Tympanic Membrane Pictures, Function and Anatomy

Ear

Question 1. What is an ear? List its subdivisions.
Answer.

The ear is the organ of hearing and balance. It is subdivided into the following three parts (from lateral to medial):

• External (outer) ear
• Middle ear
• Internal (inner) ear

Question 2. Discuss the sensory nerve supply of the auricle/pinna.
Answer.

Lateral (facial) surface

• Lower one-third by great auricular nerve (C2, C3)
• Upper two-thirds by the auriculotemporal nerve

Medial (cranial) surface

• Lower one-third by great auricular nerve (C2, C3)
• Upper two-thirds by lesser occipital nerve (C2)

Question 3. Write a short note on external auditory (acoustic) meatus.
Answer.

• The external acoustic meatus is an ‘S’-shaped osseocartilaginous tube, that extends from the bottom of the concha to the tympanic membrane.
• It is about 24 mm long, of which the medial two-thirds (16 mm) is bony and the lateral one-third (8 mm) is cartilaginous.
• It conducts sound waves from the concha to the tympanic membrane.
• It develops from the first pharyngeal cleft.