The external ear



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THE EAR


ANATOMY



THE EXTERNAL EAR

It consists of the PINNA or AURICLE and the EXTERNAL AUDITORY MEATUS.

THE AURICLE :

It consists of a plate of yellow elastic cartilage, except for the lobule which is composed of fibro fatty tissue. The skin of the lateral surface is closely adherent to the perichondrium. The auricle is attached to the side of the head by ligaments and rudimentary auricular muscles.



Parts of the auricle include:

Helix, Antihelix, Tragus, Antitragus, Concha and Lobule

THE EXTERNAL ACOUSTIC MEATUS

It measures about 2.5 cm in the adults. It is composed of two parts: an outer or lateral third, which has a cartilaginous skeleton continuous with that of the pinna and directed medially upwards and backwards; and an inner two thirds which has a bony skeleton and is directed medially, slightly downwards and forwards. The meatus can be partly straightened in adults by pulling the auricle upwards, outwards and backwards.

The external canal ends medially at the tympanic membrane.

The skin of the cartilaginous canal is closely adherent to the underlying tissues and contains sebaceous glands, ceruminous glands and hair follicles. These structures are absent in the bony canal.

The blood supply: superficial temporal and posterior auricular branches of the external carotid artery.



Nerve supply: fifth, ninth, tenth cranial nerves, greater auricular and lesser occipital nerves of the cervical plexus.





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