OF THE SOLE OF THE FOOT. FIRST LAYER. 



351 



Fig. 194. Muscles of the Sole of the Foot. 

 First Layer. 



The Abductor Pollicis lies along the inner border of the foot. It arises from 

 the inner tuberosity on the under surface of the os calcis ; from the internal annular 

 ligament; from the plantar fascia; 1 and from the intermuscular septum between it 

 and the Flexor brevis digitorum. The fibres terminate in a tendon, which is 

 inserted, together with the innermost tendon of the Flexor brevis pollicis, into the 

 inner side of the base of the first phalanx of the great toe. 



Relations. By its superficial surface, with the plantar fascia. By its deep 

 surface, with the Flexor brevis polli- 

 cis, the Flexor accessorius, and the 

 tendons of the Flexor longus digitorum 

 and Flexor longus pollicis, the Tibialis 

 anticus and posticus, the plantar ves- 

 sels and nerves, and the articulations 

 of the tarsus. 



The Flexor Brevis Digitorum lies 

 in the middle line of the sole of the 

 foot, immediately beneath the plantar 

 fascia, with which it is firmly united. 

 It arises, by a narrow tendinous pro- 

 cess, from the inner tuberosity of the 

 os calcis ; from the central part of the 

 plantar fascia ; and from the intermus- 

 cular septa between it and the adjacent 

 muscles. It passes forwards, and 

 divides into four tendons. Opposite 

 the middle of the first phalanges, each 

 tendon presents a longitudinal slit, to 

 allow of the passage of the correspond- 

 ing tendon of the Flexor longus digi- 

 torum, the two portions forming a 

 groove for its reception, and, after re- 

 uniting, divides a second time into two 

 processes, which are inserted into 

 the sides of the second phalanges. 

 The mode of division of the tendons 

 of the Flexor brevis digitorum, and 

 of their insertion into the phalanges, is 

 analogous to that of the Flexor sublimis 

 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 ex- 

 ternal 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 prolongations of 

 the plantar fascia. 



The Abductor Minimi Digiti lies along the outer border of the foot. It arises, 

 by a very broad origin, from the outer tuberosity of the os calcis, from the under 

 surface of the % os calcis in front of both tubercles, from the plantar fascia, and the 

 intermuscular septum between it and the Flexor brevis digitorum. Its tendon, 

 after gliding 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 the little toe. 



