The in the horse is a very strong muscle, resembling in its origin that of the human subject ; but in some rumi nants, as, for example, in the sheep, the ana logue of the oino-hyoideus is derived from the transverse processes of the inferior cer vical vertebrw.
The and the have nearly the same arrangement in all mani miferous quadrupeds.
In the horse, all three of the above muscles are present. The furnishes a sheath to the longer portion of the digastricus, and extends from the furcate extremity of the styloid bone to the base of the posterior corner of the os hyoides : this is the " grand cerato hyoidien " of Gerard. There is also a " cera toidien lateral" of Girard, ex tending between the corner of the os h3oides and that of the thyroid cartilage.
Thirdly, there is the of Gerard), a short thick muscle, derived from the long pyriform apo physis of occipital bone, whence it descends towards the angle of the styloid bone, into which it is inserted, above the origin of the stylo-hyoideus.
The other muscles of this region exhibit no peculiarities worthy of notice.
The nzuscics of the tongue, of the palate, and (f the larynx, are in most quadrupeds strictly comparable to those of the human species.
Muscles of the These, from the con formity of their general arrangement with what exists in man, are distinguishable by the same names as are employed in human an atomy.
The epicranius, or °cc/pito-frank:Es, exhibits the usual origin from the posterior part of the cranium, whence, running forwards, it covers the skull with its tendinous aponeu rosis, and, in front, spreads in muscular slips upon the forehead, some of which (fig. 504.0 extend downwards, to spread over those of the orbicularis palpebrarum.
Situated upon the outer side of the orbit there is another descending slip of muscle (fig.504.d), apparently derived from the lateral muscle of the cartilage of the ear which, by elevating the external canthus of the eye, contributes much to the expression of that organ.
The orbicularis palpebrarunz ( fig. 50 4. a a) arises, as in the human subject, from the coin missural ligatnent at the inner canthus of the eyelids, whence it winds round the orbit, its lower fibres receiving attachment from the os lachrymale.
Internal to the last-named muscle are a few fibres, that represent the corrugatur supercilii.
The Levator anguli oris ( fig. 501. f, g) is, likewise, extensively inserted into the upper lip and margin of the nostril : it has two origins, derived from the surface of the supe rior maxillary bone, between which the lateral dilator of the nostril and upper lip passes to its destination.
The depressor of the lower eyelid (fig. 504. c) is a short muscular slip, the use of which is sufficiently indicated by its name.
The zygomaticus (fig. 504. e) is a depressor of the external angle of the eye, as well as an elevator of the corner of the mouth, its fibres being intermixed. with those of the orbicu laris palpebrarum, as well as of the orbicularis oris.
The long dilator of the nostril, and ele vator of the upper lip (fig. 501. i), arises at a little distance below the inferior margin of the orbit ; and, passing between the two ori gins of the levator anguli oris, terminates in a tendon, which becomes connected with that of the opposite side, and then spreads out in front of the upper lip.
From the tendon of the last muscle arises the anterior dilator of the nostril (fig. 504 h ), which, acting upon the interior nasal carti lage, powerfully expands the aperture of the nose.
The other muscles — viz. the orbicularis oris, the levator labii superioris, the elevator of the chin, and the dPpressors of the lower lip, and angle qf the mouth — need no particular de scription.