Special Senses (Vestibular) Flashcards
- Consists of receptors located in the inner ear on both sides of the head
- 8th cranial nerve transmits the vestibular information (for equilibrium) from the receptors to the CNS
Functions:
* Maintains body balance
* Coordinates eye, head and body movements
* Permits the eyes to remain fixed on a point in space as the head moves
Vestibular Sense / Apparatus
vestibule and the semicircular canals are components of the bony labyrinth associated with balance
Vestibule Organs
Receptors in Vestibular sense:
- Cristae Ampullaris
- Macula
➢ found in the dilatations of semicircular ducts called ampulla
➢ stimulated by angular acceleration
➢ contains gelatinous substance called cupula
Cristae Ampullaris
➢ found in the vestibule
➢ stimulates by linear acceleration
➢ contains gelatinous substance called otolithic membrane
➢ containing otoconia, which are calcium carbonate crystals
Macula
- Mediated mostly by the utricle
- Allow detection of the position of the head in relation to gravity
- Important in control of posture
Static Functions
- Mediated largely by the semicircular canals
- Can detect motion of head in space
Dynamic Function
Chambers of Vestibule :
- Utricle
- Saccule
- Endolymphatic duct
– largest membranous component of the vestibular system
Utricle
- spherical and smaller communicates with the cochlear duct through the short narrow ductus reunions and with the utricle through the utriculo-saccular duct.
Saccule
Vestibular Nuclei :
- Superior
- Inferior
- Medial
- Lateral
- tubular evagination of the utriculo-saccular duct ; it terminates as a blind expansion called the endolymphatic sac
Endolymphatic duct
descending spinal
Inferior
vestibular nucleus of Bechterew
Superior
vestibular nucleus of Schwalbe
Medial
