes into contact with the elemental bursa between the left kidney and the spleen. The lienal vessels pass between its two layers. The other fold, the gastro-lienal ligament is also formed of two layers derived from the general cavity and the elemental respectively where they meet between the spleen and the stomach. The short gastric and left gastroepiploid branches of the lienal artery run between its two layers. The lower end of the spleen is supported by the frinico-colic ligament. The size and weight of the spleen are liable to very extreme variations at different periods of life in different individuals and in the same individual under different conditions. In the adult it is usually about 12 cm in length, 7 cm in breadth, and 3 or 4 cm in thickness, and weighs about 200 g. At birth its weight in proportion to the entire body is almost equal to what is observed in the adult being as 1 to 350 while in the adult it varies from 1 to 320 and 400. In old age the organ not only diminishes in weight but decreases considerably in proportion to the entire body being as 1 to 700. The size of the spleen is increased during and after digestion and varies according to the state of nutrition of the body being large and highly fed and small and starved animals. In malarial fever it becomes much enlarged weighing occasionally as much as 9 kg. Frequently in the neighborhood of the spleen and especially in the gastrolyena ligament and greater omentum small nodules of spleenic tissue may be found either isolated or connected to the spleen by thin bands of spleenic tissue. They are known as accessory spleens. Lion assessorias, super numerary spleen. They vary in size from that of a P to that of a plum. Structure. The spleen is invested by two coats an external cirrus and an internal fibroelastic coat. The external or cirrus coat, tunica cirrosa, is derived from the peritoneum. It is thin, smooth, and in the human subject intimately adherent to the fibroelastic coat it invests the entire organ except at the hyalum and along the lines of reflection of the frenicolienal and gastrolyena ligaments. The fibroelastic coat, tunica albuginia invests the organ and at the hyalum is reflected inward upon the vessels in the form of sheaths. From these sheaths, as well as from the inner surface of the fibroelastic coat, numerous small fibrous bands, trebriculi are given off in all directions. These uniting constitute the framework of the spleen. The spleen therefore consists of a number of small spaces or areoli formed by the trebriculi and these areoli is contained the spleenic pulp. The fibroelastic coat, the sheaths of the vessels and the trebriculi are composed of white and yellow elastic fibrous tissues, the latter predominating. It is owing to the presence of the elastic tissue that the spleen possesses a considerable amount of elasticity which allows of the very great variations in size that it presents under certain circumstances. In addition to these constituents of this tunic, there is found in man a small amount of non-striped muscular fiber and in some mammalia, for example dog, pig, and cat, a large amount so that the trebriculi appear to consist chiefly of muscular tissue. The spleenic pulp, pulpa laenus is a soft mass of dark reddish brown color resembling grumis blood. It consists of a fine reticulum of fibers continuous with those of the trebriculi to which are applied flat branching cells. The meshes of the reticulum are filled with blood in which, however, the white corpuscles are found to be in larger proportion than they are in ordinary blood. Large rounded cells, termed spleenic cells are also seen. These are capable of amoeboid movement and often contain pigment and red blood corpuscles in their interior. The cells of the reticulum each possess a round or oval nucleus and like the spleenic cells, they may contain pigment granules in their cytoplasm. They do not stain deeply with carmine and in this respect differ from the cells of the malpigian bodies. In the young spleen giant cells may also be found each containing numerous nuclei or one compound nucleus. Nucleated red blood corpuscles have also been found in the spleen of young animals. Blood vessels of the spleen. The lienal artery is remarkable for its large size in proportion to the size of the organ and also for its torturous course. It divides into six or more branches which enter the hylum of the spleen and ramify throughout its substance receiving sheaths from an involution of the external fibrous tissue. Similar sheaths also invest the nerves and veins. Each branch runs in the transverse axis of the organ from within outward diminishing in size during its transit and giving off in its passage smaller branches some of which pass to the anterior others to the posterior part. These ultimately leave the trabicular sheaths and terminate in the proper substance of the spleen in small tufts or pencils of minute arterioles which open into the interstices of the reticulum formed by the branch sustenticular cells. Each of the larger branches of the artery supplies chiefly that region of the organ in which the branch ramifies having no anastomosis with the majority of the other branches. The arterioles supported by the minute trabicule traverse the pulp in all directions in bundles, pencil-eye of straight vessels. Their trabicular sheaths gradually undergo a transformation, become much thickened and converted into adenoid tissue. The bundles of connective tissue becoming looser and their fibrils more delicate and containing in their interstices an abundance of lymph corpuscles, W. Mueller. The altered coat of the arterioles consisting of adenoid tissue presents here and there thickenings of a spheroidal shape the lymphatic nodules malpighian bodies of the spleen. These bodies vary in size from about 0.25 millimeters to 1 millimeter in diameter. They are merely local expansions or hypoplasia of the adenoid tissue of which the external coat of the smaller arteries of the spleen is formed. They are most frequently found surrounding the arterioles which thus seems to tunnel them but occasionally they grow from one side of the vessel only and present the appearance of a sessile bud growing from the arterial wall. In transverse sections the artery in the majority of cases is found in an eccentric position. These bodies are visible to the naked eye on the surface of a fresh section of the organ appearing as minute dots of a semi-opaque whitish color in the dark substance of the pulp. In minute structure they resemble the adenoid tissue of lymph glands consisting of a delicate reticulum in the meshes of which light ordinary lymphoid cells. The reticulum is made up of extremely fine fibrils and is comparatively open in the center of the corpuscle becoming closer at its periphery. The cells which it encloses are possessed of amoeboid movement. When treated with carmine they become deeply stained and can be easily distinguished from those of the pulp. The arterioles end by opening freely into this spleenic pulp. Their walls become much attenuated they lose their tubular character and the endothelial cells become altered presenting a branched appearance and acquiring processes which are directly connected with the processes of the reticular cells of the pulp. In this manner the vessels end and the blood flowing through them finds its way into the interstices of the reticulated tissue of the spleenic pulp. Thus the blood passing through the spleen is brought into intimate relation with the elements of the pulp and those important changes. After these changes have taken place the blood is collected from the interstices of the tissue by the rootlets of the veins which begin much in the same way as the arteries end. The connective tissue corpuscles of the pulp arrange themselves in rows in such a way as to form an elongated space or sinus. They become elongated and spindle shaped and overlap each other at their extremities and thus form a sort of endothelial lining of the path or sinus which is the radical of a vein. On the outer surfaces of these cells are seen delicate transverse lines or markings which are due to minute elastic fibulae arranged in a circular manner around the sinus. Thus the channel obtains an external investment and gradually becomes converted into a small vein which after a short course acquires a coat of ordinary connective tissue lined by a layer of flattened epithelial cells which are continuous with the supporting cells of the pulp. The smaller veins unite to form larger ones. These do not accompany the arteries but soon enter the tubercular sheaths of the capsule and by their junction form six or more branches which emerge from the hyalum and uniting constitute the linole vein, the largest radical of the portal vein. The veins are remarkable for their numerous anastomoses while the arteries hardly anastomose at all. The lymphatics are described on page 711. The nerves are derived from the celiac plexus and are chiefly non-modulated. They are distributed to the blood vessels and to the smooth muscle of the capsule and tubercule. End of section 46 Section 47 of Grease Anatomy Part 5 This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information and to volunteer, please visit LibriVox.org Recording by John K. Thomas also known as Vern or John Coose. Anatomy of the Human Body Part 5 by Henry Gray 12. Surface Anatomy and Service Markings 1. Surface Anatomy of the Head and Neck 2. Figure 1193 Various bony surfaces and prominences on the skull can be easily identified by palpation. The external occipital protuberance is situated behind in the middle line at the junction of the skin of the neck with that of the head. The superior neutral line runs lateralward bending downward. From it, the median neutral crest situated deeply at the bottom of the neutral furrow. Above the superior neutral lines the vault of the cranium is thinly covered with soft structures so that the form of this part of the head is almost that of the upper portion of the occipital the parietal and the frontal bones. The superior neutral line can be followed lateralward to the mastoid portion of the temporal bone from which the mastoid process projects downward and forward behind the ear. The interior and posterior borders, the apex and the external surface of this process are all available for superficial examination. The interior border lies immediately behind the concha the apex is on a level with the lobule of the auricula about one centimeter below and in front of the apex of the mastoid process. The transverse process of the atlas can be distinguished. In front of the ear the zygomatic arch can be felt throughout its entire length its posterior end is narrow and is situated a little above the level of the tragus its anterior end is broad and is continued into the zygomatic bone. The lower border of the arch is more distinct than the upper which is obscured by the attachment of the temporal fascia. In front and behind the upper border of the arch can be followed into the superior temporal line. In front this line begins at the zygomatic process of the frontal bone as a curved ridge which runs at first forward and upward on the frontal bone and then curving backward separates the forehead into the temporal fascia. It can be traced across the parietal bone where though less marked it can generally be recognized. Finally it curves downward and forward and passing above the external acoustic meiasis ends in the posterior root of the zygomatic arch near the line of the greatest transverse diameter of the head are the parietal eminences on either side of the middle line. Further forward on the forehead are the frontal eminences which vary in prominence in different individuals and are frequently unsymmetrical. Below the frontal eminences the super ciliary arches which indicate the position of the frontal sinuses can be recognized. As a rule they are small in the female and absent in children. In some cases the prominence of the super ciliary arches is related to the size of the frontal sinuses but frequently there is no such relationship. Situated between and connecting the super ciliary ridges is a smooth somewhat triangular area the glabella below which the nation the frontal nasal suture can be felt as a slight depression at the root of the nose. Below the nation the nasal bones scantily covered by soft tissues can be traced to their junction with the nasal cartilages and on either side of the nasal bone the complete outline of the orbital margin can be made out. At the junction of the medial and intermediate thirds of the super orbital margin the super orbital notch when present can be felt. Close to the medial end of the infra orbital margin is a little tubercle which serves as a guide to the position of the lacrimal sac. Low and lateral to the orbit on either side is the zygomatic bone forming the prominence of the cheek its posterior margin is easily palpable and on it just above the level of the lateral palpable commissure is the zygomatic tubercle. A slight depression about one centimeter above this tubercle indicates the position of the zygomatic cofrontal suture. Directly below the orbit is a considerable part of the anterior surface of the maxilla and the whole of its alveolar process can be palpated. The outline of the mandible can be recognized throughout practically its entire extent in front of the tragus and below the zygomatic arch is the condyle and from this posterior border of the ramus can be followed to the angle. From the angle to the symphysis the lower rounded border of the mandible can be easily traced the lower part of the anterior and the alveolar process can be made out without difficulty. In the receding angle below the chin is the hyoid bone and the finger can be carried along the bone to the tip of the greater cornu which is on level with the angle of the mandible. The greater cornu is most readily appreciated by making pressure on one side when the cornu of the opposite side will be rendered prominent and can be felt distinctly beneath the skin. Joints and muscles the temporal mandibular articulation is quite superficial and is situated below the posterior end of the zygomatic arch in front of the external acoustic meatus. Its position can be ascertained by defining the condyle of the mandible. When the mouth opens the condyle advances out of the triangular fossa onto the articular tubercle and the depression is felt in the situation of the joint. The outlines of the muscles of the head and face cannot be traced on the surface except in the case of the masseter and temporalis. The muscles of the scalp are so thin that the outline of the bone is perceptible beneath them. Those of the face are small covered by soft skin and often by a considerable layer of fat and their outlines are therefore concealed. They serve, however, to round off and smooth prominent borders and to fill up what would otherwise be unsightly angular depressions. Thus, the orbicularis oculi rounds off the prominent margin of the orbit and the proseris fills in the sharp depression below the gobella. In like manner, the labial muscles converging phillips and assisted by the superimposed fat fill up the sunken hollow of the lower part of the face. When in action, the facial muscles produce the various expressions and in addition throw the skin into numerous folds and wrinkles. The masseter imparts fullness to hinder part of the cheek. If firmly contracted, as when the teeth are clenched, its quadrilateral outline is plainly visible. The interior border forms a prominent vertical ridge behind which is a considerable fullness, especially marked at the lower part of the muscle. The temporalis is fan shaped and fills the temporal fossa substituting for the concavity, a somewhat convex swelling, the interior part of which, on account of the absence of hair on the overlying skin, is more marked than the posterior and stands out in strong relief when the muscle is in action. In the neck, the platysma, when contracted, throws the skin into oblique ridges parallel with the fasci-culi of the muscle. The sternocleidomastoidus has the most important influence on the surface form of the neck. When the muscle is at rest, its interior border forms an oblique rounded edge ending below on the sharp outline of the sternal head. The posterior border is only distinct for about 2 or 3 cm, above the middle of the clavicle. During contraction, the sternal head stands out as a sharply defined ridge, while the clavicular head is flatter and less prominent. Between the two heads is a slight depression. The fleshy middle portion of the muscle appears as an oblique elevation, with a thick rounded anterior border best marked in its lower part. The sternal heads of the two muscles are separated by a V-shaped depression in which are the sternohioidus and sternothyroidus. Above the hyoid bone, near the middle line, the anterior belly of the didrasticus produces a slight convexity. The anterior border of the trapezius presents as a faint ridge running from the superior neutral line downward and forward to the junction of the intermediate and lateral thirds of the clavicle. Between the sternocleidomastoidus and the trapezius is the posterior triangle of the neck, the lower part of which appears as a shallow concavity, the supraclavicular fossa. In this fossa, the inferior belly of the omohioidus when in action presents as a round cord-like elevation a little above and almost parallel to the clavicle. Figure 1195 of the neck. Arteries The positions of several of the larger arteries can be ascertained from their pulsations. The subclavian artery can be felt by making pressure downward, backward and medial ward behind the clavicular head of the sternocleidomastoidus. Its transverse cervical branch may be detected parallel to and about a finger's breath above the clavicle. The common and external carotid arteries can be recognized immediately beneath the anterior edge of the sternocleidomastoidus. The external axillary artery can be traced over the border of the mandible just in front of the anterior border of the masseter, then about one centimeter, lateral to the angle of the mouth and finally as it runs up the spine. In the pulsation of the occipital artery can be distinguished about three or four centimeters lateral to the external occipital protuberance and that of the posterior auricular in the groove between the mastoid process and the auricular. The course of the superficial temporal artery can be readily followed across the posterior end five centimeters above this where it divides into its frontal and parietal branches. The pulsation of the frontal branch is frequently visible on the side of the forehead. The suber orbital artery can usually be detected immediately above the suber orbital notch or foreman. End of section 47 recording by John K. Thomas also known as Verne or John Kuz web address www.validateyourlife.com or www.oneandthesamerecordings.com by Henry Gray surface markings of special regions of the head and neck part one. The cranium scalp The soft parts covering the upper surface of the skull form the scalp and comprise the following layers one skin two subcutaneous tissue three occipitalis frontalis and gallia aponeurotica four subaponeurotic tissue five pericranium the subcutaneous tissue consists of a close mesh work of fibers the meshes of which contain fatty tissue the fibers bind the skin and gallia aponeurotica firmly together so that when the occipitalis or the frontalis is in action the skin moves with the aponeurosis the subaponeurotic tissue which intervenes between the gallia aponeurotica and the pericranium is much looser in texture and permits the movement of the aponeurosis over the underlying bones bony landmarks in addition to the bony points already described which can be determined by palpation the following are utilized for surface markings auricular point the center of the orifice of the external acoustic meatus pre-auricular point a point on the posterior root of the zygomatic arch immediately in front of the external acoustic meatus asterion the point of meeting of the lamdoidal masto-oxipital and masto-parietal sutures it lies four centimeters behind and 12 millimeters above the level of the auricular point terion the point where the great wing of the sphenoid joins the sphenoidal angle of the parietal it is situated 35 millimeters behind and 12 millimeters above the level of the frontal zygomatic suture inion the external occipital protuberance lambda the point of meeting of the lamdoidal and sagittal sutures it is in the middle line about 6.5 centimeters above the inion bregma the meeting point of the coronal and sagittal sutures it lies at the point of intersection of the middle line of the scalp with a line drawn vertically upward through the pre-auricular point a line passing through the inferior margin of the orbit and the auricular point is known as reed's base line the lamdoidal suture can be indicated on either side by the upper two-thirds of a line from the lambda to the tip of the mastoid process the sagittal suture is in the line joining the lambda to the bregma the position of the coronal suture on either side is sufficiently represented by a line joining the bregma to the center of the zygomatic arch the floor of the middle the fossa of the skull is at the level of the posterior three-fourths of the upper border of the zygomatic arch the articular eminence of the temporal bone is opposite the foramen spinosum and the simulunar ganglion brain the general outline of the cerebral hemisphere on either side may be mapped out on the surface in the following manner starting from the nasion a line drawn along the middle of the scalp to the inion represents the superior border the line of the lower margin behind is that of the transverse sinus or more roughly a line convex upward from the inion to the posterior root of the zygomatic process of the temporal bone that's along the posterior two-thirds of the upper border of the zygomatic arch where the line turns up to the terion the front part of the lower margin extends from the terion to the glabella about one centimeter above the supra-orbital margin the cerebellum is so deeply situated that there is no reliable surface marking for it a 0.4 centimeters behind and 1.5 centimeters below the level of the auricular point is situated directly over it the relations of the principal fissures in gyrie of the cerebral hemispheres to the surface of the scalp are of considerable practical importance and several methods of indicating them have been devised necessarily these methods can only be regarded as approximately correct yet they are all sufficiently accurate for surgical purposes the longitudinal fissure corresponds to the medial line of the scalp between the nasion and inion in order to mark out the lateral cerebral sylvian fissure a point termed the sylvian point which practically corresponds to the terion is defined 35 millimeters behind and 12 millimeters above the level of the frontal zygomatic suture this point marks the spot where the lateral fissure divides another method of defining the sylvian point is to divide the distance between the nasion and inion into four equal parts from the junction of the third and fourth parts reckoning from the front draw a line to the frontal zygomatic suture from the junction of the first and second parts align to the auricular point these two lines intersect at the sylvian point and the portion of the first line behind this point overlies the posterior ramus of the lateral cerebral fissure the position of the posterior ramus can otherwise be obtained by joining the sylvian point to a point 2 centimeters below the summit of the parietal eminence the anterior ascending ramus can be marked out by drawing a line upward at right angles to the line of the posterior ramus for 2 centimeters and the anterior horizontal ramus by a line of the same length drawn horizontally forward both from the sylvian point to define the central sulcus fissure of Rolando 2 points are taken one is situated 1.25 centimeters behind the center of the line joining the nasion and inion the second is at the intersection of the line of the posterior ramus of the lateral cerebral fissure with a line through the pre-auricular point at right angles to Reed's baseline the upper 9 centimeters of the line joining these two points overlies the central sulcus and forms an angle opening forward of about 70 degrees with the middle line of the scalp an alternative method is to draw two perpendicular lines from Reed's baseline to the top of the head one from the pre-auricular point and the other from the posterior border of the mastoid process at its root a line from the upper end of the posterior line to the point where the anterior intersects the line of the posterior ramus of the lateral fissure indicates the position of the central sulcus the pre-central and post-central sulky are practically parallel to the central sulcus they are situated respectively about 15 millimeters in front of and behind it the superior frontal sulcus can be mapped out by a line drawn from the junction of the upper and middle thirds of the pre-central sulcus in a direction parallel with the longitudinal sulcus to a point midway between the far head and the temporal line 4 centimeters above the super-orbital notch the inferior frontal sulcus begins at the junction of the middle and lower thirds of the pre-central sulcus and follows the course of the superior temporal line the horizontal limb of the intra-parietal sulcus begins from the junction of the lower with the middle third of the post-central sulcus and curves backward parallel to the longitudinal fissure midway between it and the parietal eminence it then curves downward to end midway between the lambda and the parietal eminence the external part of the parietal occipital fissure runs lateralward at right angles to the longitudinal fissure for about 2.5 centimeters from a point 5 millimeters in front of the lambda if the line of the posterior ramus of the lateral cerebral fissure be continued back to the longitudinal fissure the last 2.5 centimeters of it the position of the parietal occipital fissure the lateral ventricle may be circumscribed by a quadrilateral figure the upper limit is a horizontal line 5 centimeters above the zygomatic arch this defines the roof of the ventricle the lower limit is a horizontal line 1 centimeter above the zygomatic arch it indicates the level of the end of the inferior horn 2 vertical lines, one through the junction of the anterior and middle thirds of the zygomatic arch and the other 5 centimeters behind the tip of the mastoid process indicate the extent of the anterior horn in front and the posterior horn behind vessels the line of the anterior division of the middle meningeal artery is equidistant from the frontal zygomatic suture in the zygomatic arch it is obtained by joining up the following points 1, 2.5 centimeters 2, 4 centimeters 3, 5 centimeters from these two landmarks the posterior division can be reached 2.5 centimeters above the auricular point the position of the transverse sinus is obtained by taking two lines the first from the enion to a point 2.5 centimeters behind the auricular point the second from the anterior end of the first to the tip of the mastoid process the second line corresponds roughly to the line of reflection of the auricular behind and its upper two thirds represents the sigmoid part of the sinus the first part of the sinus has a slight upward convexity and its highest point is about 4 centimeters behind and 1 centimeter above the level of the auricular point the width of the sinus is about 1 centimeter the face air sinuses the frontal and maxillary sinuses vary so greatly in form and size and their surface markings must be regarded as only roughly approximate to mark out the position of the frontal sinus 3 points are taken 1. the nasion 2. a point in the middle line 3 centimeters above the nasion 3. a point at the junction of the lateral and intermediate thirds of the super orbital margin by joining these a triangular field is described which overlives the greater part of the sinus the outline of the maxillary sinus is irregularly quadrilateral and is obtained by joining up the following points 1. the lacrimal tubercle 2. a point on the zygomatic bone at the level of the inferior and lateral margins of the orbit 3 and 4 points on the alveolar process above the last molar and the second premolar teeth respectively external maxillary artery the course of this artery on the face may be indicated by a line starting from the lower border of the mandible at the anterior margin of the masseter and running at first forward and upward to a point 1 centimeter lateral to the angle of the mouth dense to the a la of the nose and upward to the medial commissure of the eye 3. trigeminal nerve terminal branches of this nerve namely the super orbital branch of the ophthalmic the infor orbital of the maxillary and the mental of the mandibular phyramina on the face the super orbital phyramin is situated at the junction of the medial and intermediate thirds of the super orbital margin a line drawn from this phyramin to the lower border of the mandible through the interval between the two lower premolar teeth passes over the infor orbital and mental phyramina the former lies about 1 centimeter below the margin of the orbit while the latter varies in position according to the age of the individual the adult it is midway between the upper and lower borders of the mandible in the child it is nearer the lower border while in the identialist jaw of old age it is close to the upper margin the position of the sphenopalatine ganglion is indicated from the side by a point on the upper border of the zygomatic arch 6 millimeters from the margin of the zygomatic bone parotid gland the upper border of the parotid gland corresponds to the posterior two thirds of the lower border of the zygomatic arch the posterior border to the front of the external acoustic miatus, the mastoid process and the anterior border of sternocleidomastoidius the inferior border is indicated by a line from the tip of the mastoid process to the junction of the body and greater corneal of the hyoid bone in front the anterior border extends for a variable distance on the superficial surface of the massager the surface marking for the parotid duct is a line drawn across the face about a finger's breadth below the zygomatic arch that is from the lower margin of the concha to midway between the red margin of the lip and the a la of the nose the duct ends opposite the second upper molar tooth and measures about 5 centimeters in length the nose the outlines of the nasal bones and the cartilages forming the external nose can be easily felt the mobile portion of the nasal septum formed by the medial crura of the greater allar cartilages and the skin is easily distinguished between the nares when the head is tilted back and a speculum introduced through the nares the floor of the nasal cavity the lower part of the nasal septum and the anterior ends of the middle and inferior nasal concha can be examined the opening of the nasal lacrimal duct which lies under cover of the front of the inferior nasal concha is situated about 2.5 centimeters behind the nares and 2 centimeters above the level of the floor of the nasal cavity end of section 48 section 49 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 recorded by Larianne Walden Anatomy of the Human Body Part 5 by Henry Gray surface markings and special regions of the neck Part 2 the mouth the orifice of the mouth is bounded by the lips which are covered externally by the whitish skin and internally by the red mucous membrane the size of the orifice varies considerably in different individuals but seems to bear a close relationship to the size and prominence of the teeth its angles usually correspond to the lateral borders of the canine teeth running down the center of the outer surface of the upper lip is a shallow groove the philtrum if the lips be averted there could be seen in the middle line of each a small fold of mucous membrane the phrenulum passing from the lip to the gum by pulling the angle of the mouth outward the mucous membrane of the cheek can be inspected and on this opposite the second molar tooth of the maxilla is the little papilla which marks the orifice of the parotid duct in the floor of the mouth is the tongue its upper surface is convex and is marked along the middle line by a shallow sulcus the anterior two thirds are rough and studded with papilla the posterior third is smooth and tuberculated the division between the anterior two thirds and the posterior third is marked by a V shaped furrow the sulcus terminalis which is situated immediately behind the line of the valate papilla on the under surface of the tongue the mucous membrane is smooth and devoid of papillae in the middle line the mucous membrane extends to the floor of the mouth as a distinct fold, the phrenulum the free edge of which runs forward to the synthesis minty sometimes the ranine vein can be seen immediately beneath the mucous membrane a little lateral to the phrenulum close to the attachment of the phrenulum to the floor of the mouth the slit like orifice of the submaxillary duct is visible on either side running backward and lateral from the orifice of the submaxillary duct is the pleca sublingualis produced by the projection of the sublingual gland which lies immediately beneath the mucous membrane the pleca serves also to indicate the line of the submaxillary duct and of the lingual nerve at the back of the mouth is the ismus falsium bounded above by the palatine velem from the free margin of which the uvella projects downward in the middle line on either side of the ismus are the two palatine arches the anterior formed by the glasopalatinas and the posterior by the pharyngeopalatinas between the two arches of either side is the palatine tonsil above which is the small super tonsil or recess the position of the tonsil corresponds to the angle of the mandible when the mouth is opened widely a tense band, the pterigomandibular rafae can be seen and felt lateral to the glasopalatine arch its lower end is attached to the mandible behind the last molar tooth and immediately below and in front of this the lingual nerve can be felt the upper end of the ligament can be traced to the pterigoid hamulus about one centimeter in front of the hamulus and one centimeter medial to the last molar tooth of the maxilla is the greater palatine foramen through which the descending palatine vessels and the anterior palatine nerve emerge behind the last molar tooth of the maxilla the carnoid process of the mandible is palpable by tilting the head well back a portion of the posterior pharyngeal wall corresponding to the site of the second and third cervical vertebrae can be seen through the ismus falsium on introducing the finger the anterior surfaces of the upper cervical vertebrae can be felt through the thin muscular wall of the pharynx if the finger be hooked around the palatine velem the coene can be distinguished in front and the pharyngeal osteum of the auditory tube on either side the level of the coene is that of the atlas while the palatine velem is opposite the body of the axis with a laryngoscope many other structures can be seen in the nasal part of the pharynx the coene, the nasal septum the nasal conchi and the pharyngeal osteum of the auditory tubes can all be examined further down the base of the tongue the anterior surface of the epiglottis with the glassoepiglottic and pharyngeal epiglottic folds bounding the veleculae and the piriform sinuses are readily distinguished beyond these is the entrance to the larynx bounded on either side by the areyepiglottic folds in each of which are two rounded immanences corresponding to the corniculate and cuneiform cartilages within the larynx on either side are the ventricular and vocal folds false and true vocal cords with the ventricle between them still deeper are seen the cricoid cartilage and the anterior parts of some of the cartilaginous rings of the trachea and sometimes, during deep inspiration the bifurcation of the trachea the eye the palpebol fissure is elliptical in shape and varies in form in different individuals and in different races of mankind normally it is oblique in a direction upward and lateral word so that the lateral commissure is on a slightly higher level than the medial when the eyes are directed forward as in ordinary vision the upper part of the cornea is covered by the upper eyelid and its lower margin corresponds to the level of the free margin of the lower eyelid so that usually the lower three fourths are exposed at the medial commissure are the caruncula lacrimalis and the pleca semulunaris when the lids are averted the tarsal glands appear as a series of nearly straight parallel rows of light yellow granules on the margins of the lids about five millimeters from the medial commissure are two small openings the lacrimal puncta in the natural condition they are in contact with the conjunctiva of the bulb of the eye so that it is necessary to avert the eyelids to expose them the position of the lacrimal sac is indicated by a little tubercle which can be plainly felt on the lower margin of the orbit the sac lies immediately above and medial to the tubercle if the eyelids be drawn lateral word so as to tighten the skin at the medial commissure a prominent core can be felt beneath the tightened skin this is the medial palpival ligament which lies over the junction of the upper with the lower two thirds of the sac thus forming a useful guide to its situation the direction of the nasolacrimal duct is indicated by a line from the lacrimal sac to the first molar tooth of the maxilla the length of the duct is about 12 or 13 millimeters on looking into the eye the iris with its opening, the pupil and the front of the lens can be examined but for investigation of the retina an ophthalmoscope is necessary with this the lens the vessels of the retina the optic disc and the macula lutea can all be inspected on the lateral surface of the nasal part of the frontal bone the pulley of the obliquus superior can be easily reached by pushing the finger backward along the roof of the orbit the tendon of the muscle can be traced for a short distance backward and lateral word from the pulley the ear the various prominences and faussy of the auricular are visible the opening of the external acoustic meatus is exposed by drawing the tragus forward at the orifice are a few short crisp hairs which serve to prevent the entrance of dust or of small insects beyond this the secretion of the ceruminous glands serves to catch any small particles which may find their way into the meatus the interior of the meatus can be examined through a speculum at the line of junction of its bony and cartilaginous portions an obtuse angle is formed which projects into the entero inferior wall and produces a narrowing of the lumen in this situation the cartilaginous part however is connected to the bony part by fibrous tissue which renders the outer part of the meatus very movable and therefore by drawing the auricular upward backward and slightly outward the canal is rendered almost straight in children the meatus is very short and this should be remembered in introducing the speculum through the speculum the greater part of the tympanic membrane is visible it is a pearly gray membrane slightly glistening in the adult placed obliquely so as to form with the floor of the meatus an angle of about 55 degrees at birth it is more horizontal and situated in almost the same plane as the base of the skull the membrane is concave outward and the point of deepest concavity the umbo is slightly below the center running upward and slightly forward from the umbo is a reddish yellow streak produced by the manubrium of the maleus this streak ends above just below the roof of the meatus at a small white rounded prominence which is caused by the lateral process of the maleus projecting against the membrane the anterior and posterior malleolar folds extend from the prominence to the circumference of the membrane and enclose the pars flaccida behind the streak caused by the manubrium of the maleus a second streak, shorter and very faint, can be distinguished this is the long crust of the incus a narrow triangular patch extending downward and forward from the umbo reflects the light more brightly than any other part and is usually described as the cone of light tympanic antrum the site of the tympanic antrum is indicated by the suprameatal triangle this triangle is bounded by the posterior root of the zygomatic arch behind, by a vertical line from the posterior border of the external acoustic meatus in front and below by the upper margin of the meatus the neck, larynx and trachea in the receding angle below the chin the hyoid bone, situated opposite the fourth cervical vertebra can easily be made out a finger's breadth below it is the laryngeal prominence of the thyroid cartilage the space intervening between the hyoid bone and the thyroid cartilage is occupied by the hyo-thyroid membrane the outlines of the thyroid cartilage are readily palpated below its lower border is a depression corresponding to the middle cricothyroid ligament the level of the vocal folds corresponds to the middle of the anterior margin of the thyroid cartilage the anterior part of the cricoid cartilage forms an important landmark in the front of the neck it lies opposite the sixth cervical vertebra and indicates the junctions of pharynx with esophagus and larynx with trachea below the cricoid cartilage the trachea can be felt though it is only in thin subjects that the separate rings can be distinguished as a rule there are seven or eight rings above the jugular notch of the sternum and of these the second, third and fourth are covered by the ismus of the thyroid gland muscles the posterior belly of digastricus is marked out by a line from the tip of the mastoid process to the junction of the greater corneal and body of the hyoid bone a line from this ladder point to a point just lateral to the symphysis mentee indicates the position of the anterior belly the line of omohyoidius begins at the lower border of the hyoid bone curves downward and lateral to cross sternocleidomastoidius the position of its middle and lower thirds that is opposite the cricoid cartilage and then runs more horizontally to the acromial end of the clavicle arteries the position of the common carotid artery in the neck is indicated by a line drawn from the upper part of the sternal end of the clavicle to a point midway between the tip of the mastoid process and the angle of the mandible from the clavicle to the upper border of the thyroid cartilage this line overlies the common carotid artery beyond this it is over the external carotid the external carotid artery may otherwise be marked out by the upper part of the line from the side of the cricoid cartilage to the front of the external acoustic myatus arching the line slightly forward the points of origin of the main branches of the external carotid in the neck are all related to the tip of the greater corneal of the hyoid bone as follows 1. the superior thyroid immediately below it 2. the lingual on a level with it 3. the facial and 4. the occipital a little above and behind it the subclavian artery is indicated on the surface by a curved line convex upward from the sternoclavicular articulation to the middle of the clavicle the highest point of the convexity is from 1 to 3 cm above the clavicle veins the surface marking for the internal jugular vein is slightly lateral and parallel to that for the common carotid artery the position of the external jugular vein is marked out by a line from the angle of the mandible to the middle of the clavicle a point on this line about 4 cm above the clavicle indicates the spot where the vein pierces the deep fascia the line of the anterior jugular vein begins close to the synthesis minty turns downward parallel width and a little to one side of the middle line and at a variable distance above the jugular notch turns lateral word to the external jugular nerves the facial nerve at it's exit from the stylo mastoid foramen is situated about 2.5 cm from the surface opposite the middle of the anterior border of the mastoid process a horizontal line from this point to the ramus of the mandible to mark the side of the accessory nerve a line is drawn from the angle of the mandible to a point on the anterior border of sternocleidomastoidius about 3-4 cm below the apex of the mastoid process or to the midpoint of the posterior border of the muscle the line is continued across the posterior triangle to trapezius the cutaneous branches of the cervical plexus as they emerge from the posterior border of sternocleidomastoidius may be indicated as follows the lesser occipital begins immediately above the midpoint of the border and runs along the border to the scalp the great auricular and cervical cutaneous both start from the middle of the border the former running upward toward the lobule of the auricular the latter crossing sternocleidomastoidius at right angles to its long axis the supraclavicular nerves emerge from immediately below the middle of the posterior border and run down over the clavicle the phrenic nerve begins at the level of the middle of the thyroid cartilage and runs behind the clavicle about midway between the anterior and posterior borders of sternocleidomastoidius the upper border of the brachial plexus is indicated by a line from the side of the cricoid cartilage to the middle of the clavicle submaxillary gland on either side of the neck the whole portion of the submaxillary gland as it lies partly under cover of the mandible can be palpated End of section 49 Part 5 by Henry Gray Bones The only subcutaneous parts of the vertebral column are the apices of the spinous processes These are distinguishable at the bottom of a furrow which runs down the middle line of the back from the external to the occipital protuberance to the middle of the sacrum In the cervical region the furrow is broad and ends below in a conspicuous projection caused by the spinous processes of the seventh cervical and first thoracic vertebrae Above this, the spinous process of the sixth cervical vertebra sometimes form a projection the other cervical spinous processes are sunken but that of the axis can be felt In the thoracic region the furrow is shallow and during stooping disappears and then the spinous processes become more or less visible The markings produced by them are small and close together In the lumbar region the furrow is deep and the situations of the spinous processes are frequently indicated by little pits or depressions especially when the muscles in the loins are well developed In the sacral region the furrow is shallower presenting a flattened area which ends below at the most prominent part of the dorsal surface of the sacrum i.e. the spinous process of the third sacral vertebra At the bottom of the sacral furrow the irregular dorsal surface of the bone may be felt and below this in the deep groove running to the anus the coccyx which can be felt from the surface or the transverse processes of the first, sixth and seventh cervical vertebrae Muscles The muscles proper of the back are so obscured by those of the upper extremity that they have very little influence on surface form The splenii by their divergence serve to broaden out the upper part of the back of the neck and produce a fullness in this situation In the loin, the sacrospinales bound down by the lumbodorsal fascia form rounded vertical eminences which determine the depth of the spinal furrow and taper below to a point on the dorsal surface, the sacrum The continuations of the sacrospinales in the lower thoracic region form flattened planes which are gradually lost on passing upward bony landmarks In order to identify any particular spinous process it is customary to count from the prominence caused by the seventh cervical and first thoracic Of these, the latter is the most prominent The root of the spine of the scapula is on a level with the tip of the spinous process of the third thoracic vertebrae and the inferior angle with that of the seventh The highest point of the iliac crest is on a level with the spinous process of the fourth lumbar and the posterior superior iliac spine with that of the second sacral The transverse process of the atlus is about one centimeter below and in front of the apex of the mastoid process The transverse process of the sixth cervical vertebra is opposite the cricoid cartilage Below it is the transverse process of the seventh and occasionally a cervical rib medulla spinalis The position of the lower end of the medulla spinalis varies slightly with the movements of the vertebral column But in the adult, in the upright posture, it is usually at the level of the spinous process of the second lumbar vertebra At birth, it lies at the level of the fourth lumbar The subdural and subarconoid cavities are then below opposite the spinous process of the third sacral vertebra End of section 50 Recording by David Lawrence March 2010 in Brampton, Ontario