The functions of vestibular apparatus

vestibular apparatus

1. The Vestibular Apparatus (Function) PBL-2 23 rd -March-2018

2. Objectives To describe the functions of vestibular apparatus

3. Vestibular system consist of Vestibular apparatus and vestibular nucleic

4. Vestibular Apparatus Sensory organ for detecting sensations of equilibrium . Consists of 2 ottolith organs and 3 semicircular canals

5. Sensory hair cell found in vestibular apparatus Mechanically (Inertia or gravitational force) disturbed hair cell get stimulated

6. Otolith Organs (Vertical and Linear Acceleration)

7. Otolith organ Are two sac like structures named Saccule and Utricle The sensory hair cells of these organs lies in the macula # Saccule - Vertically oriented maculae Detect – upward and downward movement # Utricle – horizontal orientation of maculae Detect - side to side movement

8. Macular Orientation

9. Also, The combine sense of utricle and macule gauge the linear forces acting on the head at any instant in 3D.

10. Semicircular Canal (Angular Acceleration )

11. Semicircular Canals Anterior Posterior Lateral Arranged in 90 Degree to each other Ampulla as a sensory organ

12. Semicircular canal works in pairs 3 pairs 1. Horizontal pairs 2. Lt. Anterior and Rt. Posterior 3. Rt Anterior and Lt. posterior

13. Vestibular nuclei Sensory impulse from Vestibular apparatus are conveyed and processed at vestibular nuclei Vestibular nuclei – a multisensory structure ( visual , somatosensory, vestibular nuclei of opposite side)

14. Two major classes of Reflexes A. for maintaining equilibrium and gaze during movement - Vestibulo -ocular reflex (VOR) B. For maintaining Posture - Vestibulo -Spinal relex (VSR) - Vestibulo -Cervical reflex (VCR)

15. 1. VOR

16. 2. VCR Medial vestibular nuclei – medial longitudinal fasciculis Maintain head position reflexly 3. VSR – lateral vestibular nucleus - vestibule-spinal tract Balance and upright positon

17. Spatial Orientation and self motion Vestibulo -visual interaction Visual flow generates strong sense of self-motion while the subject is not moving ( Vection ) In this case , vestibular system suppress the sense of self generated motion (Astronauts , pt with vestibular damage)

18. Reference Guyton and Hall, 13 th edition Ganong’s Review of Medical Physiology 24 th edition Neuroscience 5e,purves et al. 2012

19. Thank you