THE REGION OF THE ELBOW. 7g 



upon the humerus, it is endangered in fractures of this bone; it is also sometimes included in the 

 callus of a uniting fracture and causes corresponding symptoms. In operative procedures upon 

 the bone the nerve must be carefully avoided. Paralysis of the nerve is manifested by distur- 

 bances of function of all of the extensor muscles of the upper extremity (inability to extend the 

 hand and the fingers, wrist-drop) as well as by sensory disturbances of the extensor surfaces of 

 the arm, of the forearm, and of the radial half of the back of the hand. 



THE REGION OF THE ELBOW. 



If the elbow is flexed in the living subject, there may be felt upon the flexor surface the strong 

 tendon of the biceps, from which the sharply defined bicipital fascia radiates toward the ulnar side 

 (see Fig. 33). The other landmarks which may be palpated are the external and internal epicon- 

 dyles and, running upward from these points, the external and internal condyloid ridges. Poste- 

 riorly is the olecranon, and, to either side, the depressions which are more or less distinctly marked 

 when the arm is extended. These depressions at the margin of the olecranon mark the points 

 at which the cavity of the elbow-joint may be most easily and directly reached from behind (by 

 aspiration, for example). In effusions into the joint these depressions become less distinct or 

 even replaced by prominences. When the forearm is extended, the tip of the olecranon is in a 

 line connecting the two condyles; when the forearm is flexed, the tip of the olecranon is about one 

 centimeter lower. It is important to observe this normal relation, since the tip of the olecranon 

 passes above this line in backward dislocations of the ulna and in fractures of the olecranon. 

 Between the olecranon and the skin there is a subcutaneous bursa (see Fig. 34) which occasionally 

 may lead to the development of a hygroma, particularly in individuals who support themselves upon 

 their elbows while at work (miner's elbow). Somewhat higher up, within the tendon of the triceps 

 muscle, there is another bursa (bursa intratendinea olecrani). If the forearm is moved slightly, 

 the articulation between the external condyle and the head of the humerus may be felt, as may 

 also the head of the radius, which will be found to rotate during the movements of pronation and 

 supination. To the inner side of the olecranon, and running in a groove upon the humerus, the 

 ulnar nerve may be easily palpated. If it is pushed about under firm pressure for a short time, 

 the effect will be experienced in the hand. Upon the flexor surface the cutaneous veins may be 

 more or less distinctly seen. They are the cephalic vein upon the radial side, the basilic vein upon 

 the ulnar side, and the median cubital vein, the vein of phlebotomy and transfusion, which runs 

 in an oblique direction from the cephalic up to the basilic vein. If the median vein, running 

 upward upon the flexor surface of the forearm, divides, we speak of a median cephalic and of a 

 median basilic vein. The transverse furrow which becomes visible upon flexion of the forearm is 

 situated at the level of the epicondyles and two centimeters higher than the joint. 



Beneath the thin skin of the flexor surface and lying upon the deep fascia, which is reinforced 

 by the bicipital fascia, are two cutaneous nerves. Upon the ulnar side is the internal cutaneous 

 nerve, which pierces the deep fascia at the hiatus basilicus (see page 78) and usually divides into 

 two branches. The posterior branch reaches the extensor surface at the internal condyle ; the 

 anterior branch usually runs beneath the median cubital vein (or the median basilic vein) and 

 passes downward upon the flexor surface as far as the wrist-joint. The musculocutaneous nerve 



