MUSCLES OF TEE fOSTERlOR LIMBS. 



365 



Fig. 202. 



3. Flexor of the Metatarsus (Flexor Metatarsi) (Fig. 202). 



Sf/noni/ms. — Tibio-premotatarsus — Girard. Its muscular portion represents the tibialis 

 antions of iintliropotoniistB. 



This muscle is situated beneath the anterior extensor of the phalanges, on the 

 extern;'.! surface of the tibia, and is composed of two distinct portions — one muscu- 

 lar, the other aponeurotic, not united from end to end, 

 but placed parallel one before the other. 



A. Tendinous Portion (Fig. 202, 1). — Course- 

 Attachments. — This is a strong, pearly-white cord, com- 

 prised between the musci/h/r jmrtion and the anterior 

 extensor of the phalanges. It commences at the inferior 

 extremity of the femur, in the fossa between the trochlea 

 and the external condyle ; it afterwards passes through 

 the superior groove of the tibia, where it is enveloped 

 by a prolongation from one of the synovial membranes 

 of the femoro-tibial articulation, giving origin, below 

 this groove, to the muscular fibres of the anterior ex- 

 tensor of the phalanges. Lower, it receives some of 

 the fasciculi from the muscular portion, to which it 

 sends, in exchange, several aponeurotic layers ; it passes 

 under the superior annular band in front of the hock, 

 in company with the anterior extensor, and reaches the 

 level of the trochlea of the astragalus, where it is 

 perforated to form a ring for the passage of the inferior 

 extremity of the muscular portion. It finally terminates 

 in two branches : a large one, inserted in front of 

 the superior extremity of the principal metatarsus (Fig. 

 202, 4) ; the other, narrower, deviates outwards to reach 

 the anterior surface of the cuboid bone (Fig. 202, 8). 



Relations. — In front, with the anterior extensor of 

 the phalanges ; behind, with the muscular portion and 

 the anterior capsular ligament of the tarsus. 



Action. — This tendon enjoys the curious property of 

 bending the hock by an action altogether mechanical, 

 whenever fiexion of the superior bones of the limb takes 

 place. It is, therefore, a conducting cord which regu- 

 lates the movements of flexion in the hock, and con- 

 forms them to those taking place in the other joints, 

 without requiring the intervention of an active agency 

 for the execution of these movements. 



Another function has also been attributed to it — 

 that of passively opposing the flexion of the femur on 

 the tibia while the animal is standing, and in this 

 way serving as an adjunct to the muscular force which supports the weight of 

 the body. But, in our opinion, this is incorrect ; as, in order that it may perform 

 this task, it would be necessary for the foot to be maintained in a fixed position 

 by the contraction of its extensor muscles. But these muscles are really the 

 heads of the gastrocnemius, which have their origin behind the femur, and 

 which undoubtedly tend to flex that bone on the tibia — that is, to determine 



26 



FLEXOR METATARSI. 



1, Tendinous portion ; 2, its 

 attachment to the femur; 

 3, its cuboiii branch ; 4, 

 its metatar>al branch ; 5, 

 muscular jiortion ; 6, its 

 tendon passing through 

 the ring of the tendinous 

 portion ; 7, cuneiform 

 portion of this tendon; 



8, its metatarsal branch; 



9, anterior extensor of the 

 phalan ges drawn out wards 

 by a hook. A, Lateral 

 extensor; B, tibial inser- 

 tion of the middle patel- 

 lar ligament ; C, femoral 

 trochlea 



