ytterøre

Ytterøre, or the outer ear, is the visible part of the ear and the external auditory canal that channels sound toward the eardrum. It consists of the auricle (pinna) and the external acoustic canal. The auricle is a cartilaginous structure with features such as the helix, antihelix, concha, tragus, and lobule. It helps collect sound and contributes to directionality and resonance, particularly at mid-high frequencies. The external auditory canal is about 2.5 cm long in adults, lined with skin containing hair follicles and ceruminous and sebaceous glands that secrete cerumen, which helps protect the canal and trap debris. The canal ends at the tympanic membrane (eardrum), which separates the outer from the middle ear and vibrates in response to sound.

Innervation of the outer ear is provided by multiple nerves, including the auriculotemporal and greater auricular nerves, with contributions from the auricular branch of the facial nerve and, to a lesser extent, the vagus nerve. Blood supply comes from branches of the external carotid artery, notably the posterior auricular and superficial temporal arteries.

Functions of the ytterøre include capturing sound, aiding in volumetric localization, protecting the middle ear, and enhancing certain frequencies through resonance. Common conditions affecting the outer ear include otitis externa (inflammation of the canal), cerumen impaction, and foreign bodies. Developmentally, the auricle forms from six hillocks on the first and second pharyngeal arches, while the external auditory canal originates from the first pharyngeal groove.