430 



THE MUSCULAE SYSTEM. 



FLEXOR HALLUCIS 

 - BREVIS 



FLEXOR 

 . DIGITORUM 



LONGUS 



FLEXOR DIGITI. 



-QUINTl BREVIS 



QUADRATUS 



PLANTS 



ABDUCTOR 

 HALLUCIS 



ABDUCTOR DIGITI 



QUINTI 



PERON^EUS 

 LONGUS 



FLEXOR 

 DIGITORUM 



LONGUS 



M. Flexor Digitorum Longus. The flexor digitorum longus lies in both 

 the back of the leg and the sole of the foot. Its origin is, by fleshy fibres, from the 

 posterior surface of the body of the tibia in its middle three-fifths, distal to 

 the oblique line, and medial to the vertical line and the origin of the tibialis 

 posterior from the fascia over it, and from an intermuscular septum on each side 



(Fig. 384, p. 428). 



Its tendon, after crossing 

 obliquely over the tendon of the 

 tibialis posterior, passes deep to 

 the ligamentum laciniatum, in- 

 vested in a special mucous sheath, 

 and enters the sole of the foot. 

 There it crosses superficially, the 

 tendon of the flexor hallucis longus, 

 and finally divides into four sub- 

 ordinate tendons, which are inserted 

 into the four lateral toes in pre- 

 cisely the same manner as the 

 flexor digitorum profundus is in- 

 serted in the hand (p. 389). Each 

 tendon enters the digital sheath 

 of the toe, perforates the tendon of 

 the flexor digitorum brevis, and is 

 inserted into the base of the ter- 

 minal phalanx. Vincula accessoria 

 (longa and brevia) are present as in 

 the hand. 



The tendon of the flexor hallucis 

 longus sends a fibrous band to the 

 tendon of the flexor digitorum 

 longus as it crosses it in the sole 

 of the foot; the band usually passes 

 to the tendons destined for the 

 second and third toes. Associated 

 with this muscle in the sole of the 

 foot are the lumbricales and quad- 

 ratus plantse muscles. 



Mm. Lumbricales. The lum- 

 bricales are four small muscles 

 which arise in association with the 

 Long plantar tendons of the flexor digitorum 

 longus in the sole. The first muscle 

 arises by a single origin from the 

 tibial side of the tendon of the 

 flexor digitorum longus for the 

 second toe ; each of the other three 

 arises by two heads from the ad- 

 jacent sides of two tendons. 



Each muscle is inserted into the 

 dorsal expansion of the extensor 

 FIG. 385. THE MUSCLES OF THE EIGHT FOOT (Second Layer), tendon, the metatarso-phalangeal 



capsule, and the base of the first 



phalanx, precisely as in the case of the lumbrical muscles of the hand. Each 

 muscle passes forwards on the tibial side of the corresponding toe, superficial to the 

 transverse metatarsal ligament. 



Nerve-Supply. The flexor digitorum longus is supplied by the tibial nerve (L. 5. S. 1.). The 

 first lumbrical is supplied by the medial plantar nerve (L. 4/5. S. 1.) ; the other three, by the 

 lateral plantar nerve (S. 1. 2.). 



Actions. The flexor digitorum longus extends the ankles and flexes the four lateral toes. 



