Eye and Eye movements Flashcards
what bones make up the orbit and what foramina are found in the orbit
frontal ethmoid sphenoid zygomatic lacrimal maxillary
optic canal
superior orbital fissure
Inferior orbital fissure
What locations on the orbit are easy to fracture?
The lateral aspect of the orbit and the floor of the orbit due to how thin the bone is there
what is considered a blow out fracture of the eye and what are its symptoms?
indirect trauma to the orbit
usually happens medially and inferiorly into the maxillary bone
orbital contents can get entrapped in maxillary sinus
leads to Diplopia,
globe ptosis (eye sinks down)
exophthalmos (protrusion of the eyeball)
what angle does the orbital socket face from midline?
what angle does the lateral walls deviate from the medial walls?
What angle does the optical axis face
45 degrees
90 degrees
o degrees (looks directly straightforward
What are all the movements of the eye
Abduction and Adduction (vertical axis)
Elevation and depression (Horizontal axis
Intorsion (medial rotation)
Extorsion (lateral rotation)
(Anterior posterior axis)
Innervation and action of levator palpebrae superioris
INN: superior branch of Oculomotor (CN III)
Action: Elevates the superior eyelid
Innervation and action of superior oblique
INN: trochlear
action: Abducts
depresses
Medially rotates the eyeball
Innervation and action of inferior oblique Muscle
INN: Oculomotor
action: ABducts
Elevates
laterally rotates the eye
Innervation and action of Superior rectus Muscle
INN: Oculomotor
Elevates, adducts and rotates eyeball medially
Innervation and action of inferior rectus muscle
INN: Oculomotor
Depresses adducts and laterally rotates the eyeball
Innervation and action of medial rectus
INN: Oculomotor
Adducts the eyeball
Innervation and action lateral rectus
INN: Abducent
Abducts the eyeball
What muscles do Extorsion
Lateral rotation
Inferior Oblique
Inferior rectus
What muscles do Introsion
Medial rotation
Superior oblique muscle
Superior rectus
What muscles do elevation
Inferior oblique
Superior rectus
WHat muscles do depression
Superior oblique
Inferior rectus
WHat muscles do ABduction
INferior oblique
lateral rectus
superior oblique
WHat muscles do ADduction
Inferior rectus
Medial rectus
Superior rectus
How do clinicians test each muscle of the eye individually
They must trap the paired muscle to test the muscle they want by trapping the visual gaze so that the paired muscle they arent testing muscle fibers are perpendicular to the muscle fibers they are testing
To test the superior rectus how must the eye be looking
THe eye must be ABducted by the Lateral rectus
then you elevate the eye
(this would make the inferior oblique perpendicular)
To test the inferior rectus how must the eye be looking
THe eye must be ABducted by the lateral rectus
then you depress the eye
(THis would make the superior oblique perpendicular)
To test the superior oblique how must the eye be looking
THe eye must be ADducted by the medial rectus
then you depress the eye
(This makes the inferior rectus perpendicular)
To test the inferior oblique how must the eye be looking
the eye must be ADducted by the medial rectus
then you elevate the eye
(this makes the superior rectus perpendicular)
What modalities are carried in Long ciliary nerve
Comes off of nasociliary N
carries sensory and sympathetics
WHat modalities are carried in short ciliary nerve
comes off of naso ciliary N
travels through ciliary ganglion
carries sensory, parasympathetics and sympathetics
What muscle is innervated by the inferior branch oculomotor
Inferior oblique
Inferior rectus
Medial Rectus
What muscle is innervated by the superior branch of oculomotor
Levator palpebrae superioris
Superior rectus
What nerves travel through the Common tendinous ring
Optic Nerve (and optical canal)
Frontal Nerve Lacraimal Nerve (V1) Trochlear Nerve (CN IV)
Oculomotor Nerve superior and inferior branches
Nasociliary nerve
Abducent Nerve
(these 4 also travel through superior orbital fisure)
WHat is horners syndrome
When the cervical ganglion is cut so that you lose all sympathetics to the face
patients present with constriction of the pupil: miosis Drop eye lid: Ptosis Anhydrosis= no sweat Dilation of the blood vessels so redness and increased temperature in the face
What do Parasympathetic innervation do in the eye
Sphinctor muscle
ciliary muscle
What do sympathetic innervation do in the eye
DIlator pupillae
superior and inferior tarsal muscles
What does seensory innervation do in the eye
Choroid
iris
Cornea
Lesions to the trochlear nerve
Trochlear palsy
headtilts away from the affected side to compensate for the laterally rotated eye
Diplopia on downward gaze
Lesions to the Abducens nerve
Abducens palsy
Cannot look laterally with the affected eye
cannot ABduct the eye
Lesion to the oculomotor nerve
Oculomotor palsy
Down and out eye: due to ocular muscle innervation only leaving Superior oblique and Lateral rectus intact
Complete ptosis: loss of innervation to levator palpebrae superioris
Pupil dilation:
Loss of parasympathetic innervation to the pupil
What are the 4 neurons in the pathway for the pupilary light reflex
1) Light sensed by CN II and will synapse on the pretectal nucleus
2) Cells from pretectal nucleus will synapse in edinger-westphal nucleus (bi-laterally)
3) Preganglionic parasympathetic neurons will travel with CN III and will synapse in the cilary ganglion
4) Postganglionic parasympathetic neurons will synapse in the pupillary constrictor muscle
Optic Nerve = sensory
oculomotor = motor
What is the 3 neuron pathway of the coneal reflex
1) receptors in corneal will detect touch or irritation, travel in CN V1 and synapse in trigeminal sensory nucleus or spinal trigeminal nucleus
2) Cells from the trigeminal nuclei project to facial nucleus
3) neuron in facial nerve will cause eye to blink
Sensory= V1 Motor= CN VII
What are the 3 layers of the eye
Fibrous layer
Vascular Layer
Inner layer
What makes up the Fibrous layer
Sclera and the cornea
What makes up the vascular layer
Choroid
ciliary body
Iris
What makes up the inner layer
Retina
What is found in the middle of CN II
Central Retinal vein and Artery
this supplies the Retina
and is surrounded by meninges
What are the two conjunctiva and what do they do
Palpebral conjunctiva: lines the innermost part of the eyelids
Bulbar (ocular) cojunctiva: lines the outermost part of the eyeball
What innervates the superior tarsal muscle
Sympathetics to help open the eye
WHat are the two types of conjunctivitis
can be bacterial and viral
bacterial conjunctivits produces yellow discharge called pheum
viral conjunctivitis produces a watery secretion
Subconjunctival hemorrhage
this is a bleed between the sclera and the bulba conjunctival
this can be caused from a blood vessel popping due to too much pressure
Complete PTOSIS
Loss of the Levator Palpebrae superioris
caused by destruction of Oculomotor CN III pr one of its branches to the Levator Palpebrae superioris muscle
Partial PTOSIS
Loss of the Tarsal muscle (of Muller)
innervated by Postganglionic sympathetic fibers that originate at the level of T1
Horners syndrome usually involves loss of this muscle
Papilledema
Cause: is increased intracranial pressure (ICP)
Emergent: need to find the cause of the increased ICP
can detect by seeing the optic disk in the back of the eye when looking into the eye
What is the macula and the fovea
Macula: center of vision
Fovea: an area of the macula most concentrated by cones
optic disk: is your blind spot
what are the arteries of the eye
Ophthalmic artery coming off of internal carotid artery gives rise to: short posterior ciliary artery long posterior ciliary artery Supratrochlear Artery Supraorbital A Ethmodial Arteries Lacrimal A
Lacrimal artery will give rise:
anterior ciliary artery
also in Optic Nerve is the central retinal A
Anastamoses with nerves in the eye
and the significance of them
Supratrochlear A = Angular A
Supraorbital A = superfical temporal A
Lacrimal A = Middle meningeal A
since it is important to get the eue blood and to central retinal A
therefore if their is a slow occulusion blood can find a way to central retinal A
if there is a fast occlusion you will go blind because cant enough blood to the eye
What is the venous drainage of the eye
Will go back through superior ophthalmic V to cavernous sinus
Inferior Ophthalmic to pterygoid venous plexus
Angular Verin to facial V
Central Retinal Vein Occulusion
looks like ketchup on the back of the eye
cause: hardening of the central retinal artery and hypertension in the CRA can compress the CRV
Hemorrhages
dilated veins
Central Retinal Artery Occlusion
Pale and red spot
caused by atherosclerosis, embolisms
Retina appears white
cherry red spot since the choroid is still getting blood supply
Veins and arteries attenuated
WHat is the pathway of the tear through the eye
goes from the lacrimal gland which is lateral of the eye
then it will cross the eye medially
then the Lacrimal canaliculi will wick the eyes into the lacrimal duct
the tears will then travel down the nasolacrimal duct into the inferior Nasal meatus
Why does blinking help clear tears
The lacrimal part of the orbicularis oculi muscle kis attached to the lacrimal sac so blinking will help widen the opening of the lacrimal sac
What is the route of parasympathetics from the brain to the lacrimal gland
Leave the superior salivatory nucleus as Facial Nerve
travel through the internal auditory foramen
through the hiatus for the greater pertrosal nerve as the greater petrosal Nerve
Meets up with deep petrosal Nerve and becomes the Nerve of the pterygoid canal and will enter the pterygoid canal
then will reach the pterygopalatine ganglion and synaspse their
Then the postganglionic parasympathetic fibers will travel on V2 the zygomatic branch
then will jump on a communicating branch
then will join on to the lacrimal Nerve of V1 and will reach the lacrimal Gland
What are the two chambers of the eye
Anterior chamber: space between the cornea and the ris/pupil
Posterior chamber: Space between the iris/pupil and the lens and ciliary body
What is the ciliary body
the circumferential tissue inside the eye composed of the ciliary muscle and ciliary processes
What is the ciliary process
secretes the aqueous humor which fills the anterior and posterior chambers
What is the flow of the Aqueous humor
1) ciliary process from the ciliary body
2) goes from the posterior chamber to the anterior chamber
3) into the scleral venous sinus (Schlemms Canal)
What happens if the schlemms canal is blocked
this can lead to increased pressure and glaucoma
What is hyphema
Rupture of an artery in the anterior chamber that causes it to fill up with blood
Ciliary body and the impact on the lense
Contraction of ciliary muscles decreases the size of the ciliary body
this reduces tension on suspensory ligament of lens
the lens then becomes more rounded to aid in near vision
aids in accomadation
