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

ampullae An ampulla (; ) was, in Ancient Rome, a small round vessel, usually made of glass and with two handles, used for sacred purposes. The word is used of these in archaeology, and of later flasks, often handle-less and much flatter, for holy water or ...

of each of the

semicircular canals The semicircular canals or semicircular ducts are three semicircular, interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the horizontal, superior and posterior semicircular canals. Structure The ...

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 which contain the receptors for the senses of equilibrium and hearing. It is lodged within the bony labyrinth in the inner ear and has the same general form; it is, howeve ...

: the vestibular sacs – the utricle and

saccule The saccule is a bed of sensory cells in the inner ear. It translates head movements into neural impulses for the brain to interpret. The saccule detects linear accelerations and head tilts in the vertical plane. When the head moves verticall ...

, and the

, which are the

vestibular organs The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes ...

, as well as the

cochlear duct The cochlear duct (bounded by the scala media) is an endolymph filled cavity inside the cochlea, located between the tympanic duct and the vestibular duct, separated by the basilar membrane and the vestibular membrane (Reissner's membrane) resp ...

, 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 (the ...

hearing Hearing, or auditory perception, is the ability to perceive sounds In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psycholog ...

. 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. I ...

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 Receptor may refer to: *Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a n ...

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 bra ...

(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