94 THE SUPERIOR EXTREMITY 



The brachial artery and its branches. 



The median, ulnar, radial and musculo-cutaneous nerves. 



The biceps, coraco-brachialis and brachialis muscles. 



It is convenient to study at the same time the cubital 

 fossa in front of the elbow. 



The skin has already been removed, and the cutaneous 

 veins and nerves have been seen (see pp. 62, 63). Now they 

 must be re-studied, and the main points of the surface anatomy 

 of the region must be revised. 



Surface Anatomy. In a muscular limb the prominence 

 formed by the biceps muscle along the front of the arm is 

 very apparent. Every one is familiar with the rounded swelling 

 which the muscle produces when powerfully contracted in the 

 living subject. On each side of the biceps there is a feebly 

 marked furrow, and ascending in each of these there is a 

 large superficial vein. In the lateral sulcus is the cephalic 

 vein ; in the distal part of the medial sulcus is the basilic vein. 

 In the proximal part of the medial bicipital sulcus is an 

 elongated bulging produced by the subjacent coraco-brachialis 

 muscle ; it is useful as a guide to the distal part of the 

 axillary and the proximal part of the brachial arteries, which 

 lie immediately behind and to the medial side of it. The 

 humerus is thickly clothed by muscles ; but towards its distal 

 part the two epicondylar ridges, leading to the epicondylar 

 eminences, may be felt. The lateral ridge is the more 

 salient of the two, and therefore the more evident to 

 touch. 



The bony points around the elbow must be studied with 

 especial care. It is by a proper knowledge of the normal 

 relative positions of them that the surgeon is able to dis- 

 tinguish between the different forms of fracture and dis- 

 location which so frequently occur in the elbow region. First 

 note the medial epicondyle of the humerus. It constitutes 

 a prominence appreciable to the eye ; grasp it between the 

 finger and thumb, and note that it inclines posteriorly as 

 well as medially. In a well-developed, fully extended arm, 

 the lateral epicondyle does not form a projection on the 

 surface, but can be felt at the bottom of a slight depression 

 on the dorsal aspect of the limb. It becomes apparent to 

 the eye as a prominence when the elbow is semi-flexed. The 

 olecranon produces a marked projection on the dorsum of 

 the elbow between the two epicondyles. It is placed slightly 



