The Inner Ear: A Primer for Radiologists, Part 1: Anatomy, Physiology, and Intrinsic Abnormalities of the Otic Capsule

This article is the first part of a 2-part series on imaging of the inner ear. It will review the normal anatomy, embryology, and intrinsic abnormalities of the otic capsule. The inner ear, comprising the osseous and membranous labyrinths, is a complex anatomic region with structures of high functional relevance. Disorders of the inner ear can consequently lead to disability and can encompass a wide range of etiologies, such as congenital anomalies, trauma, inflammation, and neoplastic conditions, which will be discussed in Part 2. These disorders can manifest as conductive and/or sensorineural hearing loss, as well as other nonspecific clinical manifestations such as vertigo or tinnitus. Given its deep location within the temporal bone and often nonspecific clinical manifestations, imaging is indispensable in the diagnostic work-up and treatment management of the inner ear. An in-depth comprehension of relevant anatomy and basic embryology provides a foundation for understanding the pathophysiologic mechanisms of diseases that can affect the inner ear.Learning Objective: After reading this article, the learner will be able to describe the anatomy and basic embryology of the inner ear, recognize intrinsic abnormalities of the otic capsule, and evaluate the role of imaging in diagnosing and managing inner ear disorders.