278 ARTERIES OF THE ARM. 



and Digito-Ulnar arteries, according to the sides of the fingers 

 on which they are placed. They are situated on the angle, 

 if it may be so termed, which is formed by the anterior and 

 lateral surfaces of each finger. In their course from the basis 

 to the extremity of the finger, they send off very small trans- 

 verse branches, which anastomose with each other, especially 

 near the end. Some transverse branches are observable on the 

 posterior as well as the antefior surface. Near the extremity 

 of each finger, beyond the insertion of the flexor tendon, 

 the extremities of these arteries ramify minutely. Some of 

 these small branches go to the skin and others anastomose with 

 their fellows of the opposite side. Some also go to the back 

 of the fingers.* 



Of the Arteries of the Arm, (see Plate VI. facing page 279.) 



A. The Scapula. 



B. The Pectoral Muscle held up. 

 c. The Deltoid Muscle. 



D. The Biceps Muscle. 



E. The Coraco-brachialis Muscle. 



F. The Triceps Extensor Muscle. 



G. The'Teres Major. 



H. The Tendon of the Lesser Pectoral Muscle. 



i. The Supinator Longus. 



K. The Extensor Carpi Eadialis. 



L. The Flexor Carpi Ulnaris. 



M- The Palmaris Longus and Flexor Muscles of the Fingers. 



* The distribution of the radial and ulnar arteries in the hand, is very differ- 

 ent in different subjects. 



Upon examining a large number of injected preparations in Philadelphia, it 

 was found that, in a very small majority of them, the ulnar artery formed an 

 arcus sublimis, whose branches extended as far as the ulnar side of the index, 

 and sometimes beyond it. 



That, in near a third of the preparations, the ulnar artery ramified without 

 forming an arcus, and supplied only two of the digital branches, viz., the first 

 two on the ulnar side. In such cases the radial artery generally made up the 

 deficiency of the ulnar, but in a few instances the interosseal was extended on 

 the palm of the hand, and supplied the radial side of the middle finger and the 

 corresponding side of the index. 



In a few instances also the ulnar artery was still more deficient, and the 

 radial was proportionally extended. 



