Equilibrium

Equilibrium (balance)

It is the function of the vestibular system , the detailed anatomy & physiology of this system complex is complex but can be divided to sensory part which consist of vestibular labyrinth, eyes and the somatosensory receptors in the muscles , joints and skin .those connected to brainstem , cerebellum & cerebrum .
Labyrinthine function (respond to horizontal acceleration by utricle , angular acceleration by semicircular ducts & to linear acceleration by saccule.

Functional examination of the labyrinth
Can be assessed by stimulating it artificially to produce nystagmus
1. Caloric test
If water at 30 * or 44* (i.e 7* above & below normal body temperature )is run into the ear under certain standerd condition nystagmus is produce in the normal person , the changes in this mormal graph indicate pathology.

2. Fistula test
The fistula in bony defect in the wall of horizontal semicircular canal may result from cholesteatoma or tumour in the temporal bone so the compression if air in the external auditory meatus lead to vertigo & nystagmus as soon as the vestibular system still functioning.

Diseases of the external ear:
? Congenital malformations of auricle & ext. aud. Meatus may be associated with the middle ear & inner ear .
1. Complete or partial absence of auricle =due to failure of development of the six auricular tubercles . treated by plastic surgery after good.
2. Pre-auricular sinus &\or cyst =due to incomplete fusion of the tubercles.
3. Accessory auricles.
4. Bat ear (protruding ear)cartilage scoring technique by (stensform).
5. Atresia of ext. aud. Canal.