week 3: reading

week 3: reading

1. orbit = human eye rotating within the socket. the eye and orbit form a ball and socket joint (no segment attached to the ball)

2. upward movement = ELEVATION downward movement = DEPRESSION towards nose = ADDUCTION towards temple = ABDUCTION tilts inward to nose = INTORSION tilts outward toward temple = EXTROSION

3. conjucate eye movement (VERSION) = coordinated eye movement of the 2 eyes move in the same direction at the same time at the same angle

   • disconjucate eye movement (VERGENCE) = the eyes move in opposite directions at the same time and same angle

4. human eye moved by the extraocular muscles. lateral rectus and medial rectus have opposing actions (abduction - adduction).

   • superior and inferior recti oppose (elevation and depression). superior and inferior oblique (intorsion - extorsion)

5. adduction = towards nose (medial rectus) adduction = towards temple (lateral rectus) elevation = upwards (superior rectus) depression = downward (inferior rectus) intorsion = tilt to temple (superior oblique) extorsion = tilt to nose (inferior oblique)

6. Vestibular ocular = responds to stimulation of vestibular organs, stimulation of semi-circular organs. keep the image stable on the retina when the head moves. conjucate movement

   • generates couter rotational eye movements, the eye compensates for the head rotation during walking e.g. 2deg to left when walking = counter rotate 2deg to the right
     • EQUAL AND OPPOSITE ROTATION.

7. Optokinetic reflex system = keep the whole image stable on retina during smooth, sustained movement. generated in response to wide-field image flow stimulation of the retinal photoreceptors

   • OKR generates compensatory eye movements in response to visual stimulation. Produced by rotational image flows
     • nystagmus - following an object but flicking back to central position

8. translational vestibulatory ocular reflex = counter-rotational movements that keep images stable during brief and cyclical translations of the head

   • translations = bob up and down/ shifts from side-side

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