The anconcus (epicon,dylo cztbitien) exists in all quadrupeds.
As might be expected from the construction of the bones of the.forearm, both the pronator muscles are in the Solipeda entirely wanting, as is the case in the Ruminantia and in the Pachydermata generally ; nevertheless, in the elephant and in the hog-tribe the pronator teres is feebly developed ; and, as the mobility of the bones of tha forearm becomes more perfect, as in the Carnivora, Qoadrumana and Marsupialia, both the pronators are found pre senting the same arrangement as in the human body.
The supinators are quite obliterated in the Solipeda, as well as in the Ruminantia and Pachydermata.
Muscles of the carpus and metacarpus. — The muscles employed in bending the wrist are in our own persons the palmaris longus, the flexor carpi radialis longior, the flexor carpi radialis brevior, the extensor carpi ra dialis, the flexor carpi ulnaris, and the ex tensor carpi ulnaris ; of these one only is in serted into the carpus, all the rest being attached to the metacarpal bones.
In all multi-digitate mammalia, such as the Quadrumana, Carnivora, Rodentia. and Eden tata, these six muscles exist and are disposed pretty nearly as in the human race; but in the Pachydermata and Ruminantia there is but one flexor carpi radialis. In all the above multidigitate animals, the muscles derived from the external condyle, and its vicinity by their co-operation, approximate the back of the hand towards the forearm, or, in other words, are extensors of the fore-foot ; while those derived from thesinternal condyle have a contrary effect, and act as flexors of the hand. Should the flexor and extensor of the same side of the limb act together, the hand will be bent laterally in the corresponding direction.
In the Solipeda, where the movements of the wrist are strictly limited to those of flexion and extension, the disposition of these muscles is considerably modified.
The extensor carpi radiahs is here ,single, arising from the anterior part of the external condyle of the humerus, and from the ex ternal surface of that bone for a consider able distance: it forms a strong fleshy belly, terminating in a powerful tendon, which runs to be inserted into the base of the anterior surface of the metacarpal or cannon bone.
This muscle, called by Bourgelat the " exten seur droit anterieur du canon," seems, from the extent of its origin, to represent the long sit pinator and the two radial extensors of the wrist combined, and all three made to co operate in the extension of the wrist The flexor carpi radialis (epitrochlo-nieta carpien) arises from the external condyle of the humerus and is inserted into the posterior surface of the base of the cannon bone, form ing the antagonist to the preceding muscle : this is the "flechisseur interne du canon" of Bourgelat.
The flexor carpi ulnaris (epitrochlo-carpien) arises from the posterior part of the external protuberance of the os humeri, and also by a distinct head from the protuberance situated above the internal condyle ; its tendon is in serted into the representative of the pisiform bone and also into the root of the rudi mentary metacarpal bone beneath it : this is the "flechisseur oblique du canon" of BOUT..
gelat.
The extensor carpi ulnaris (cithito-sus.me lacarpien) arises from the posterior part of the external condyle of the humerus, and is inserted, like the preceding, into the os pisiforme, whence it is prolonged beneath the carpus, so as to perform the office of a flaxor of the wrist (" ftechisseur externe " Bourgelat.) The palmaris long= does not exist in the Solipeda ; nor is it found in the Pachydermata and Ruminantia, being in these orders of qua drupeds apparently combined with the flexor sublimis digitorum, as is likewise the case with this muscle in the bear, the badger, and the dog ; in all other unguiculate quadrupeds it is disposed as in the human subject.
Muscles of the hand.— The extensor com minis digitoruna (epicondylo-sus-phalangettien COMV1U11. - This muscle in the horse is called by Bourgelat "l'extcnseur antcrieur du pied," and by Lafosse, "1' extenseur du pied :" it arises from the external condyle of the humerus and from the contiguous fascim, also from the upper and lateral part of the radius ; its fleshy belly is strong, and terminates in a single tendon, which runs over the foot to be inserted into the last phalanx or coffin-bone, having pre viously given off a slip to join the tendon of the extensor mininti digiti.