430 



MUSCLES AND FASCI.E. 



plantar ligament, and Peroneus Longus. On its inner side are the external 

 plantar vessels and nerve, and it is separated from the Flexor Brevis Digitorum 

 by a vertical septum of fascia. 



Dissection. The muscles of the superficial layer should be divided at their origin, by insert- 

 ing the knife beneath each, and cutting obliquely backwards, so as to detach them from the bone ; 

 they should then be drawn forwards, in order to expose the second layer, but not cut away at 

 their insertion. The two layers are separated by a thin membrane, the deep plantar fascia, on 

 the removal of which is seen the tendon ot the Flexor Longus Digitorum, the Flexor Acces- 



sorius,the Flexor Longus Pollicis, and the Lum- 

 bricales. The long flexor tendons cross each other 

 at an acute angle, the Flexor Longus Pollicis run- 

 ning along the inner side of the foot, on a plane 

 superior to that of the Flexor Longus Digitorum, 

 the direction of which is obliquely outwards. 



262. Muscles of the Sole of the Foot. 

 Second Layer. 



Second Layer. 



Flexor Accessorius. 

 Lumbricales. 



The Flexor Accessorius arises by two 

 heads; the inner or larger, which is mus- 

 cular, being attached to the inner concave 

 surface of the os calcis, and to the cal- 

 caneo-scaphoid ligament ; the outer head, 

 flat and tendinous, to the under surface of 

 the os calcis, in front of its outer tuber- 

 cle, and to the long plantar ligament ; the 

 two portions join at an acute angle, and 

 are inserted into the outer margin and 

 upper and under surfaces of the tendon of 

 the Flexor Longus Digitorum, forming a 

 kind of groove, in which the tendon is 

 lodged. It is supplied by the external 

 plantar nerve. 



Relations. By its superficial surface, 

 with the muscles of the superficial layer, 

 from which it is separated by the external 

 plantar vessels and nerves. By its deep 

 surface, with the os calcis and long cal- 

 caneo-cuboid ligament. 



The Lumbricales are four small muscles, 

 accessory to the tendons of the Flexor 

 Longus Digitorum; they arise from the 

 tendons of the long flexor, as far back as 

 their angle of division, each arising from 

 two tendons, except the internal one. 

 Each muscle terminates in a tendon, which 

 passes forwards on the inner side of each 

 of the lesser toes, and is inserted into the 

 expansion of the long Extensor and base 

 of the second phalanx of the corresponding toe. The two internal Lumbri- 

 cales muscles are supplied by the internal, and the two external by the external 

 plantar nerve. 



Dissection. The flexor tendons should be divided at the back part of tlic foot, and the Flexor 

 Accessorius at its origin, and drawn forwards, in order to expose the third layer. 



