EXTERN AL EAR 



871 



ear, ends below at the posterior margin of the lobule. On the upper part of 

 the inverted edge of the hehx a little irregular process often exists, which has been 

 regarded as the shrivelled tip of the primitive ear, and anteriorly, where it begins 

 to bend backwards, there is a small projection, the spine of the helix (Fig. 495). 

 The hollow from which the helix starts is called the concha. Within the helix, 

 but separated from it by the scaphoid fossa (fossa of the helix) runs a second 

 curved ridge, the antihelix. It commences lielow in the little process known as 

 the antitragus, and bifurcating superiorly bounds a shallow fossa just above the 

 concha, the so-called triangular fossa (fossa of the antihelix). The concha, 

 bounded by the antihelix, is deeply notched below (incisura intertragica). Over- 

 lapping the commencement of the notch before and behind are two eminences, 

 the anterior and larger, the tragus ; the posterior, the antitragus. The auricle 

 varies greatly in different individuals, and the lobule perhaps more than any 

 other part. 



The cartilaginous framework of the ear, although it does not enter into all 

 its parts, gives to it the general character and appearance already described. 

 It consists of pliable reticular cartilage of the yellow elastic kind. It does not 

 enter into the formation of the lobule, which consists entirely of dense connec- 

 tive tissue and fat. Its lower portion is so rolled upon itself as to form a tube 

 incomplete above, which tails off as it passes inwards to be attached to the lower 

 third of the external auditory meatus. This attachment is effected by means 



Fig. 494. — Section through the Orifice of the Right External Auditory Meatus. 



Fissure of Santorin 

 Posterior auricular artery 



Section of cartilaginous portion 



EXTERNAL AUDITORY CANAL 



Lining membrane 



Fissure of Santorini 



of a dense fibro-elastic tissue which allows considerable shifting on traction of 

 the pinna upwards and backwards. A section passing through the orifice of the 

 meatus shows the cartilage greatly in excess of the fibrous membrane which 

 completes its contour. Deeper sections show the cartilage diminishing more 

 and more until it forms scarcely a third of the lumen of the tube near the bony 

 meatus. 



The wall of the channel is traversed by fissures, the fissures of Santorini ; 

 l:»ut these are not constant in their m^mber, extent, or direction; they are filled with 

 fibrous tissue, and allow the canal to be straightened by traction on the pinna. 

 The lower segment of the cartilaginous meatus is in close contact with the parotid 

 gland. An abscess in this region may thus burrow through the fissures and dis- 

 charge itself through the external meatus. There is also a gap between the helix 

 and the tragus bridged over by a band of dense fibrous tissue. Several fissures 

 traverse the cartilage, and a deep cleft dividing the antihelix severs the caudate 

 process from the rest of the cartilage below. 



Ligaments. — An anterior ligament connects the spine of the helix with the 

 root of the zygoma, and a posterior passes from the concha to the mastoid pro- 

 cess. 



A pair of ligaments belong to the cartilage itself, the strong band already 

 described completing the orifice of the meatus, and one less marked passing l)etween 

 the concha and the processus caudatus. 



Muscles. — The extrinsic muscles, the attollens, attrahens, and retrahens 



