DISSECTION OF SUPERFICIAL STRUCTURES 73 



Both the bands are bound to the adjacent bones and 

 they act as straps which bind down the tendons, which pass 

 deep to them, and prevent them from springing away from 

 the bones when the hand is bent volarwards or dorsally. 



The transverse carpal ligament is attached on the ulnar 

 side to the pisiform bone and the hook of the hamatum, 

 and on the radial side to the tubercle of the navicular bone 

 and the ridges on the volar surface of the multangulum majus. 



Five structures cross the superficial aspect of the trans- 

 verse carpal ligament: (i) the ulnar artery; (2) the ulnar 

 nerve ; (3) the palmar cutaneous branch of the ulnar nerve ; 

 (4) the palmar cutaneous branch of the median nerve; (5) 

 the tendon of the palmaris longus. The palmar cutaneous 

 branches of the median and ulnar nerves have already been 

 seen. The ulnar artery and nerve pierce the deep fascia 

 proximal to the transverse carpal ligament, pass across its 

 superficial surface close to the lateral side of the pisiform 

 bone and disappear deep to the palmaris brevis. As they 

 cross the ligament they are bound down to it by a slip of 

 fascia, called the volar carpal ligament, which passes from the 

 pisiform bone to the superficial surface of the transverse 

 carpal ligament. The tendon of the palmaris longus pierces 

 the deep fascia proximal to the transverse carpal ligament, 

 crosses it and blends with the apex of the intermediate part 

 of the palmar aponeurosis which is attached to the distal 

 border of the ligament. 



Distal to the transverse carpal ligament the deep fascia is 

 called the palmar aponeurosis, of which there are three parts, 

 (i) A relatively thin lateral part which covers the muscles of 

 the thenar eminence; (2) a relatively thin medial part o\er 

 the muscles of the hypothenar eminence ; and (3) a strong 

 intermediate part which conceals and protects the main 

 vessels, nerves, and the tendons passing to the fingers. The 

 lateral and medial parts consist mainly of transverse fibres ; 

 the intermediate part on the other hand is formed principally 

 by strong longitudinal fibres bound together by transverse 

 fibres. 



The intermediate part of the palmar aponeurosis is triangular 

 in outline. Its apex blends with the tendon of the palmaris 

 longus and the transverse carpal ligament. Its borders 

 blend with the thinner lateral and medial parts, and from 

 them septa, which will be dissected later, pass into the depths 



