no Anatomy Applied to Medicine and Swgery. 



Musculo-cutaneous. Loss of power of flexion of the 

 forearm (biceps and brachialis anticus). This loss of 

 flexion is especially marked if the forearm be supinated so 

 that another flexor the supinator longus would cease 

 to act. 



Musculo-spiral. Loss of power of the extensors of 

 the forearm, thumb, and of the fingers, as well as of the 

 supinator brevis. This injury is frequently the result of 

 pressure by a crutch in the axilla, or, of lying, while intoxi- 

 cated, with the forearm under the head, etc. It may also 

 arise from injury to the nerve in fracture of the humerus. 

 The triceps and the anconeus, being paralyzed, cause loss 

 of power of extending the forearm. The loss of power of 

 the extensors of the wrist, thumb and fingers, results in 

 "wrist drop." The fingers are flexed from the unopposed 

 action of the muscles supplied by the ulnar and median 

 nerves. Extension of the second and third phalanges, 

 however, may still be performed by the interossei and 

 lumbricales (supplied by the ulnar and median nerves). 

 Sensation in this injury is lost on the outer side of the arm 

 from the insertion of the deltoid down to the external 

 condyle ; on the outer side of the forearm, except about 

 its middle third which is supplied by the unimpaired mus- 

 culo-cutaneous nerve, and, lastly, on the outer side of the 

 dorsum of the hand, and over the greater part of the 

 dorsal surfaces of the thumb, index, middle, and the outer 

 half of the ring fingers. The patient will have his fore- 

 arm flexed and somewhat pronated while the fingers and 

 thumb will be flexed. 



Median nerve. Here the arm is unaffected, but, in 

 the forearm, pronation is almost lost, although modified 

 form of pronation is present, since the supinator longus 

 may still pronate the hand, i.e., bring it to a position of 

 mid-pronation if it be first supinated, and then, when it is 



