What are the main parts of the external ear?

The external ear consists of two primary structures: the auricle (pinna), which is the visible outer part, and the external auditory meatus, which is the ear canal leading to the tympanic membrane. Together, they function to collect and direct sound waves inward.

What are the key surface features of the auricle?

The auricle has several distinct surface features, including the concha (leads into the ear canal), helix (the outer rim), antihelix (a ridge anterior to the helix), and tragus and antitragus (small elevations near the ear canal opening). These structures help in sound localization and collection.

How is the external auditory meatus structured?

The external auditory meatus is about 24 mm long and divided into two parts: the cartilaginous part (outer third, with hair and glands) and the bony part (inner two-thirds, with thin skin). It has an S-shaped course and a narrow isthmus where foreign bodies can get impacted.

What nerves provide sensory supply to the external ear?

Sensory innervation varies by region: on the lateral surface, it's supplied by the great auricular nerve, auriculotemporal nerve, and auricular branch of vagus; on the medial surface, by the great auricular nerve, lesser occipital nerve, and auricular branch of vagus. This distribution is important for clinical conditions like Ramsay Hunt syndrome.

What are some clinical correlations related to the external ear?

Key clinical points include furuncles (occurring only in the cartilaginous part), the ear cough reflex (triggered by vagal innervation), and development issues like atresia or accessory auricles. These highlight anatomical vulnerabilities and developmental anomalies.

How does the external ear develop embryologically?

The external ear develops from two main sources: the external auditory meatus from the 1st pharyngeal cleft, and the auricle from six mesodermal tubercles. Malformations can result from failures in these processes, leading to conditions like atresia.

What is the blood supply to the external ear?

The arterial supply primarily comes from the posterior auricular artery, superficial temporal artery, and occipital artery. Venous drainage is into the superficial temporal and external jugular veins.

External Ear – Auricle & External Acoustic Meatus

❓ Frequently Asked Questions