FOREARM AND HAND 



161 



longed, distally, to the base of the terminal phalanx of the thumb. 

 The extent of this sheath can be investigated by a blunt probe 

 introduced through a small opening made opposite the first 

 phalanx of the thumb. 



In some cases the mucous sheath which ensheaths the flexor tendons of 

 the fingers is divided into a medial and a lateral compartment by a fibrous 

 septum, and the lateral compartment may communicate with the sheath 

 of the flexor pollicis longus by means of a small aperture situated at 

 the proximal margin of the transverse carpal ligament. 



Ligamentum Carpi Trans versum (O.T. Anterior Annular 

 Ligament). The transverse carpal ligament should now be 



Pal mar is longus 



Median nerve Transverse carpal ligament 



I/lnar artery 



Flexor pollicis longus . 

 Superficial volar artery, ; 



Flexor carpi radialis - 

 Short muscles of thumb 



Palmaris brevis 

 / Ulnar nerve 



Abductor pollicis 

 longus 



Short muscles of 

 .little finger 



Extensor polli 

 brev 



Radial artery ^X&Cj 

 Extensor pollicis longus - 



Extensor carpi radialis longus 



Radial nerve, superficial 

 branch 



Extensor carpi radialis brevis 



jjfxf Extensor carpi ulnaris 



*y^' 'Extensor digiti quinti 

 .. proprius 



Dorsal branch of the ulnar nerve 



Extensor digitorum communis and extensor 

 indicis proprius 



FIG. 70. Transverse section through the Wrist at the level of the Distal 

 Row of Carpal Bones to show the Carpal Tunnel. The Tendons of the 

 Flexor Digitorum Sublimis, Flexor Digitorum Profundus, and Flexor 

 Pollicis Longus are seen within the Tunnel. 



thoroughly examined before it is divided to expose the 

 portions of the flexor tendons, which lie behind it. It is a 

 thick, dense, fibrous band, which stretches across the volar 

 aspect of the concavity of the carpus, and converts it into an 

 osteo-fibrous tunnel for the passage of the flexor tendons into 

 the palm. On each side it is attached to the piers of 

 the carpal arch, viz., on the lateral side to the tubercle of 

 the navicular bone and the ridge of the greater multangular 

 bone, and on the medial side to the pisiform bone and the 

 hook of the os hamatum. Its proximal margin is continuous 

 with the deep fascia of the forearm, of which it may be 

 VOL. i 11 



