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The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear.The adult human ear canal extends from the auricle to the eardrum and is about 2.5 centimetres (1 in) in length and 0.7 centimetres (0.3 in) in diameter.
The auricle consists of the curving outer rim called the helix, the inner curved rim called the antihelix, and opens into the ear canal. The tragus protrudes and partially obscures the ear canal, as does the facing antitragus. The hollow region in front of the ear canal is called the concha. The ear canal stretches for about 1 inch (2.5 cm).
Cerumen keeps the eardrum pliable, lubricates and cleans the external auditory canal, waterproofs the canal, kills bacteria, and serves as a barrier to trap foreign particles (dust, fungal spores, etc.) by coating the guard hairs of the ear, making them sticky. [1] These glands are capable of developing both benign and malignant tumors.
The stapedius reflex of the middle ear muscles helps protect the inner ear from damage by reducing the transmission of sound energy when the stapedius muscle is activated in response to sound. The middle ear still contains the sound information in wave form; it is converted to nerve impulses in the cochlea .
The auricular branch of the vagus nerve is often termed the Alderman's nerve ("a reference to the old Aldermen of the City of London and their practice of using rosewater bowls at ceremonial banquets, where attendees were encouraged to place a napkin moistened with rosewater behind their ears in the belief that this would aid digestion") or Arnold's nerve (an eponym for Friedrich Arnold).
The brain uses information from the vestibular system in the head, and from proprioception throughout the body to enable an understanding of the body's dynamics and kinematics (including its position and acceleration) from moment to moment. How these two perceptive sources are integrated to provide the underlying structure of the sensorium is ...
Schematic diagram of the human ear [clarification needed] The outer ear includes the pinna, the visible part of the ear, as well as the ear canal, which terminates at the eardrum, also called the tympanic membrane. The pinna serves to focus sound waves through the ear canal toward the eardrum.
The crista ampullaris itself is a cone-shaped structure, covered in receptor cells called "hair cells". Covering the crista ampullaris is a gelatinous mass called the cupula. Upon angular acceleration (rotation), the endolymph within the semicircular duct deflects the cupula against the hair cells of the crista ampullaris.