THE HAND. 



357 



THE PALMAR FASCIA. 



The palmar fascia is the continuation downward of the palmaris longus tendon. 

 It consists of a thick triangular middle portion and two thin lateral portions which 

 cover the thenar and hypothenar eminences. The triangular middle portion can be 

 divided into two layers. Its under layer is composed of transverse fibres, and blends 

 with the anterior annular ligament ; its upper layer is composed of longitudinal fibres, 

 the continuation of the palmaris longus, and when it reaches the middle of the palm 

 it divides into four slips which blend with the sheaths of the flexor tendons and 



Thin lateral portion 

 over thenar eminence 



Palmaris longus tendon 



Palmaris brevis muscle 



Dense triangular portion 

 of palmar fascia 



Thin lateral portion over 

 hypothenar eminence 



Digital nerves 



Superficial transverse 

 ligament 



Digital arteries 



FIG. 370. The palmar fascia. 



lateral ligaments of the metacarpophalangeal joints to insert into the sides of the base 

 of the proximal phalanges, and aid in flexing them. The digital arteries and nerves 

 lie between these slips on their way to the webs of the fingers. The superficial sur- 

 face is intimately adherent to the skin above, especially at the webs of the fingers, 

 where its fibres form the superficial transverse ligament. The intimate attachment 

 between the skin above and fascia beneath binds these two structures so closely and 

 firmly together that pus cannot travel for any distance between them. It either 

 burrows deeper, or perforates the skin, or collects beneath the epiderm, forming a 

 bleb. A strong band from the palmar fascia frequently goes to the thumb also, and 

 when the palmaris longus contracts it tends to bring the thumb forward. The 

 lateral portions covering the thenar and hypothenar eminences are thin and are 

 prolonged beneath the long flexor tendons to become attached to the third and fifth 

 metacarpal bones (Fig. 370). 



