EXTENSOR BREVIS DIGITORUM. 269 



portions of the plantar fascia pass deeply into the sole of the foot ; they separate 

 the flexor brevis digitorum from the abductor hallucis on the inner side, and from 

 the abductor minimi digiti on the outer side, and give partial origin to each of 

 these muscles 



The superficial transverse ligament cf the toes is a thin band of fibres contained 

 in the folds of skin limiting the interdigital clefts, and connected to the subjacent 

 sheaths of the tendons. Like the transverse metatarsal ligament, it differs from the 

 corresponding structure in the hand in being attached to all five digits. 



MUSCLES. On the dorsurn of the foot, besides the tendons continued from the 

 muscles of the front of the leg, one short muscle is present, viz., the extensor brevis 

 digitorum. In the sole the muscles are more numerous, and are described in four 

 layers as they are met with in the course of a dissection. 



The extensor brevis digitorum pedis arises from the fore part of the upper 

 and outer surfaces of the os calcis, in front of the groove for the peroneus brevis 

 muscle, and from the lower band of the anterior annular ligament. It divides into 

 four tapering slips, each of which terminates in a tendon ; the first or most internal 

 of these is inserted separately into the dorsal surface of the first phalanx of the 

 great toe at its tarsal extremity ; and the other three become severally united to 

 the outer borders of the tendons of the long extensor proceeding to the three 

 next toes. 



The innermost portion of the muscle is commonly separate much farther back than the 

 other slips, and is described by many anatomists as a distinct muscle under the name of 

 extensor brerix hallucis. 



Relations. It crosses the dorsum of the foot somewhat obliquely, resting on the tarsus- 

 and metatarsus, and lying beneath the tendons of the peroneus tertius and long extensor of 

 the toes. Its inner slip also crosses the dorsal artery of the foot and the anterior tibial nerve. 



Varieties. An accessory fasciculus of origin from the astragalus and navicular bone, or 

 from the external cuneiform and third metatarsal bones, has been observed passing to the 

 second slip of the muscle, and one from the cuboid to the third slip. The tendons vary 

 considerably both as to number and position ; they may be reduced to two, or one of them 

 may be doubled, or an additional slip may pass to the little toe. A supernumerary slip ending 

 on one of the metatarso-phalangeal articulations, or joining a dorsal interosseous muscle, is 

 not unfrequent. especially in the interval between the great and second toe bellies. Deep 

 slips forming a transition between this muscle and the dorsal interossei also occur. 1 There is 

 occasionally a single or double bursa between the short extensor muscle and the bases of the 

 second and third metatarsal bones (Synnestvedt). 



The FIRST LAYER OF MUSCLES OF THE SOLE includes the short common flexor 

 of the toes, and the abductors of the great and little toes. 



The flexor fore-vis digitorum, or flexor perforatus, arises by a small pointed 

 attachment from the fore part of the inner tubercle of the calcaneum, from the deep 

 surface of the plantar fascia for about two inches forwards, and from the intermus- 

 cular septum on each side. The muscle terminates in four slender tendons which are 

 inserted into the sides of the second phalanges of the four outer toes. Each tendon 

 prior to its insertion divides and gives passage to the tendon of the long flexor, in a 

 manner precisely similar to the arrangement of the tendons of the flexor sublimis 

 and flexor profundus muscles of the hand. 



Relations. This muscle lies between the abductor hallucis and abductor minimi digiti, 

 and is covered by the plantar fascia ; it conceals the flexor accessorius, with the tendons of the 

 flexor longus digitorum. and the external plantar vessels and nerve. 



Varieties. The slip of this muscle to the little toe, which is regularly much smaller than 

 the others, is frequently wanting (23 per cent.) ; or it may be replaced (5 per cent.) by a 

 small fusiform muscle arising from the long flexor tendon, or occasionally from the flexor 

 accessorius. In rare cases the origin of the slip to the fourth toe is also transferred to the 

 long flexor tendon. (In apes the perforated flexors of the outer toes arise regularly from the 



1 See Ruge, " Entwicklungsvorgange an der Muskulatur des menschlichen Fusses," Morph. 

 Jahrb., iv, 1878. 



