56 THE ANATOMY OF VEETEBRATED ANIMALS. 



flexors arise from the radius, iilna, and interosseous mem- 

 brane, and run parallel witli one another, though discon- 

 nected, to the digits. These are, on the pre-axial side — the 

 flexor poinds longus, to the distal phalanx of the pollex; 

 and the flexor digitorum perforans, to the distal phalanges 

 of the other digits. 



In the hind limb, two homologous muscles, the flexor hal- 

 lucis longus and the flexor- digitorum perforans, arise from the 

 tibia and fibula and interosseous membrane, and their ten- 

 dons are distributed to the distal phalanges of the digits. 

 But, before they divide, the tendons become connected to- 

 gether in such a way, that many of the digits receive tendi- 

 nous fibres from both sources. 



In the fore limb, there are no other deep flexors, but the 

 internal, or post-axial, condyle of the humerus gives origin 

 to a number of muscles. These, proceeding from the pre- 

 axial to the post-axial side, are the flexor carpi radialis to the 

 base of the second metacarpal ; the palmaris longus to the 

 fascia of the palm, the flexor perforatus digitorum to the 

 middle phalanges of the iour ulnar digits ; the flexor carpi 

 ulnaris to the base of the fifth metacarpal. The sesamoid, 

 pisiform bone is developed in the tendon of the last muscle. 



The only muscle which exactly con-esponds with any of 

 these, in the hind limb, is the plantaris ; which, in Man, is 

 a slender and insignificant muscle proceeding from the outer 

 (post-axial) condyle of the femur to the plantar fascia — and 

 answers to the palmaris longus. In many quadrupeds, as 

 the Rabbit and Pig, the plantaris is a large muscle, the ten- 

 don of which passes over the end of the calcaneal process 

 ensheathed in the tendo-achillis, and divides into slips, 

 which become the perforated tendons of more or fewer of 

 the digits. The flexor carpi radialis is also roughly repre- 

 sented by the tibialis posticus — a muscle which passes from 

 the tibia and interosseous membrane to the entocuneiform, 

 and therefore differs in insertion, as well as in origin, from 

 its analogue in the fore limb. The flexor perforatus digi- 

 torum of the foot takes its origin sometimes from the calca- 

 neum ; sometimes, in part from the calcaneum, and in 



