130 THE SUPERIOR EXTREMITY 



In the superficial group are the brachio-radialis, pronator teres, 

 the flexor carpi radialis, the palmaris longus, and the flexor 

 carpi ulnaris, in that order from the lateral to the medial 

 side. On a deeper plane lies the fleshy belly of the flexor 

 digitorum sublimis which only partially comes to the surface. 

 The deep group is composed of three muscles, placed in con- 

 tact with the bones and interosseous membrane of the fore- 

 arm, viz., the flexor digitorum profundus, in relation to the 

 ulna, the flexor pollicis longus, in relation to the radius, and 

 the pronator quadratus, closely applied to the distal ends of 

 both bones. The brachio-radialis lies along the lateral border 

 of the volar aspect. 



The brachio-radialis extends from the lateral supra-con- 

 dylar ridge of the humerus to the distal end of the radius. 

 The pronator teres ends at the middle of the radius. The 

 flexor carpi radialis passes to the ball of the thumb, where 

 its tendon disappears into a cleft in the lateral border of 

 the transverse carpal ligament. The tendon of the pal- 

 maris longus lies medial to the tendon of the flexor carpi 

 radialis ; it passes anterior to the transverse carpal ligament 

 to join the intermediate part of the palmar aponeurosis. 

 Still more medial, descending to the pisiform bone, is the 

 tendon of the flexor carpi ulnaris. The tendons of the flexor 

 digitorum sublimis, enclosed in their mucous sheath, lie deep 

 to the palmaris longus between the flexor carpi radialis and 

 the flexor carpi ulnaris. 



Dissection. Clean the brachio-radialis, from its origin from 

 the humerus to its insertion into the base of the styloid process 

 of the radius. To expose the insertion it will be necessary to 

 push backwards the tendons of the abductor pollicis longus and 

 the extensor pollicis brevis which overlap it posteriorly. Pull 

 the brachio-radialis aside and clean the radial artery and its 

 branches and the superficial branch of the radial nerve. 



Arteria Radialis. The radial artery is the smaller of the 

 two terminal branches of the brachial artery, but its direction 

 gives it the appearance of being the continuation of the 

 parent trunk in the forearm. It takes origin in the cubital 

 fossa, opposite the neck of the radius, and it proceeds distally, 

 in the lateral part of the front of the limb, until it reaches 

 the distal end of the radius. There it turns round the 

 lateral border of the wrist and leaves the present dissection. 

 At first it lies between the pronator teres and the brachio- 

 radialis, and is overlapped to some extent on the lateral side 



