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4. Control of Movements of the Eye ball
Optic nerve
fibers

5. Extra ocular muscles Six muscles Medial rectus Lateral rectus
Superior rectus
Inferior rectus
Superior oblique
Inferior oblique

6. Extra ocular muscles Function in pairs
Lateral and medial recti – side to side movements(adduction & Abduction)
Superior and inferior recti - upward and downward movement
Superior and inferior oblique – rotational movements

7. Innervation of extra ocular muscles
Lateral rectus –------
Superior oblique ---
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Nuclei are interconnected by Medial longitudinal fasciculus
Also connected to vestibular nuclei
Reciprocal Innervation of the pairs of muscles
abducent nerve (VI)
trochlear nerve (IV)
occulomotor nerve (III)

8. Extra ocular muscles of the eye

9. Fixation movements Voluntary fixation mechanism
Unlocking
Pre-motor cortex in frontal lobe -Area 8
Fronto-tectal tract
Involuntary fixation mechanism
Locking
Secondary visual area in occipital cortex
Occipito-collicular and occipito-tectal

10. Neural pathways for control of conjugate movement of the eyes.

11. Three types of fixation movements
Continuous tremor
Frequency 30-80
Image tremors on different photoreceptors
Slow drift
To one side or the other
Till the image reaches the margins of the fovea
Sudden flick
Opposite to slow drift
To bring the image back in the fovea

12. Conjugate eye movements
Saccadic movements
Fast eye movement to place the object on to the fovea or to move the eyes from one object to another (up to 800’/sec)
Smooth pursuit
slow eye movements to maintain fixation on a target
Non – optical reflexes(V-O Reflex)
vestibular reflexes which maintain eye position with respect to any changes in head and body position

13. Opticokinetic movement
Saccadic movement
Jumping of eyes from one object, frame, scene etc to next
Driving- saccades from frame to frame
Reading – saccades from word to word
10% time for unlocking
90% time to keep the image locked

14. Three types of fixation movements

15. Superior colliculus Responsible for
Control of conjugate movement of the eyes
Control of movement of head
Control of movement of whole body
Through medial longitudinal fasciculus
even if visual cortex has been destroyed

16. Autonomic nerves to the eyes

17. Autonomic nerves to eyes
Parasympathetic pre-ganglionic neurons in Edinger-Westphal nucleus
Fiber in occulomotor nerve
Ciliary ganglion contains postganglionic neurons
Short ciliary nerve
Supply
Ciliary muscles - accommodation
Sphincter pupillae muscles – light reflex

18. Autonomic nerves to eyes
Sympathetic pre-ganglionic neurons in intermediolateral horn of 1st spinal segment
Synapse in superior cervical ganglion of sympathetic chain
Post ganglionic fibers pass along carotid artery and its branches
Supply 3 muscles
1. Dilator pupillae muscles (radial muscle of iris)
2. Smooth muscle embedded in upper eye lid
3. Ciliary muscle

19. Autonomic innervation of the eye

20. Pupillary light reflex
Light shone in eye → constriction of pupil
Reflex arc
Retina (photoreceptors)
Optic nerve
Pretectal nuclei
Edinger-Westphal nuclei
Occulomotor nerve
Ciliary ganglion
Short ciliary nerve
Sphincter pupillae muscles
Consensual light reflex- constriction of the pupil of opposite eye
Optic chiasma crossing
Some fibers from pretectal nuclei cross to opposite side as well

21. Pathway of Pupillary light reflex

22. Abnormal pupillary reflex
Damage in Pretectal region
(CNS syphilis, alcoholism, encephalitis )
Chronically constricted pupil
Light reflex absent
Accommodation reflex may be present
Argyll Robertson pupil

23. Horner’s syndrome
Interruption of sympathetic supply from superior cervical ganglion
Constricted pupil
Ptosis – drooping of upper eye lid
Vasodilatation
Absence of sweating