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Relations of the third part.-The third part of the radial artery passes volarwards, between the two heads of the first dorsal interosseous muscle, to reach the palm, where it turns ulnarwards, deep to the proximal oblique part of the adductor muscle of the thumb, and, after passing through the proximal fibres of the transverse part of the adductor pollicis, or between the adjacent borders of the oblique and transverse parts of that muscle, it unites with the deep branch of the ulnar artery, completing the deep volar (palmar) arch.
Branches of the third part.(1) The princeps pollicis branch is given off as soon as the radial artery enters the palm. It runs distally, on the volar aspect of the first metacarpal bone, between the adductor and the opponens pollicis, and under cover of the long flexor tendon, and divides, near the distal end of the bone, into collateral branches which run along the sides of Radial artery the thumb and anastomose with the dorsales pollicis arteries.
(2) The arteria volaris indicis radi
alis is a branch which runs distally
Brachioradialis Muscular branch of
between the ulnar head of the first dorsal Pronator teres interosseous muscle and the adductor of
the thumb and along the radial side of Flexor pollicis
The ulnar artery (Figs. 768 and 769) is the larger terminal branch, but the less direct continuation of the brachial artery. It commences in the cubital fossa, opposite the neck of the radius, and terminates in the palm of the hand, where it anastomoses with the superficial Radialis volar artery to form the superficial volar (palmar) arch.
From its origin it runs obliquely, distally and ulnarwards, deep to the muscles arising from the medial epicondyle, to the junction of the proximal and middle thirds of the forearm, where it comes into relation with the ulnar nerve; it then passes directly distally, on the radial side of the ulnar nerve, to the wrist; crosses anterior to the main part of the transverse carpal ligament, on the radial side of the pisiform bone, and
ulnar collateral artery
Dorsal ulnar recurrent artery
Flexor digitorum profundus
Volar interosseous artery
FIG. 769.- DEEP DISSECTION OF THE FRONT OF THE FOREARM AND HAND, showing the radial and ulnar arteries and their branches and the deep volar arch and its branches.
enters the palm of the hand to form the main part of the superficial volar (palmar) arch.
Relations-Dorsal.-Proximo-distally it lies volar to the distal part of the brachialis,
the flexor digitorum profundus, and the transverse carpal ligament (O.T. anterior annular). Volar. On its volar aspect it is crossed, in the oblique part of its course, by the pronator teres, the median nerve, which is separated from the artery by the deep head of the pronator teres, the flexor digitorum sublimis, the flexor carpi radialis, and the palmaris longus. In the middle third of the forearm it is overlapped by the volar border of the flexor carpi ulnaris, and in the distal third it is covered by skin and fascia only. A short distance proximal to the wrist the palmar cutaneous branch of the ulnar nerve lies volar to it, and as it crosses the transverse carpal ligament, it is bound down by a fascial expansion from the tendon of the flexor carpi ulnaris. Two venæ comites, which frequently communicate with one another, lie one on each side of the artery. On the radial side there is also, in its distal two-thirds, the flexor digitorum sublimis. On its ulnar side are the flexor carpi ulnaris and the ulnar nerve.
Branches. (1) The volar ulnar recurrent is a small branch which arises in the cubital fossa, frequently in common with the dorsal ulnar recurrent. It passes proximally, to the anterior aspect of the medial epicondyle, under cover of the pronator teres, and anastomoses with branches of the superior and inferior ulnar collateral arteries.
(2) The dorsal ulnar recurrent branch, larger than the volar, arises in the cubital fossa, from the ulnar side of the ulnar artery, and ascends, on the brachialis and under cover of the muscles which arise from the medial epicondyle, to the posterior aspect of that prominence, where it passes between the humeral and olecranoid heads of the flexor carpi ulnaris, and anastomoses with the superior and inferior ulnar collateral arteries. It gives branches to the adjacent muscles and to the elbow-joint.
(3) The common interosseous artery, a short trunk which springs from the radial and dorsal aspect of the ulnar artery, in the distal part of the cubital fossa. It passes dorsally, towards the proximal border of the interosseous membrane, and divides into volar and dorsal interosseous branches.
(3a) The volar interosseous artery runs distally, on the volar surface of the interosseous membrane, between the adjacent borders of the flexor pollicis longus and the flexor digitorum profundus, to the proximal border of the pronator quadratus; there it pierces the interosseous membrane, and continues distally, first on the dorsal surface of the membrane, deep to the extensor pollicis longus and extensor indicis proprius, and then on the dorsal surface of the radius, in the groove for the extensor digitorum communis and it terminates, on the dorsum of the carpus, by joining the dorsal carpal arch. It is accompanied on the volar aspect of the interosseous membrane by the volar interosseous nerve, and, after it has pierced the membrane, by the dorsal interosseous nerve.
Branches.—(a) Nutrient to the radius and ulna; (b) Muscular to the adjacent muscles; (c) The volar communicating, a slender branch which passes distally, deep to the pronator quadratus and on the volar surface of the interosseous membrane, to anastomose with the volar carpal arch; (d) Small anastomotic branches are given off, on the dorsum of the forearm, to anastomose with the dorsal interosseous artery; (e) The median artery (O.T comes nervi mediani is a long slender branch which arises from the proximal part of the volar interosseous artery and runs with the median nerve to the palm, where it anastomoses with recurrent branches of the superficial volar arch.
(36) The dorsal interosseous artery is usually smaller than the volar interosseous. It passes dorsally between the proximal border of the interosseous membrane and the oblique cord, and then between the supinator and abductor pollicis longus (O.T. ext oss. met. poll.), after which it runs distally, between the superficial and deep muscles on the dorsum of the forearm, to the wrist. At the wrist it anastomoses with the volar interosseous artery and with the dorsal carpal arch. As it crosses the abductor pollicis longus it is accompanied by the dorsal interosseous nerve, but in the remainder of its course it is separated from the nerve by the deep muscles.
Branches.—(a) An interosseous recurrent branch is given off at the dorsal margin of the distal border of the supinator. It runs proximally, on the dorsal surface of the supinator, under cover of the anconeus, to the back of the lateral epicondyle of the humerus, where it anastomoses with the posterior terminal branch of the profunda and with branches of the inferior ulnar collateral artery. (b) Muscular branches to both superficial and deep muscles on the dorsum of the forearm. (c) Cutaneous branches to the skin on the dorsum of the forearm and the wrist.
(4) The volar carpal branch of the ulnar artery is a small branch, given off proximal to the transverse carpal ligament; it passes towards the radial side, deep to the flexor tendons and their sheaths, on the volar surface of the proximal attachments of the volar radio-carpal ligament, and anastomoses with the volar carpal branch of the radial to form the volar carpal arch.
(5) The dorsal carpal branch of the ulnar artery arises from the ulnar side of the ulnar artery, immediately proximal to the pisiform bone. It passes dorsally, deep to the ulnar flexor and the ulnar extensor of the carpus, to the dorsum of the carpus, where it unites with the dorsal carpal branch
of the radial to form the dorsal carpal arch.
(6) Profunda. This branch passes distally between
abductor and flexor brevis digiti quinti, and, turning towards the radial side, deep to the flexor brevis, the opponens digiti quinti, and the long flexor tendons and their sheaths, it joins the termination of the radial artery to complete the deep volar (palmar) arch.
THE ARTERIAL ARCHES OF
Arcus Carpeus Volaris -The Volar Carpal Arch(Figs. 768 and 769). The volar carpal arch lies on the volar aspect of the volar carpal ligaments, deep to the long flexor tendons and their synovial sheaths. It is formed by the union of the volar carpal branches of the radial and ulnar arteries, and it receives the communicating branch from the volar interosseous artery and recurrent branches from the deep volar arch. The branches of distribution which pass from it supply the ligaments Dorsal carpal arch and synovial membrane of the radio-carpal and intercarpal joints.
Arcus Carpeus Dorsalis. -The Dorsal Carpal Arch. (Fig. 770). This arch lies on the dorsal carpal ligaments deep to the extensor tendons and their sheaths. It is formed by the union of the dorsal carpal branches. of the radial and ulnar arteries, and receives the terminations of the volar and dorsal interosseous arteries.
Proximal perforating artery
Dorsal metacarpal arteries
Extensor digitorum communis
Dorsales pollicis arteries
Dorsalis indicis radialis
FIG. 770.-THE DORSAL INTEROSSEOUS ARTERY AND THE SECOND
Branches. (a) Articular to the adjacent articulations. (6) Dorsal metacarpal, two slender branches which run distally, along the third and fourth dorsal interosseous muscles, to the clefts of the fingers, where each divides into dorsal digital branches. They communicate near their origins with the deep volar arch by the proximal perforating arteries, and near their terminations with the volar digital vessels through the distal perforating arteries. Their digital terminal branches run
distally, on the dorso-lateral aspects of the fingers which bound the third and fourth interosseous spaces, and they anastomose with the special volar digital branches of the volar digital arteries.
Arcus Volaris Superficialis.-The superficial volar arch (O.T. superficial palmar) (Fig. 768) includes the terminal portion of the ulnar artery, and is usually completed on the radial side by the superficial volar, or by the volaris indicis radialis or the princeps pollicis branches of the radial artery. It extends from the ball of the little finger to the ulnar border of the superficial head of the flexor pollicis brevis, and reaches distally to a line drawn across the palm at the level of the distal border of the fully abducted thumb. It is accompanied by venæ comites and it is covered by the integuments and the central portion of the palmar aponeurosis, and, on the ulnar side of the palm, by the palmaris brevis. It is in contact dorsally with the flexor brevis and opponens digiti quinti, and with the common digital branches of the ulnar and median nerves, as well as with the flexor tendons and the lumbrical muscles.
Branches. Four volar common digital arteries arise from the convexity of the arch. The most ulnar of the four passes along the ulnar border of the little finger, accompanied by the common digital branch of the ulnar nerve; the other three pass distally superficial to the common digital nerves, one along the middle of each of the ulnar three interosseous spaces, towards the interdigital clefts, just proximal to which each common digital artery divides into two special digital arteries which supply the contiguous sides of the fingers bounding the cleft. As the special digital branches pass along the sides of the fingers they lie superficial to the corresponding special digital nerves, and supply branches to the joints, to the flexor tendons and their sheaths, and to the skin and subcutaneous tissues on the volar surfaces of the fingers; they give off dorsal branches also which anastomose with the dorsal digital arteries and supply the tissues on the dorsal aspects of the second and terminal phalanges. Some of the dorsally directed branches form a plexus in the matrix of the nail. In the pulp of the finger-tips anastomosing twigs join to form arches from which numerous branches are given off to the skin and subcutaneous fat.
Each of the three most radial special digital arteries is joined, immediately proximal to its division, by a volar metacarpal artery from the deep volar arch and a distal perforating artery from a dorsal metacarpal artery. The most ulnar digital artery is joined by a branch which arises either from the most ulnar volar metacarpal artery or from the deep volar arch.
Arcus Volaris Profundus. The deep volar arch (O.T. deep palmar) (Fig. 769) extends from the base of the metacarpal bone of the little finger to the proximal end of the first interosseous space, and is formed by the terminal part of the radial artery anastomosing with the profunda branch of the ulnar. It is from 12 to 18 mm. (half to three-quarters of an inch) proximal to the level of the superficial volar arch. It lies deeply in the palm, in contact with the proximal ends of the bodies of the metacarpal bones and on the origin of the interossei muscles, and deep to the long flexor tendons and their synovial sheaths.
Branches. (a) The proximal perforating: three small arteries which pass dorsally, through the ulnar three interosseous spaces and between the origins of the dorsal interosseous muscles. They anastomose on the dorsum of the hand with the dorsal metacarpal arteries.
(b) Small irregular recurrent branches pass proximally and unite with the volar carpal arch.
(c) The articular to the adjacent articulations.
(d) The volar metacarpal arteries are three vessels which pass distally, on the interosseous muscles of the three ulnar interosseous spaces, deep to the flexor tendons. They terminate by anastomosing with the volar digital arteries just before the latter vessels divide into special volar digital branches.
(e) The communicating, a small irregular branch which passes ulnarwards between the flexor tendons and the short muscles of the little finger to anastomose with the ulnar volar digital artery.
BRANCHES OF THE DESCENDING THORACIC AORTA.
The branches given off from the thoracic portion of the descending aorta are distributed chiefly to the walls of the thorax and to the thoracic viscera. They
contribute also to the supply of the spinal medulla and its membranes, and to that of the vertebral column and of the upper part of the abdominal wall. The branches, which are numerous and for the most part arranged in pairs, are as follows:
VISCERAL BRANCHES OF THE DESCENDING THORACIC AORTA.
1. Arteriæ Bronchiales. The bronchial branches of the thoracic aorta are usually two in number an upper and a lower-and both pass to the left lung. The upper left bronchial artery arises from the front of the aorta opposite the fifth thoracic vertebra; the inferior left bronchial artery usually takes origin near the lower border of the left bronchus. Both vessels are directed downwards and laterally to the back of the bronchus which they accompany, and, dividing similarly they follow its ramifications in the lung. They not only supply the walls of the bronchial tubes and the substance of the lungs, but also give branches to the bronchial glands, the pulmonary vessels, the pericardium, and the oesophagus.
As a rule there is only one right bronchial artery. It arises either from the first right aortic intercostal artery or from the upper left bronchial artery. More rarely it springs directly from the aorta. In its course and distribution it corresponds to the bronchial arteries of the left side.
2. Arteriæ Esophageæ.-The œsophageal branches are variable; usually four or five small branches spring from the front of the aorta and pass forwards to the cesophagus, in the walls of which they ramify, anastomosing above with branches of the left bronchial and inferior thyreoid arteries, and below with œsophageal branches of the left gastric and the phrenic arteries.
3. The pericardial branches are three or four small irregular vessels which are distributed on the surface of the pericardium.
4. Small mediastinal branches pass to the areolar tissue and glands in the posterior mediastinum, and to the posterior part of the diaphragm.
PARIETAL BRANCHES OF THE DESCENDING THORACIC AORTA.
1. Arteriæ Intercostales-The Intercostal Arteries.-There are nine pairs of aortic intercostal arteries which usually arise separately from the back of the aorta, but, not uncommonly, a pair may take origin by a common trunk. They are distributed to the lower nine intercostal spaces, to the vertebral column, to the contents of the vertebral canal, and to the muscles and skin of the back The first three on each side give branches to the mammary gland also. The arteries of opposite sides closely correspond, but, since the aorta, in the thoracic region, lies on the left of the vertebral column, the right intercostal arteries cross the front of the column, posterior to the oesophagus, the thoracic duct, and the vena azygos, and are longer than the left arteries. In other respects the courses of all the aortic intercostal arteries are almost identical. As each artery runs postero-laterally, across the side of the vertebral column, to an intercostal space, it passes posterior to the pleura, and is crossed, opposite the head of a rib, by the sympathetic trunk. The lower arteries are crossed by the splanchnic nerves also, and those on the left side are crossed by the hemiazygos or accessory hemiazygos veins.
As each artery passes laterally, between the necks of two adjacent ribs, it gives off' a posterior branch. Then it ascends to the upper border of the space to which it belongs, and, passing either behind or in front of the corresponding intercostal nerve, is continued along the space, in the costal groove. In the space, as far as the angle of the rib, it lies between the pleura and the posterior intercostal membrane, and, in that part of its course, it is embedded in the endothoracic fascia. Then it is continued forward between the internal and external intercostal muscles. In the