Anatomy and Physiology of Hearing
Ananth Vijendren, Peter Valentine
Abstract
The auricle is the outermost projection of the ear with its lateral surface characterised by prominences and depressions. The body is composed of elastic fibrocartilage and is a continuous plate except for a narrow band between the tragus and anterior crus of the helix where endaural incisions can be made. The auricle functions to collect acoustic energy and direct it into the external auditory canal (EAC), and to create incident angle–dependent modifications that help with sound localisation. Both the pinna and EAC derive their blood supply from branches of the external carotid artery. The middle ear consists of the tympanic cavity (TC), Eustachian tube and the mastoid air cell system. The TC is bounded by the tympanic membrane laterally and the osseous labyrinth medially.