MUSCLES OF THE SOLE OF THE FOOT. 



261 



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, ten- 

 dinous. The muscle is inserted into the outer side and upper surface 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 digitorum, 

 and inserted into the expansion of the extensor tendons, and into the base 

 of the first phalanx of the four lesser toes. 



Relations. By their superficial surface, with the Fig. 138.* 



tendons of the flexor brevis digitorum. By their deep 

 surface, with the third layer of muscles of the sole of 

 the foot. They pass between the digital slips of the 

 deep fascia to reach their insertion. 



Third Layer. 



Flexor brevis pollicis, 

 Adductor pollicis, 

 Flexor brevis minimi digiti, 

 Traiisversus pedis. 



Dissection. The tendons of the long flexors, and 

 the muscles connected with them, must be removed, 

 to see clearly the attachments of the third layer. 



The JEjLExoR BJIEVIS POLLICIS arises, by a pointed 

 tendinous process, from the side of the cuboid, and 

 from the external cuneiform bone ; it is inserted, by 

 two heads, into the base of th6 first phalanx of the 

 great toe. Two sesamoid bones are developed in the 

 tendons of insertion of these two heads, and the tendon of the flexor longus 

 pollicis lies in the groove between them. 



Relations. By its superficial surface, with the abductor pollicis, tendon 

 of the flexor longus pollicis, and plantar fascia. By its deep surface, with 

 the tarsal bones and their ligaments, the metatarsal bone of the great toe, 

 and the insertion of the tendon of the peroneus longus. By its inner bor- 

 der, with the abductor pollicis ; and by its outer border, with the adductor 

 pollicis ; with both of these muscles it is blended near its insertion. 



The ADDUCTOR POLLICIS arises from the cuboid bone, from the sheath 

 of the tendon of the peroneus longus, and from the base of the third and 



* Deep-seated muscles in the sole of the foot. 1. Tendon of the flexor longus pollicw 

 2. Tendon of the flexor communis digitorum pedis. 3. Flexor accessorius. 4,4. Lum- 

 bricales. 5. Flexor brevis digitorum. 6. Flexor brevis pollicis pedis. 7. Flexor brev ; s 

 minimi digiti peJis. 



