OF THE FOOT. 



445 



of the os calcis, from the central part of the plantar fascia, and from the 

 intermuscular septa between it and the adjacent muscles. It passes forward, 

 and divides into four tendons, one for each 

 of the four outer toes. Opposite the bases 

 of the first phalanges each tendon divides 

 into two slips, to allow of the passage of 

 the corresponding tendon of the Flexor longus 

 digitorum; the two portions of the tendon 

 then unite and form a grooved channel for 

 the reception of the accompanying long flexor 

 tendon. Finally, they divide a second time, 

 to be inserted into the sides of the second 

 phalanges about their middle. The mode of 

 division of the tendons of the Flexor brevis 

 digitorum and their insertion into the pha- 

 langes is analogous to the Flexor sublimis digi- 

 torum in the hand. 



Relations. By its superficial surface, with 

 the plantar fascia ; by its deep surface, with 

 the Flexor accessorius, the Lumbricales, the 

 tendons of the Flexor longus digitorum, and 

 the external plantar vessels and nerve, from 

 which it is separated by a thin layer of fascia. 

 The outer and inner borders are separated from 

 the adjacent muscles by means of vertical pro- 

 longations of the plantar fascia. 



Fibrous Sheaths of the Flexor Tendons. 

 These are not so well marked as in the fingers. 

 The flexor tendons of the toes as they run 

 .along the phalanges are retained against the 

 bones by a fibrous sheath, forming osseo-apo- 

 neurotic canals. These sheaths are formed 

 by strong fibrous bands which arch across the 

 tendons and are attached on each side to the 

 margins of the phalanges. Opposite the 

 middle of the proximal and second phalanges 

 the sheath is very strong, and the fibres pass 

 transversely, but opposite the joints it is much 

 thinner, and the fibres pass obliquely. Each 

 sheath is lined by a synovial membrane which 

 is reflected on the contained tendon. 



The Abductor minimi digiti lies along the 

 outer border of the foot. It arises, by a very broad origin, from the outer tubercle 

 of the os calcis, from the under surface of the os calcis between the two tubercles, 

 from the fore part of the inner tubercle, from the plantar fascia arid the intermus- 

 cular septum, between it and the Flexor brevis digitorum. Its tendon, after glid- 

 ing over a smooth facet on the under surface of the base of the fifth metatarsal 

 bone, is inserted with the short Flexor of the little toe into the outer side of the 

 base of the first phalanx of this toe. 



Relations. By its superficial surface, with the plantar fascia ; by its deep sur- 

 face, with the Flexor accessorius, the Flexor brevis minimi digiti, the long plantar 

 ligament, and the tendon of the 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 backward, so as to detach them from the 

 . bone ; they should then be drawn forward, in order to expose the second layer, but not cut 



FIG. 261. Muscles of the sole of the foot. 

 First Layer. 



