374 A MANUAL OF ANATOMY 



Ulnar Nerve in the Hand. — ^The ulnar nerve enters the hand by 

 passing over the anterior annular ligament, where it lies on the inner 

 side of the ulnar vessels, and is overhung by the pisiform bone. 

 It then breaks up into two divisions — superficial and deep. The 

 superficial division passes downwards beneath the palmaris brevis, 

 which it supplies, and it ends in two digital nerves. The inner 

 is a single nerve, and is distributed to the inner side of the little 

 finger. The outer, which is compound, passes to near the cleft 

 between the ring and little fingers, where it divides into two collateral 

 digital nerves for the supply of their contiguous sides. This nerve 

 communicates with the innermost digital branch of the median. 

 The distribution of the nerves on the fingers corresponds with 

 that of the median, and the branches which turn to the backs of 

 the fingers are for the most part distributed as follows : (i) to the 

 back of the terminal, and distal end of the second, phalanges of the 

 ring finger, and (2) to the matrix of the nail of the little finger. 

 The deep division of the ulnar nerve, along with the profunda branch 

 of the ulnar artery, passes between the abductor and flexor brevis 

 minimi digiti, and then through the opponens minimi digiti. There- 

 after it accompanies the deep palmar arch, above which it lies, to 

 the thenar region, and it has an extensive muscular distribution, 

 as follows : it supplies the abductor, flexor brevis, and opponens, 

 miniini digiti, the inner two lumbricales, the seven interossei, and 

 two and a half muscles of the thenar eminence — namely, the deep 

 head of the flexor brevis poUicis, adductor obliquus pollicis, and 

 adductor transversus pollicis. It also gives articular twigs to the 

 wrist-joint, and several of the joints of the hand. 



Summary of the Ulnar Nerve. — Muscular. — In the forearm it supplies the 

 flexor carpi ulnaris and inner portion of the flexor profundus digitorum; 

 and in the hand it supplies (i) the palmaris brevis, (2) the three hypothenar 

 muscles, (3) the inner two lumbricales, (4) the seven interossei, and (5) two 

 and a half muscles of the thenar eminence, namely, the deep head of the flexor 

 brevis, adductor obliquus, and adductor transversus, pollicis. Cutaneous. — 

 It supplies the integument of (i) the front of the forearm for a little below 

 the centre, and internal to the middle line ; (2) the inner portion of the palm ; 

 and (3) the inner one and a half fingers. Articular. — It supplies branches toi 

 the elbow- and wrist-joints, and several of the joints of the hand. j 



I 



Great Palmar Bursa. — ^This bursa has two compartments, inner] 

 and outer. I 



The inner compartment, which is large and loose, invests the? 

 superficial and deep flexor tendons and median nerve as they pas<' 

 beneath the anterior annular ligament. It extends upwards ini 

 the forearm for rather more than an inch above the ligament, an 

 downwards to about the centre of the palm. It is shut off from tin 

 synovial sheaths of the flexor tendons of the index, middle, and rin 

 fingers, but internally it is prolonged downwards \o be, as a nil 

 continuous with the synovial sheath of the flexor tendons of tlii 

 little finger. 



The outer compartment, which is long and narrow, invests t! 

 tendon of the flexor longus pollicis beneath the anterior annul. 



