THE LIMBS 



163 



versatile functions, can be traced in the horse. That 

 would be obviously impossible with such a reduction of 

 the bony elements. The difference (far less marked in 

 the upper part of the arm) is especially pronounced in 

 the last segment or manus, or hand proper, where the 

 fifteen intrinsic muscles of the human hand are repre- 

 sented by only five 1 in the horse. Four of these — the 

 two interossei and the two lumbricales — are in a very 

 greatly reduced condition ; and the fifth, the short flexor 

 (represented in the human foot by the muscle called the 

 : first plantar interosseous '), is a remarkable instance of 

 a structure not becoming rudimentary and useless, but, 

 while retaining its size, position, and connections, being 

 diverted from its original purpose and completely 

 changing not only its function but its structure. It is 

 termed in veterinary anatomy c the suspensory ligament 

 of the fetlock,' and appears as a very strong band or 

 cord of non-elastic fibrous tissue, lying close to the 

 back of the large metapodial bone, attached above to 

 the posterior surface of the upper extremity of this 

 bone, and at its lower end dividing into two portions, 

 which, diverging from each other, embrace the meta- 

 tarsophalangeal or fetlock joint, and are inserted 

 partly into the sesamoid bones and partly into the 

 extensor tendon on the dorsal aspect of the first phalanx 



1 This is the number according to the usual statements, but recent 

 careful dissections have shown traces of others. 



m 2 



