THE BRACHIAL AETERY. 



437 



afterwards and for the greater part of its length with the biceps, the inner border 

 of one or both muscles overlapping it to a greater or less extent according to the 

 muscular development of the individual. 



Relation to veins. Two vence comites are in close contact with the brachial 

 artery, short transverse branches of communication passing between them, so as at 

 many points to encircle it. The basilic vein is placed to the inner side of the artery, 

 but is separated from it by the deep fascia of the limb in the lower half or more, 

 according to the level at which the vein perforates that membrane ; and at the 

 bend of the elbow the median-basilic vein crosses over the artery, The" semilunar 

 fascia of the biceps lying between them. 



Relation to nerves. The median nerve descends in contact with the artery, lying 

 on its outer side in the upper half of the arm, directly in front of it below the 



Fig. 358. SUPERFICIAL DISSECTION OP THE BLOOD-VESSELS AND 



NERVES AT THE FRONT OF THE ELBOW. (R. Quain.) i 



a, internal cutaneous nerve ; a! a", descending twigs of 

 the same nerve ; 6, placed over the biceps near its insertion 

 and close to the external cutaneous nerve ; &', i', branches of 

 this nerve descending along the outer part of the forearm ; 1, 

 placed on the fascia ot the arm near the bend of the elbow, 

 above the place where it has been opened to show the lower 

 part of the brachial artery with its venas comites, of which 

 one is entire, marked 2, and the other has been divided ; + , 

 is placed between the artery and the median nerve ; 3, basilic 

 vein ; 3', 3', ulnar veins ; 4, cephalic vein ; 4', radial vein : 

 5, 5, median vein ; 3', 5, median-basilic vein ; 4', 5, median- 

 cephalic vein. 



middle, and on the inner side at the elbow. The 

 large infernal cutaneous nerve accompanies the 

 artery, being placed over or to the inner side of 

 the vessel, until it pierces the fascia about the 

 middle of the arm. The ulnar nerve lies on the 

 inner side of the artery as far as the insertion of 

 the coraco-brachialis ; and the musculo- spiral nerve 

 is behind it for a short distance at its upper end. 



BRANCHES. In addition to the four named 

 branches which are described below, and which 

 proceed backwards from the main trunk, the brachial 

 artery gives small offsets to the integument of the 



arm, and a variable number of muscular branches, which pass forwards and out- 

 wards to the coraco-brachialis, biceps and brachialis anticus muscles. One more 

 constant branch, arising from the upper part of the artery (sometimes from the 

 superior profunda), passes outwards transversely in front of the humerus and ter- 

 minates in the lower part of the deltoid muscle. A special bicipital branch, which 

 varies much in size, is usually present, arising at or somewhat above the middle of 

 the arm, and descending outwards in front of the median nerve to the inner part of 

 the biceps muscle. 



1. The superior profunda artery (iv), the largest of the branches, arises 

 from the posterior part of the brachial artery, just below the border of the teres 

 major, and inclines backwards as it descends to reach the interval between the 

 inner and long heads of the triceps muscle. Accompanying the musculo-spiral 

 nerve, it then winds round the back of the humerus, in the spiral groove, and under 

 cover of the outer head of the triceps. In its course it gives off several branches to 

 the three heads of the trifceps ; one offset passes upwards between the long and 

 outer heads of that muscle, to anastomose beneath the hinder part of the deltoid 



F F 2 



