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What is the only extraocular muscle that has a single blood supply?
Lateral rectus (single vessel derived from lacrimal artery)
What is the blood supply to the extraocular muscles?
Each muscle (except LR) is fed by 2 anterior ciliary arteries.
What muscles are innervated by the superior division of CNIII? By the inferior division?
Superior CNIII: Levator, SR
Inferior CNIII: MR, IO, IR
What is the ratio of nerve fibers to muscle fibers in the extraocular muscles?
1:3 - 1:5. Very high, allowing for precise control.
Are the eye muscles made up of slow, tonic fibers or fast, twitch fibers?
Both. Slow, tonic fibers do smooth pursuit, and fast, twitch fibers do saccades.
What are the different layers of the eyelid from anterior to posterior?
1. Skin (epidermis, dermis)
2. Eyelid margin
3. Subcutaneous tissue
7. Muller's muscle
What are the two portion of the orbicularis muscle?
1. Orbital (voluntary)
2. Palpebral (voluntary and involuntary)
--palpebral further divided into preseptal and pretarsal portions
What structure divides the main lacrimal gland into its palpebral and orbital components?
The levator palpebrae superioris
Extramacular fibers from the inferonasal retina cross where in the chiasm?
Anteriorly, at the Wilbrand knee
Describe the course of visual information from retina to brain.
Optic nerve, optic chiasm, optic tract, lateral geniculate body, optic radiations, visual cortex in occipetal lobe.
Name the four nuclei that give rise to CN V.
1. Mesencephalic nucleus
2. Main sensory nucleus
3. Spinal nucleus and tract
4. Motor nucleus located in pons
Bilateral, concentric sensory loss centered about the mouth ("onionskin") is caused by a lesion in the...
Trigeminal sensory nucleus in brainstem
When and where does myelination of the optic nerve begin? End?
Begins at optic chiasm at 7 mths gestation
Ends at lamina cribrosa at 1 mth old
What goes through the superior orbital fissure?
CN III, IV, VI, V1, sympathetics, and superior ophthalmic vein
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