This document summarizes a presentation on the olfactory and optic nerves given by Dr. Naresh Mullaguri. It discusses the pathways and central processing regions of the olfactory nerve, as well as causes of olfactory dysfunction. For the optic nerve, it describes the course and vascular supply of the nerve, primary and association visual cortices, and clinical manifestations and examples of lesions along the optic nerve pathway.

1. NEUROANATOMY CONFERENCE
OLFACTORY AND OPTIC NERVES
NARESH MULLAGURI MD
RESIDENT PHYSICIAN – PGY2
UNIVERSITY OF MISSOURI
COLUMBIA, MISSOURI

2. OBJECTIVES
• PATHWAYS OF THESE SPECIAL CRANIAL
NERVES
• SOME PHYSIOLOGY
• LESIONS AT DIFFERENT REGIONS ON THEIR
COURSE

3. Olfactory Nerve

6. Central regions and their functions
Primary Auditory cortex Brodmann area 34.
Mitral cells send their axons to number of brain areas including the Anterior
Olfactory nucleus, piriform cortex, Medial Amygdala, Entorhinal cortex and Olfactory
tubercle
The Piriform cortex is the most closely associated with identifying Odor. The medial
Amygdala is involved in social functions such as mating and recognition of animals of
same species
The Entorhinal cortex is associated with memory eg: to pair odors with proper
memories. Still there is a debate of these higher functions

7. Causes of Olfactory Dysfunction
• Age
• Viral infections
• Exposure to toxic chemicals
• Head trauma
• Neurodegenerative Diseases
Alzheimer’s and Parkinson’s disease – 85-90% of early stage patients showed
decreased activity in central odor processing structures
Huntington’s disease, Multi-infarct Dementia, ALS, Schizophrennia – moderate
effects on the olfactory system.
PSP and Parkinsonism are associated with only minor Olfactory problems.
Linda B Buck and Richard Axel won the 2004 Nobel prize in physiology of
Medicine for their work on the Olfactory System

8. OPTIC NERVE
METRICS
- Intraocular portion or optic disc consists of unmyelinated
retinal ganglion call axons and astrocytes. As the nerve exits
the globe, crossing the collagenous lamina Cribrosa, it
increases in diameter as it becomes myelinated by
Oligodendrocytes.
- Intraorbital Segment measures approx. 25-30mm. Within the
orbital apex the nerve is surrounded by Dura, arachnoid and
pia mater. The dural covering fuses with the sclera around the
nerve and more posteriorly around the periosteum of the
optic canal. The nerve courses through the annulus of Zinn
which contains connective tissue origins of the EOMs.

9. Course of the Optic Nerve
• The nerve then passes through the Optic
foramen into the bony optic canal, which
lies posteromedially in the lesser wing of
the Sphenoid bone, and is about 4-10mm in
length. The Ophthalmic artery and ocular
sympathetic nerve fibers also travel through
the Optic canal.
• Intracranially, Optic nerve courses medially
and rises at an angle of 45 degrees toward
the chiasm. This segment is approx. 16mm
in length and lies superior to the cavernous
sinus and inferior to the frontal lobe,
anterior cerebral and ACOM arteries.

10. Vascular Supply of the Optic Nerve and Orbit

11. VISUAL PATHWAY

15. Primary and association visual cortices

16. Clinical Anatomy
• Optic Nerve lesions produce monocular vision loss
• Pain is a variable feature
• Other features include APD, Central vision loss(Scotoma),
Dyschromatopsia, Papillitis, Eventual optic atrophy

21. MACULAR STAR

22. Neuroretinitis - Rubella

23. Syphilitic Optic Neuritis

24. Leber’s Hereditary Optic Neuropathy
Circumpapillary Telangiectasia