62C 



HUMAN ANATOMY. 



less distinct to both sight and touch than the outer edge. Just within the inner 

 edge is the brachial artery and farther in the median nerve. 



The fold of the elbow is a transverse crease in the skin, seen in flexion, convex 

 downward, and running from the tip of one condyle to the tip of the other. It lies 

 above the line of the elbow-joint. In dislocation of the radius and ulna backward 

 the lower end of the humerus is below this crease ; in fracture of the humerus above 

 the condyles the lower end of the upper fragment is either on a line with or above 

 the crease. This relation will not be demonstrable in the presence of much swelling, 

 as this fold is then obliterated. 



On the front of the forearm, below the apex of the triangular space resulting from 

 the convergence of the two muscular masses descending from the condylar regions, 

 there are no salient surface landmarks, and none of great practical importance until 

 the wrist is reached. Many of those of that region and of the hand have been de- 

 scribed (pages ^8, ^29, 230, 320). It should, however, be noted that, instead of 

 being flattened from before backward and widest from side to side as when in the 

 supine position, the forearm when the hand is pronated becomes rounded and its 

 antero-posterior slightly exceeds its lateral thickness (Thomson). This is due to 

 the fact that the tendons of the supinator and extensor masses are held in grooves 

 \n the lower end of the radius by the posterior annular ligament, and are thus car- 

 ried towards the ulna when the radius moves in that direction. 



Fig. 596. 



Outer head of triceps 

 . Deltoid 



Biceps 



Brachialis aiiticus 



External bicipital furrow 

 Brachio-radialis 



Common extensor 



Extensor longus pollicis 



I Olecranon Ulna 

 Internal condyle 



Posterior surface of arm shown in preceding figure. 



Ulnar styloid process 



Of the two transverse furrows on the flexor surface of the wrist the lower is the 

 more marked. It is almost three-quarters of an inch below the summit of the upward 

 curve of the wrist-joint, is on the line of the intercarpal joint and of the upper border 

 of the anterior annular ligament, and is about a half-inch above the carpo-metacarpal 

 joint. At the wrist the palmaris tendon — when present — is made prominent by 

 extending the digits, slightly flexing the wrist, and closely approximating the thenar 

 and hypothenar eminences. To its radial side from within outward lie the median 

 nerve, the tendon of the flexor carpi radialis, and the radial artery. To its ulnar 

 side lie first the rounded elevation made by the flexor sublimis tendons, then the ulnar 

 artery, and then the flexor carpi ulnaris tendon, made easily palpable, although not 

 very prominent, by strong flexion of the wrist and little finger. 



On the postero-lateral aspect of the forearm may be seen : 



1. The elevation of the anconeus, triangular in shape, to the radial side of the 

 posterior subcutaneous surface of the olecranon and separated from the common 

 extensor mass by a well-defined depression. This muscle and the expansion of the 

 triceps tendon that covers it are of great value in the movement of extension of the 

 forearm after excision of the elbow. 



2. The curved border of the ulna (subcutaneous in supination), at the bottom 

 .of the 2ihiar furrozv, between the flexor carpi ulnaris and the common extensor 

 group, is easily accessible for examination through its whole length (page 289). 



3. The very importart depression just below the external condyle and ej^ter- 

 nal to the olecranon has been described (page 296). 



