280 I>nitic/ics of (7//tir Artery 



Crunches in the hand. The profunda ulnaris clips between the 

 abductor and flexor brevis minimi digiti to complete the deep palmar 

 arch (p. 277) by joining with the radial. 



Four digital branches come from the convexity of the superficial 

 arch. The innermost runs along the ulnar border of the little finger, 

 whilst the three others pass clown to the clefts, where they divide to 

 supply the adjacent sides of the four inner fingers. The outennost 

 branch joins the radialis indicis in the pulp of the index-finger, and. so 

 completes the superficial arch. These digital arteries descend straight 

 to the clefts, and thus lie in the lines of the interosseous spaces ; the 

 flexor tendons run in the lines of the fingers. In making exploratory 

 incisions the lines of the clefts must be avoided. 



In the palm the arteries are superficial to the nerves, but along the 

 fingers the nerves are anterior. 



At the clefts the digital arteries are joined by the palmar inter- 

 osseous branches of the radial, and by the dorsal interosseous twigs 

 of the posterior carpal arch. 



Irregularities. In the case of a high division of the brachial the 

 ulnar artery may reach the inner border of the fore-arm by passing 

 superficial to the group of muscles arising from the internal condyle, 

 lying sometimes superficial even to the deep fascia. 



The comes nervi mediant is occasionally almost as large as the 

 radial or ulnar, and, accompanying the median nerve into the hand, 

 may enter into the formation of one of the palmar arches. Sometimes 

 it leaves its nerve and descends in front of the annular ligament. 



As in the case of recurrent or obstinate hemorrhage from a wound 

 of the palm, it is quite possible that an irregular comes nervi may 

 be involved, and, as in every case collateral circulation between the 

 radial and ulnar arteries is extremely free, it is proper to tie the 

 brachial at once, rather than the radial and ulnar arteries, or one 

 of them singly. 



THE BACK OF THE FORE-ARM 



The extensor carpi radialis longlor arises from the lower third 

 of the external condylar ridge ; it has a long tendon which is inserted 

 into the base of the second metacarpal bone. Nerve , the musculo- 

 spiral. 



The extensor carpi radialis brevior arises from the external 

 condyle by the common tendon, and is inserted into the base of the 

 middle metacarpal bone. Nerve, the posterior interosseous. 



These two muscles lie beneath the supinator longus, and their fleshy 

 bellies project behind that muscle over the upper third of the radius. 

 Their tendons run together under the annular ligament in the wide 

 groove behind the radial styloid process, and are crossed by the 

 tendons of the thumb-extensors. 



