388 DR. C. F. SO^NTAG ON THE ANATOMY, 



There is no anastomosis round the elbow joint as there is 

 in Man. 



The Radial Artery (text-fig. 39 A), which is the largest vessel 

 in the forearm, runs down the forearm very superficially, curves 

 round the back of the wrist and over the trapezium, and passes 

 into the first interosseous space, so it is divisible into three parts 

 as in Man. The first part, lying in the forearm, gives ofi" the 

 following branches: — 1, A large muscular artery to the supi- 

 nator brevis (S.B) ; 2. Numerous fine twigs to the superficial 

 flexor muscles ; 3. Anterior radial carpal artery (A.R.O.A), 

 which arises in the upper third of the forearm, runs down 

 parallel to the radial artery, and crosses behind it in the lower 

 part of the forearm. It ends by a series of arteries over the 

 palmar ligaments of the inferior radio-ulnar, radio-carpal, inter- 

 carpal, and carpo-metacarpal joints. It also supplies the flexor 

 muscles ; 4. Swperficialis voice (S.V.A) runs downwards and in- 

 wards across the thenar eminence and supplies its muscles. And 

 it is continued along the inner border of the pollex. It gives off 

 a fine twig which curves inwards and helps to form the irregular 

 superficial palmar arch. The second part of the artery, lying on 

 the ti-apezium, gives off twigs to the dorsal aspect of the inter- 

 carpal joints (D.O.B), and a muscular artery to the first dorsal 

 interosseous muscle (D.I.M). From the dorsal carpal branch 

 there rises a vessel to the adjacent sides of the dorsal aspect of 

 the index and medius. The third part of the artery lies in the 

 interval between the palmar aspects of the index and pollex. 

 It gives off a thenar artery (T.A) to the thenar muscles, a 

 muscular artery to the first dorsal interosseous muscle (D.I.M), 

 several adductor twigs and branches to the lumbricales. Over 

 the heads of the metacarpal bones it gives a branch to the radial 

 side of the index finger. 



The Ulnar Artery (text-fig. 39 B, U.A) runs downwards as 

 in Man, curves round the mesial aspect of the pisiform bone and 

 enters the palm. It bifurcates about the middle of the palm. 

 One branch runs to the inner border of the minimus ; and the 

 second divides into two branches which supply respectively, the 

 adjacent sides of the minimus and annularis, and annularis and 

 medius. From the latter branch, two arteries pass to join with 

 branches of the radial artery and form the superficial and deep 

 palmar arches. As the artery turns round the pisiform it gives 

 off a dorsal branch which curves round the ulnar border of the 

 manus to supply the tissues on the back of the ulnar border of 

 the carpus. 



The anterior interosseous artery (text-fig. 39 B, A.I. A) is as 

 in Man. 



Three palmar arterial arches are present (text-fig. 39 A) : — 

 (1) The deep arch (D.A), lying in front of the carpus, is formed 

 by a branch of the ulnar artery, the superficialis volae, and the 

 branch of the radial artery to the thenar eminence ; (2) the 

 superficial arch (S.A), lying in the front of the deep arch, is 



