THE EAR. 



By ARTHUR HENSMAN, F.R.C.S. 

 Revised by ARTHUR ROBINSON, M.D., M.R.C.S. 



LECTURER ON AUATOMY IN THE MIDDLESEX HOSPITAL MEDICAL SCHOOL. EXAMINER IN ANATOMY FOR THE 



CONJOINT BOARD OF ENGLAND 



The organ of hearing may he (Hvidcd into three parts: — the EXTERNAL EAR, 

 wliich inchides the pinna and external auditory meatus; the middle ear, or 

 tympanum, with its ventilating shaft the Eustachian tube ; and the internal 

 EAR, which inchides the osseous labyrinth, within which is placed — the essential 

 portion of the organ — the membranous labyrinth. 



THE EXTERNAL EAR 



The Pinna, or Auricle, is attached to the side of the head, midway hetween 

 the forehead and occiput. Its level is indicated by horizontal lines extending back- 

 wards from the evebrows above, and from the tij) of the nose beloAv. SomcAvhat 



Fig. 493.— Exterxal View of the Left Aukicle. 



Triangular fossa 



TRAGUS 



Scaphoid fossa 



j)yrif()rm in shape, its irregular concave outer surface is turned morc^ or less for- 

 wards, but the angle of inclination varies considerably in diiferent sulgects. The 

 incurved rim of the ear, which divides its surfaces from each other, commences 

 below in a deej) concavity which surrovnids, like the mouth of a trumpet, the 

 external auditory meatus. This rim is called the helix, and, traced round the 



870 



