1. Gross Anatomy of the Eye Cornea at anterior –Light passes to lens Retina at posterior –sensory tissue –sensory cells: rods and cones

3. 1. Cornea 2. Lens 3. Iris 4. Sclera 5. Macula 6. Optic Nerve Head 7. Retinal vessels 8. Vortex Veins Med. Lat. Sup. Inf.

4. Looking at the Retina Macula- 3 by 5 mm area at the posterior pole of the eye Fovea- in center of macula, free of blood vessels contains only cone cells

5. Retinal Anatomy

6. Back of the Eye Front of the Eye

7. Extrinsic Eye Musculature For moving eye within its socket. 6 muscles per eyeball Innervated by 3 Cranial nerves

8. Eye Movements Yaw: gaze shifts L/R Pitch: gaze shifts up/down Roll: eye rotates around line of gaze (torsion) Adduction: shifting gaze toward midline Abduction: shifting gaze laterally PITCH YAW ROLL

9. Extraocular Muscles Anterior View of Left Orbit

10. Oculomotor Muscle Actions MuscleActionNerve Supply Sup. rectuselevates & abducts eyeball upper division of oculomotor n. (III) Sup. obliquedepresses & abducts eyeballtrochlear n. (IV) Med. rectusadducts the eyeball lower division of oculomotor n. (III) Lat. rectusabducts the eyeballabducens n. (VI) Inf. rectusdepresses & abducts eyeball lower division of oculomotor n. (III) Inf. obliqueelevates & abducts eyeball lower division of oculomotor n. III) levator palpebrae superiorisraises the eyelid upper division of oculomotor n. (III)

11. 3 branch of CN III to Inf Obl. 5 Sup. Rectus 7 Inf Rectus 8 Optic Nerve 10 Abducens Nerve 11 Oculomotor Nerve (CN III) Ant. Post. Sup. Inf.

12. Ocular Musculature Superior Rectus (SR) Inferior Rectus (IR) Lateral Rectus (LR) Medial Rectus (MR) Superior Oblique (SO) Inferior Oblique (IO)

13. CN Nuclei Important to Oculomotor Function

14. Cranial Nerves III, IV, and VI III - Oculomotor IV - Trochlear VI - Abducens

15. III (Oculomotor) innervates: 1) Medial rectus 2) Superior rectus 3) Inferior rectus 4) Inferior oblique Levator palpebrae sup Pupillary sphincter Ciliary muscle

16. IV (Trochlear) innervates: Superior oblique

17. VI (Abducens) innervates Lateral rectus.

18. Proprioceptive info from eye muscles comes through Trigeminal nerve.

19. Eye Movements Saccades—rapid shift in gaze Pursuit—stabilize image of moving object Fixation—stabilize image of still object VOR—stabilize image during head motion OKN—backup for when VOR decays to cont’d head rotation Vergent movements—change depth of focus –Accommodation-- automatic changes to see at different distances which is chiefly brought about by changes in the convexity of the lens. Horizontal vergence and accommodation normally occur together. The two responses are accompanied by an appropriate change in pupil diameter. The three concomitant changes are known as the near-triad response.

20. Cortical Areas: Oculomotor Control Occipital Eye Fields (areas 18 and 19) Frontal Eye Fields (area 8) Temporal Eye Fields (area 22)

21. Basic Eye Exam

22. Vestibulo-Ocular Reflex

23. VOR Pathways Vestibular nuclei Abducens N. Median Longitudinal Fasciculus Trochlear N. Oculomotor N.

24. Horizontal/Lateral Canal VOR

25. Anterior/Superior Canal VOR

26. Posterior Canal VOR

27. Anatomy & Physiology of a Horizontal Saccade

28. Pause cells inhibit Burst Neurons which stimulate: III & VI (horizontal) or III & IV (vertical) Saccades