THE EAR. 



ately firmly attached to the cartilage. The subcutaneous tissue contains little or 

 no fat. Although well supplied with blood, the exposed condition of the blood-vessels 

 renders the ear sensitive to cold, and frost-bites are common. Injuries and wounds 

 of the cartilage are slow to heal, and if inflamed the cartilage becomes exceedingly 

 sensitive. Swelling of the ear readily occurs from injury or erysipelas, and the tension 

 is quite painful. 



Crus antihelix superius 

 Fossa triangularis 



Crus antihelix inferius 



Tragus 

 Incisura intertragica 



Helix 

 Fossa scaphoidea 



Tuberculum superius 



Lobule 



FIG. 99. The external ear. 



H&matoma auris, or effusions of blood, occur from traumatism, especially in the 

 insane. While a haematoma may occur between the skin and perichondrium, on 

 account of the firm binding of the skin to the cartilage it is usually between the 

 perichondrium and cartilage. 



Angioma, or enlargement of the blood-vessels, not infrequently affects the 

 external ear and may not only be disfiguring but, by showing a tendency to 



Chorda tympani 

 Facial nerve 



Internal auditory meatus 

 Semicircular canals 



Jugular vein 



FIG. loo. Vertical section of the right ear. 



extension, may demand operation. The external ear derives its blood supply from 

 the auricular branches of the temporal, internal maxillary, posterior auricular, and 

 occipital arteries. As these are all branches of the external carotid, that artery is 

 sometimes tied as a preliminary step to excising the angiomatous vessels. 



The External Meatus. The external auditory meatus extends from the 

 concha to the drumhead, and is about 2.5 cm. in length. A little less than one-half 



