378 A MANUAL OF ANA TOMY. 



The Superficial Veins of the Forearm. 



There are usually two main trunks, the posterior ulnar 

 and posterior radial veins. These begin at the back of the 

 hand in an irregular plexus and proceed up the back of the 

 forearm, communicating with each other by branches. The 

 posterior ulnar curves forward just below the internal con- 

 dyle of the humerus to unite with the anterior ulnar to form 

 the common ulnar. See page 282. The posterior radial 

 empties into the radial at the outer side of the upper part 

 of the forearm. 



The Superficial Nerves of the Forearm and Hand 



These are for the forearm the external cutaneous branch 

 of the musculospiral and a posterior branch of the cuta- 

 neous portion of the musculocutaneous nerve, for the outer 

 half; and the posterior division of the internal cutaneous, 

 for the inner half of the forearm. 



In the hand the radial nerve supplies the outer half of 

 the dorsum and the outer two and one-half fingers, while 

 the dorsal cutaneous branch of the ulnar nerve completes 

 the inner half of the back of the hand and two and one- 

 half fingers. 



DISSECTION. 



Remove the deep fascia from the back of the forearm, hand, and fingers. 

 At the wrist leave a band of the deep fascia about an inch wide, the posterior 

 annular ligament of the wrist. 



Clean all the muscles, vessels, and nerves presenting. 



The Posterior Annular Ligament. Fig. 78. 



This will be found to consist of the fibres of the deep 

 fascia which have been reinforced by additional transverse 

 fibres. This thickened band is about an inch wide, and is 

 attached from the outer border of the radius around the 

 back of the wrist to the inner border of the pisiform and 



