Case 4 Summary - ILOs

Case 4 summary
General ILOs:

- To demonstrate knowledge of the anatomy and function of the vestibular system

The main peripheral component of the vestibular system is the labyrinth. It uses specialised
hair cells to transduce physical motion (from head movements) into neural impulses.

The labyrinth consist of two otolith organs (forward and backward movement) and three
semi-circular canals (rotational acceleration of the head).

Otolith organs

 Utricle:
o Maculae of the floor
o Hair cells point up
o Horizontal tilt
 Saccule:
o Maculae of the wall
o Hair cells point out
o Vertical tilt




Semi-circular canals

These canals are filled with endolymph, which enables detection of motion via the hair cells
located in the ampulla.




1
Guillaume Antem – MBChB Y2

, Hair cells in the auditory and vestibular systems are activated in a similar fashion. Movement
of endolymph will cause stereocilia to bend (due to inertia). If the stereocilia bend towards
the kinocilium, potassium channels open, leading to depolarisation and glutamate release.




The kinocilium is the black stick on the right of the ampulla

Some important reflexes linked to the vestibular system are:

 Vestibulo-ocular reflex: allows gave to remain fixed even if the head moves.
 Vestibulo-cervical reflex: head movement

2
Guillaume Antem – MBChB Y2