Ear, internal: There are three sections of the ear. They are the external ear, the middle ear, and the internal ear. The internal ear is far and away the most highly complex. The essential component of the internal ear for hearing is the membranous labyrinth, located inside the bony cochlea, where the fibers of the auditory nerve (the nerve connecting the ear to the brain) end. The membranous labyrinth is a system of communicating sacs and ducts (tubes) filled with fluid (endolymph). The membranous labyrinth is lodged within a cavity called the bony labyrinth. At some points the membranous labyrinth is attached to the bony labyrinth and at other points the membranous labyrinth is suspended in a fluid (the perilymph) within the bony labyrinth. The bony labyrinth has three parts: a central cavity (the vestibule), semicircular canals (which open into the vestibule) and the cochlea (a snail-shaped spiral tube). The membranous labyrinth also has a vestibule which consists of two sacs (called the utriculus and sacculus) connected by a narrow tube. The utriculus, the larger of the two sacs, is the principal organ of the vestibular system (which informs us about the position and movement of the head). The smaller of the two sacs, the sacculus (literally, the little sac) is connected with a membranous tube in the cochlea containing the organ of Corti. It is in the organ of Corti that are situated the hair cells, the special sensory receptors for hearing. The internal ear is also called the inner ear.
- Ear, low-set
Ear, low-set: A minor anomaly involving an ear situated down below its normal location. The ear is low-set when the helix (of the ear) meets the cranium at a level below that of a horizontal plane through both inner canthi (the inside corners of the eyes). .
- Ear, middle
Ear, middle: A part of the ear that consists of the eardrum (tympanic membrane) and, beyond it, a cavity (tympanum). This cavity is connected to the pharynx (nasopharynx) via a canal known as the Eustachian tube. The middle ear cavity also contains a chain of three little bones, the ossicles (the malleus, incus, and stapes), […]
- Ear, outer
Ear, outer: The part of the ear that is visible along the side of the head. The outer ear consists of the pinna, or auricle (the visible projecting portion of the ear), the external acoustic meatus (the outside opening to the ear canal), and the external ear canal, which leads to the eardrum. The outer […]
- Ear, slanted
Ear, slanted: An ear that is slanted more than usual, with the angle of the slope of the auricle more than 15 degrees from the perpendicular. Also called a malrotated ear.
Earache: Pain in the ear. This can occur because of conditions within the ear itself, the ear canal, or the visible external portion of the ear. Acute infection of the middle ear, medically called acute otitis media (AOM), is inflammation of the middle ear and is the most frequent diagnosis in sick children in the […]