298 THE MUSCLES. 



through the femur at its middle. Dissect the insertions of the long vastus, the short 

 adductor of ihe leg, and the semitendinosus, to observe the continuity of these muscles 

 with the tibial aponeurosis ; study the insertions of this aponeurosis, particularly that 

 which it has on the summit of the calcis. To expose the muscles, remove their 

 aponeurotic envelope, leaving, however, the band it forms in front of the tendon of the 

 hock, as well as the bands which retain the tendons. Remove the hoof in the manner 

 already indicated for the anterior extremity, and, finally, separate the muscles from one 

 another an operation so very simple as not to require any special directions. 



A. Anterior Tibial Region. 



This is composed of three muscles : the flexor of the metatarsus, the 

 anterior extensor, and the lateral extensor of ihe phalanges. The first is 

 deep-seated, the other two are superficial. 



1. Anterior Extensor of the Phalanges. (Fig. 135, 20.) 



Synonyms. Femoro-prephalangeus Girard. The extensor -longus digitorum pedis 

 of Man. (Extensor pedis Percivall. ) 



Situation Direction Extent. This muscle, situated in front of the 

 leg and foot, follows the direction of these two rays for their whole extent. 



Form Structure. It is formed of a muscular body and a tendon. The 

 first is fusiform, depressed from before to behind, aponeurotic at its superficies 

 in its superior moiety, and tendinous internally in its inferior moiety. The 

 tendon, at first round, then flat, commences a little above the inferior fourth 

 of the tibia, and reaches the anterior face of the principal metatarsus, where 

 it receives the pedal (extensor brevis digitorum) muscle, the tendon of the 

 lateral extensor, and a funicular prolongation of the tibial aponeurosis. It 

 afterwards descends on the fetlock, where it comports itself exactly as the 

 corresponding tendon in the anterior extremity. (See the anterior extensor 

 of the phalanges in the fore-limb, page 262.) 



Attachments. Above, in the digital fossa placed between the trochlea and 

 external condyle of the femur, through the medium of the tendinous portion 

 of the flexor of the metatarsus fixed insertion. Below, on the capsular liga- 

 ment of the metatarso-phalangeal articulation, the anterior face of the two 

 first phalanges, and the pyramidal eminence of the os pedis. 



^Relations. The muscular portion responds : outwardly, with the tibial 

 aponeurosis ; inwardly, to the flexor of the metatarsus ; posteriorly, to the 

 lateral extensor of the phalanges. The tendon successively covers : the 

 anterior aspect of the tibia, the anterior capsular ligament of the tarsus, the 

 pedal muscle, the anterior face of the principal metatarsal, the articulation of 

 the fetlock, and the two first phalanges. It is covered by the tibial aponeu- 

 rosis, and by three annular fibrous bands destined to maintain the tendon in 

 the bend of the hock. One of these bands, the superior, is fixed by its ex- 

 tremities to the tibia, a little above the tibio-tarsal articulation ; it is common 

 to the muscle we are describing, and to the flexor of the metatarsus. The 

 middle band, attached to the cuboid branch of the latter muscle and the 

 inferior extremity of the calcis, is exclusively intended for the anterior ex- 

 tensor of the phalanges. The inferior maintains the two extensors against 

 the superior extremity of the principal metatarsal. 



Action. This muscle extends the digit and flexes the entire foot. 



2. Lateral Extensor of ihe Phalanges. (Fig. 135, 28.) 



Synonyms. Peroneo-prephalangeus Girard. The peroneus brevis of Man. (Peroneus 

 Percivall. Tibio-prephalangeusLeyh.) 



Situation Form Structure Extent Direction. This muscle, situated 



