384 THE MUSCLES 



Insertion. — The outer jtart of the under surface of the base of the first i)halanx 

 of the <rreat toe. 



Structure. — Arising by sliort tendinous fibres, the muscle converges iu bipen- 

 niforni fasliion upon a short tendon, which blends with that of the flexor brevis 

 hallucis and the outer sesamoid Ijone internally, and the transversus pedis exter- 

 nally. 



Nerve-supply. — From the external plantar division of the posterior tibial 

 nerve l)v tilann-nts which enter the upper surface of the muscle upon its outer 

 border near its origin. 



Action. — (1) To adduct the first phalanx of the great toe towards the middle 

 line of the foot; (2) to Hex the first phalanx. Usually it will act during walking 

 in combination with the flexor Ijrevis hallucis and ah)ductor hallucis, and the three 

 muscles contracting together will produce direct flexion of the first phalanx, so 

 that when the weight of the body rests upon the front part of the foot the second 

 phalanx is pressed firmly against the ground by the action of the flexor longus 

 hallucis. while the first phalanx is acted upon in the same manner by the combi- 

 nation of these three short muscles. As Duchenne has pointed out, the abductor 

 and adductor will have an imijortant function in adjusting the pressure when the 

 step has to be made upon uneven ground. Thus, in walking upon a slope the 

 adductor hallucis of the one foot will direct the pressure downwards and slightly 

 outwards, while the abductor of the other foot will direct the pressure downwards 

 and slightly inwards. 



Relations. — Superficially, the flexor longus digitorum tendons and their lum- 

 bricales; deeply, the interossei with the external plantar vessels and nerve; at the 

 sides, the flexor brevis hallucis and transversus pedis. 



Variations. — The adductor hallucis sometimes sends a slip to the first phalanx of the second 

 toe. 



3. TRAXSVERSUS PEDIS 



The transversus pedis — named from the direction of its fibres — is a small 

 muscle consisting of three or four fusiform bundles lying side by side, and uniting 

 in a single tendon. 



Origin. — (1) The plantar ligaments of the three outer metatarso-phalangeal 

 joints: ( 2 ) the under surface of the adjacent deep transverse metatarsal ligaments. 



Insertion. — The outer side of the base of the first phalanx of the great toe. 



Structure. — The fleshy fibres form a series of small bundles which converge 

 slightly as they pass inwards and somewhat forwards, and after uniting terminate 

 in a short tendinous insertion which is closely blended with the outer surface of 

 the tendon of the adductor hallucis. 



Nerve-supply. — Fnmi the external plantar division of the posterior tibial 

 nerve by filaments which pass to the upper part of the posterior edge of the muscle. 



Action. — (1) To adduet the first phalanx of the great toe; (2) to draw together 

 the heads of the metatarsal bones after the}' have been sej^arated by the pressure 

 of the weight of the body during the tread. 



Relations. — .Superficially, the flexor longus digitorum tendons and lumbri- 

 cales; deeply, the interossei. 



Variations. — Some or all of the bundles may be absent ; most frequently the outermost one. 

 OLXiisionally fibres join the muscle from the fascia covering the int^erossei below the lower border 

 of the adductor hallucis, so that the two muscles are more or less blended. 



4. FLEXOR BREVIS MINIMI DIGITI PEDIS 



The flexor brevis minimi digiti pedis — named from its action u])on the little 

 toe — is small. Unttcned. and fuHiforni. 



Origin. — (1) The under surface of the base of tlie fifth metatarsal l)one; (2) 

 the adjacent part of the sheath of the ])eroneus longus tendon. 



Insertion. — (1) The outer part of the under surface of the base of the first 



