Notwithstanding that for certain of these muscles it is possible to trace their analogy with those of the auricular region of man, it is very difficult, because of their complexity, to trace this analogy for all. This is why we shall not be able here, as we have done for the other muscles of the subcutaneous layer, to give at the head of each paragraph the name of a human muscle, and then to group in the same paragraph the muscles which correspond to it in different quadrupeds. Therefore the nomenclature and the divisions adopted for these latter must serve us as a base or starting-point. Because the pinna of the horse's ear is so very mobile, we will first begin with a study of its auricular muscles. =Zygomatico-auricularis= (Fig. 92, 11).--This muscle, which is formed of two small bands of fleshy fibres, arises from the zygomatic arch in blending with the orbicular muscle of the eyelids; thence it is directed towards the base of the pinna of the ear, and is inserted into this base, and also into the cartilaginous plate situated in front of and internal to this, and resting on the surface of the temporal muscle; this is the scutiform cartilage. The zygomatico-auricularis, which we look on as the homologue of the anterior auricular of man, draws the pinna of the ear forwards. =Temporo-auricularis Externus= (Fig. 92, 12).--This, which is thin and very broad, covers the temporal muscle. It arises from the whole extent of the parietal crest, blending in this plane, in its posterior half, with the muscle of the opposite side. Thence it is directed outwards towards the pinna of the ear, and is inserted into the internal border of the scutiform cartilage and on the inner side of the concha--that is to say, of the conchinian cartilage--which forms the principal part of the pinna. We are supposing, in the description of the muscles which move it, that this pinna has its opening directed outwards. The external temporo-auricular, which recalls, from its situation, the superior auricular of man, is an adductor of the ear; besides, it causes it to describe a movement of rotation from without inwards, so as to direct its opening forwards. =Scuto-auricularis Externus.=--This muscle may be considered as supplementary to the external temporo-auricular; the concha fasciculus of this latter partly covers it. Extending from the scutiform cartilage to the inner side of the concha, it contributes to the movement of rotation by which the opening of the pinna of the ear is directed forwards. =Cervico-auricular Muscles= (Fig. 92, 13).--These muscles, three in number, are situated behind the pinna of the ear; they are called, from their mode of superposition, the superficial, middle, and deep. These arise, all three, from the superior cervical ligament, and pass from there towards the cartilage of the concha. They recall, as regards situation, the posterior auricular muscle of man.