122 ANATOMY OF THE DOMESTIC FOWL 



Insertion. Passing in an oblique manner along posterior to the 

 tibia, extends through the superficial part of the tibial cartilage to 

 the outer side of the leg; then crossing the tibio-tarsal joint, it 

 passes through a special canal of the hypotarsus, down the back 

 of the tarso-metatarsus, under the annular ligament of the sole of 

 the foot and a cartilaginous structure below this ligament, over 

 the trochlea, and is inserted to the middle shaft of the second 

 phalanx of the second toe. 



Shape. Thin, flat, broadly spindle-shaped. 



Relations. Posteriorly, with the flexor perforatus medius secun- 

 dus pedis, and anteriorly, with the flexor perforatus annularis 

 primus pedis. 



Action. Flexes the toes. 



Flexor Longus Hallucis (Fig. 17, No. 7; Fig. 25, No. 2). Loca- 

 tion. The posterior tibial region. 



Origin. By two tendinous heads: one from the posterior part of 

 the femur, just below the two condyles; the other from the outer 

 part of the external condyle of the femur. The deep flexor passes 

 between these two heads. 



Insertion. Becoming tendinous at the lower third of the leg, 

 passes beneath the superficial flexors in a special canal on the outer 

 side of the tibial cartilage, and extends through the large canal of 

 the hypotarsus (Fig. 12, No. F, 5) next to the shaft, then down to 

 the apex of the accessory metacarpal bone. It is inserted to the 

 tubercle on the inferior proximal end of the ungual phalanx. 



Shape. Large, fusiform. 



Relations. With the exterior of the deep flexors. 



Action. Flexes the hallux as its long flexor. 



Flexor Perforatus Annularis Primus Pedis (Fig. 17, Nos. D, 8 

 and C, 6). Location. -The posterior tibial region. 



Origin. From the inner side of the belly of the flexor longus 

 hallucis. 



Insertion. Becoming tendinous at the lower third of the tibia, 

 passes a little to the outer side and through the tibial cartilage, 

 then over the ankle-joint and through the hypotarsal canal (Fig. 

 12, No. 5) to the under side of the outer toe, where it forms a sheath 

 through which the deep flexors extend. It gives off on either side 

 a tendinous slip which attaches to the basal phalanx. 



Shape. Long, slender, compressed laterally. 



