Internal auditory meatus

Internal Auditory Meatus

Base of the skull. Internal auditory meatus is labeled at right (click image to view detail)

The Internal Auditory Meatus (IAM) is a canal within the temporal bone of the skull. It is a significant structure in the human anatomy as it allows passage for two crucial cranial nerves, the facial nerve (VII) and the vestibulocochlear nerve (VIII).

Anatomy

The IAM is located in the posterior part of the temporal bone, opening into the posterior cranial fossa. It is approximately 1 cm in length and runs from the inner ear to the cranial cavity. The canal is divided into two sections: the facial nerve canal and the cochlear nerve canal.

Facial Nerve Canal

The facial nerve (VII) travels through the facial nerve canal. This nerve is responsible for controlling the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity.

Cochlear Nerve Canal

The vestibulocochlear nerve (VIII) travels through the cochlear nerve canal. This nerve is divided into two parts: the cochlear nerve, which transmits sound information, and the vestibular nerve, which carries balance information.

Clinical Significance

The IAM is clinically significant as it can be affected by various conditions such as vestibular schwannoma, meningioma, and facial nerve palsy. These conditions can cause symptoms such as hearing loss, tinnitus, and vertigo.

See Also

• Cranial nerves
• Temporal bone
• Vestibular schwannoma