UPPER EXTREMITY AND THORAX, ANTERIOR. 291 



Action. To pronate the forearm ; to aid in flexion of 

 the forearm. This muscle is a valuable accessory to the 

 flexors of the elbow-joint. 



Flexor Carpi Radialis. Fig. 66. 



Origin. By the common tendon, from the internal con- 

 dyle of the humerus. (See note above.) 



Insertion. Into the base of the second metacarpal bone. 

 The tendon grooves the trapezium upon its inner side and 

 passes superficial and external to the central compartment 

 of the annular ligament. 



Nerve Supply. The median, by filaments from the sixth 

 cervical nerve. 



Actions. To flex the wrist and slightly abduct the wrist, 

 to pronate and feebly flex the forearm. 



Pahnaris Longus. Fig. 66. 



Origin. Same as the flexor carpi radialis. (See note 

 above.) 



Insertion. Into the anterior annular ligament and central 

 portion of the palmar fascia. 



Nerve Supply. The median from the eighth cervical 

 nerve. 



Action. Tensor of palmar fascia, feeble flexor of wrist 

 and forearm. 



The Plexor Carpi Ulnaris. Fig. 66. 



Origin. By the common tendon from the internal con- 

 dyle (see note), by a second head from the internal surface 

 of the olecranon and the upper two-thirds of the posterior 

 ridge of the ulna. 



Insertion. Into the pisiform bone, hook of the unciform, 

 and base of the fifth metacarpal bone. 



