Anatomy of the external ear THE external ear is composed of the pinna( also known as the auricle) and the external auditory canal. The pinna is composed of elastic cartilage that is covered by perichondrium and then skin. The skin covering the pinna is tightly bound to the anterolateral surface and loosely bound to the posteromedial aspect. Inferiorly, the pinna is made up of the lobule, which does not contain cartilage but is instead made of fibro-fatty tissue.

The external auditory canal is a 2.5-3cm long tube. The outer third is cartilaginous and the medial twothirds is bony; the isthmus is where these two parts meet and is usually the narrowest part of the canal. The cartilaginous part contains hair follicles, sebaceous glands, apocrine glands and ceruminous glands. The medial aspect of the external auditory canal is covered in thin squamous epithelium and ends at the

tympanic membrane, which separates the external ear and the middle ear.

The pinna and external auditory canal are supplied by the posterior auricular and superficial temporal arteries and drained by the corresponding veins. The lymph from the ear drains to the occipital, pre-auricular and superficial cervical lymph nodes.

The nerve supply of the external ear is complex, with many contributions from both spinal and cranial nerves. The main cutaneous nerves for the pinna are from the spinal nerves, the great auricular nerve, lesser occipital nerve and auriculotemporal nerve. The nerve supply of the external auditory canal predominantly comes from the auriculotemporal nerve with branches from the trigeminal, facial, glossopharyngeal and vagal nerves. cont’ d next page

Figure 1. Anatomy of the pinna.

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