ANATOMY OF A MONODACTYLOUS FOETUS 411 



At the carpus a strong cutaneous branch is given off on each 

 side and on the lateral side also a muscular twig to the lumbrical 

 muscle. The rest of the nerve runs on the ventral surface of 

 the single digit, finally forking to each side of the digit about the 

 level of the second phalanx to let the underlying flexor digi- 

 torum profundus tendon pass through it. This nerve was at 

 first mistaken for the tendon of the flexor digitorum sublirais 

 muscle, so typical in appearance was it to this latter structure, 

 when only its course in the forearm and hand was uncovered. 



6. Ulnar nerve. Runs down the arm under the deep fascia 

 (figs. 7 and 8, U. N .) in company with the basilic vein, pierces 

 the deep fascia a little above the elbow, and divides into two 

 branches, a volar and a dorsal, both running subcutaneously 

 on the medial border of the forearm. 



No muscular branches whatever were found on this nerve, its 

 whole distribution being as a sensory nerve to the forearm. 



All other nerves of the brachial plexus which are not specially 

 described here are normal in their extent and distribution. 



VESSELS OF THE AKM 



The vessels of the arm were not dissected above the axilla as 

 it did not seem that any noteworthy changes from the normal 

 would be likely to occur. No injection was employed as it was 

 feared that if a vessel wall ruptured structures around the break 

 might be so stained as to obscure valuable results. Small ves- 

 sels were thus hard to follow, and arteries to the hand could not 

 be identified. * 



ARTERIES (figs. 8 and 10) 



The axillary artery and all its branches were normal in extent 

 and position. 



The brachial artery lay in the groove medial to the biceps 

 muscle, with the median nerve on its medial side throughout 

 its course, so that there is no crossing of nerve and artery. 



The brachial artery gave origin to numerous muscular branches 

 and also to three larger branches, the profunda brachii, coursing 



