434 



THE MUSCULAK SYSTEM. 



(p. 430). They lie deep to the abductor hallucis and the flexor digitorum brevis, 

 and occupy the hollow of the tarsus and the space between the first and fifth 

 metatarsal bones; their deep surfaces are in contact with the adductor of the 



great toe and the interossei muscles. 



THIRD LAYER. 



M. Flexor Hallucis Brevis. The 

 flexor hallucis brevis arises by tendinous 

 fibres from (1) the medial part of the 

 plantar surface of the cuboid bone (Fig. 

 386, p. 432), and (2) the tendon of the 

 tibialis posterior. Directed forwards, over 

 the first metatarsal bone, the muscle 

 separates into two parts, between which 

 is the tendon of the flexor hallucis longus. 

 Each portion gives rise to a tendon 

 which is inserted into the corresponding 

 side of the base of the first phalanx 

 of the great toe ; in each tendon, 

 under the metatarso-phalangeal 

 articulation, a sesamoid bone is 

 developed. The medial tendon is 

 united with the insertion of the 

 abductor, the lateral tendon with 

 the insertions of the adductor 

 muscle of the great toe. 



Long plantar 

 ligament 

 FLEXOR HAL- 

 LUCIS LONGUS 

 FLEXOR DIGI- 

 TORUM LONGUS 

 QUADRATUS - 



PLANTS I 



(origins) * 



PERON^EUS 

 LONGUS 



FLEXOR DIGITI 

 QUINTI BREVIS 



FLEXOR HAL- - 

 LUCIS BREVIS 



INTEROSSEOUS-" 



MUSCLES 



ADDUCTOR 



HALLUCIS 



(oblique head) 



ADDUCTOR 



HALLUCIS 



(transverse head) 



Nerve - Supply. Medial plantar 

 nerve (L. 4. 5. S. 1.). 



Actions. A flexor of the metatarso- 

 phalangeal joint of the great toe. 



M. Adductor Hallucis. The 

 adductor hallucis consists of two 

 parts. The oblique head of the 

 muscle arises (1) from the sheath 

 of the peronseus longus, and (2) 

 from the plantar surfaces of the 

 bases of the second, third, and 

 fourth metatarsal bones (Fig. 386, 

 p. 432). It lies in the hollow of 

 the foot, on a deeper plane than 

 the long flexor tendons and lum- 

 bricales, and on the lateral side 

 of the flexor hallucis brevis, and 

 it runs obliquely medially and 

 forwards, to be inserted on the 

 lateral side of the base of the first 

 phalanx of the great toe between 

 and along with the flexor brevis 

 and the transverse head of the adductor hallucis. 



The transverse head arises from (1) the capsules of the lateral four metatarso- 

 phalangeal articulations and (2) the transverse metatarsal ligament. 



It runs transversely medially under cover of the flexor tendons and 

 lumbricales, the muscle is inserted, along with the oblique head, into the lateral 

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



FIG. 388. DEEP MUSCLES OF THE SOLE OP THE FOOT. 



Nerve-Supply. Lateral plantar nerve (S. 1. 2.). 



Actions. Flexion and adduction of the great toe towards the middle line of the toot. 



