 Section 14 of Grey's Anatomy Part 3. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Read by Carolyn Power. The side of the neck presents a somewhat quadrilateral outline, limited above by the lower border of the body of the mandible and an imaginary line extending from the angle of the mandible to the mastoid process below by the upper border of the clavicle, in front by the middle line of the neck, behind by the anterior margin of the trapezius. This space is subdivided into two large triangles by the sternocleidomastoidius, which passes obliquely across the neck from the sternum and clavicle below to the mastoid process and occipital bone above. The triangular space in front of this muscle is called the anterior triangle and that behind it the posterior triangle. The anterior triangle is bounded in front by the middle line of the neck, behind by the anterior margin of the sternocleidomastoidius. Its base, directed upward, is formed by the lower border of the body of the mandible and a line extending from the angle of the mandible to the mastoid process. Its apex is below at the sternum. This space is subdivided into four smaller triangles by the digastricus above and the superior belly of the omohoidius below. These smaller triangles are named the inferior carotid, the superior carotid, the submaxillary and the suprahyoid. The inferior carotid or muscular triangle is bounded in front by the median line of the neck from the hyoid bone to the sternum, behind by the anterior margin of the sternocleidomastoidius, above by the superior belly of the omohoidius. It is covered by the integument supraficial fascia, platysma and deep fascia, ramifying in which are some of the branches of the supraclavicular nerves. Beneath these supraficial structures are the sternohyoidius and the sternothyroidius which, together with the anterior margin of the sternocleidomastoidius, conceal the lower part of the common carotid artery. Footnote, therefore the common carotid artery and the internal jugular vein are not, strictly speaking, contained in this triangle, since they are covered by the sternocleidomastoidius, that is to say, they lie under that muscle which forms the posterior border of the triangle. But as they lie very close to the structures which are really contained in the triangle and whose position it is essential to remember in operating on this part of the artery, it is expedient to study the relations of all these parts together. End footnote. This vessel is enclosed within its sheath, together with the internal jugular vein and vagus nerve. The vein lies lateral to the artery on the right side of the neck, but overlaps it below on the left side. The nerve lies between the artery and vein, on a plane posterior to both. In front of the sheath are a few descending filaments from the ancehypoglossae. Behind the sheath are the inferior thyroid artery, the recurrent nerve, and the sympathetic trunk. And on its medial side, the esophagus, the trachea, the thyroid gland, and the lower part of the larynx. By cutting into the upper part of this space and slightly displacing the sternocleidomastoidius, the common carotid artery may be tied below the omohoidius. The superior carotid, or carotid triangle, is bounded behind by the sternocleidomastoidius, below by the superior belly of the omohoidius, and above by the stylohoidius, and the posterior belly of the digastricus. It is covered by the integument superficial fascia, platysma, and deep fascia, ramifying in which are branches of the facial and cuteness cervical nerves. Its floor is formed by parts of the thyroid hyoidius, hyoglossus, and the constrictor's pharyngeus medius and inferior. This space, when dissected, is seen to contain the upper part of the common carotid artery, which bifurcates opposite the upper border of the thyroid cartilage into the external and internal carotid. These vessels are somewhat concealed from view by the anterior margin of the sternocleidomastoidius, which overlaps them. The external and internal carotids lie side by side, the external being the more anterior of the two. The following branches of the external carotid are also met with in this space, the superior thyroid running forward and downward, the lingual directly forward, the external maxillary forward and upward, the occipital backward, and the ascending pharyngeal directly upward on the medial side of the internal carotid. The veins met with are the internal jugular, which lies on the lateral side of the common and internal carotid arteries, and veins corresponding to the above mentioned branches of the external carotid. This, the superior thyroid, the lingual, common facial, ascending pharyngeal, and sometimes the occipital, all of which end in the internal jugular. The nerves in this space are the following. In front of the sheath of the common carotid is the ramus descendants hypoglossi. The hypoglossal nerve crosses both the internal and external carotids above, curving around the origin of the occipital artery. Within the sheath, between the artery and vein, and behind both, is the vagus nerve, behind the sheath, the sympathetic trunk. On the lateral side of the vessels, the accessory nerve runs for a short distance before it pierces external clidomastoidias, and on the medial side of the external carotid, just below the hyoid bone, may be seen the internal branch of the superior laryngeal nerve, and still more inferiorly, the external branch of the same nerve. The upper portion of the larynx, and lower portion of the pharynx, are also found in the front part of this space. The sub-maxillary, or digastric, triangle corresponds to the region of the neck immediately beneath the body of the mandible. It is bounded above, by the lower border of the body of the mandible, and a line drawn from its angle to the mastoid process, below, by the posterior belly of the digastricus and the stylohioideus, in front, by the anterior belly of the digastricus. It is covered by the entanglement superficial fascia, platysma, and deep fascia, ramifying in which are branches of the facial nerve, and ascending filaments of the cuteness cervical nerve. Its floor is formed by the mylohioideus, hyoglossus, and constrictor pharyngeus superior. It is divided into an anterior and a posterior part by the stylo-mandibular ligament. The anterior part contains the sub-maxillary gland, superficial to which is the anterior facial vein, while embedded in the gland is the external maxillary artery, and its glandular branches. Beneath the gland, on the surface of the mylohioideus, are the sub-mental artery and the mylohioid artery and nerve. The posterior part of this triangle contains the external carotid artery, ascending deeply in the substance of the carotid gland. This vessel lies here in front of and superficial to the internal carotid, being crossed by the facial nerve, and gives off, in its course, the posterior auricular superficial temporal and internal maxillary branches. More deeply are the internal carotid, the internal jugular vein, and the vagus nerve, separated from the external carotid by the stylo-glossus and the stylo-pharyngeus, and the glossopharyngeal nerve. Footnote. The remark made about the inferior carotid triangle applies also to this one. The structures enumerated as contained in its posterior part lie, strictly speaking, beneath the muscles which form the posterior boundary of the triangle. But as it is very important to bear in mind their close relation to the carotid gland, all these parts are spoken of together. End footnote. The suprahioid triangle is limited behind by the anterior belly of the digastricus, in front by the middle line of the neck between the mandible and the hyoid bone, below by the body of the hyoid bone. Its floor is formed by the mylohioideus. It contains one or two lymph glands and some small veins, the latter unite to form the anterior jugular vein. Posterior triangle. The posterior triangle is bounded in front by the sternocleidomastoidius, behind by the anterior margin of the trapezius, its base is formed by the middle third of the clavicle, its apex by the occipital bone. The space is crossed about 2.5 cm above the clavicle by the inferior belly of the omohioideus, which divides it into two triangles, an upper or occipital and a lower or subclavian. The occipital triangle, the larger division of the posterior triangle, is bounded in front by the sternocleidomastoidius, behind by the trapezius, below by the omohioideus. Its floor is formed from the above downward by the splenius capitus, levator scapulae, and the scelinae medius and posterior. It is covered by the skin, the superficial and deep fashy, and by the platysma below. The accessory nerve is directed obliquely across the space from the sternocleidomastoidius, which it pierces, to the under surface of the trapezius, below the supraclavicular nerves and the transverse cervical vessels, and the upper part of the brachial plexus across this space. A chain of lymph glands is also found running along the posterior border of the sternocleidomastoidius from the mastoid process to the root of the neck. The subaclavian triangle, the smaller division of the posterior triangle, is bounded above by the inferior belly of the omohioideus, below by the clavicle. Its base is formed by the posterior border of the sternocleidomastoidius. Its floor is formed by the first rib with the first digitation of the serratus anterior. The size of the subaclavian triangle varies with the extent of attachment of the clavicular portions of the sternocleidomastoidius and trapezius, and also with the height at which the omohioideus crosses the neck. Its height also varies according to the position of the arm, being diminished by raising the limb on account of the ascent of the clavicle and increased by drawing the arm downward when that bone is depressed. This space is covered by the integument, the superficial and deep fasci and the platysma and crossed by the superclavicular nerves. Just above the level of the clavicle, the third portion of the subaclavian artery curves lateralward and downward from the lateral margin of the scalenus anterior across the first rib to the axilla, and this is the situation most commonly chosen for ligaturing the vessel. Sometimes this vessel rises as high as 4 cm above the clavicle. Occasionally, it passes in front of the scalenus anterior or pierces the fibres of that muscle. The subclavian vein lies behind the clavicle and is not usually seen in this space, but in some cases it rises as high as the artery and has even been seen to pass with that vessel behind the scalenus anterior. The brachial plexus of nerves lies above the artery and in close contact with it. Passing transversely behind the clavicle are the transverse scapular vessels and traversing its upper angle in the same direction the transverse cervical artery and vein. The external jugular vein runs vertically downward behind the posterior border of the sternocleidomastoidius to terminate in the subclavian vein. It receives the transverse cervical and transverse scapular veins which form a plexus in front of the artery and occasionally a small vein which crosses the clavicle from the cephalic. The small nerve to the subclavius also crosses this triangle about its middle and some lymph glands are usually found in the space. End of section 14, read by Carolyn Power. Section 15 of Grace Anatomy Part 3 This is a LibriVox recording, all LibriVox recordings on the public domain. For more information or to volunteer, please visit LibriVox.org, recording by Ellie. Anatomy of the Human Body Part 3 by Henry Gray The internal carotid artery, arteriocarotis interna. The internal carotid artery supplies the anterior part of the brain, the eye and its appendages and sends branches to the forehead and nose. Its size in the adult is equal to that of the external carotid, though in the child it is larger than that vessel. It is remarkable for the number of curvatures that it presents in different parts of its cause. It occasionally has one or two plexus near the base of the skull, while in its passage through the carotid canal and along the side of the body of the sphenoid bone it describes a double curvature and resembles the italic letter S. Cause and Relations In considering the cause and relations of this vessel, it may be divided into four portions, cervical, pedros, cavernous and cerebral. Cervical portion This portion of the internal carotid begins at the bifurcation of the coming carotid, opposite the upper border of the thyroid cartilage and runs perpendicularly upward in front of the transverse processes of the upper three vertebrae to the carotid canal in the pedros portion of the temporal bone. It is comparatively superficial at its commandment, where it is contained in the carotid triangle and lies behind and lateral to the external carotid, overlapped by the sternocleidomastodeus and carried by the tipvestia, platysma and entachement. It then passes beneath the carotid gland being crossed by the hypoclosal nerve with the digestricus and stelaehiadeus and the occipital and posterior auricular arteries. Higher up, it is separated from the external carotid by the styloclosus and styloferingius. The tip of the styloid process and the stylohiade ligament, the claustropharyngeal nerve, the pharyngeal branch of the vagus. It is in relation, behind, with the longest capitis, the superior cervical ganglion of the sympathetic trunk and the superior laryngeal nerve. Laterally, is the internal tracheular vein and vagus nerve, the nerve lying on a plain posterior to the artery. Medially, is the pharynx, superior laryngeal nerve and ascending pharyngeal artery. At the base of the skull, the claustropharyngeal, vagus, accessory and hypoclosal nerves lie between the artery and the internal tracheular vein. Petrose portion When the internal carotid artery enters the canal in the petrose portion of the temporal bone, it first ascends a short distance, then curves forward in medial ward and again ascends, as it leaves the canal to enter the cavity of the skull between the lingula and the petrosal process of the sphenoid. The artery lies at first in front of the cochlear and tympanic cavity. From the latter cavity, it is separated by a synbonilamela, which is creep reform in the young subject and often partially absorbed in old age. Further forward, it is separated from the similunar ganglion by a synblade of bone, which forms the floor of the fossa for the ganglion and the roof of the horizontal portion of the canal. Frequently, this bony blade is more or less deficient, and then the ganglion is separated from the artery by fibros membrane. The artery is separated from the bony wall of the carotid canal by a prolongation of the ramata and is surrounded by a number of small veins and by filaments of the carotid plexus, derived from the ascending branch of the superior cervical ganglion of the sympathetic trunk. Cavanaus portion. In this part of its course, the artery is situated between the layers of the ramata, forming the cavernous sinus, but covered by the lining membrane of the sinus. It at first ascends toward the posterior clinoid process, then passes forward by the side of the body of the sphenoid bone and again curves upward on the medial side to the anterior clinoid process and perforates the duramata forming the roof of the sinus. This portion of the artery is surrounded by filaments of the sympathetic nerve and on its lateral side is the abducent nerve. Cerebral portion. Having perforated the duramata on the medial side of the interior clinoid process, the internal carotid passes between the optic and ocular motor nerves to the interior perforated substance at the medial extremity of the lateral cerebral fissure, where it gives off its terminal or cerebral branches. Peculiarities. The lengths of the internal carotid varies according to the lengths of the neck and also according to the point of bifocation from the common carotid. It arises sometimes from the arch of the water. In such rare instances, this vessel has been found to be placed nearer the middle line of the neck than the external carotid, as far upward as the larynx when the latter vessel crossed the internal carotid. The course of the artery, instead of being straight, may be very torturous. A few instances are recorded in which this vessel was altogether absent. In one of these, the common carotid passed up the neck and gave off the usual branches of the external carotid. The cranial portion of the internal carotid was replaced by two branches of the internal maxillary, which entered the skull through the foramen rotundum and foramen ovale and joined to form a single vessel. Branches. The cervical portion of the internal carotid gives off no branches. Those from the other portions are from the pedros portion, keretico-tunpanic, artery of the pterigrid canal, from the cavernous portion, cavernous epiphyseal, semiluna, anterior meningeal of telmic. From the cerebral portion, anterior cerebral, middle cerebral, posterior communicating, corridor. One, the keretico-tunpanic branch. Remus keretico-tunpanicus. Tunpanic branch is small. It enters the tunpanic cavity through a minute foramen, the carotid canal, Anastomosis is the anterior tunpanic branch of the internal maxillary and with the stylomystoid artery. Two, the artery of the pterigrid canal. Aterior canalis pterigoidae, with the an artery. It's a small, inconstant branch which passes through the pterigrid canal and Anastomosis with the branch of the internal maxillary artery. Three, the cavernous branches are numerous small vessels, which supply the epiphysis, the semi-lunar ganglion, the walls of the cavernous, and inferior petrosal sinuses. Some of them, Anastomosis, branches of the middle meningeal. Four, the hypofusial branches. On one or two minute vessels, supplying the hypofusus. Five, the semi-lunar branches, are small vessels to the semi-lunar ganglion. Six, the anterior meningeal branch, aterior meningea anterior. It's a small branch which passes over the small wing of the sphenoid to supply the duramata of the anterior cranial fossa. It anastomosis with the meningeal branch from the posterior etymoidal artery. Seven, the oftalmic artery, aterior oftalmica, arises from the internal carotid just as the vessel is emerging from the cavernous sinus on the medial side of the interior clenoid process, and enters the optical cavity through the optic foramen below and lateral to the optic nerve. It then passes over the nerve to reach the medial wall of the orbit and then horizontally forward beneath the lower border of the obliques superior and divides it into two terminal branches, the frontal and the dorsal nasal. As the artery crosses the optic nerve it is accompanied by the nasociliary nerve, and is separated from the frontal nerve by the rectus superior and the levator palpebrae superioris. Branches. The branches of the oftalmic artery may be divided into an orbital group distributed to the orbit with the surrounding parts in an ocular group through the muscles and bulb of the eye. Orbital group. Lekrimal, supra-orbital, posterior etymoidal, interior etymoidal, medial palpebrae, frontal, dorsal nasal. Ocular group. Central artery of the retina short posterior ciliary, long posterior ciliary, muscular. The lacrimal artery, arterial lacrimalis, arises from the optic foramen and is one of the largest branches derived from the oftalmic. Not infrequently, it is given off before the artery enters the orbit. It accompanies the lacrimal nerve along the upper border of the rectus lateralis and supplies the lacrimal gland. Its terminal branches, escaping from the gland, are distributed to the eyelids and conjunctiva. Of those supplying the eyelids, two are of considerable size and are named the lateral palpebrae arteries. They run medial rod in the upper and lower lids respectively and endostomals with the medial palpebrae arteries, forming an arterial circling its situation. The lacrimal artery gives off one or two psychometric branches, one of which passes through the psychometric or temporal foramen to reach the temporal fossa and endostomosis with the tipped temporal arteries. Another appears on the cheek through the psychometric or facial foramen and endostomosis is the transverse facial. A recurrent branch passes backward through the lateral part of the superior orbital fissure to the duoramata and endostomosis is the branch of the middle meningeal artery. The lacrimal artery is sometimes derived from one of the anterior branches of the middle meningeal artery. In the supra-orbital artery, ethyria supra-orbitalis comes from the ophthalmic as that vessel is crossing over the optic nerve. It passes upward to the medial borders of the rectus superior and levator palpebrae and meeting the supra-orbital nerve accompanies it between the periostrum and levator palpebrae to the supra-orbital foramen. Passing through this, it divides into a superficial in the deep branch which supplied in tecument the muscles in the perigranium of the forehead endostomosing is the frontal branch of the superficial temporal and the artery of the opposite side. This artery in the orbit supplies the rectus superior and the levator palpebrae and sends the branch across the pulley to the obliques superior to supply the parts of the medial palpebral commissure. At the supra-orbital foramen, it frequently transmits a branch to the diploid. The etymodal arteries are two in number, posterior and anterior. The posterior etymodal artery, the smaller, passes through the posterior etymodal canal, supplies the posterior etymodal cells and, entering the cranium, gives off a meningeal branch to the duramata and nasal branches which descend into the nasal cavity through the aparchus and the crepoform plate. Endostomosing is branches of the sphenopalatine. The interior etymodal artery accompanies the nasociliary nerve through the interior etymodal canal, supplies the interior middle etymodal cells and frontal sinus and, entering the cranium, gives off a meningeal branch to the duramata and nasal branches this letter descend into the nasal cavity through the slit by the side of the crystal gully. And running along the groove on the inner surface of the nasal bone, supply branches to the lateral wall and septum of the nose and the terminal branch which appears on the dorsum of the nose between the nasal bone and the lateral cartilage. The medial palpebral arteries, atere palpebralis medialis, internal palpebral arteries, twin number superior and inferior arise from the aftermic opposite the pulley of the obliquous superior. They leave the orbit to encircle the eyelids near their free margins forming a superior and an inferior arch which lie between the obicularis oculi and the tarsi. The superior palpebral anastomosis at the lateral angle of the orbit is the psychometric orbital branch of the temporal artery and with the upper two of the two lateral palpebral branches from the lacrimal artery. The inferior palpebral anastomosis at the lateral angle of the orbit is the lower of the two lateral palpebral branches from the lacrimal and with the transverse facial artery and at the medial part of the lid is the branch from the angular artery. From this last anastomosis a branch passes to the nasal lacrimal duct hemifying in its mucous membrane as far as the inferior myatus of the nasal cavity. The frontal artery, arterial frontalis is one of the terminal branches of the othermic. It leaves the orbit at its medial angle with the supratrochlear nerve and ascending to the forehead supplies the integument, muscles and perigranium anastomosing with the suprorbital artery and with the artery of the opposite side. The dorsal nasal artery, arterial dorsalis nasi, nasal artery. The other terminal branch of the othermic emerges from the orbit above the medial palpebral ligament. And after giving a tweak to the upper part of the lacrimal sac divides into two branches one of which crosses the root of the nose and the anastomosis with the angular artery. The other runs along the dorsum of the nose supplies its outer surface and the anastomosis is the artery of the opposite side and with the lateral nasal branch of the external artery. The central artery of the retina, the first and one of the smallest branches of the othermic artery. It runs for a short distance within the dual sheets of the optic nerve but about 2.25 cm behind the eyeball it pierces the nerve obliquely and runs forward in the center of its substance to the retina. Its mode of distribution will be described with the anatomy of the eye. The ciliares arteries arteria ciliares are divisible into three groups the long and short, posterior anterior. The short posterior ciliares arteries from 6 to 12 in number arise from the othermic or its branches. They pass forward around the optic nerve to the posterior part of the eyeball pierce the sclera around the entrance of the nerve and supply the coroid in ciliares processes. The long posterior ciliares arteries to in number pierce the posterior part of the sclera at some distance from the optic nerve and run forward along either side of the eyeball between the sclera and the coroid to the ciliares muscle where they divide into two branches. These form an anterior circle, the circular arteriosus minor, around the circumference of the iris. From which numerous converging branches run, the substance of the iris to its popular margin where they form a second arterial circle the circular arteriosus minor. The anterior ciliares arteries are derived from the muscular branches. They run to the front of the eyeball in company with the tendons of the recti. Form a vascular zone beneath the conjunctiva and then pierce the sclera a short distance from the cornea and end in the circular arteriosus minor. The muscular branches, remi muscularis, to in number superior and inferior, frequently spring from a common trunk. The superior, often wanting, supplies the levator palpeperis superioris, rectus superior and obliquus superior. The inferior were constantly present passes forward between the optic nerve and the rectus inferior and is distributed to the rectilateralis, medialis and inferior and the obliquus inferior. This vessel gives off most of the anterior ciliares arteries. Additional muscular branches are given off from the lecramoral and the supra-orbital arteries or from the trunk of the oftalmic. 8. Interior cerebral artery, arterial cerebrine anterior, coronal keratid at the medial extremity of the lateral cerebral fissure. It passes forward in medial across the interior perforated substance above the optic nerve to the commandment of the longitudinal fissure. Here it comes into close relationship with the opposite artery to which it is connected by a short trunk, the interior communicating artery. From this point the two vessels run side by side in the longitudinal fissure. Curve around the gano of the corpus callusum and turning backward, continue along the upper surface of the corpus callusum to its posterior part where they end by anistomosing the posterior cerebral arteries. 9. Branches. In its course the interior cerebral artery gives off the following branches. Interior medial ganglionic, anterior, posterior, inferior and middle. The interior medial ganglionic branches form a group of small arteries which arise at the commandment of the interior cerebral artery. They pierce the interior perforated substance and laminar terminalis and supply the rostrum of the corpus callusum, the septum pellucidum and the head of the codate nucleus. The inferior branches 2 and 3 in number are distributed to the orbital surface of the frontal lobe where they supply the olfactory lobe, gyrus rectus and internal orbital gyrus. The interior branches supply a part of the superior frontal gyrus and send twigs over the edge of the hemisphere to the superior middle frontal gyrus and upper part of the interior central gyrus. The middle branches supply the corpus callusum, the singular gyrus, the medial surface of the superior frontal gyrus and the upper part of the interior central gyrus. The posterior branches supply the precunius and the adjacent lateral surface of the hemisphere. The interior communicating artery, arterial communicant's interior connects the two interior cerebral arteries across the commandment of the longitudinal fissure. Sometimes this vessel is wanting. The two arteries joining together to form a single trunk which afterwards divides or it may be wholly or partially divided into two. Its length averages about 4 mm but varies greatly. It gives off some of the intermedial ganglionic vessels but these are principally derived from the interior cerebral. 9. The middle cerebral artery, a posterior cerebral media, the largest branch of the internal carotid runs at first lateral valve in the lateral cerebral oesilvian fissure and then backward and upward to the surface of the insular where it divides into a number of branches which are distributed to the lateral surface of the cerebral hemisphere. Branches. The branches of this vessel are interlateral ganglionic, inferior lateral frontal, ascending frontal, ascending perietal, perietotemporal and temporal. The interlateral ganglionic branches, a group of small arteries which arise at the commandment of the middle cerebral artery are arranged in two sets. 1. The internal striate passes upwards through the inner segments of the lentiform nucleus and supplies it. The carotid nucleus and the internal capsule. The other, the external striate, ascends through the outer segment of the lentiform nucleus and supplies the carotid nucleus and telomeres. One artery of this group is of larger size than the rest and is of special importance as being the artery in the brain most frequently ruptured. It has been termed by Charcot the artery of cerebral hemorrhage. It ascends between the lentiform nucleus and the external capsule and ends in the carotid nucleus. The inferior lateral frontal supplies the inferior frontal gyrus, procused convolution and the lateral part of the orbital surface of the frontal lobe. The ascending frontal supplies the interior central gyrus. The ascending parietal is distributed to the posterior central gyrus in the lower part of the superior parietal lobe rule. The parietotemporal supplies the supramaginal and angular gyrus. The parietotemporal supplies the supramaginal and angular gyrus. And posterior parts of the superior and middle temporal gyrus. The temporal branches, 2 or 3 number are distributed to the lateral surface of the temporal lobe. 10. The posterior communicating artery a teriocommunicons posterior runs backward from the internal carotid and anestomosis is the posterior cerebral a branch of the basilar. It varies in size being sometimes small and occasionally so large that the posterior cerebral may be considered as arising from the internal carotid rather than from the basilar. It is frequently larger on one side than on the other. From its posterior half a given of a number of small branches the posterior medial ganglionic branches which with similar vessels from the posterior cerebral pierce the posterior perforated substance and supply the medial surface of the talami and the walls of the third ventricle. 11. The anterior corital coroid artery is a small but constant branch which arises from the internal carotid near the posterior communicating artery. Passing backward and lateral rod between the temporal lobe and the cerebral peduncle it enters the inferior horn of the lateral ventricle through the coroidal fissure and ends in the coroid plexus. It is distributed to the hippocampus fimbria tiller coroidia of the third ventricle and coroid plexus. 12. End of section 15 recording by Ellie Section 16 of Grey's Anatomy Part 3. 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 3 by Henry Grey The Arteries of the Brain Since the mode of distribution of the vessels of the brain has an important bearing upon the considerable number of pathological lesions which may occur in this part of the nervous system it is important to consider a little in more detail the manner in which the vessels are distributed. The cerebral arteries are derived from the internal carotid and vertebral which at the base of the brain form a remarkable anastomosis known as the arterial circle of Willis. It is formed in front by the anterior cerebral arteries branches of the internal carotid together by the anterior communicating behind by the two posterior cerebral arteries, branches of the basilar which are connected on either side with the internal carotid by the posterior communicating. The parts of the brain included within this arterial circle are the lamina terminalis, the optic chiasma, the infundibulum, the tuberosinirium, the corpore mammalaria, and the posterior perforated substance. The three trunks which together supply each cerebral hemisphere arise from the arterial circle of Willis. From its anterior part proceed the two anterior cerebrals from its anterior lateral parts the middle cerebrals, and from its posterior part the posterior cerebrals. Each of these principal arteries gives origin to two different systems of secondary vessels. One of these is named the ganglionic system and the vessels belonging to it supply the thalamine and corpore striata. The other is the cortical system and its vessels ramify in the Pia matyr and supply the cortex and sub- adjacent brain substance. These two systems do not communicate at any point of their peripheral distribution but are entirely independent of each other and there is between the parts supplied by the two systems a borderland of diminished nutritive activity where it is said softening is especially liable to occur in the brains of old people. The ganglionic system. All the vessels of this system are given off from the arterial circle of Willis or from the vessels close to it. They form six principal groups. One, the anterior medial group derived from the anterior cerebrals and anterior communicating. Two, the posterior medial group from the posterior cerebrals and posterior communicating. Three and four the right and left anterior lateral groups from the middle cerebrals and five and six the right and left posterior lateral groups from the posterior cerebrals after they have wound around the cerebral peduncles. The vessels of this system are larger than those of the cortical system and are what Coulnheim designated terminal arteries. That is to say vessels from which they're origin to their termination neither supply nor receive any anesthetic branch. So that through any one of the vessels only a limited area of the thalamus or corpus triatum can be injected and the injection cannot be driven beyond the area of the part supplied by the particular vessel which is the subject of the experiment. The cortical arterial system the vessels forming this system are the terminal branches of the anterior, middle and posterior cerebral arteries. They divide and ramify in the substance of the Pia mater and give off branches which penetrate the brain cortex perpendicularly. These branches are divisible into two classes long and short. The long or medullary arteries pass through the gray substance and penetrate the sub adjacent white substance to the depth of three or four centimeters without intercommunicating otherwise than by very fine capillaries and thus constitute so many independent small systems. The short vessels are confined to the cortex where they form with the long vessels a compact network in the middle zone of the gray substance. The outer and inner zones being sparingly supplied with blood. The vessels of the cortical arterial system are not so strictly terminal as those of the ganglionic system but they approach this type very closely so that injection of one area from the vessel of another area though possible is frequently very difficult and is only affected through vessels of small caliber. As a result of this obstruction of one of the main branches or its divisions may have the effect of producing softening in a limited area of the cortex. End of section 16 Section number 17 of Gray's Anatomy Part 3 This is a LibriVox recording All LibriVox recordings are in the public domain. For more information or to volunteer please visit LibriVox.org Recording by Morgan Scorpion Anatomy of the Human Body Part 3 by Henry Gray Arteries of the upper extremity the subclavian artery Part 1 The artery which supplies the upper extremity continues as a single trunk from its commencement down to the elbow but different portions of it have received different names according to the regions through which they pass. The part of the vessel which extends from its origin to the outer border of the first rib is termed the subclavian. Beyond this point to the lower border of the axilla it is named the axillary and from the lower margin of the axillary space to the bend of the elbow it is termed brachial. Here the trunk ends by dividing into two branches, the radial and ulna. The subclavian artery Arteria subclavia On the right side the subclavian artery arises from the inominate artery behind the right sternoclavicular articulation. On the left side it springs from the arch of the aorta. The two vessels therefore in the first part of their course differ in length, direction and relation with neighbouring structures. In order to facilitate the description each subclavian artery is divided into three parts. The first portion extends from the origin of the vessel to the medial border of the scalinus anterior. The second lies behind this muscle and the third extends from the lateral margin of the muscle to the outer border of the first rib where it becomes the axillary artery. The first portions of the two vessels have different descriptions. The second and third parts of the two arteries are practically alike. First part of the right subclavian artery The first part of the right subclavian artery arises from the inominate artery behind the upper part of the right sternoclavicular articulation and passes upward and lateralward to the medial margin of the scalinus anterior. It extends a little above the clavicle the extent to which it does so varying in different cases. Relations It is covered, in front by the integument, superficial fascia platysma, deep fascia the clavicular origin of the sternocleidomastoid deus the sternohiodeus and sternothiodeus and another layer of the deep fascia. It is crossed by the internal jugular and vertebral veins by the vagus nerve and the cardiac branches of the vagus and sympathetic subclavian loop of the sympathetic trunk which forms a ring around the vessel. The anterior jugular vein is directed lateralward in front of the artery but is separated from it by the sternohiodeus and sternothiodeus. Below and behind the artery is the pleura which separates it from the apex of the lung. Behind is the sympathetic trunk the longus culli and the first thoracic vertebra. The right recurrent nerve winds around the lower and back part of the vessel. First part of the left subclavian artery The first part of the left subclavian artery arises from the arch of the aorta behind the left common carotid and at the level of the fourth thoracic vertebra. It ascends in the superior mediastinal cavity to the root of the neck and then arches lateralward to the medial border of the scalinas anterior. Relations It is in relation in front with the vagus, cardiac and phrenic nerves which lie parallel with it. The left common carotid artery left internal jugular and vertebral veins and the commencement of the left inominate vein and is covered by the sternothiodeus sternohiodeus and sternoclydomastoidase. Behind it is in relation with the esophagus thoracic duct left recurrent nerve inferior cervical ganglion of the sympathetic trunk and longus colli. Higher up however, the esophagus and thoracic duct lie to its right side the latter ultimately arching over the vessel to join the angle of union between the subclavian and internal jugular veins. Medial to it are the esophagus, trachea, thoracic duct and left recurrent nerve. Lateral to it, the left pleura and lung. Second and third parts of the subclavian artery The second portion of the subclavian artery lies behind the scalenus anterior. It is very short and forms the highest part of the arch described by the vessel. Relations It is covered in front by the skin, superficial fascia, platysma, deep cervical fascia, sternoclydomastoidase and scalenus anterior. On the right side of the neck the phrenic nerve is separated from the second part of the artery by the scalenus anterior while on the left side it crosses the first part of the artery close to the medial edge of the muscle. Behind the vessel are the pleura and the scalenus medius above the brachial plexus of nerves below the pleura. The subclavian vein lies below and in front of the artery separated from it by the scalenus anterior. The third portion of the subclavian artery runs downward and lateral from the lateral margin of the scalenus anterior to the border of the first rib where it becomes the axillary artery. This is the most superficial portion of the vessel and is contained in the subclavian triangle. Relations It is covered in front by the skin, the superficial fascia, the platysma, the supraclavicular nerves and the deep cervical fascia. The external jugular vein crosses its medial part and receives the transverse scapula, transverse cervical and anterior jugular veins, which frequently form a plexus in front of the artery. Behind the veins the nerve to the subclavius descends in front of the artery. The terminal part of the artery lies behind the clavicle and the subclavius and is crossed by the transverse scapula vessels. The subclavian vein is in front of and at a slightly lower level than the artery. Behind it lies on the lowest trunk of the brachial plexus which intervenes between it and the venous medius. Above and to its lateral side are the upper trunks of the brachial plexus and the umohaui oteus. Below it rests on the upper surface of the first rib. Peculiarities The subclavian arteries vary in their origin, their course, and the height to which they rise in the neck. The origin of the right subclavian from the enominate takes place in some cases above the sternoclavicular articulation originally but less frequently below that joint. The artery may arise as a separate trunk from the arch of the aorta and in such cases it may be either the first, second, third, or even the last branch derived from that vessel. In the majority, however, it is the first or last, rarely the second or third. When it is the first branch it occupies the ordinary position of the enominate artery. When the second or third, it is behind the right carotid and when the last branch it arises from the left extremity of the arch and passes obliquely toward the right side usually behind the trachea esophagus and right carotid sometimes between the esophagus and trachea to the upper border of the first rib when it follows its ordinary course. In very rare instances this vessel arises from the thoracic aorta as low down as the fourth thoracic vertebra. Occasionally it perforates the scalenus anterior more rarely it passes in front of that muscle. Sometimes the subclavian vein passes with the artery behind the scalenus anterior. The artery may ascend as high as 4 cm above the clavicle or any intermediate point between this and the upper border of the bone. The right subclavian usually ascending higher than the left. The left subclavian is occasionally joined at its origin with the left carotid. The left subclavian artery is more deeply placed than the right in the first part of its course and as a rule does not reach quite as high a level in the neck. The posterior border of the sternocleidomastoid deus corresponds pretty closely to the lateral border of the scalenus anterior so that the third portion of the artery the part most accessible for operation lies immediately lateral to the posterior border of the sternocleidomastoid deus. Collateral circulation After ligature of the third part of the subclavian artery the collateral circulation is established mainly by three sets of vessels thus described in a dissection. 1. A posterior set consisting of the transverse scapula and the descending ramus of the transverse cervical branches of the subclavian and astromosing with the sub scapula from the axillary. 2. A medial set produced by the connection of the internal mammary on the one hand with the highest intercostal lateral thoracic arteries and the branches from the sub scapula on the other. 3. A middle or axillary set consisting of a number of small vessels derived from branches of the subclavian above and passing through the axilla terminating either in the main trunk or some of the branches of the axillary below. This last set presented most conspicuously the peculiar character of newly formed or rather dilated arteries being excessively tortuous and forming a complete plexus. The chief agent in the restoration of the axillary artery below the tumour was the sub-scapular artery which communicated most freely with the internal mammary transverse scapula and descending ramus of the transverse cervical branches of the subclavian from all of which it received so great an influx of blood as to dilate it to three times its natural size. Footnote Guy's Hospital reports Volume 1, 1836 case of axillary aneurysm in which Aston Key had tied the subclavian artery on the lateral edge of the scalinus anterior twelve years previously. End of footnote When a ligature is applied to the first part of the subclavian artery the collateral circulation is carried on by 1. The anastomosis between the superior and inferior thyroids 2. The anastomosis 3. The anastomosis of the internal mammary with the inferior epigastric and the aortic intercostals 4. The cost of cervical anastomosing with the aortic intercostals 5. The profunda cervicus anastomosing with the descending branch of the occipital 6. The scapula branches of the thyrocervical trunk anastomosing with the branches of the axillary and 7. The thoracic branches of the axillary anastomosing with the aortic intercostals 7. Branches The branches of the subclavian artery are vertebral thyrocervical internal mammary costoservical On the left side all four branches generally arise from the first portion of the vessel but on the right side the costoservical trunk usually springs from the second portion of the vessel On both sides of the neck the first three branches arise close together at the medial border of the scaliness anterior in the majority of cases a free interval of from 1.25 to 2.5 cm exists between the commencement of the artery and the origin of the nearest branch 1. The vertebral artery arteria vertebralis is the first branch of the subclavian and arises from the upper and back part of the first portion of the vessel by a plexus of nerve fibres derived from the inferior cervical ganglion of the sympathetic trunk and ascends through the foramina in the transverse processes of the upper six cervical vertebrae 4. Footnote The vertebral artery sometimes enters the foramin in the transverse process of the fifth vertebra and has been seen entering that of the seventh vertebra End of footnote It then winds behind the superior articular process and entering the skull through the foramin magnum unites at the lower border of the pons with the vessel of the opposite side to form the basilar artery Relations The vertebral artery may be divided into four parts The first part runs upward and backward between the longest collar and the scaliness anterior In front of it are the internal jugular and vertebral veins and it is crossed by the inferior thyroid artery, the left vertebral and the thoracic duct also Behind it are the transverse process of the seventh cervical vertebra the sympathetic trunk and its inferior cervical ganglion The second part runs upward through the foramina in the transverse processes of the upper sixth cervical vertebrae and is surrounded by branches from the inferior cervical sympathetic ganglion and by a plexus of veins which unite to form the vertebral vein at the lower part of the neck It is situated in front of the trunk of the cervical nerves and pursues an almost vertical course as far as the transverse process of the atlas above which it runs upward and lateralward to the foramina in the transverse process of the atlas The third part is used from the lateral foramina on the medial side of the rectus capitis lateralis and curves backward behind the superior articular process of the atlas the anterior ramus of the first cervical nerve being on its medial side It then lies in the groove of the upper surface of the posterior arch of the atlas and enters the vertebral canal by passing between the posterior atlantaoccipital membrane This part of the artery is covered by the semispinalis capitis and is contained in the suboccipital triangle a triangular space bounded by the rectus capitis posterior major the oblicuous superior and the oblicuous inferior The first cervical or suboccipital nerve lies between the artery and the posterior arch of the atlas The fourth part pierces the duomata and inclines medial wood to the front of the medulla of longata It is placed between the hypoglossal nerve and the anterior root of the first cervical nerve and beneath the first digitation of the ligamentum denticulatum At the lower border of the pons it unites with the vessel of the opposite side to form the basilar artery Branches The branches of the vertebral artery may be divided into two sets those given off at the neck and those within the cranium cervical branch spinal, cranial branches meningeal cervical branch muscular, cranial branches posterior spinal anterior spinal posterior inferior cerebellum medullary spinal branches Ramai spinalis enter the vertebral canal through the intervertebral foramina of these one passes along the roots of the nerves to supply the medulla spinalis and its membranes anastomosing with the other arteries of the medulla spinalis The other divides into an ascending and a descending branch which unites with similar branches from the arteries above and below so that two lateral anastomotic chains are formed on the posterior surfaces of the bodies of the vertebrae near the attachment of the pedicles From these anastomotic chains are supplied to the periosteum and the bodies of the vertebrae and others form communications with similar branches from the opposite side From these communications small twigs arise which join similar branches above and below to form a central anastomotic chain on the posterior surface of the bodies of the vertebrae Muscular branches are given off to the deep muscles of the neck where the vertebral artery curves around the articular process of the atlas the anastomose with the occipital of the spine and deep cervical arteries The meningeal branch Ramus meningis Posteria meningeal branch Springs from the vertebral opposite the foramen magnum ramifies between the bone and uramata in the cerebellar fossa and supplies the fulc cerebelli It is frequently represented by one or two small branches The posterior spinal artery A spinalis posterior dorsal spinal artery and the vertebral at the side of the medulla oblongata Passing backward it descends on this structure lying in front of the posterior roots of the spinal nerves and is reinforced by a succession of small branches which enter the vertebral canal through the intervertebral foramina By means of these it is continued to the lower part of the medulla spinalis and to the corda equina Branches from the posterior spinal arteries form a free anastomosis around the posterior roots of the spinal nerves which communicate by means of very torturous transverse branches with the vessels of the opposite side Close to its origin each gives off an ascending branch which ends at the side of the fourth ventricle The anterior spinal artery Arteriospinalis anterior Vental spinal artery is a small branch which arises near the termination of the vertebral and descending in front of the medulla oblongata unites with its fellow of the opposite side at the level of the foramin magnum One of these vessels is usually larger than the other but occasionally they are about equal in size The single trunk, thus formed descends on the front of the medulla spinalis and is reinforced by a succession of small branches which enter the vertebral canal through the intervertebral foramina These branches are derived from the vertebral and the ascending cervical of the inferior thyroid at the neck From the intercostalis in the thorax and from the lumbar, iliolumbar and lateral sacral arteries in the abdomen and pelvis They are unite by means of ascending and descending branches to form a single anterior median artery which extends as far as the lower part of the medulla spinalis and is continued as a slender twig on the filum terminale This vessel is placed in the piermata along the anterior median fissure It supplies that membrane of the medulla spinalis and sends off branches at its lower part to be distributed to the corda equina The posterior inferior cerebellar artery Arterio cerebelli inferior posterior the largest branch of the vertebral winds backward around the upper part of the medulla oblongata passing between the origins of the vagus and accessory nerves over the inferior peduncle to the under surface of the cerebellum where it divides into two branches The medial branch is continued backward to the notch between the two hemispheres of the cerebellum while the lateral supplies the under surface of the cerebellum As far as its lateral border where it anastomoses with the anterior inferior cerebellar and the superior cerebellar branches of the basilar artery Branches from this artery supply the coid plexus of the fourth ventricle The medullary arteries bulma arteries are several minute vessels of the vertebral and its branches and are distributed to the medulla oblongata End of section number 17 Section 18 of Grey's Anatomy Part 3 This is a LibriVox recording All LibriVox recordings are in the public domain For more information or to volunteer please visit LibriVox.org Recording by Morgan Scorpion Anatomy of the Human Body Part 3 by Henry Gray The subclavian artery Part 2 The basilar artery, arteria basilaris so named from its position at the base of the skull is a single trunk formed by the junction of the two vertebral arteries It extends from the lower to the upper border of the pons lying in its median groove under cover of the arachnoid It ends by dividing into the two posterior cerebral arteries Branches on either side are the following pontine, anterior inferior cerebellar internal auditory superior cerebellar posterior cerebral The pontine branches Reimi ad pontem transverse branches are a number of small vessels which come off at right angles from either side of the basilar artery and supply the pons and adjacent parts of the brain The internal auditory artery Arterius auditiva interna auditory artery A long slender branch arises from near the middle of the artery It accompanies the acoustic nerve through the internal acoustic meadows and is distributed to the internal ear The anterior inferior cerebellar artery Arterius cerebelli inferior anterior passes backward to be distributed to the anterior part of the under surface of the cerebellum and astromosing with the posterior inferior cerebellar artery Arterius cerebelli superior arises near the termination of the basilar It passes lateralward immediately below the ocular motor nerve which separates it from the posterior cerebral artery Wines around the cerebral peduncle close to the trochlear nerve and, arriving at the upper surface of the cerebellum, divides into branches which remify in the pia-matter and anastomose which is the upper surface of the cerebellum which remify in the pia-matter and anastomose with those of the inferior cerebellar arteries Several branches are given to the pineal body the anterior medullary vellum and the telecooidaea of the third ventricle The posterior cerebral artery Arterius cerebri posterior is larger than the proceeding from which it is separated near its origin by the ocular motor nerve Passing lateralward parallel to the superior cerebellar artery and receiving the posterior communicating from the internal carotid it winds around the cerebral peduncle and reaches the tentorial surface of the occipital lobe of the cerebrum where it breaks up into branches for the supply of the temporal and occipital lobes The branches of the posterior cerebral artery are divided into two sets ganglionic and cortical ganglionic posterior medial posterior cooidal posterior lateral cortical posterior temporal calcarene parieteroxipital ganglionic The posterior medial ganglionic branches are a group of small arteries which arise at the commencement of the posterior cerebral artery These, with similar branches from the posterior communicating pierce the posterior perforated substance and supply the medial surfaces of the retinae and the walls of the third ventricle Posterior cooidal branches run forward beneath the splenium of the corpus callosum and supply the telocooidaea of the third ventricle and the cooid plexus The posterior lateral ganglionic branches are small arteries which arise from the posterior cerebral artery after it has turned around the cerebral peduncle They supply a considerable portion of the phalamus Cortical The cortical branches are the anterior temporal distributed to the uncus and the anterior part of the fusiform gyrus The posterior temporal to the fusiform and the inferior temporal gyrus The calcarene to the cuneus and gyrus lingualis and the back part of the convex surface of the occipital lobe and the parieterooccipital to the cuneus and the precuneus 2. The thioservical trunk Truncus thioservicalis thyroid axis is a short, thick trunk which arises from the front of the first portion of the subclavian artery close to the medial border of the sculliness anterior and divides almost immediately into three branches The inferior thyroid transverse scapula and transverse cervical The inferior thyroid artery Arteria thyroidaea inferior passes upward in front of the vertebral artery and longest collie then turns medial wood behind the carotid sheath and its contents and also behind the sympathetic trunk the middle cervical ganglion resting upon the vessel Reaching the lower border of the thyroid gland it divides into two branches which supply the postor inferior parts of the gland and anastomers with the superior thyroid and with the corresponding artery of the opposite side The recurrent nerve passes upward generally behind but occasionally in front of the artery The branches of the inferior thyroid are inferior laryngeal tracheal esophageal ascending cervical muscular The inferior laryngeal artery Arteria laryngea inferior ascends upon the trachea to the back part of the larynx under cover of the constrictor pharingis inferior in company with the recurrent nerve and supplies the muscles and mucous membrane of this part anastomosing with the branch from the opposite side and with the superior laryngeal branch of the superior thyroid artery The tracheal branches Raymy trachealis are distributed upon the trachea and anastomose below with the bronchial arteries The esophageal of branches Raymy esophageal supply the esophagus and anastomose with the esophageal branches of the aorta The ascending cervical artery Arteria cervicalis ascendance is a small branch which arises from the inferior thyroid as that vessel is passing behind the carotid sheath It runs up on the anterior tubercles of the transverse processes of the cervical vertebrae in the interval between the scalinas anterior and longest capitis To the muscles of the neck it gives twigs which anastomose with branches of the vertebral and it sends one or two spinal branches into the vertebral canal through the intervertebral foramina to be distributed to the medulla spinalis and its membranes and to the bodies of the vertebrae and the spinal branches from the vertebral It anastomoses with the ascending pharyngeal and occipital arteries The muscular branches supply the depressors of the hyoid bone and the longest collie, scalinas anterior and constrictor pharyngis inferior The transverse scapular artery Arteria transversa scapulae suprascapular artery passes at first downward and lateral across the scalinas anterior and phrenic nerve being covered by the sternocleidomastoidaeus It then crosses the subclavian artery and the brachial plexus and runs behind in parallel with the clavicle and the subclavius and beneath the inferior belly of the omohiodaeus to the superior border of the scapula It passes over the superior transverse ligament of the scapulae which separates it from the suprascapular nerve and enters the supraspinatus fossa In this situation it lies close to the bone and ramifies between it and the supraspinatus to which it supplies branches It then descends behind the neck of the scapula through the great scapular notch and under cover of the inferior transverse ligament to reach the infaspinatus fossa where it anastomoses with the scapula circumflex and the descending branch of the transverse cervical Besides distributing branches to the sternocleidomastoidaeus subclavius and neighboring muscles it gives off a suprasternal branch which crosses over the sternal end of the clavicle under the skin of the upper part of the chest and an acromial branch which pierces the trapezius and supplies the skin over the acromion anastomosing with the thoracoacromial artery As the artery passes over the superior transverse ligament of the scapula it sends a branch into the subscapular fossa where it ramifies beneath the subscapularis and anastomoses with the subscapular artery and with the descending branch of the transverse cervical It also sends articular branches to the acromioclavicular and shoulder joints and a nutrient artery to the clavicle The transverse cervical artery Arteriotransversa coli transversalis coli artery lies at a higher level than the transverse scapula It passes transversely above the inferior belly of the omohiodaeus to the anterior margin of the trapezius beneath which it divides into an ascending and a descending branch It crosses in front of the phrenic nerve and the scalene and in front of or between the divisions of the brachial plexus and is covered by the platysma and sternocleidomastoidaeus and cost by the omohiodaeus and trapezius The ascending branch Remus ascendens superficial cervical artery ascends beneath the anterior margin of the trapezius distributing branches to it and to the neighbouring muscles Anastomosing with the superficial branch of the descending remus of the occipital artery The descending branch Remus descendens posterior scapula artery passes beneath the levita scapulae to the medial angle of the scapula and then descends under the rhomboidae along the vertical border of that bone as far as the inferior angle It supplies the rhomboidae, latissimus dorsae and trapezius and anastomoses with the transverse scapula and subscapular arteries and posterior branches of some of the intercostal arteries peculiarities The ascending branch of the transverse cervical frequently arises directly from the thyroservical trunk and the descending branch from the third more rarely from the second part of the subclavian The internal mammary artery arteria mammaria interna arises from the under surface of the first portion of the subclavian opposite the thyroservical trunk It descends behind the cartilages of the upper six ribs at a distance of about 1.25 cm from the margin of the sternum and at the level of the sixth intercostal space divides into the muscular phrenic and superior epigastric arteries relations It is directed at first downward forward and medial wood behind the sternal end of the clavicle the subclavian and internal jugular veins and the first coastal cartilage and passes forward close to the lateral side of the inominate vein As it enters the thorax the phrenic nerve crosses from its lateral to its medial side Below the first coastal cartilage it descends almost vertically to its point of bifurcation It is covered in front by the cartilages of the upper six ribs and the intervening intercostalis interne and anterior intercostal membranes and is crossed by the terminal portions of the upper six intercostal nerves It rests on the pleura as far as the third coastal cartilage below this level upon the transversus thoracus It is accompanied by a pair of veins These unite above to form a single vessel which runs medial to the artery and ends in the corresponding inominate vein Branches The branches of the internal mammary are pericardiacophrenic anterior medial steinal pericardial sternal intercostal perforating muscular phrenic superior epigastric The pericardiacophrenic artery arteria pericardiacophrenica arteria cometh nervi phrenicii is a long slender branch which accompanies the phrenic nerve between the pleura and pericardium to the diaphragm to which it is distributed It anastomoses with the muscular phrenic and inferior phrenic arteries The anterior medial steinal arteries AA medial steinalis anterioris medial steinal arteries are small vessels distributed to the aureolytis and lymph glands in the anterior medial steinal cavity and to the remains of the thymus The pericardial branches supply the upper part of the anterior surface of the pericardium The lower part receives branches from the muscular phrenic artery The sternal branches are distributed to the transversus thoracus and to the posterior surface of the sternum The anterior medial steinal and sternal branches together with some twigs from the pericardiac of phrenic anastomose with branches from the intercostal and bronchial arteries and form a subproal medial steinal plexus The intercostal branches Raymai intercostalis anterior intercostal arteries supply the upper 5 or 6 intercostal spaces 2 in number in each space these small vessels pass lateral one lying near the lower margin of the rib above and anastomose with the intercostal arteries from the aorta They are at first situated between the pleura and the intercostalis interne and then between the intercostalis interne and externe They supply the intercostalis and by branches which perforate the intercostalis externe the pectoralis and the mamma The perforating branches Raymai perforantis correspond to the 5 or 6 intercostal spaces They pass forward through the intercostal spaces and curving lateral wood supply the pectoralis major and the integument Those which correspond to the 2nd, 3rd and 4th spaces give branches to the mamma and during lactation are of large size The musculophrenic artery arteria musculophrenica is directed obliquely downward and lateral wood behind the cartages of the false ribs It perforates the diaphragm at the 8th or 9th costal cartilage and ends considerably reduced in size opposite the last intercostal space It gives off intercostal branches to the 7th, 8th and 9th intercostal spaces These diminish in size as the spaces decrease in length and are distributed in a manner precisely similar to the intercostals from the internal mammary The musculophrenic also gives branches to the lower part of the pericardium and others which run backward to the diaphragm and downward to the abdominal muscles The superior epigastric artery arteria epigastrica superior continues in the original direction of the internal mammary It descends to the interval between the costal and sternal attachments of the diaphragm and enters the sheath of the rectus abdominis at first lying behind the muscle and then perforating and supplying it and anastomosing with the inferior epigastric artery from the external iliac Branches perforate the anterior wall of the sheath of the rectus and supply the muscles of the abdomen and the integument and the small branch passes in front of the ziphoid process and anastomoses with the artery of the opposite side It also gives some tweaks to the diaphragm while from the artery of the right side small branches extend into the falciform ligament of the liver and anastomoses with the hepatic artery The costicocervical trunk Trunker's costicocervicalis superior intercostal artery arises from the upper and back part of the subclavian artery behind the scalenus anterior on the right side and medial to that muscle on the left side Passing backward it gives off the profunda cervicalis and, continuing as the highest intercostal artery descends behind the pleura in front of the necks of the first and second ribs and anastomoses with the first aortic intercostal As it crosses the neck of the first rib it lies medial to the anterior division of the first thoracic nerve and lateral to the first thoracic ganglion of the sympathetic trunk In the first intercostal space it gives off a branch which is distributed in a manner similar to the distribution of the aortic intercostals The branch for the second intercostal space usually joins with one from the highest aortic intercostal artery This branch is not constant but is more commonly found on the right side when absent its place is supplied by an intercostal branch from the aorta Each intercostal gives off a posterior branch which goes to the posterior vertebral muscles and sends a small spinal branch to the corresponding intervertebral foramen to the medulla spinalis and its membranes The profunda cervicalis arteria cervicalis profunda deep cervical branch arises in most cases from the costa cervical trunk and is analogous to the posterior branch of an aortic intercostal artery Occasionally it is a separate branch from the subclavian artery Passing backward from the eighth cervical nerve and between the transverse process of the seventh cervical vertebra and the neck of the first rib it runs up the back of the neck between the semispinalis, cubitis and coli as high as the axis vertebra supplying these under adjacent muscles and anastomosing with the deep division of the descending branch of the occipital and with branches of the vertebral It gives off a spinal twig which enters the canal through the intervertebral foramen between the seventh cervical end of section 18 section 19 of case anatomy part 3 this is a liprevox recording all liprevox recordings are in the public domain for more information or to volunteer please visit liprevox.org recording by Ellie anatomy of the human body part 3 by Henry Gray the axilla, the axillary artery phobie, the axilla the axilla is a pyramidal space located between the upper lateral part of the chest and the medial side of the arm boundaries the apex, which is directed upward toward the root of the neck corresponds to the interval between the outer border of the first rib the superior border of the scapula and the posterior surface of the glavicle and through it the axillary vessels and nerves pass the base directed downward is brought at the chest but narrow and pointed at the arm it is formed by the integument of the fascia, the axillary fascia extending between the lower border of the pectoralis major in front and the lower border of the latissimus dorsi behind the anterior wall is formed by the pectoralis major and minor, the former covering the whole of this wall and the latter only the central part the space between the upper border of the pectoralis minor and the glavicle is occupied by the corococlavicular fascia, the posterior wall which extends somewhat lower than the anterior is formed by the subscapularis above, the teres major and the latissimus dorsi below on the medial side are the first four ribs is their corresponding intercostals and part of the serratus interior on the lateral side where the anterior and posterior walls converge the space is narrow and bounded by the humerus the corococobrachialis and the biceps brachii contents it contains the axillary vessels and the brachial plexus of nerves is their branches some branches of the intercostal nerves together with the quantity of fat and loose areolar tissue the axillary artery and vein is the brachial plexus of nerves extend obliqually along the lateral boundary of the axilla from its apex to its base and are placed much nearer to the interior than the posterior wall the vein lying to the thoracic side of the artery and partially concealing it at the four part of the axilla the pectoralis are the thoracic branches of the axillary artery and along the lower margin of the pectoralis minor the lateral thoracic artery extends to the side of the chest at the back part in contact with the lower margin of the subscapularis are the subscapular vessels and nerves binding around the lateral border of this muscle are the scapular circumflex vessels and close to the neck of the humerus the posterior humeral circumflex vessels and the posterior nerve curve backward to the shoulder along the medial or thoracic side no vessel of importance exists the upper part of the space being crossed merely by a few small branches from the highest thoracic artery there are some important nerves however in this situation vice the long thoracic nerve descending on the surface of the serratus anterior to which it is distributed and the intercostobrachial nerve perforating the upper and interior part of this wall and passing across the axilla to the medial side of the arm the position and arrangement of the lymph glands are described on pages 699 and 700 1. The axillary artery the continuation of the subclavian commands is at the outer border of the first rib and ends at the lower border of the tendon of the teres major where it takes the name of brachial its direction varies with the position of the lymph thus the vessel is nearly straight the arm is directed it rides angles with the trunk concave upward when the arm is elevated above this and convex upward and lateral when the arm lies by the side at its origin the artery is very deeply situated but near its termination is superficial being covered only by the skin and vestia to facilitate the description of the vessel it is divided into three portions the first part lies above the second behind and the third below is minor relations the first portion of the axillary artery is covered interiorly with a clavicular portion of the bacterialis major and the coracoclavicular vestia and is crossed by the lateral anterior thoracic nerve and the thoracic coracromial and cephalic veins posterior to it are the first intercostal space the corresponding intercostalis externus the first and second digitations of the serratus anterior are the medial anterior thoracic nerves and the medial cord of the brachial plexus on its lateral side is the brachial plexus from which it is separated by a little areola tissue on its medial thoracic side is the axillary vein which overlaps the artery it is enclosed together with the axillary vein and the brachial plexus in a fibrous sheath the axillary sheath continuous above is the deep cervical vestia the second portion of the axillary artery is covered anteriorly by the bacterialis major and minor posterior to it are the posterior cord of the brachial plexus and some areola tissue which intervenes between it and the subscapularis on the medial side is the axillary vein separated from the artery by the medial cord of the brachial plexus and the medial anterior thoracic nerve on the lateral side is the lateral cord of the brachial plexus brachial plexus tests around the artery on three sides and separates it from direct contact with the vein and adjacent muscles the third portion of the axillary artery extends from the lower part of the pectoralis minor to the lower part of the tendon of the teres major in front it is covered by the lower part of the pectoralis major above but only by the intacument infestia below behind it is in relation with the lower part of the subscapularis and the tendons of the latissimostosia and the teres major on its lateral side is the coricobrachialis and on its medial arteritic side the axillary vein the nerves of the brachial plexus are the following relations to this part of the artery on the lateral side are the lateral head and the trunk of the median and the muscular cutanus for a short distance on the medial side the ulna between the vein and the artery and the medial brachial cutanus on the medial side of the vein the radial head of the median and the medial antibrachial cutanus and behind the radial and axillary the latter only as far as the lower part of the subscapularis collateral circulation of the ligature of the axillary artery if the artery betrayed above the origin of the teracochromia the collateral circulation will be carried on by the same branch as after the ligature on the third part of the subclavian if at the lower point between the teracochromia and the subcapular the lateral vessel by its free anestomosis with the transverse scapula and the transverse cervical branches of the subclavian will become the chief agent in carrying on the circulation the lateral thoracic if it be below the ligature will materially contribute by its anestomosis with the intercostal and internal mammary arteries if the point included in the ligature is below the origin of the subscapular artery it will most probably also be below the origins of the two humeral circumflex arteries the chief agents in restoring the circulations will then be the subscapular and the two humeral circumflex arteries anestomosing with the arterial profunda brachii branches branches of the maxillary are from first part highest to retic from second part teracochromial lateral to retic from third part subscapular posterior humeral circumflex anterior humeral circumflex 1. the highest thoracic artery arterial thoracalis suprema superior thoracic artery is a small vessel which may rise from the thoricochromial running forward and medialward along the upper board of the pectoralis minor it passes between it and the pectoralis major to the side of the chest it supplies branches to the muscles and to the parties of the thorax and anestomosis with the internal mammalian intercostal arteries 2. the thoracochromial artery anterior thoracochromialis acromiothoracic artery thoracic axis is a short trunk which arises from the four part of the axillary artery it's origin being generally overlapped by the upper edge of the pectoralis minor projecting forward to the upper board of this muscle it pierces the coracoclavicular fascia and divides it into four branches pectoral, acromial, clavicular and deltoid the pectoral branch descends between the two pectoralis and is distributed to them and to the mama anestomosing with the intercostal branches of the internal mammary and with the lateral thoracic the acromial branch runs lateral ward over the coracoid process and under the deltoid areas to which it gives branches it then pierces the muscle and ends in the acromium in an arterial network formed by branches from the transverse scapula thoricoracromial and posterior humeral circumflex arteries the clavicular branch runs upward and medial ward to the sternoclavicular joint supplying this articulation and the subclavius the deltoid humeral branch often arising with the acromial crosses over the pectoralis minor and passes in the same growth as the cephalic vein between the pectoralis major and deltoid aeus and gives branches to both muscles 3. the lateral thoracic artery arteriatoricalis lateralis long thoracic artery external mammary artery follows the lower board of the pectoralis minor to the side of the chest supplying the serratus anterior and the pectoralis and sending branches across the axilla to the axillary cleanse and the subscapularis it anestomoses with the internal mammary, subscapular and intercostal arteries and with the pectoral branch of the thoracoacromial in the female it supplies the external mammary branch which turns around the free edge of the pectoralis major and supplies the mammary 4. the subscapular artery arteriosubscapularis the largest branch of the axillary artery arises at the lower board of the subscapularis which it follows to the inferior angle of the scapular where it anestomoses with the lateral thoracic and intercostal arteries and with the descending branch it follows the transverse cervical and ends in the neighboring muscles about 4 cm from its origin it gives off a branch the scapular circumflex artery the scapular circumflex artery a teriosurconflexus capule dorsalis scapular artery is generally larger than the continuation of the subscapular it curves around the axillary border of the scapular transversing the space between the subscapularis above teris major below the triceps laterally it enters the infraspinatus fossa under cover of the teris minor and anestomoses with the transverse scapular artery and descending branch of the transverse cervical in its course it gives off 2 branches 1. infrascapular enters the subscapular fossa beneath the subscapularis which it supplies anestomosing with the transverse scapular artery and the descending branch of the transverse cervical the other is continued to the upper border of the scapular between the teris major and minor and at the dorsal surface of the inferior angle anestomoses with the descending branch of the transverse cervical in addition to these small branches are distributed to the back part of the deltoid ears and the long head of the triceps brachii anestomosing with the ascending branch of the arterial profunda brachii 5. the posterior humeral circumflex artery arterial circumflexorhumory posterior posterior circumflex artery arises from the axillary artery at the lower border of the subscapularis and runs backward with the axillary nerve through the quadrangular space bounded by the subscapularis and teris minor above the teris major below the long head or the triceps brachii immediately the surgical neck of the humerus laterally it winds around the neck of the humerus and is distributed to the deltoid ears and shoulder joint anestomosing with the interior humeral circumflex and profunda brachii 6. the interior humeral circumflex artery arterial circumflexorhumory anterior anterior circumflex artery considerably smaller than the posterior arises nearly opposite it from the lateral side of the axillary artery and runs horizontally beneath the quadragular brachialis and short head of the biceps brachii in front of the neck of the humerus and reaching the intertopercular sulcus it gives off a branch which ascends the sulcus to supply the head of the humerus in the shoulder joint the trunk of the vessel is then continued onward beneath the long head of the biceps brachii and the deltoid ears and anestomosis is the posterior humeral circumflex artery peculiarities the branches of the axillary artery very considerable in different subjects occasionally the subscapular humeral circumflex and profunda arteries arise from a common trunk and when this occurs the branches of the brachial blexus surround this trunk instead of the main vessel sometimes the axillary artery divides into the radial and ulnar arteries and occasionally it gives origin to the volle interossus artery of the forearm end of section 19 recording by elli august 2009 section 20 of graze anatomy part 3 this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Leanne Howlett anatomy of the human body part 3 by Henry Gray the brachial artery 4b2 the brachial artery a brachialis the brachial artery commences at the lower margin of the tendon of the teres major and passing down the arm ends about 1 centimeter below the bend of the elbow where it divides into the radial and ulnar arteries at first the brachial artery lies medial to the humerus but as it runs down the arm it gradually gets in front of the bone and at the bend of the elbow it lies midway between its two epicondyles relations the artery is superficial throughout its entire extent being covered in front by the integument and the superficial and deep fascia the laceritis fibrosis bycipital fascia lies in front of it opposite the elbow and separates it from the vena mediana cubitii the median nerve crosses from its lateral to its medial side opposite the insertion of the coricobrachialis behind it is separated from the long head of the triceps brachii by the radial nerve and a profunda brachii it then lies upon the medial head of the triceps brachii next upon the insertion of the coricobrachialis and lastly on the brachialis laterally the insertion above with the median nerve and the coricobrachialis below with the biceps brachii the two muscles overlapping the artery to a considerable extent medially its upper half is in relation with the medial anti-brachial cutaneous and ulnar nerves its lower half with the median nerve the bacillic vein lies on its medial side but is separated from it in the lower part of the arm the artery is accompanied by two vene comitants which lie in close contact with it and are connected together at intervals by short transverse branches the anti-cubital fossa at the bend of the elbow the brachial artery sinks deeply into a triangular interval the anti-cubital fossa the base of the triangle is directed upward and is represented by a line with two epicondyles of the humerus the sides are formed by the medial edge of the brachial radialis and the lateral margin of the pronator t-rease the floor is formed by the brachialis and supinator this space contains the brachial artery with its accompanying veins the radial and ulnar arteries the median and radial nerves and the tendon of the biceps brachii the brachial artery occupies the middle of the space and divides opposite the neck of the radius into the radial and ulnar arteries it is covered in front by the integument the superficial fascia and the vena mediana cubitii the last being separated from the artery by the lacertis fibrosis behind it is the brachialis which separates it from the elbow joint the median nerve lies close to the medial side of the artery above but is separated from it below by the ulnar head of the pronator t-rease the tendon of the biceps brachii lies to the lateral side of the artery the radial nerve is situated upon the supinator and concealed by the brachio radialis peculiarities of the brachial artery as regards its course the brachial artery accompanied by the median nerve of the biceps brachii descend toward the medial epicondyle of the humerus in such cases it usually passes behind the supercondular process of the humerus from which a fibrous arch is in most cases thrown over the artery it then runs beneath or through the substance of the pronator t-rease to the bend of the elbow this variation bears considerable analogy with the normal condition of the artery and some of the carnivora which has been referred to in the description of the humerus as regards its division occasionally the artery is divided for a short distance at its upper part into two trunks which are united below frequently the artery divides at a higher level than usual and the vessels concerned in this high division are three these radial ulnar and interosseous most frequently the radial is given off high up the other limb of the bifurcation consisting of the ulnar and interosseous in some instances the ulnar rises above the ordinary level and the radial and interosseous form the other limb of the division occasionally the interosseous arises high up sometimes long slender vessels vesa aberrantia connect the brachial or the axillary artery with one of the arteries of the forearm or branches from them these vessels usually join the radial varieties and muscular relations the brachial artery is occasionally concealed in some part of its course by muscular or tendinous slips derived from the coraco brachialis biceps brachii brachialis or pronator t-rease collateral circulation after the application of a ligature to the brachial artery and the upper third of the arm the circulation is carried on by branches from the humoral circumflex and subscapular arteries anastomizing with ascending branches from the profunda brachii if the artery be tied below the origin of the profunda brachii and superior ulnar collateral the circulation is maintained by the branches of these two arteries anastomosing with the inferior ulnar collateral the radial and ulnar recurrence and the dorsal interosseous branches the branches of the brachial artery are profunda brachii superior ulnar collateral nutrient inferior ulnar collateral muscular one the arteria profunda brachii superior profunda artery is a large vessel which arises from the medial and back part of the brachial just below the lower border of the t-rease major it follows closely the radial nerve running it first backward between the medial and lateral heads of the triceps brachii then along the groove for the radial nerve where it is covered by the lateral head of the triceps brachii to the lateral side of the arm there it pierces the lateral intermuscular septum and descending between the brachioradialis and the brachialis to the front of the lateral epicondyle of the humerus ends by anastomosing with the radial recurrent artery it gives branches to the deltoidius and to the muscles between which it lies it supplies an occasional nutrient artery which enters the humerus behind the deltoid tuberosity a branch ascends between the long and lateral heads of the triceps brachii to anastomose with the posterior humeral circumflex artery a middle collateral branch descends in the middle head of the triceps brachii and assists in forming the anastomosis above the olocranin and lastly a radial collateral branch runs down behind the lateral intermuscular septum to the back of the lateral epicondyle of the humerus where it anastomoses with the enteroceus recurrent and the inferior ulmar collateral arteries two the nutrient artery a nutritious humeri of the body of the humerus arises about the middle of the arm and enters the nutrient canal near the insertion of the coricobrachialis three the superior ulmar collateral artery a collateralis ulnarus superior inferior profunda artery of small size arises from the brachial a little below the middle of the arm it frequently springs from the upper part of the a profunda brachii it pierces the medial intermuscular septum and descends on the surface of the medial head of the triceps brachii to the space between the medial epicondyle and olocranin accompanied by the ulnar nerve and ends under the flexor carpi ulnarus by anastomosing with the posterior ulmar recurrent and inferior ulmar collateral it sometimes sends a branch in front of the medial epicondyle to anastomose with the interior ulmar recurrent four the inferior ulmar collateral artery a collateralis ulnarus inferior anastomotica magna artery arises about five centimeters above the elbow it passes medial word upon the brachialis and piercing the medial intermuscular septum winds around the back of the humerus and the triceps brachii and the bone forming by its junction with the profunda brachii an arch above the olocranin fossa as the vessel lies on the brachialis it gives off branches which ascend to join the superior ulmar collateral others descend in front of the medial epicondyle to anastomose with the anterior ulmar recurrent behind the medial epicondyle a branch anastomoses with the superior ulmar collateral and posterior ulmar recurrent arteries five the muscular branches rami muscularis three or four in number are distributed to the coricobrachialis biceps brachii and brachialis the anastomosis around the elbow joint the vessels engaged in this anastomosis may be conveniently divided into those situated in front of and those behind the medial and lateral epicondyle of the humerus the branches anastomosing in front of the medial epicondyle r the anterior branch of the inferior ulmar collateral the anterior ulmar recurrent and the anterior branch of the superior ulmar collateral those behind the medial epicondyle r the inferior ulmar collateral collateral, the posterior ulnar recurrent, and the posterior branch of the superior ulnar collateral. The branches anastomosing in front of the lateral epicondyle are the radial recurrent and the terminal part of the profunda brachii. Those behind the lateral epicondyle, perhaps more properly described as being situated between the lateral epicondyle and the olocranin are the inferior ulnar collateral, the interosseous recurrent, and the radial collateral branch of the profunda brachii. There is also an arch of anastomosis above the olocranin formed by the interosseous recurrent joining with the inferior ulnar collateral and posterior ulnar recurrent. Executive Section 20, Recording by Leanne Howlett. Section 21 of Gray's Anatomy, Part 3. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Leanne Howlett. Anatomy of the Human Body, Part 3 by Henry Gray. The Radial Artery, Part 4B3, The Radial Artery, A Radialis. The Radial Artery appears from its direction to be the continuation of the brachial, but it is smaller in caliber than the ulnar. It commences at the bifurcation of the brachial just below the bend of the elbow and passes along the radial side of the forearm to the wrist. It then winds backward around the lateral side of the carpus beneath the tendons of the abductor polisus longus and extensors polisus longus and brevis to the upper end of the space between the metacarpal bones of the thumb and index finger. Finally, it passes forward between the two heads of the first interosseous dorsalis into the palm of the hand where it crosses the metacarpal bones and at the ulnar side of the hand unites with the deep volar branch of the ulnar artery to form the deep volar arch. The radial artery therefore consists of three portions, one in the forearm, a second at the back of the wrist, and a third in the hand. Relations A. In the forearm, the artery extends from the neck of the radius to the forepart of the styloid process, being placed to the medial side of the body of the bone above and in front of it below. Its upper part is overlapped by the fleshy belly of the brachio radialis. The rest of the artery is superficial, being covered by the integument and the superficial and deep fasciae. In its course downward, it lies upon the tendon of the biceps brachii, the suponator, the pronator t-rease, the radial origin of the flexor digitorum sublimus, the flexor polycyst longus, the pronator quadratus, and the lower end of the radius. In the upper third of its course, it lies between the brachio radialis and the pronator t-rease, in the lower two-thirds between the tendons of the brachio radialis and flexor carpi radialis. The superficial branch of the radial nerve is close to the lateral side of the artery and the middle third of its course, and some filaments of the lateral anti-brachial cutaneous nerve run along the lower part of the artery as it winds around the wrist. The vessel is accompanied by a pair of vene comitants throughout its whole course. B. At the wrist, the artery reaches the back of the carpus by passing between the radial collateral ligament of the wrist and the tendons of the abductor palisus longus and extensor palisus brevis. It then descends on the navicular and greater multangular bones, and before disappearing between the heads of the first enterosius dorsalis is crossed by the tendon of the extensor palisus longus. In the interval between the two extensor's palisus, it is crossed by the digital ramai of the superficial branch of the radial nerve which go to the thumb and index finger. C. In the hand, it passes from the upper end of the first enterosius space between the heads of the first enterosius dorsalis, transversely across the palm between the adductor palisus obliquus and adductor palisus transversus, but sometimes piercing the ladder muscle to the base of the metacarpal bone of the little finger where it anastomosis with the deep volar branch from the ulnar artery completing the deep volar arch. Peculiarities. The origin of the radial artery is, in nearly one case in eight, higher than usual. More often it arises from the axillary or upper part of the brachial than from the lower part of the ladder vessel. In the forearm, it deviates less frequently from its normal position than the ulnar. It has been found lying on the deep fascia instead of beneath it. It has also been observed on the surface of the brachial radialis instead of under its medial border. And in turning around the wrist, it has been seeing lying on, instead of beneath, the extensor tendons of the thumb. Branches. Branches of the radial artery may be divided into three groups corresponding with the three regions in which the vessel is situated. In the forearm, radial recurrent, muscular, volar carpal, superficial volar. At the wrist, dorsal carpal, first dorsal metacarpal. In the hand, princeps polysis, volaris indusis radialis, volar metacarpal, perforating recurrent. The radial recurrent artery, A recurrents radialis, arises immediately below the elbow. It ascends between the branches of the radial nerve lying on the supinator and then between the brachio radialis and brachialis, supplying these muscles in the elbow joint and anastomosing with the terminal part of the profunda brachii. The muscular branches, rami muscularis, are distributed to the muscles on the radial side of the forearm. The volar carpal branch, ramus carpius volaris, anterior radial carpal artery, is a small vessel which arises near the lower border of the pronator quadratus and, running across the front of the carpus, anastomosis with the volar carpal branch of the ulnar artery. This anastomosis is joined by a branch from the volar enterosius above and by recurrent branches from the deep volar arch below, thus forming a volar carpal network which supplies the articulations of the wrist and carpus. The superficial volar branch, ramus volaris superficialis, superficialis voli artery arises from the radial artery just where this vessel is about to wind around the lateral side of the wrist. Running forward, it passes through, occasionally over, the muscles of the ball of the thumb, which it supplies and sometimes anastomosis with the terminal portion of the ulnar artery completing the superficial volar arch. This vessel varies considerably in size, usually it is very small and ends in the muscles of the thumb, sometimes it is as large as the continuation of the radial. The dorsal carpal branch, ramus carpius dorsalis, posterior radial carpal artery is a small vessel which arises beneath the extensor tendons of the thumb, crossing the carpus transversely toward the medial border of the hand, anastomosis with the dorsal carpal branch of the ulnar and with the volar and dorsal enterosius arteries to form a dorsal carpal network. From this network are given off three sundar dorsal metacarpal arteries which run downward on the second, third and fourth enterosiae dorsalis and bifurcate into the dorsal digital branches for the supply of the adjacent sides of the middle, ring and little fingers respectively, communicating with the proper volar digital branches of the superficial volar arch. Near their origins, they anastomosis with the deep volar arch by the superior perforating arteries and near their points of bifurcation with the common volar digital vessels of the superficial volar arch by the inferior perforating arteries. The first dorsal metacarpal arises just before the radial artery passes between the two heads of the first enterosius dorsalis and divides almost immediately into two branches which supply the adjacent sides of the thumb and index finger. The radial side of the thumb receives a branch directly from the radial artery. The arterial princeps polisus arises from the radial just as it turns medial word to the deep part of the hand. It descends between the first enterosius dorsalis and adductor polisus obliquus along the owner side of the metacarpal bone of the thumb to the base of the first phalanx where it lies beneath the tendon of the flexor polisus longus and divides into two branches. These make their appearance between the medial and lateral insertions of the adductor polisus obliquus and run along the sides of the thumb forming on the volar surface of the last phalanx and arch from which branches are distributed to the integument and subcutaneous tissue of the thumb. The arterial volaris endosus radialis endosus artery arises close to the preceding descends between the first enterosius dorsalis and adductor polisus transversus and runs along the radial side of the index finger to its extremity where it anastomosis with the proper digital artery supplying the owner side of the finger. At the lower border of the adductor polisus transversus, this vessel anastomosis with the princeps polisus and gives a communicating branch to the superficial volar arch. The A princeps polisus and A volaris endosus radialis may spring from a common trunk termed the first volar metacarpal artery. The deep volar arch, arcus volaris profundus, deep palmar arch, is formed by the anastomosis of the terminal part of the radial artery with the deep volar branch of the ulnar. It lies upon the carpal extremities of the metacarpal bones and on the enterosii being covered by the adductor polisus obliquus, the flexor tendons of the fingers and the lumbar callus. Alongside of it, but running in the opposite direction, that is to say, toward the radial side of the hand, is the deep branch of the ulnar nerve. The volar metacarpal arteries, AA metacarpi volaris, palmar enterosius arteries, three or four in number, arise from the convexity of the deep volar arch. They run distally upon the enterosii and anastomosis at the clefts of the fingers with the common digital branches of the superficial volar arch. The perforating branches, rami perforantus, three in number, pass backward from the deep volar arch through the second, third, and fourth enterosius spaces and between the heads of the corresponding enterosii dorsalis to anastomosis with the dorsal metacarpal arteries. The recurrent branches arise from the concavity of the deep volar arch. They ascend in front of the wrist, supply the enterocarpal articulations, and end in the volar carpal network. End of section 21, recording by Leanne Howlett.