UPPER EXTREMITY AND THORAX, ANTERIOR. 303 



wrist to the base of the little finger muscles (pisiform and 

 hook of the unciform). Above it is continuous with the 

 deep layer of the forearm fascia, tendon of the palmaris 

 longus muscle, and thin fascia intervening between the 

 superficial and deeper layer of flexor muscles of the fore- 

 arm. Below the palmar fascia passes off from its lower 

 border and anterior surface. 



Behind the ligament the tendons of the long flexors of 

 the fingers and thumb and the median nerve (and artery if 

 present) pass into the hand. Over the ligament, yet con- 

 tained in compartments of the deep fascia, are found the 

 tendon of the ulnar flexor, ulnar vessels and nerve, the 

 tendon of the palmaris longus and radial flexor of the car- 

 pus, then the radial vessels, and the tendons of the extensor 

 muscles of the thumb. This order is from within outward. 



Sheaths of the tendons of the long- flexors of the 

 fingers. These are formed of fibrous tissue passing from 

 the sides of the fingers over the front of the tendons. In 

 front of the joints the sheaths are very thin, but over the first 

 and second phalanges they are reinforced by transverse fibres 

 (vaginal ligaments). The sheaths are continuous above 

 with the lower margins of the divided fasciculi of the palmar 

 fascia. Internally they are lined with synovial membrane. 



The Superficial Palmar Arch. Fig. 66. 



This arterial arch is formed by the ulnar artery curving 

 downward from the inside to the outside of the hand, where 

 an anastomosis is established with the radialis indicis, prin- 

 ceps pollicis, superficialis volae, separately ; or with any two 

 or all of them. It is sometimes formed by the median 

 artery, see page 297. The position of the superficial arch is 

 indicated by a line drawn across the palm on a level with 

 the base of the extended thumb. 



