Lecture 12: Eye and Eye Movements Flashcards
What structures exit the Optic Canal?
CN II
Opthalmic Artery
What structures pass through the Inferior Orbital Fissure?
Maxillary N. –> Infraorbital Nerve
Maxillary N. –> Zygomatic Nerve (CN V2)
Infraorbital Artery
In comparision with the orbit, where are these sinuses located?
Frontal
Ethmoid
Maxillary
Sphenoid
- Frontal: superior and medial
- Ethmoid: medial
- Maxillary: inferior
- Sphenoid: posterior
What can cause optic neuritis?
Chronic infections in the ethmoid sinus that erodes into the orbit
What bone of the orbit is normally involved in an orbital blowout fracture?
Maxillary Bone
-Inferior to orbit
What are some consequences of an orbital blowout fracture?
- Diplopia (eyes not aligned)
- Globe ptosis (eyeball falling through orbit)
- Eye prolapses into maxillary sinus (if inferior bone breaks)
- Eye prolapses into ethmoid sinus (if medial wall breaks)
- Exophthalmos (protrusion of eyeball)
What is the movement of the eyeball around the vertical, horizontal, and AP axis?
Vertical Axis
- Abduction
- Adduction
Horizontal Axis
- Elevation
- Depression
AP Axis
- Intorsion (medial rotation)
- Extorsion (Lateral rotation)
What extra-ocular muscles abduct the eyeball?
Superior Oblique Muscle
Inferior Oblique Muscle
Lateral Rectus Muscle
What extra-ocular muscles adduct the eyeball?
Superior Rectus Muscle
Inferior Rectus Muscle
Medial Rectus Muscle
What extra-ocular muscles are involved in bilateral eyeball depression?
Superior Oblique Muscle
Inferior Rectus Muscle
What extra-ocular muscles are involved in bilateral eyeball elevation?
Superior Rectus Muscle
Inferior Oblique Muscle
How do you test exta-ocular eye muscles?
How do you test Superior Rectus, Inferior Rectus, Superior Oblique, and Inferior Oblique Muscles?
Trap an individual muscle and test its functional pair.
Basically do the opposite of its normal function
- Superior Rectus: Trap Inferior Oblique
- Inferior Rectus: Trap Superior Oblique
- Superior Oblique: Trap Inferior Rectus
- Inferior Oblique: Trap Superior Rectus
What structures go through the Cavernous Sinus?
- Oculomotor Nerve
- Trochlear Nerve
- Trigeminal Nerve
- Ophthalmic Nerve
- Maxillary Nerve
- Abducens Nerve
- Internal Carotid ARtery
What are branches of the Ophthalmic Nerve?
Frontal nerve
- Supraorbital n.
- Supratrochlear n.
Lacrimal nerve
Nasociliary n.
- Long ciliary nn. (Ciliary ganglion?)
- Posterior ethmoidal n.
- Anterior ethmoidal n.
- infratrochlear n.
What are branches of the Nasociliary Nerve?
- Anterior and Posterior Ethmoidal Nerve
- Nasal Cavity
- Long Ciliary Nerve (goes to cornea)
- Sensory
- Sympathetic
- Short Ciliary Nerve (comes off ciliary ganglion)
- Parasympathetic to iris and ciliary body
- Sympathetic
- Infratrochlear Nerve
What does the superior and inferior branches of the Oculomotor Nerve innervate?
Superior
- Levator Palpebrae Superioris Muscle
- Superior Rectus Muscle
Inferior
- Inferior Rectus Muscle
- Inferior Oblique Muscle
- Medial Rectus Muscle
What nerves pass through the superior orbital fissure?
- CN III: Oculomotor Nerve
- CN IV: Trochlear Nerve
- CN V1: Ophthalmic Nerve
- Lacrimal
- Frontal
- Nasociliary
- CN VI: Abducens Nerve
What nerves pass through the common tendinous ring of the orbit?
- CN II: Optic Nerve
- CN III: Superior/Inferior divisions of Oculomotor Nerve
- CN V1: Nasociliary Nerve
- CN VI: Abducens Nerve
Common Tendinous Ring is made up of Rectus muscles
How does sympathetic innveration work with the eye muscles?
What are its actions?
Postganglioninc Sympathetic fibers arise from Superior Cervical Ganglion
- Will travel with Internal or External Carotid Plexus
Actions
- Deep Petrosal Nerve: constrict blood vessels
- Innervates Levator Papebrae Suprerioris to open eye
- Oculomotor Nerve
- Innervates Tarsal Muscles to keep eye opens
- Innverates Dilator Pupilae to dilate eye
-
Carries sensory info to choroid, iris, and cornea
- Ophthalmic Nerve
Travels through ciliary ganglion but does not synapse there!
How does parasympathetic innveration work with the eye muscles?
What are its actions?
Preganglioninc Parasympathetic run with Oculomotor nerve and will synapse in ciliary ganglion and then travel with Short Ciliary Nerves
Actions
- Innervate Sphincter pupillae
- Constrict pupil
- Contracts ciliary muslce
- lense is rounder for near vision
What are the 3 main symptoms of Horner Syndrome?
- Ptosis: droopy eyelid
- Anhidrosis: No sweat
- Miosis: constricted pupil
(PAM Horner)
A patient who is unable to look laterally with the left eye but is still able to perform all other ocular movements most likely has what disorder? What muscle is affected?
Abducens CN VI
Lateral Rectus M.
In a patient with CN IV palsy, what muscle is affected?
How will the patient compensate?
Superior Oblique Muscle
Patient will turn head down and away from the affected side
When would a patient complain the most of diplopia if they have trochlear palsy?
When they have downward gaze (reading or walking downstairs)
A patient presents with L eye looking down and out, droopy eyelid, and pupil dilation, what cranial nerve has been affected?
Oculomotor Nerve
Aneursysm of the follow arteries can affect what autonomic division?
Posterior Cerebral Artery
Posterior Communicating Artery
Superior Cerebellar Artery
Parasympathetic
What are the steps of the pupillary light reflex?
-
Step 1: Light synapses at pretectal nucleus
- Carried by Optic Nerve (sensory)
- Step 2: Cells from pretectal nucleus will synapse at Edinger-Westphal Nuclues
-
Step 3: Preganglioninc parasympathetic neurons will synapse in ciliary ganglion
- Carried by Oculomotor Nerve (motor)
-
Step 4: Postganglioninc parasympathetic neurons will synapse in pupillary constrictor muscle
- Constriction of Eye
How does an afferent lesion affect the pupillary light reflex?
Ipsilateral side will not perform a direct response but will still perform a consensual response because motor innervation is still intact
How does an efferent lesion affect the pupillary light reflex?
Ipsilateral side will not have pupillary muscle constriction but the contralateral side will still have a consensual response because afferents are still intact
What are the steps of the corneal light reflex?
-
Step 1: Receptors that sesne Touch/Irritation will synapses at trigeminal sensory nucleus.
- Carried by Ophthalmic Nerve (sensory)
- Step 2: Cells from trigeminal sensory nucleus will synapse at facial nuclues.
- Step 3: Facial Nerve will cause blinking (motor)
What composes the fibrous layer of the eyeball?
Sclera
Cornea
Continuous with each other
What composes the vascular layer of the eyeball?
Choroid (tiny blood vessels)
Ciliary Body
Iris
What composes the inner layer of the eyeball?
Retina
What comprises the outer covering of the Optic Nerve?
All 3 layers of the Meninges, continuous with meninges from the cranium
What vessels are found running within the Optic Nerve?
Central Retinal Artery and Vein
What is the conjunctiva that lines the innermost part of the eyelids?
Palpebral Conjunctiva
What is the conjunctiva that lines the outermost part of the eyeball?
Bulbar (ocular) Conjunctiva
Where would a subconjunctival hemorrhage collect?
How does it happen?
Below bulbar conjunctiva and sclera
-Valsava maneuvers (increase in intra-abdominal pressure) can cause this
Complete Ptosis results from destruction of what CN?
What muscle is affected?
CN III
Levator Palpebrae Superioris M.
Partial Ptosis results from destruction of what?
What muscle is affected?
Postganglionic sympathetic fibers
Tarsal Muscles
Ptosis as a result of Horner’s syndrome is failure of what muscle?
Tarsal Muscle
How does papilledema present?
What is it caused by?
Bulging optic disc (swelling of optic N)
Caused by increased intracranial pressure
Can be seen in the back of the eye (retina)
What branch of the Opthlamic A. anastamoses with Middle Meningeal A.?
Lacrimal A.
Sphenopalantine A. anastamoses with what arteries in the nasal cavity?
Anterior and Posterior Ethmoidal As.
Occlusion of what terminal artery will result in blindness?
Central Retinal Artery
If the occlusion happens quickly. If its slow, anatsomes can help prevent blindness.
A patient presenting with dilated veins and small hemorrhages in the eye has occlusion of what vessel?
Central Retinal Vein
Looks like splattered ketchup
A patient presenting with a pale retina and a red spot in the eye most likely has occlusion of what vessel?
Central Retinal Artery
Where is the lacrimal gland located?
Lateral and superior aspect of the eye
What muscle is responsible for opening the lacrimal sac and pulling tears in?
Lacrimal part of Orbicularis Oculi Muscle
What is the pathway of tears?
- Lacrimal Gland
- Lacrimal Canaliculi
- Lacrimal Sac
- Nasolacrimal Duct –> Inferior Nasal Meatus
How are tears produced?
Basically Parasympathetic Pathway to Lacrimal Gland
- Facial Nerve gives off Greater Petrosal Nerve that joins Deep Petrosal Nerve to form Vidian Nerve.
- Enters Pterygopalatine Fossa and synapses at its ganglion.
- Joins Zygomatic Branch of V2 and then goes to Lacrimal Branch of V1
- Synapses at Lacrimal Gland
Where does aqueous humor come from?
Ciliary Processes
What are the anterior and posterior chambers between?
Anterior: Between Cornea and Iris/Pupil
Posterior: Between Iris/Pupil and Lens
How does aqueus humor flow in the eye?
- Aqueus Humor is produced in ciliary body by ciliary processes.
- Posterior Chamber
- Anterior Chamber
- Schlem’s Canal (scleral venous sinus)
Blockage of the scleral venous sinus can result in what disorder?
Glaucoma
Rupture of blood vessels in the anterior chamber of the eye can result in what disorder?
Hyphema
What attaches the ciliary processes to the lens of the eye?
Zonular fibers/suspensory ligament of the lens
What is the action of the ciliary muscles for near vision?
What is the effect on the lens?
Contract and decrease size of ciliary body, reduces tension on suspensory ligament
Lens become round
What is the action of the ciliary muscles for far vision?
What is the effect on the lens?
Relaxed ciliary muscles and increased size of ciliary body, increases tension on suspensory ligament
Flatten lens
What does the Sphincter Pupillae muscle do?
Constrict pupil
What does the Dilator Pupillae muscle do?
Dilate pupil
