THE EXTERNAL EAR 871 
(which are chiefly elastic), the integument, and a complicated arrangement of 
muscles. 
The conchal or auricular cartilage (Cartilago auricule) determines the shape 
of the ear; its form can be made out in a general way without dissection, except 
below, where it is concealed by the muscles and the parotid gland. The basal part 
is coiled so as to form a tube, which encloses the cavity of the concha (Cavum con- 
che). This part is funnel-shaped and curves outward and a little backward. Its 
medial surface is strongly convex, forming a prominence termed the eminentia 
conche. The lowest part of the medial margin bears a narrow, pointed prolongation, 
the styloid process. This process is about an inch long and projects downward 
over the annular cartilage; the guttural pouch is attached to its free end. Behind 
its base there is a foramen through which the auricular branch of the vagus passes. 
The basalpart of the posterior border is cut into by a notch, which separates two irregular 
quadrilateral plates. The upper plate (Tragus) is overlapped by the anterior border, and is sep- 
arated from the adjacent part of the posterior border (Antitragus) by a notch (Incisura inter- 
tragica). The lower plate is curved to form a half ring and partly overlaps the anterior border and 
the annular cartilage. Behind the notch there is a foramen, which transmits the internal auricular 
artery and internal auricular branch of the facial nerve. 
The annular cartilage (Cartilago annularis) is a quadrilateral plate, curved to 
form about three-fourths of a ring; its 
ends are a little less than half an inch (ca. 
1 cm.) apart medially and are united by 
elastic tissue. It embraces the external 
acoustic process and forms with the lower 
part of the conchal cartilage the carti- 
laginous part of the external acoustic 
meatus. 
The scutiform cartilage (Cartilago 
scutiformis s. Scutulum) is an irregular 
quadrilateral plate which lies on the tem- 
poral muscle in front of the base of the 
conchal cartilage. Its superficial face is 
slightly convex from side to side and 
its deep face is correspondingly concave. 
The anterior end is thin and rounded; the 
posterior part or base is wider and thicker, 
and its medial angle is prolonged by a 
pointed process half an inch or more in 
length. The cartilage moves very freely 
Fic. 699.—ConcHat aND ANNULAR CARTILAGES OF 
over the underlying parts. Ear or Horse, ExTernat View. 
The external acoustic meatus leads 1, Base of concha; 2, posterior border, 3, anterior 
from the cavum conche to the tympanic border of concha; 4, intertragic notch; 5, eminentia 
= conche; 6, styloid process; 7, annular cartilage; 9, 
membrane. It does not continue the zygomatic arch. (After Ellenberger-Baum, Anat. fir 
general direction of the cavity of the Kunstler.) 
concha, but extends medially, downward, 
and slightly forward. It consists of a cartilaginous part (Meatus acusticus ex- 
ternus cartilagineus) which is formed by the lower part of the conchal cartilage 
and the annular cartilage, and an osseous part formed by the external acoustic 
process of the temporal bone. These are united by elastic membranes to form a 
complete tube. Its caliber diminishes medially, so that the lumen of the inner end 
is about half of that of the outer end. 
The skin on the convex surface of the concha presents no special features; it 
is attached to the cartilage by a considerable amount of subcutaneous tissue except 
at the apex. The integument which lines the concave surface is intimately ad- 
