OF THE HAXD 487 



IV. MUSCLES AND FASC T jE OF THE HAND. 



The muscles of the hand are subdivided into three groups: (1) Those of the 

 thumb, which occupy the radial side and produce the thenar eminence. (2) Those 

 of the little ringer, which occupy the ulnar side and give rise to the hypothenar 

 eminence. (3) Those in the middle of the palm and within the interosseous spaces. 



Dissection (Fig. 346). Make a transverse incision across the front of the wrist, and a second 

 across the heads of the metacarpal bones; connect the two by a vertical incision in the middle 

 line, and continue it through the centre of the middle finger. The anterior and posterior annular 

 ligaments and the palmar fascia should then be dissected. 



ANTERIOR 

 ANNULAR 

 LIGAMENT, 

 FLEXOR LONGUS POLLIC1S. / JfiM&M nfTVC. 



FLEXOR CARPI RADiALis. \ If .I'lniir rrxxels. 



MUSCLES OF THUMB. V \ \ | / j fPALMARIS BREVIS. 



MUSCLES OF 



EXT. CARPI 

 ULNARIS. 



EXTENSOR 

 ^MINIMI 



Radial vessels. / ^^j^j^jj^gj^^ ,G,T,. 



EXT. CARP. RAD. LOW S^^Sil^iiiJj^i^X^ EXTENSOR 



Trapesoid. 7 T^ \COMMUNIS 



EXTENSOR CARPI RADIALIS/ ./ EXT ENSOR INDICl's^ 

 BREVIOR. / 



Os magnum. 



FIG. 364. Transverse section through the carpus, showing the relative positions of the tendons, vessels, and 



nerves. (Henle.) 



The Anterior Annular Ligament (ligamentum carpi transversum*) ( Fig. 364) is a 

 strong, fibrous band which arches over the carpus, converting the deep groove on 

 the front of the carpal bones into a canal, beneath which pass the Flexor tendons 

 of the fingers. It is attached, internally, to the pisiform bone and the hook of 

 the unciform bone, and externally to the tuberosity of the scaphoid and to the 

 inner part of the anterior surface and the ridge of the trapezium. It is continuous, 

 above, with the deep fascia of the forearm, of which it may be regarded as a thick- 

 ened portion, and, below, with the palmar fascia. It is crossed by the ulnar ves- 

 sels and nerve and the cutaneous branches of the median and ulnar nerves. At 

 its outer extremity is the tendon of the Flexor carpi radialis, which lies in the groove 

 on the trapezium between the attachments of the annular ligaments to the bone. 

 It has inserted into its'anterior surface a part of the tendon of the Palmaris longus 

 and part of the tendon of the Flexor carpi ulnaris, and has arising from it, below, 

 the small muscles of the thumb and little finger. Beneath it pass the tendons of 

 the Flexores sublimis and Profundus digitorum, the tendon of the Flexor longus 

 pollicis, and the median nerve. 



The Synovial Membranes of the Flexor Tendons at the Wrist. There are two 

 vaginal synovial membranes which enclose all the tendons as they pass beneath 

 this ligament one for the Flexores sublimis and Profundus digitorum, the 

 other for the Flexor longus pollicis. They extend up into the forearm for about 

 an inch above the annular ligament, and downward about half-way along the 

 metacarpal bone, where they terminate in a blind diverticulum around each pair 



