Macroscopic anatomy of the ear

Summary:

This unit reviews the external ear and associated structures which are relevant to the small animal veterinarian.

Rationale:

While relatively limited in number, the relevant structures associated with the ear are important because of procedures associated with draining the external auditory meatus.

Objectives:

Upon completion of this unit you should be able to locate and describe the following structures:

auricular cartilage, tragus, antitragus, intertragic incisure, pretragic incisure, annular cartilage.

Notes:

I.          Auricular cartilage

A.        Helix - folded medial and lateral margin of the auricular cartilage

B.         Antehelix - transverse ridge on the internal, concave wall of the helix

C.        Tragus - the initial part of the ear canal formed by a thick, quadrangular plate of auricular cartilage

D.        Antitragus - completes the lateral border of the ear canal

E.         Intertragic incisure - separates the tragus from the antitragus

F.         Pretragic incisure - separation between the medial and lateral crura

G.        Medial and lateral crura - two curved portions of cartilage that form the medial border of the ear canal

II.         Annular cartilage - band of cartilage that overlaps the bony projection of the meatus and sits between the meatus and the auricular cartilage

Resources:

Textbook of Veterinary Anatomy, Dyce, Sack, and Wensing, 3rd ed. Saunders, 2002. Pp. 336-337.

Guide to the Dissection of the Dog, Evans and deLahunta, 6th ed. Saunders, 2004. Pp. 284-285.