MUSCLES OF THE TRUNK. 281 



cartilage which form the concha. These are three in number : 1. Conchal 

 cartilage. 2. Annular cartilage. 3. Scutiform cartilage. 



1. Conceal Cartilage. — The principal portion of the pavilion, this cartilage 

 determines its general configuration. In shape it resembles a trumpet with a 

 wide opening on one side. Its entrance is elliptical, and elongated vertically, 

 being circumscribed by two thin borders which unite above at a point that 

 constitutes the summit (apex) of the organ. Its base, bulging in a cul-de-sac, 

 terminates in front by a constricted infundibulum ; it is attached to the margin 

 of the auditory hiatus by means of the annular cartilage, to the surface of 

 the guttural pouch by a pointed prolongation that descends outside this annular 

 cartilage, beneath the parotid gland, and terminates by several fibrous filaments. 

 This portion of the framework of the concha is a cartilaginous plate, rolled on 

 itself in such a manner as to circumscribe, between its borders, the entrance to 

 the ear, and to form, inferiorly, the complete infundibuliform canal just men- 

 tioned. (Externally, the integument of the ear is covered by ordinary hair, but 

 internally there are long fine hairs, especially near the entrance ; these prevent 

 the intrusion of foreign substances.) 



In Ruminants, this cartilage is thin, inclined outwards, and largely open. In the Fig, 

 it differs slightly according to breed, but it is always much developed, sometimes erect, and 

 more frequently drooping forward. It is always short, pointed, erect, and open towards the front 

 in the Cat. In the Dog, it is sometimes short and straight ; in others broad and pendant. 



2. AjraruLAR Cartilage. — By this name is known a little ring-shaped plate, 

 placed at the lower part of the conchal cartilage, intermediate between it and the 

 auditory canal. The internal integumentary membrane, with some yellow elastic 

 fasciculi, unites this cartilage to the other two portions between which it is situ- 

 ated. Its relations with these are such, that it receives within its lower border 

 the bony circular prominence forming the margin of the auditory hiatus, while it 

 may itself be received into the infundibuliform canal of the conchal cartilage — 

 an arrangement resembling the tubes of a telescope. 



3. Scutiform Cartilage. — This is a small cartilaginous plate, situated in 

 front of the base of the concha, at the surface of the temporal muscle ; it is 

 irregularly triangular, is attached to the conchal cartilage by some muscular 

 fasciculi, and transmits to that cartilage the action of some other muscles which 

 are fixed on the cranial bones. 



(The arteries of the concha proceed from branches of the external carotid, 

 and the veins pass to a trunk of the same name ; the nerves are divisions of the 

 facial and the first cervical pair.) 



An adipose cushion, placed at the base of the ear, facilitates the movements of 

 the cartilages when they are acted upon by these muscles. 



1. Zygomaticus-auricularis (Attollens Anticus) (Figs. 168, 4, 5 ; 170, 19). 



This muscle is generally composed of two fleshy bands joined by connective 

 tissue, and rising from the zygomatic process of the temporal bone by means of an 

 aponeurosis common to it and the orbicularis palpebrae. The inferior of these 

 two bands is inserted into the outside of the base of the concha, its fibres mixing 

 with those of the abducens ; the superior band terminates on the outer border 

 of the scutiform cartilage. 



Placed immediately beneath the skin, this muscle partly covers the superior 

 extremity of the parotid gland, and the zygomatic process. 



It draws the ear forward. 



