34 TOPOGRAPHICAL ANATOMY OF 



this the cutaneous nerves and the superficial veins must be preserved. 

 The nerves are branches of the ulnar, radial, axillary, and median, and, 

 with one exception, their origins from the parent nerves have already- 

 been observed. 



(1) The volar cutaneous branch (ramus cutaneus volaris) of the ulnar 

 nerve spreads out over the posterior border of the forearm. (2) The 

 dorsal cutaneous nerve (n. cutaneus antibrachii dorsalis) is that branch 

 of the radial which becomes superficial at the distal border of the lateral 

 head of the triceps, and is distributed over the lateral aspect of the 

 forearm. (3) The lateral cutaneous nerve (n. cutaneus brachii lateralis) 

 is derived from the axillary, appears from beneath the deltoid, and 

 divides into two branches for the skin of the lateral and anterior part 

 of the forearm. (4) The lateral cutaneous nerve of the forearm (n. 

 cutaneus antibrachii lateralis) left the median about the middle of the 

 arm, and is now seen to be distributed over the anterior and medial 

 aspects of the forearm, carpus, and metacarpus. It divides into two 

 main branches, which follow the cephalic and accessory cephalic 

 veins. (5) The only cutaneous nerve of the forearm that does not 

 proceed from the arm is the superficial branch (ramus superficialis) of the 

 ulnar. This becomes subcutaneous immediately proximal to the acces- 

 sory carpal (pisiform) bone. Some of its filaments are distributed over 

 the lateral aspect of the carpus, but the greater part of the nerve is 

 continued into the metacarpal region. 



The superficial veins of the forearm are the cephalic and accessory 

 cephalic. 



V. CEPHALIOA ANTIBRACHII. — The Cephalic vein of the forearm is the 

 direct continuation of the median volar metacarpal vein. Lying at first 

 in the groove between the radial flexor of the carpus and the radius, it 

 crosses the medial aspect of the forearm very obliquely and becomes 

 continuous with the cephalic vein of the arm. This latter, ascending 

 the groove formed by the brachiocephalic and superficial pectoral 

 muscles, enters the triangular space at the root of the neck and ends 

 by uniting with the jugular. A considerable communicating branch 

 connects the cephalic vein of the forearm with the brachial about the 

 insertion of the biceps. 



V. CEPHALIOA ACCESSORiA. — The accessory cephalic vein begins in a 

 network of vessels on the dorsal aspect of the carpus and the distal 

 part of the radius and runs up the forearm, following the median border 

 of the radial extensor of the carpus, to join the cephalic vein close to 

 the elbow. 



Dissection. — The loose and scanty superficial fascia into which the 

 superficial pectoral muscle is inserted, must be removed, in order that a 

 clear view of the dense and definite deep fascia may be obtained. 



Fascia of the Forearm. — The glistening antibrachial fascia ^ (fascia 

 antibrachii) forms a complete investment to the muscles of the forearm 

 and is firmly connected with those parts of the radius and ulna that 

 are not covered with muscles. In the neighbourhood of the carpus 



^Fascia [L-J,^.b)^^d^^ ^jvrg^l W^ swathe, girth. 



