THE FOOT. 313 



parts, if it has not a good foundation ; it is the same with a war- 

 horse ; he will be good for nothing if, being perfect otherwise, he has 

 bad legs (members) ; for he is unable to use whatever good points he 

 ma}' have. 



" In the examination of the legs, look first at the foot P' ' 



This is the same idea which is reproduced, in our days, in the forms 

 of aphorisms in all treatises on the exterior : 



^^ No foot, no horse r' said Lafosse. 



" No foot, no horse /" repeat the English. 



Bracy-Clark has only translated the thought of Xenophon when 

 he said, " Incerta basis instabile sedificium !" 



The foot is formed by a certain number of internal parts, covered 

 by a modified skin admirably adapted to its special functions, as well 

 as by a horny envelope known under the name hoof. Let us examine 

 them rapidly. 



I. Internal Parts of the Foot. 



These parts are complex and numerous ; their relation can be clearly recog- 

 nized in a vertical and antero-postefior section of the organ (Fig. 106). 



Three ho7ies form its osseous base and permit it to accomplish its various 

 movements. These are : the third phalanx or pedal bone (a) ; the second phalanx, 

 or coronary bone (b) ; finally, the navicular, or small sesamoid bone (c), situated 

 behind the preceding and complementing the articulation which the other two 

 form. 



Short, strong ligaments consolidate the joint on the sides, while two wide 

 fibro-cartilaginous plates, lateral cartilages of the third phalanx, intimately united 

 to this bone, seem like two elastic and diverging springs, placed on the outside 

 and on the inside of this bone, to prevent it from descending or rocking too sud- 

 denly in the hoof at the moment when the latter strikes the ground. 



Two strong, expanded tendons terminate upon the third phalanx : the anterior 

 (d) carries it into extension ; the posterior (e) permits, on the contrary, the flexion 

 of this bone upon the os coronse ; it glides over the inferior face of the navicular 

 bone by means of a synovial sheath designated under the name small sesamoid 

 sheath (better called the navicular sheath). 



Finally, a voluminous fibro-elastic cushion (g), called the plantar cushion^ 

 bifurcated behind and pointed in front (Fig. 107, B : d), is placed under the flexor 

 tendon, to which it serves as a flexible buffer when the foot has reached the 

 ground. All pressure upon the hoof from below upward tends to depress it and 

 force it against the lateral parts, where it is maintained by the two elastic carti- 

 lages indicated above. 



Cutaneous Envelope of the Foot.— This is the skin, modified in its 

 functions and external characters, which covers the surface of all these organs. 

 The proof of this can be easily obtained by maceration of the hoof, or the arti- 

 ficial removal of the hoof and the hairs of the digital extremity, in order to see 



» X6nophon, De rEquitation, traduction du baron de Curnieu, chap. i. p. 7. Paris, 1840. 



