QS Study

The external ear functions to collect and amplify sound, which then gets transmitted to the middle ear. The external ear includes the auricle as well as the external acoustic meatus, also known as the ear canal, which ends at the tympanic membrane separating the external ear from the middle ear.

Clinical anatomy of the External Ear

(1) Accumulation of wax in the external acoustic meatus is often a source of excessive itching, although fungal infection and foreign bodies should be excluded. Troublesome impaction of large foreign bodies (seeds, grains, and insects) is common.  The development of the external ear is a complex process that involves the merger of the 6 auricular hillocks.

(2) Involvement of the car in herpes zoster of the geniculate ganglion depends on the connection between the auricular branch of the vagus and the facial nerve within the petrous temporal bone. Superior to it is the squamous part of the temporal bone, while the styloid process is located inferiorly.

Clinical anatomy of External Ear 1

Fig: Clinical anatomy of the External Ear

(3) Small pieces of skin from the lobule of the pinna are commonly used for demonstration of lepra bacilli to confirm the diagnosis of leprosy. The lobule of the pinna is made of fibrofatty tissue covered with skin. The superior wall of the bony portion borders on the middle cranial fossa; the posterior wall borders on air-cells of the mastoid process and, particularly, on the antrum. That makes 3 understandable the development of pathognomonic signs of acute inflammation in the mastoid process (mastoiditis), that is, sagging of the posterosuperior wall in the bony portion of the meatus, which narrows its lumen due to developing periostitis.

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