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60 Cards in this Set

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The venous drainage of the orbit is via the _______________?
Pterygoid plexus and cavernous sinus
What are the seven bones of the orbit?
1. Sphenoid
2. Ethmoid
3. Frontal
4. Zygomatic
5. Palatine
6. Lacrimal
7. Maxilla
There are two different conjunctivas.
Name
Location
1. Bulbar - on sclera of eye
2. Palpebral - on eyelid
What is the innervation of the cornea?
V1 (Trigeminal)
The outer, fibrous layer of the eye is known as the __________?
Sclera
The middle, vascular layer of the eye is known as the __________?
Choroid
What produces aqueous humor?
Ciliary body
What are the 3 branches of V1?
Nasociliary
Frontal
Lacrimal
The nasociliary nerve divides into _____________, __________ & _____________.
Ethmoidal nerve (anterior)
Ethmoidal nerve (posterior)
Infratrochlear nerve
Which nerve supplies the eyelids, skin of nose, conjuntiva?
Infratrochlear nerve
1. The frontal nerve supplies?
2. It does this via which branches?
1. upper eyelid, forehead & scalp
2. Supratrochlear nerve, Supraorbital nerve
What areas does the lacrimal nerve supply?
conjunctiva, skin of eyelid (sensory)
parasympathetic to lacrimal gland (motor)
CN ___ is the sensory nerve to the retina.
II (Optic)
What 5 muscles does the oculomotor nerve (CN III) supply?
1. levator palpebrae superioris
2. superior rectus
3. inferior rectus
4. medial rectus
5. inferior oblique
1. What innervates the superior oblique?
2. What innervates the lateral rectus?
1. Trochlear (IV) nerve
2. Abducens (VI) nerve
What is the clinical term for an unopposed dilator pupilae muscle? What is deficient?
mydriasis
parasympathetics
What is the artery of the orbit?
What is it a branch of?
Opthalmic artery
Internal Carotid
What are the 3 components of a short ciliary nerve?
1. Parasympathetics -> to ciliary muscle and sphincter pupillae
2. Sympathetics -> from superior cervical ganglion, to dilator pupillae and superior tarsal muscles
3. Afferent sensory -> nasociliary nerve (branch of opthalmic)
What do the long ciliary nerves carry?
sympathetic to dilator pupillae, sensory from cornea and iris.
Describe the innervation of the lacrimal gland
parasympathetic. Preganglionic neuron originates in the superior salivatory nucleus (brainstem). Fibers travel with: 1st Facial, 2nd greater Petrosal n., 3rd. nerve of pterygoid canal. Synapse at ganglion; then follow zygomaticotemporal (CN V2) and lacrimal nerves to lacrimal gland.
Describe the flow of tears once they exit the lacrimal gland.
gland -> duct -> papillae/puncta -> canalliculi -> sac -> nasolacrimal duct -> inferior meatus
What is the autonomic component of CN III?
The Eddinger-Westphal nucleus
Of the CN that supply the eye: which one is the only one to project contralaterally?
CN IV, Trochlear
The Oculomotor Nucleus and fibers run through the ___________ and exit the brain at the _______________.
through crus cerebri
rostral midbrain
The nucleus of CN IV is found _____________. The roots pass around the periaqueductal gray to exit in the __________. Then they ________________.
1. in the MLF of the caudal midbrain
2. tectum
3. run their long external course through the midbrain (along the SCA)
The nucleus of CN VI is found _________. The roots pass through the ___________ and __________, then exit at the ______________.
1. In the floor of the caudal pons
2. tectum and ventral pons
3. ponto-medullary junction
ptosis, lateral strabismus and mydriasis are indicative of a CN_____ injury.
III injury
Failure to deoress or abduct the affected eye suggests a CN___ injury.
CN IV injury (superior oblique)
The abducens nucleus runs _________ (med/lat) to the MLF.
lateral
Medial strabismus suggests a CN___ injury.
CN VI injury (lat. rectus)
Ischemia to the Paramedian Arteries (branches of the PCA) would present as _______________.
Ptosis and lateral strabismus (blood flow to CN III is diminished)
Ischemic damage to the PM arteries from the SCA (or the SCA itself) would result in_________________.
Failure to depress or abduct eye (CN IV works contralaterally - hence, no adduction)
Ischemic damage to the PM or long circumferential a. from AICA presents as _____________.
medial strabismus (CN VI is affected)
Damage to CN III
What type of damage?
Damage to L CN VI
?
What is damaged?
How many types of neurons does CN VI have? Name them. WHere do they run?
1. a-motor neurons to lateral rectus (LMN)
2. internuclear interneurons (to OPPOSITE oculomotor nucleus)
*Axons run in MLF
How many types of neurons does CN III have? Name them. Where do they run?
Three:
1. a-motor neurons to extraocular eye muscles
2. preganglionic parasympathetic (GVE)in E-W nucleus
3. internuclear interneurons to IPSILATERAL abducens nucleus.
The MLF runs from _________ to __________.
rostral midbrain to cervical spinal cord
Is the MLF myelinated or unmyelinated?
What important neuron runs through the MLF?
myelinated
the internuclear interneurons (motor to CN III, IV, VI)
1. The MLF carries ascending vestibular signals that result in _________ if damaged.
2. MLF carries descending vestibular signals responsible for ___________.
1. Nystagmus
2. orientation of head
Function of the MLF in the brainstem ____________?
Interconnects nuclei of CN III, IV, VI with the auditory and vestibular system.
The MLF also coordinates eye movements, both voluntary and reflexive. Give an example of each.
volitional -> horizontal and vertical conjugate gaze

Reflexive -> orientation of eyes in the startle reflex; nystagmus
1. Are saccadic eye mvmnts. coordinated/uncoordinated?
2. Are saccadic eye mvmts. voluntary or involuntary. Why?
1. Coordinated - paired movement of eyes.
2. Voluntary - b/c they occur when one voluntarily shifts vision.
Although the intercortical circuits are not clear: they know the ___________ is involoved in initiating the saccadic eye movement.
Frontal eye fields (area 8)
1. Define slow pursuit movements (tracking)
2. Is it voluntary or involuntary?
1. coordinated mvmnt. of both eyes when an object enters and moves in visual field
2. involuntary
Slow pursuit movements involve the _________ eye field of the brain?
Parietal. <br />parietal eye field projects to the PPRF -> cerbellum and brainstem motor nuclei (coordinates)
1. Define horizontal conjugate gaze.<br />2. This involves the _________ eye field of the brain.
1. Coordinated horizontal mvmnt of both eyes in the same direction.<br />2. frontal eye field
Elaborate on control of horizontal conj. gaze by the frontal eye field.
Left area 8 controls ___________, Right area 8 controls_________.
Significance?
L -> conjugate mvmnt to the R
R -> conjugate mvmnt to the L
This equal opposition keeps eyes in midline.
Describe the motor portion of the horiz. conj. gaze starting at the frontal eye field -> ending at inhibition of CN VI.
frontal eye field -> via CBF to IPSILATERAL superior colliculus -> to OPPOSITE tectobulbar tract --> PPRF (gaze ctr.)- - -> stimulates neurons in ipsilateral nucleus of CN VI, Inhibits contralateral nucl. of CN VI.
Continue the pathway of horizontal conjugate gaze starting at the inhibition of CN VI.
inh. CN VI -> innervates Lateral Rectus -> has internuclear interneurons that cross and enter MLF -> oculomotor nucleus. END RESULT: One eye:
(+)Medial Rectus
(-) Lateral Rectus
Other eye:
(-) Medial Rectus
(+) Lateral rectus
Now eyes move in same dir.
Vertical Conjugate Gaze involves the ____________ complex, which is in the rostral midbrain.
accessory oculomotor complex
A lesion in the vertical conjugate gaze pathway will present as _____________?
Rotatory Nystagmus (involuntary reflex)
Define opthalmoplegia
disturbance in eye movement
What are the 3 classes of opthalmoplegia?
1. Nuclear (at nucleus)
2. Internuclear (in MLF between nuclei)
3. Supranuclear (in cerebral cortex or gaze centers)
Strabismus and diplopia is a nuclear opthalmoplegia that involves CN____ & _____.
CN III, IV
A dilated pupil that is unresponsive to light indicates an injury to CN ___
CN III
In a supranuclear opthalmoplegia the eyes look ___________ the side of the lesion.
towards
The periorbita is continuous with the ____________.
Where is the periorbita found?
periostial layer of the dura
Periorbita lines the bones of the orbit and becomes the fascial sheath of the eyeball.
CN ___ is medial to the MLF
CN ____ is cradled in the MLF
CN ____ is lateral to the MLF
III - medial
IV - cradled
VI - lateral
Define saccadic eye movements.
rapid, quick paired movements of both eyes. Occur when one shifts vision, therefore they are voluntary