MEDIAL CUTANEOUS NEKVE OF THE FOBEAKM. 709 



The articular branch is .distributed to the elbow-joint and arises as the nerve 

 passes behind the medial epicondyl6 of the humerus. 



The muscular branches arise as soon as the nerve enters the forearm. They are 

 distributed to the muscles between which the ulnar nerve lies the flexor carpi 

 ulnaris and the medial half of the flexor digitorum profundus. 



The cutaneous branches are two in number, palmar and dorsal. 



The palmar cutaneous ramus is variable in size and position. It pierces the 

 deep fascia in the distal third of the forearm and passes to the hypothenar 

 eminence and palm of the hand, to the skin over which it is distributed. It gives 

 branches to the ulnar artery, and communicates often with the medial cutaneous 

 nerve of the forearm and the palmar branch of the median nerve. 



The dorsal ramus of the hand is much larger (Fig. 618). It arises from the 

 ulnar nerve in the middle third of the forearm ; and, directed obliquely distally and 

 backwards, beneath the tendon of the flexor carpi ulnaris, it becomes cutaneous on 

 the medial side of the forearm in its distal fourth. It passes on to the back of 

 the hand, and, after giving off branches to the skin of the wrist and hand which 

 communicate with the superficial ramus of the radial nerve, it terminates in two 

 dorsal digital nerves, to supply the little finger and half the ring-finger, in the 

 following way : the medial branch courses along the medial side of the dorsum 

 of the hand and little finger : the lateral branch subdivides at the cleft between 

 the ring and little fingers to supply the adjacent sides of these fingers ; this 

 branch communicates with the superficial ramus of the radial nerve. The nerve 

 may supply two and a half fingers on the dorsum of the hand. 



Ramus Volaris Manus. In the palm the ulnar nerve supplies a small muscular 

 branch to the palmaris brevis, and then subdivides into its terminal branches, 

 which are named superficial and deep. 



Ramus Superficialis. The superficial branch is purely cutaneous ; it passes 

 distally deep to the palmar aponeurosis, and subdivides into a medial and a lateral 

 branch. The medial branch courses along the medial border of the little finger, 

 which it supplies on its palmar aspect. The lateral branch (common volar digital 

 nerve} becomes superficial at the cleft between the fourth and fifth fingers, between 

 the slips of the palmar aponeurosis, and subdivides into two branches (proper volar 

 digital nerves) which supply the adjacent sides of these fingers on their palmar 

 aspect. It communicates with the adjacent digital branch of the median nerve. 



Ramus Profundus. The deep branch is purely muscular. It separates from the 

 superficial branch, and passes deeply between the flexor brevis and abductor digiti 

 quinti muscles ; it supplies those muscles and the opponens digiti quinti, and, 

 turning laterally along the line of the deep palmar arch and under cover of the 

 deep flexor tendons, it supplies branches to the following muscles : interossei, third 

 and fourth lumbricales (on their deep surfaces), the adductor pollicis (oblique and 

 transverse parts), and the interosseus primus volaris (deep part of the flexor pollicis 

 brevis). 



Communications. The ulnar nerve communicates (1), in some cases, with the median 

 nerve in the forearm ; (2) with the medial cutaneous nerve of the forearm, and sometimes 

 with the median nerve, by its palmar branch ; (3) with the cutaneous part of the median 

 nerve in the palm, by means of its terminal cutaneous branches ; (4) with the superficial 

 ramus of the radial nerve on the dorsum of the hand, by means of its dorsal branch. 



NERVUS CUTANEUS ANTIBRACHII MEDIALIS. 



The medial cutaneous nerve of the forearm (O.T. internal cutaneous nerve) 



arises from the medial cord of the brachial plexus, from the eighth cervical and first 

 thoracic nerves (Figs. 614 and 617). In the axilla and proximal half of the arm it 

 lies superficial to the main artery. It becomes cutaneous by piercing the deep fascia 

 about the middle of the arm on its medial side, and accompanying the basilic vein 

 through the distal half of the arm, it divides at the front of the elbow into its two 

 terminal branches. 



Branches. In the arm, as soon as it becomes superficial, the nerve gives off a 

 branch which supplies the skin of the distal half of the anterior surface of the 



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