1 V 



. MUSCLES OF THE SOLE OF THE FOOT. 243 



Relations. By its superficial surface with the internal portion of 

 the plantar fascia. By its deep surface with the flexor brevis pollicis, 

 musculus accessorius, tendons of the flexor longus digitorum and 

 flexor longus pollicis, tendons of the tibialis anticus and posticus, 

 the plantar vessels and nerves and the tarsal bones. On its outer 

 border with the flexor brevis digitorum, from which it is separated 

 by a vertical septum of the plantar fascia. 



The Abductor minimi digiti lies along the outer border of the foot. 

 It arises from the outer tuberosity of the os calcis, and from the 

 base of the metatarsal bone of the little toe, and is inserted into the 

 base of the first phalanx of the little toe. 



Relations. By its superficial surface with the external portion of 

 the plantar fascia. By its deep surface with the musculus acces- 

 sorius, flexor brevis minimi digiti, with the tarsal bones, and with 

 the metatarsal bone of the little toe. By its inner side with the 

 flexor brevis digitorum, from which it is separated by the vertical 

 septum of the plantar fascia. 



The Flexor brevis digitorum (perforatus) is placed between the 

 two preceding muscles. It arises from the under surface of the os 

 calcis and plantar fascia, and is inserted by four tendons into the 

 base of the second phalanx of the four lesser toes. Each tendon 

 divides, previously to its insertion, to give passage to the tendon of 

 the long flexor ; hence its cognomen perforatus. 



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

 its deep surface with a thin layer of fascia which separates it from 

 the musculus accessorius, tendons of the flexor longus digitorum and 

 flexor longus pollicis, and plantar vessels and nerves. By its borders 

 with the vertical septa of the plantar fascia, which separate the 

 muscle, on the one side from the abductor pollicis, and on the other 

 from the abductor minimi digiti. 



Second Layer. 



Musculus accessorius, 

 Lumbricales. 



Dissection. The three preceding muscles must be divided from 

 their origin, and anteriorly through their tendons, and removed, in 

 order to bring into view the second layer. 



The Musculus accessorius arises by two slips from either side of 

 the under surface of the os calcis ; the inner slip being fleshy, the 

 outer tendinous. The muscle is inserted into the. outer side of the 

 tendon of the flexor longus digitorum. 



Relations. By its superficial surface with the three muscles of 

 the superficial layer, from which it is separated by their fascial 

 sheaths, and with the external plantar vessels and nerves. By its 

 deep surface with the under surface of the os calcis and the long 

 calcaneo-cuboid ligament. 



The Lumbricales (lumbricus, an earthworm) are four little muscles 

 arising from the tibial side of the tendons of the flexor longus digi- 



