ANATOMY OF THE BEND OF THE ELBOW 643 



THE ANATOMY OF THE BEND OF THE ELBOW (ANTECUBITAL 



FOSSA). 



At the bend of the elbow the brachial artery sinks deeply into a triangular inter- 

 val, the antecubital fossa, the base of which is directed upward, and may be repre- 

 sented by a line connecting the two condyles of the humerus; the sides are bounded, 

 externally, by the inner edge of the Brachioradialis; internally, by the outer mar- 

 gin of the Pronator teres; its floor is formed by the Brachialis anticus and Supi- 

 nator [brevis]. This space contains the brachial artery with its accompanying 

 veins, the radial and ulnar arteries, the median and musculospiral nerves, and the 

 tendon of the Biceps. The brachial artery occupies the middle line of this space, 

 and divides opposite the neck of the radius into the radial and ulnar arteries; it is 

 covered, in front, by the integument, the superficial fascia, and the median basilic 

 vein, the vein being separated from direct contact with the artery by the bicipital 

 fascia. Behind, it lies on the Brachialis anticus, which separates it from the 

 elbow-joint. The median nerve lies on the inner side of the artery, close to it 

 above, but separated from it below by the coronoid origin of the Pronator teres. 

 The tendon of the Biceps lies to the outer side of the space, and the musculospiral 

 nerve still more externally, situated upon the Supinator and partly concealed by 

 the Brachioradialis. 



Peculiarities of the Brachial Artery as Regards its Course. The brachial artery, accom- 

 panied by the median nerve, may leave the inner border of the Biceps and descend toward the 

 inner condyle of the humerus, where it usually curves around a prominence of bone, the supra- 

 condylar process. From this process, in most subjects, a fibrous arch is thrown over the artery. 

 The vessel then inclines outward, beneath or through the substance of the Pronator teres 

 muscle, to the bend of the elbow. The variation bears considerable homology to the normal 

 condition of the artery in some of the carnivora; it has been referred to in the description of the 

 humerus (page 181). 



As Regards its Division. Occasionally, the artery is divided for a short distance at its upper 

 part into two trunks which are united above and below. A similar peculiarity occurs in the 

 main vessel of the lower limb. 



The vessels concerned in the high division of the brachial artery are three viz., radial, ulnar, 

 and interosseous. Most frequently the radial is given off high up, the other limb of the bifurca- 

 tion consisting of the ulnar and interosseous. In some instances the ulnar arises from the 

 brachial above the ordinary level, and the radial and interosseous form the other limb of the 

 division; and occasionally the interosseous arises high up. 



Sometimes long slender vessels, vasa aberrantia, connect the brachial or axillary arteries 

 with one of the arteries of the forearm or a branch from them. These vessels usually join the 

 radial. 



Varieties in Muscular Relations. 1 The brachial artery is occasionally concealed in some 

 part of its course by muscular or tendinous slips derived from the Coracobrachialis, Biceps, 

 Brachinlis anticus, and Pronator teres muscles. 



Surface Marking. The direction of the brachial artery is marked by a line drawn along 

 the inner edge of the Biceps from the junction of the anterior and middle thirds of the axillary 

 outlet to the middle of the front of the elbow-joint. 



Applied Anatomy. Compression of the brachial artery is required in cases of amputation 

 and some other operations in the arm and forearm ; and it will be observed that it may be effected 

 in almost any part of the course of the artery. If pressure is made in the upper part of the 

 limb, it should be directed from within outw r ard, and if in the lower part, from before backward, 

 as the artery lies on the inner side of the humerus above and in front of the humerus below. 

 The most favorable situation is about the middle of the arm, where it lies on the tendon of the 

 Coracobrachialis on the inner flat side of the humerus. 



The application of a ligature to the brachial artery may be required in case of wound of the 

 vessel and in some cases of wound of the palmar arch. It is also sometimes necessary in cases 

 of aneurism of the brachial, the radial, ulnar, or interosseous arteries. The artery may be 

 secured in any part of its course. The chief guides in determining its position are the sur- 

 face markings produced by the inner margin of the Coracobrachialis and Biceps, the known 



1 See Struther's Anatomical and Physiological Observations. 



