96 ANATOMY IN A NUTSHELL. 



The anterior carpal is a small branch which has itsorigin at the distal part 

 of the ulnar artery near the anterior annular ligament. It passes outward to 

 anastomose with the anterior carpal of the radial. These two arteries make 

 the anterior carpal arch. It anastomoses with the anterior interosseous, and 

 recurrent branches from the deep palmar arch. It lies beneath the tendons of 

 the Flexor profundus digitorum. 



'The posterior carpal arise- a little proximally of the pisiform hone. It 

 passes beneath the Extensor carpi ulnaris to the hack of the wrist to join the 

 posterior carpal of the radial under the extensor tendons. 



'The superficial palmar arch is made by the continuation of the ulnar in 

 the hand, joining the superficialis volae, or the radialis indicis, or the princeps 

 pollicis, rarely joining a large median artery. 



The deep ulnar branch passes between the Abductor minimi digiti and the 

 Flexor brevis minimi digiti to make the deep palmar arch. The convexity of 

 the superficial palmar arch gives four digital branches, one to the ulnar side and 

 palmar aspect of the little finger, and the other three to the adjacent sides of 

 the little, ring, middle and index fingers. On the fingers these arteries are pos- 

 terior to the nerves. 



Relations of the Ulnar Artery in the Forearm. 



1\ Front. Upper half. — (1) Superficial layer of flexor muscles. (2) Me- 

 dian nerve. Lower half — (3) Superficial fascia. (4) Deep fascia. 



Behind. — (1) Brachialis anticus, (2) Flexor profundus digitorum. 



Outer Side.— Flexor sublimis digitorum. 



Inner Side. -(1) Flexor carpi ulnaris. (2) Ulnar nerve (lower two-thirds.) 



Relations of the Superficial Palmar Arch. 



1\ Front. — (1) Skin. (2) Palmaris brevis, (3) Palmar fascia. 



Behind. — (1) Annular ligament, (2) Flexor brevis minimi digiti, (3) 

 Superficial flexor tendons. (4) Divisions of median and ulnar nerves. 



BRACHIAL PLEXUS. 



LESSON XXIV. 



A plexus is a net-work. The Brachial Plexus is a net-work of nerves sit- 

 uated in the axilla. Its branches supply the upper extremity. It is called 

 "brachial" because it supplies the arm or brachium. It is composed of the 

 anterior primary branches (Principle IV Lesson III) of the fifth, sixth, seventh, 

 eighth cervical and first dorsal nerves. The anterior branches of the fifth and 

 sixth cervical nerves make the first trunk. The anterior branch of the seventh 

 cervical nerve makes the second trunk. The anterior branches of the eighth 

 cervical nerve and part of the first dorsal nerve make the third trunk. These 

 trunks divide into anterior and posterior branches (secondary). The anterior 

 branches of the firsl and second trunk make the outer cord; the anterior branch 

 of the third trunk make- the inner cord; and the posterior branches of all three 

 trunks make the posterior cord. They are called outer, inner, and posterior 

 cords of the brachial plexus <m account of occupying that relation to the second 

 part of the axillary artery. (Plates VI-XVI-XVII.) 



