THE PLANTAR MUSCLES OF THE FOOT 



The Second Layer (Fig. 444). 

 Quadratus plantse. Lumbricales. 



The Quadratus plantse (Flexor accessorius) is separated from the muscles of 

 the first layer by the lateral plantar vessels and nerve. It arises by two heads, 

 which are separated from each other by the long plantar ligament: the medial 

 or larger head is muscular, and is attached to the medial concave surface of the 

 calcaneus, below the groove which lodges the tendon of the Flexor hallucis longus; 



the lateral head, flat and tendinous, arises from the lateral border of the inferior 

 surface of the calcaneus, in front of the lateral process of its tuberosity, and from 

 the long plantar ligament. The two portions join at an acute angle, and end in a 

 flattened band which is inserted into the lateral margin and upper and under sur- 

 faces of the tendon of the Flexor digitorum longus, forming a kind of groove, in 

 which the tendon is lodged. It usually sends slips to those tendons of the Flexor 

 digitorum longus which pass to the second, third, and fourth toes. 



Variations. Lateral head often wanting; entire muscle absent. Variation in the number of 

 digital tendons to which fibers can be traced. Most frequent offsets are sent to the second, third 

 and fourth toes; in many cases to the fifth as well; occasionally to two toes only. 



The Lumbricales are four small muscles, accessory to the tendons of the Flexor 

 digitorum longus and numbered from the medial side of the foot; they arise from 

 these tendons, as far back as their angles of division, each springing from two 

 tendons, except the first. The muscles end in tendons, which pass forward on 

 the medial sides of the four lesser toes, and are inserted into the expansions of 

 the tendons of the Extensor digitorum longus on the dorsal surfaces of the first 

 phalanges. 



Variations. Absence of one or more; doubling of the third or fourth. Insertion partly or wholly 

 into the first phalanges. 



The Third Layer (Fig. 445). 



Flexor hallucis brevis. Adductor hallucis. 



Flexor digiti quinti brevis. 



The Flexor hallucis brevis arises, by a pointed tendinous process, from the medial 

 part of the under surface of the cuboid bone, from the contiguous portion of the 

 third cuneiform, and from the prolongation of the tendon of the Tibialis posterior 

 which is attached to that bone. It divides in front into tw r o portions, which are 

 inserted into the medial and lateral sides of the base of the first phalanx of the 

 great toe, a sesamoid bone being present in each tendon at its insertion. The medial 

 portion is blended with the Abductor hallucis previous to its insertion; the lateral 

 portion with the Adductor hallucis; the tendon of the Flexor hallucis longus lies 

 in a groove between them; the lateral portion is sometimes described as the first 

 Inter osseous plantaris. 



Variations. Origin subject to considerable variation; it often receives fibers from the calcaneus 

 or long plantar ligament. Attachment to the cuboid sometimes wanting. Slip to first phalanx 

 of the second toe. 



The Adductor hallucis (Adductor obliquus hallucis) arises by two heads oblique 

 and transverse. The oblique head is a large, thick, fleshy mass, crossing the foot 

 obliquely and occupying the hollow space under the first, second, third, and fourth 

 metatarsal bones. It arises from the bases of the second, third, and fourth meta- 

 tarsal bones, and from the sheath of the tendon of the Peronseus longus, and is 

 inserted, together with the lateral portion of the Flexor hallucis brevis, into the 

 lateral side of the base of the first phalanx of the great toe. The transverse head 

 ( Transversus pedis) is a narrow, flat fasciculus which arises from the plantar meta- 



