In the same category as the above cutaneous muscles may be associated the musculus prepu tialis seu umbilicus, the superficial orbicularis palpebrarum, and certain of the complicated set of organs which act upon the concha and scu tum of the external ear. Of the latter, sixteen pairs have been described as common to the Ox, and nearly as many have been indicated in the Sheep. In both genera they surround the ear on all sides, and offer similar characters in respect of relative size and position. By their reciprocal action the auricular appendage is turned in every direction, as well as rotated upon its own axis ; it is likewise expanded and contracted by such of them as proceed from one part of the concha to another. The orbicular muscle of the eyelid (5,fig. 349) is thick and fleshy, and its action is aided above and below by thin strata of fibres coming from the panniculus ; these are independent of the ordinary elevators and depressors of the lid.
Muscles of the head and trunk. — Referring to the accompanying figures for a general outline of the superficial and deep muscular layers included in the above division, we propose to treat in detail of such muscles as acquire a particular interest in respect of their position or importance in a physiological point of view.
In the clavicle-bearing mammals the tra pezius consists of two parts, — an anterior or clavicular portion, and a posterior or scapular division • but in ruminants and other quad rupeds which are unprovided with these bones, the posterior section is alone represented by the trapezius properly so called ( I 0, 11, fig. 349). On this account it is comparatively small and restricted in its superior attachments, the fore-part being narrow and connected to the elastic ligament of the neck and the dorsal portion, which is somewhat shorter and thicker, becoming attached to the spinous processes of the anterior six or eight dorsal vertebrm. In the Camel it originates from the posterior half of the cervical ligament and the spinous apophyses proper to the first half of the thorax. It is more limited in the Giraffe, where, according to the investigations of Prof. Owen, " it consists of two pretty distinct portions ; one arises from the trans verse processes of the fifth and sixth cervical vertebrae ; its fleshy part is thick and strong, but expands as it passes downwards and backwards, and finally is lost in a strong fascia overspreading the large shoulder joint. The second portion is thin and broad ; it arises from the ligarnenturn nuchm, and is in serted into the fascia covering the scapula."*
That part corresponding to the clavicular or anterior division of the trapezius in the human subject is widely separated from the muscle just described, and is associated Nrith the cleido-mastoideus and deltoides so as to form a tripartite mass, for which Cuvier pro posed the name of masto-humeralis. It is the levator humeri proprius of Stubbs, the COMVITZ nis capitis, pectoris et brachii of some, and the deltoides °fathers (8,8,8,fig.349). In the Sheep and in the Ox it consists principally of two portions with an intervening smaller muscular bundle situated at the centre of the neck, and connecting the clavicular portion of the tra pezius to the tendon of the cleido-rnastoidens. The superior or rnore superficial belly be comes implanted into the humerus, while the inferior or deeper division is inserted into the sternum. At their upper attachments the duplicity is very apparent, the broad muscular part being united to the ligamentum nuchm, and the rounded tendon being fixed to the mastoid apophysis.
After removing the trapezius, our attention is at once directed to a large broad muscle, which in the human subject is represented by the splenius capitis and splen. cervids. In the Ox and most other ruminants, the cranial division is alone present ; but in the Sheep, according to the researches of Meckel, there are two portions — an anterior or cranial, which is narrow and insignificant, and a posterior of large size, taking its origin by two bundles from the third and fourth cer vical vertebrm, to be attached to the trans verse process of the atlas. In the Camels both may be said to be absent, but there is a small muscular slip, proceeding from the ten don of the digastricus to be inserted into the occipttt, which 111eckel thinks may constitute a rudimentary form of the splenius capitis.
Beneath the splenius, and often incorpo rated with it, lies the trachelo-mastoideus, which is feebly developed in ruminants and solipeds, but is of large size in the marsupials and edentate mammals. The great camplexus and digastricus colli muscles are united into a sin gle mass, as in the Horse, and in these animals this compound muscle arises by nine or ten fleshy and tendinous slips —intersected by aponeurotic prolongations — from the third cervical to the second or third dorsal ver tehrm inclusive. In the Camel there are only seven bundles of origin, and a single long aponeurotic septum, and in the Sheep all traces of the latter are absent.