36o A MANUAL OF ANATOMY 



entire course, but in the lower half of the forearm the border of the 

 flexor carpi ulnaris is the guide. 



Relations — Superficial. — In the upper half of the forearm the 

 artery is deeply placed, being covered by both heads of the pronator 

 radii teres, flexor carpi radialis, palmaris longus, and flexor sub- 

 limis digitorum. In the lower half it is overlapped by the tendon 

 of the flexor carpi ulnaris, except for a little above the wrist, where 

 it lies superficially on the outer side of that tendon. The palmar 

 cutaneous branch of the ulnar nerve descends over the artery in 

 the lower half. Deep. — Brachialis anticus for about i inch, and 

 thereafter the flexor profundus digitorum. External. — ^The external 

 vena comes, and, in the lower half, the flexor sublimis digitorum. 

 Internal. — ^The internal vena comes, ulnar nerve for rather more than 

 the lower half, and the tendon of the flexor carpi ulnaris for a little 

 above the wrist. The nerves related to the first part of the artery 

 are the median, ulnar, and palmar cutaneous branch of the ulnar. 

 The median nerve lies for a little at first on the inner side of the 

 vessel, but, at the point where the vessel passes beneath the deep 

 head of the pronator radii teres, the nerve crosses it, being separated 

 from it by the deep head of that muscle, and so gains its outer side. 

 The ulnar nerve, having come from behind the internal epicondyle, 

 is widely separated from the artery for rather more than the upper 

 third of the forearm. A little above the centre the nerve and artery 

 meet, and then descend in close contact, the nerve being on the 

 inner side, with the intervention of the internal vena comes. The 

 palmar cutaneous branch of the ulnar nerve, as stated, descends 

 over the lower half of the vessel. 



Branches of the First Part. — The first part gives off the following 

 branches, namely, anterior ulnar recurrent, posterior ulnar re- 

 current, common interosseous (giving off anterior and posterior 

 interosseous), muscular, posterior ulnar carpal, and anterior ulnar 

 carpal. 



The anterior ulnar recurrent artery, of small size, passes 

 upwards and inwards on the brachialis anticus and beneath the 

 superficial head of the pronator radii teres, to supply these muscles 

 and anastomose with the anterior branch of the anastomotica 

 magna of the brachial. 



The posterior ulnar recurrent artery, of large size, arises just 

 below the preceding, or sometimes in common with it. It passes 

 inwards beneath the flexor sublimis digitorum, and then ascends 

 with the ulnar nerve between the two heads of the flexor carpi 

 ulnaris to the interval between the internal epicondyle and olecranon 

 process. It supplies the adjacent muscles, ulnar nerve, and elbow- 

 joint, and it anastomoses with the inferior profunda and posterior 

 branch of the anastomotica magna. It also gives twigs over the 

 back of the olecranon, which anastomose with the posterior inter- 

 osseous recurrent, thus forming the olecranon rete. 



The common interosseous artery is a short, thick trunk, which 

 arises, below the preceding, about i inch from the commencement 



