PLANTAR REGION. 



429 



261. Muscles of the Sole of the Foot. 

 First Layer. 



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 Polli- 

 cis, into the inner side of the base of the first 

 phalanx of the great toe. It is supplied by 

 the internal plantar nerve. 



Relations. By its superficial surface, with 

 the plantar fascia. By its deep surface, with 

 the Flexor Brevis Pollicis, the Flexor Ac- 

 cessorius, and the tendons of the Flexor 

 Longus Digitorum and Flexor Longus Polli- 

 cis, the Tibialis Anticus and Tibialis Posticus, 

 the plantar vessels and nerves, and the ar- 

 ticulations of the tarsus. 



The Flexor Brevis Digitorum (Perforatus) 

 lies in the middle of the sole of the foot, im- 

 mediately beneath the plantar fascia, with 

 which it is firmly united. It arises by a 

 narrow tendinous process, from the inner tu- 

 bercle of the os calcis ; from the central part 

 of the plantar fascia; and from the inter- 

 muscular 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 longi- 

 tudinal slit, to allow of the passage of the 

 corresponding tendon of the Flexor Longus 

 Digitorum ; the two portions form a groove 

 for the reception of that tendon. The tendon 

 of the short Flexor then reunites and imme- 

 diately divides a second time into two pro- 

 cesses, which are inserted into the sides of 

 the second phalanges. The mode of division 

 of the tendons of the Flexor Brevis Digi- 

 torum and their insertion into the phalanges, 

 is analogous to the Flexor Sublirnis in the 

 hand. It is supplied by the internal plantar 

 nerve. 



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 sepa- 

 rated 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 the 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. It is supplied 

 by the external plantar nerve. 



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

 surface, with the Flexor Accessorius, the Flexor Brevis Minimi Digiti, the long 



