The crista ampullaris is the sensory organ of rotation. They are found in the ampullae of each of the

semicircular canals The semicircular canals are three semicircular interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the lateral, anterior and posterior semicircular canals. They are the part of the bony labyrinth, ...

of the

inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...

, meaning that there are three pairs in total. The function of the crista ampullaris is to sense angular acceleration and deceleration.

Background

The inner ear comprises three specialized regions of the

membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers in the inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for soun ...

: the vestibular sacs – the utricle and

saccule The saccule (Latin: sacculus) is a bed of sensory cells in the inner ear that detects linear acceleration and head tilting in the vertical plane, and converts these vibrations into electrical impulses to be interpreted by the brain. When the he ...

, and the

, which are the vestibular organs, as well as the

cochlear duct Cochlear, the adjective form of cochlea, may refer to: * Cochlear implant, a sensory aid for the deaf * Cochlear nuclei, the ventral cochlear nucleus and the dorsal (or lateral) cochlear nucleus * Vestibular-cochlear or Vestibulocochlear nerve, ...

, which is involved in the

special sense In medicine and anatomy, the special senses are the senses that have specialized organs devoted to them: * vision (the eye) * hearing and balance (the ear, which includes the auditory system and vestibular system) * smell (the nose) * taste ...

hearing Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory sci ...

. The semicircular canals are filled with

endolymph Endolymph is the fluid contained in the membranous labyrinth of the inner ear. The major cation in endolymph is potassium, with the values of sodium and potassium concentration in the endolymph being 0.91 mM and 154 mM, respectively. ...

due to its connection with the cochlear duct via the saccule, which also contains endolymph. It also contains an inner membranous sleeve that lines the semicircular canals. The canals also contain the crista ampullaris. The receptor cells located in the semicircular ducts are innervated by the eighth cranial nerve, the

vestibulocochlear nerve The vestibulocochlear nerve or auditory vestibular nerve, also known as the eighth cranial nerve, cranial nerve VIII, or simply CN VIII, is a cranial nerve that transmits sound and equilibrium (balance) information from the inner ear to the br ...

(specifically the vestibular portion). 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. The hair cells thus respond by stimulating neurons that innervate them.

References

External links

* http://faculty.une.edu/com/abell/histo/CristaAmp.jpg * http://www.kumc.edu/instruction/medicine/anatomy/histoweb/eye_ear/ear04.htm * http://www.anatomyatlases.org/MicroscopicAnatomy/Section16/Plate16314.shtml * http://www.med.uiuc.edu/histo/small/atlas/objects/1296.htm * https://web.archive.org/web/20070703152544/http://education.vetmed.vt.edu/curriculum/VM8054/Labs/Lab11/Ear/EXAMPLES/Excrista.htm {{Authority control Auditory system