1. Ocular Motor Nerves Visual Pathways – Neuroanatomy – for grade III medical students
蔡子同
成大醫院神經科
2012/05/09

2. Visual System -- Afferent and Efferent --
Afferent Visual System
Retina (ganglion cell axons), Optic nerve, Optic chiasm, Optic tract, Lateral geniculate nucleus (thalamic relay nucleus), Optic radiation, Visual cortex (occipital lobe)
Efferent Visual System
Extraocular muscles
Cranial nerves
Supranuclear pathways
Ocular Autonomic Pathways
Sympathetic pathway
Parasympathetic pathway

3. Cranial Nerves II Optic nerve III Oculomotor nerve IV Trochlear nerve
VI Abducens nerve

4. Manifestations of the Visual System Dysfunction
Afferent Visual System
Visual loss (loss of visual acuity)
Visual field defect
Efferent Visual System
Diplopia (double vision)
Gaze palsy
Ptosis (blepharoptosis)
Ocular Autonomic Pathways
Anisocoria (unequal pupil size)
Mild ptosis

5. Visual System -- Afferent and Efferent --
Afferent Visual System
Retina (ganglion cell axons), Optic nerve, Optic chiasm, Optic tract, Lateral geniculate nucleus (thalamic relay nucleus), Optic radiation, Visual cortex (occipital lobe)
Efferent Visual System
Extraocular muscles
Cranial nerves
Supranuclear pathways
Ocular Autonomic Pathways
Sympathetic pathway
Parasympathetic pathway

6. Eye Ball; Retina; Fundus

7. Retina

8. Cellular Organization of the Retina
Cell Layer
Neuronal and Glial Nuclei
Outer nuclear layer
• Photoreceptors (rod; cone)
Inner nuclear layer
• Horizontal cells
• Bipolar cells
• Interplexiform cells
• Amacrine cells
• Müller cells
Ganglion cell layer
• Ganglion cells
• Displaced amacrine cells
• Astrocytes
Miller NR et al (eds): Walsh & Hoyt's Clinical Neuro-Ophthalmology: The Essentials, 2nd ed, Chapter 2, pp 43

9. Visual Pathway

10. Visual Field
Confrontation test

11. *** Visual Pathways

12. Visual Pathways

13. *** Visual Field Defects Localization

14. Visual System -- Afferent and Efferent --
Afferent Visual System
Retina, Optic nerve, Optic chiasm, Optic tract, Optic radiation, Cortex
Efferent Visual System
Extraocular muscles
Cranial nerves
Supranuclear pathways
Ocular Autonomic Pathways
Sympathetic pathway
Parasympathetic pathway

15. *** Extrinsic Ocular Muscles
Superior view
Anterior view
Right lateral view

16. Actions of the Extraocular Muscles -- with the Eye in Central Position --
Cranial nerve
Primary action
Secondary action
Tertiary action
Medial rectus
III
Adduction --
Superior rectus
Elevation
Intortion
Inferior rectus
Depression
Extortion
Inferior oblique
Extorsion
Abduction
Superior oblique IV
Intorsion
Lateral rectus VI

17. Origins of the Ocular Motor Nerves - Sagittal & transverse sections of the Brainstem -

18. Ocular Motor Nerves
Schuenke M et al. Thieme Atlas of Anatomy- Head and Neuroanatomy, Thieme, 2007

19. Oculomotor Control - Final Common Pathway -

20. Conjugate Eye Movement-- Gaze

21. Purposes of Eye Movements
Purpose of eye movements
to place and maintain the image of regard on the foveas
Classification of eye movements
saccade
smooth pursuit
vestibuloocular reflex
optokinetic response
vergence

22. Pathways between Semicircular Canals and Eye Muscles in the Cat
Stimulation
Inhibition

23. Pathways of Saccade- Horizontal Gaze

24. Ocular Motor Control System
INC
III
MLF
Vestibular nucleus
PPRF

25. Visual System -- Afferent and Efferent --
Afferent Visual System
Retina, Optic nerve, Optic chiasm, Optic tract, Optic radiation, Cortex
Efferent Visual System
Extraocular muscles
Cranial nerves
Supranuclear pathways
Ocular Autonomic Pathways
Sympathetic pathway
Parasympathetic pathway

26. *** Pupillary Light Reflex -- Sympathetic & parasympathetic pathways --

27. *** Intrinsic Ocular Muscles
Ciliary muscles (parasympathetic)
When the ciliary muscle contracts, it pulls the choroid forward and relaxes the zonular fibers. As these fibers become lax, the intrinsic resilience of the lens causes it to assume the more convex relaxed shape.
Pupillary sphinctor (parasympathetic)
an anular muscle
contraction of the muscle constricts the pupil
Pupillary dilator (sympathetic)
radially disposed
contraction of the muscle dilates the pupil
Schuenke M et al. Thieme Atlas of Anatomy- Head and Neuroanatomy, Thieme, 2007

28. Pupillary Abnormality

29. Pupillary Light Reflex and Accommodation Reaction
Light reflex– The afferent pathway is the optic nerve and tract, from the retina to the pretectal region of the midbrain. The efferent pathway is in the oculomotor nerve: parasympathetic fibers from the accessory oculomotor nucleus (E-W nucleus), synapsing in the ciliary ganglion, and supplying the sphincter pupillae. Because of contralateral connections, exposure of only one eye to light causes constriction of both pupils (consensual light reflex).
Accommodation reaction– The afferent pathway extends from the retina to the visual cortex, and then to the pretectal region. The efferent pathway, similar to that of the light reflex, ends in the ciliary muscle (accommodation for focusing on near objects), sphincter pupillae (miosis), and medial rectus (convergence of the eyes).

30. Levator Palpebrae Superioris; Superior Tarsal Muscle (or Müller’s Muscle)
Schuenke M et al. Thieme Atlas of Anatomy- Head and Neuroanatomy, Thieme, 2007