THE MUSCLES OF THE LIMBS. 53 



naris to tlie base of the fifth metacarpal. In tlie hind-limb, 

 fchere are no homologues of the first two of these muscles. 

 The homologue of the extensor communis is the long extensor, 

 which arises, not from the femur, but from the fibula. The 

 2')eronceics tertlus^^ passing from the dorsal face of the fibula 

 to the fifth metatarsal, is the only representative of the exten- 

 sor carpi uhiaris. 



On the ventral aspect of the human fore-limb, two deej^ 

 flexors arise from the radius, ulna, and interosseous membrane, 

 and run parallel with one another, thoug-h disconnected, to 

 the digits. These are, on the pre-axial side — t\iQ flexor p)olli- 

 cis longus^ to the distal phalanx of the pollex ; and t\\e flexor 

 iUgitorum perforans^ to the distal phalanges of the other 

 diOTts. 



In the hind-limb, two homologous muscles, ^q flexor hair 

 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 Wiq flexor carpi radialis to the base 

 of the second metacarpal ; the palmaris longus to the fascia 

 of the palm; \\iQ flexor per for atus digitorum to the middle 

 phalanges of the four ulnar digits ; \hQ flexor carpi idnaris 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 corresponds with any of 

 these, in the hind-limb, is the p>lantaris j 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 pcdmaris longus. In many quadrupeds, as the 

 Rabbit and Pig, the plantaris is a large muscle, the tendon 

 of which passes over the end of the calcaneal process en- 

 sheathed in the tendo achilUs^ and divides into slips, which 

 become the perforated tendons of more or fewer of the digits. 



* This muscle, which lies altogether on the dorsal face of the hind-limb, 

 find which I have seen only in Man, should not be confounded, as it often is, 

 with one or more muscles, the peroncei Stii, 4.ti, et bti digiti. which are very 

 often developed in other Mammalia^ but arise on the ventral face of the fibula, 

 Rnd send their tendons below the external malleolus to the extensor sheatha 

 of the fifth, -^^urth and even third di^jits. 



