1 62 THE SUPERIOR EXTREMITY 



considered to be a thickened part ; whilst distally it is con- 

 nected with the palmar aponeurosis. 



Upon the volar surface of the transverse carpal ligament the 

 expanded tendon of the palmaris longus is prolonged distally 

 to the intermediate part of the palmar aponeurosis, whilst 

 from its sides some of the short muscles of the thumb and 

 little finger take origin. Close to its medial attachment the 

 ulnar artery and nerve find their way into the palm by pass- 

 ing superficial to it and deep to a more superficial fascial 

 band, the volar carpal ligament, which is attached on the 

 medial side to the pisiform and the hook of the os hamatum, 

 and on the lateral side to the volar surface of the transverse 

 carpal ligament, 



The tunnel which the transverse carpal ligament forms 

 with the volar concavity of the carpus is transversely oval in 

 shape, and it opens distally into the intermediate compartment 

 of the palm. Through it pass the tendons of the flexor 

 digitorum sublimis, the flexor digitorum profundus, the tendon 

 of the flexor pollicis longus and the median nerve. The 

 relation of the tendon of the flexor carpi radialis to the 

 transverse carpal ligament is peculiar. It pierces the lateral 

 attachment of the ligament, and proceeds distally, in the 

 groove of the os multangulum majus, in a special compartment 

 provided with a special mucous sheath. 



Dissection. Clean the fibrous sheaths of the flexor tendons 

 of the fingers and the thumb. They lie immediately subjacent 

 to the superficial fascia and the digital vessels and nerves, and 

 they bind the tendons to the volar aspects of the phalanges and 

 the interphalangeal joints. 



Flexor Sheaths. Immediately subjacent to the skin, 

 the superficial fascia and the volar digital arteries and 

 nerves, lie the fibrous sheaths which bind the flexor tendons 

 to the volar surfaces of the phalanges, and to the volar 

 accessory ligaments of the metacarpo-phalangeal and inter- 

 phalangeal joints. Each fibrous sheath consists of a number 

 of parts of which the two strongest, the digital vaginal 

 ligaments, lie opposite the bodies of, and are attached to the 

 margins of, the first and second phalanges. Such strong bands 

 placed opposite the metacarpo-phalangeal and interphalangeal 

 joints would seriously interfere with their movements; therefore, 

 in those regions, weaker transverse bands, the annular liga- 

 ments, are formed. In addition, cruciate bands the cruciate 



