outerear

The outer ear consists of the auricle (pinna) and the external auditory canal, extending from the rim of the pinna to the tympanic membrane. It functions to collect sound waves from the environment and funnel them toward the middle ear while contributing to sound localization and protection of the more delicate inner structures.

The auricle is the visible part of the outer ear. Its irregular, cartilaginous shape includes features such as the helix, antihelix, concha, and lobule (earlobe). This shape helps capture sound and provides cues for localizing sounds in vertical and horizontal planes. There is considerable anatomical variation in size and form among individuals.

The external auditory canal is about 2.5 centimeters long in adults. It has a lateral cartilaginous portion and a medial bony portion and is lined with skin bearing hairs and ceruminous glands that produce cerumen (earwax) along with sebaceous glands. Cerumen traps dust, lubricates the canal, and offers protective properties against infection. The canal also acts as a resonator, amplifying certain high-frequency sounds, typically in the range of about 2 to 4 kilohertz.

The tympanic membrane marks the inner boundary of the outer ear and transmits vibrational energy from sound to the middle ear via the ossicles. The outer ear is innervated by multiple sensory nerves from the trigeminal, facial, vagus, and other nerves, reflecting its complex protective and functional roles.

Common conditions affecting the outer ear include cerumen impaction, otitis externa (inflammation of the canal), foreign bodies, and trauma.