The external auditory meatus is the anatomical term for the ear canal, a tube-like structure extending from the outer ear to the eardrum. This passageway connects the outside world to the middle ear and is the first part of the hearing pathway. In adults, the canal is about 2.5 centimeters long and directs sound waves inward.
Anatomy of the Ear Canal
The external auditory meatus follows a gentle S-shaped curve through the skull, which helps protect the inner structures of the ear. The canal is composed of two sections. The outer one-third is framed by flexible cartilage continuous with the auricle, while the inner two-thirds are housed within the temporal bone of the skull. The entire canal is lined with skin, and the outer portion contains hair follicles and specialized glands. These include sebaceous glands that produce oil and ceruminous glands that create a waxy secretion.
Functions of the External Auditory Meatus
The primary function of the ear canal is to channel sound waves toward the eardrum. Its shape and length act as a natural resonator, amplifying sound frequencies important for human speech and efficiently transferring sound energy to the middle ear. The canal also has a protective role. Its S-shaped structure creates a physical barrier against injury, and hairs in the outer part trap dust and small particles. The glands produce cerumen, or earwax, which lubricates the skin, contains antimicrobial enzymes to help prevent infections, and is part of a self-cleaning mechanism that carries debris outward.
Common Conditions Affecting the Canal
Several medical issues can arise within the external auditory meatus. One of the most frequent is cerumen impaction, where earwax accumulates and hardens into a blockage. This can lead to symptoms such as temporary hearing loss, a sensation of fullness in the ear, ringing, or dizziness because the blockage prevents sound from reaching the eardrum.
Another common condition is otitis externa, often called “swimmer’s ear.” This is an inflammation or infection of the skin lining the ear canal, often occurring when trapped water encourages bacterial or fungal growth. Symptoms include pain, redness, swelling, and sometimes discharge from the ear canal.
Foreign bodies can also become lodged within the canal, which is common among young children. Small objects like beads, toy parts, or food can be inserted into the ear and become stuck. This can cause pain and may damage the delicate skin of the canal or the eardrum if not removed by a healthcare professional.