Eye. and Eye movements Flashcards
what are the bones in the bony. orbit
- Frontal bone
- Sphenoidal bone
- Zygomatic bone
- Maxillary bone
- Ethmoid bone
- Lacrimal bone
The optic canal carries
- optic nerve (CN II)
2. opthalmic artery.
superior orbital fissure carries
CN III, IV, V1, 6,
ophthalmic veins.
inferior orbital fissure
maxillary nerve (as it changes into infraorbital N), infraorbital artery, zygomatic nerve (branch of V2)
Sinus and location
- Frontal sinus: superior and medial to the orbit
- Ethmoid sinus: medial to orbit
- Maxillary sinus: inferior to orbit
- Sphenoid sinus: medial to orbit, but posterior
what is a blow out fracture and what. bone is usually “blown out”?
the medial and inferior walls of the orbit are THIN AS FUCC.
a punch to the eye can cause things to prolapse through the broken maxillary bone (inferior wall) and protrude into the maxillary sinus. this can also send blood into the ethmoid sinus, located behind the zygomatic bone.
blow out fracture can cause what
diplopia (eyes not lining up)
globe ptosis (eyeball fall thru sinus)
exopthalmos (protrusion of eyeball)
What does the LPS do?
lift up eyelids
what. is the position of our eyeballs?
medial walls of orbit are parallel, however, the lateral walls are approximately at a right angle.
thus, the axes of the orbit diverge at 45 degrees, while the optical axes (axis of gaze) are parell
what are the movement of the pupil and what. is their axis
abduction, adduction in vertical axis.
Elevate or depress. in horizontal axis.
Intorsion (medial rotation) or extorsion (lateral rotation) in the AP axis
Levator palpebrae M.
Action:
I:
Levator palpebrae opens the EYELID and is innervated by oculomotor (CN III).
Medial rectus M.
I
Oculomotor N (CNIII)
lateral rectus M.
I
Abducens (CNVI)
superior rectus m
action
I
look up and medially Oculomotor N (CNIII)
inferior rectus m
action
I
look down and medially Oculomotor N (CNIII)
Superior oblique M.
action
I:
down and out and intorsion (medially rotate)
Trochlear N (CNIV)
inferior oblique m.
action
I:
Up and out and lateral rotates (extortion)
Oculomotor N
The obliques are abductors (LOOK OUT) due to their
insertion on the posterior surface of the eye.
what m muscles help us look to the left
Lateral rectus of left eye
Medial rectus of right eye
what m help us look straight down
superior oblique and inferior rectus both eyes
what muscles help us look straigt up
superior rectus and inferior oblique of both eyes
what m help us look to your left upper corner
L eye: inferior oblique
R: superior rectus
can m perform function when visual gaze is perpendicular. to the direction of the m fiber
no. they are trapped
how. do we. test. superior rectus m?
look up. and out
how do we test inferior oblique
look up and in
how do we test super oblique
look down and in
YOU ARE. JUST Changing THE LAST PART:
M WILL CONTINUE TO MOVE UP AND DOWN AS BEFORE
How to test lateral rectus
look out
what are the branches of CN V1: ophthalmic N
- Lacrimal N
- Frontal N.
Supratrochlear N
Supraorbital N - Nasociliary
A. Infratrochlear N (not on list)
B. Long ciliary N (NOL)
C. Anterior ethmoidal N (NOL)
D. Posterior ethmoidal N
E. Sensory root of the ciliary ganglion
Also associated with the visceral motor
component of the oculomotor nerve. Short ciliary N will then come off ciliary ganglion
What does the short ciliary N do?
- afferent fibers to cornea
2. parasympathetics to the iris and ciliary body
Lacrimal gland innervations
Lacrimal N does GENERAL sensation to the lacrimal gland.
Facial N: parasympathetics
Innvervation to the extra ocular m is done by?
- Oculomotor (CN3)
- Trochlear (CN4)
- Abducens (CN6)
path of oculomotor N
Comes from the midbrain and carries parasympathetic fibers.
Travels next to the diaphragma sellae in the cavernous sinus before it travels through the superior orbital fissure.
path of trochlear N
Comes out from the midbrain as well, but on the dorsal aspect - causing it to have a really long cranial path.
This enters the dura near the tentorium cerebelli.
Also goes lateral to cavernous sinus and the superior orbital fissure.
Trochlear nerve innervates SO m.
Path of abducens
- Nucleus: in pons.
- Leaves pontine medullary junction
- Enters the dura near the clivus, then runs THROUGH the cavernous sinus next to the internal carotid artery.
- superior orbital fissure.
Branches of oculomotor N
- Superior division of the oculomotor N: innervates LPS, SR
2. Inferior division of oculomotor N: innervates IO, IR, MR
What does NOT go through the common tendinous ring?
- Frontal N. (CN V1)
- Lacrimal N (CN V1)
- Trochlear N (CN 4)
4 and 5 STAY OUTSIDE
What structures can get compressed if issue with common tendinous ring?
The following run in it:
- Optic N (CN II)
- Superior division of oculomotor N. (CNIII)
- Inferior division of oculomotor N. (CNIII)
- Abducens N (CN 6)
- Nasociliary N
They also go in the superior orbital tissue
Which cranial nerve comes out dorsally from the midbrain?
trochlear
What cranial nerve carries parasympathetics for tear production?
facial (via greater petrosal)
Parasympathetics to the eye run with what nerve?
Sympathetics to the eye run with what nerve?
Parasympathetics: Oculomotor nerve
Sympathetics:
1. Come from T1-T4 -> synapse in. the superior cervical chain ganglion -> internal carotid plexus -> Nasociliary nerve (from the ophthalamic branch of the trigeminal N) -> goes to LPS (skeletal muscle to open eye and innervated by oculomotor N) -> innervates TARSUS M (smooth muscle to keep eye open) and dilator papillae.
how do we keep our eyes open?
- Come from T1-T4 -> synapse in. the superior cervical chain ganglion -> internal carotid plexus -> Nasociliary nerve (from the ophthalamic branch of the trigeminal N) -> goes to LPS (skeletal muscle to open eye and innervated by oculomotor N) -> innervates TARSUS M (smooth muscle to keep eye open) and dilator papillae.
Parasympathetics to the eye path
Parasympathetics come from the root of the oculomotor nerve, and synapse in the ciliary ganglion.
Then they travel with the short ciliary nerves to reach the sphincter pupillae and the ciliary m.
__________ from the eye travel with the nasociliary nerve to get back to the sensory root of the trigeminal N.
general somatic afferent fibers
abducens palsy
Abducens is an abductor. Notice the patient’s left eye cannot abduct.
Trochlear palsy
LO:
AXN:
Loss of SO
Action of eye: down, out and intorsion
Result: extorsion, up and in (medial), head will tilt away from affected site to compensate
oculomotor palsy can be caused by?
- Tumors of midbrain
- Aneurysms of
posterior cerebral,
posterior communicating, and
posterior cerebellar
oculomotor palsy sx
- Eye is down and out d/t SO and LR still being intact.
- Complete ptosis d/t loss of interaction of LPS
- Pupil is dilated d/t loss of parasympathetic innervation to pupil.
Also recall that parasympathetics to the ________ travel with the oculomotor nerve.
ciliary body
What is the FIRST thing to be lost in oculomotor palsy?
The parasympathetic division is usually the first to be lost, resulting in mydriasis in the early stages of palsy.
horners syndrome
- Ptosis (drooping of superior eyelid)
- Anhydrosis (no sweating)
- Miosis (constriction of pupil)
- Vasodilation (redness and increased temp of skin)
pupillary light reflex requires what CN
2 (to see) and 3 (to constrict)
how does pupillary light reflex twerk
- CNII senses light; will synapse in pretectal nucleus
- Sends signals to Edinger-Westphal
- Preganglionic parasympathetic neurons will travel with CN III and synapse in the ciliary. ganglion
- Short ciliary n (postganglionic parasympathetic nerve fibers) then activate the pupillary constrictor muscle.
diff between direct and consensual pupillary. reflex
direct: affected eye constricts
Consensual: opp will constrict at. the same time
What CN does the corneal reflex need?
- Parasympathetics (CN 5/trigeminal) to feel it
2. Sympathetics (CN 7/facial) to close eye
how does corneal. light reflex twerk
- When receptors in cornea detect touch - travel in CN V (trigeminal) -> synapse of trigeminal sensory nucleus
- cells from trigeminel nuclei -> synapse with the facial nucleus.
- Neuron in facial nerve will innervate -> orbicularis oculi (ocular and palpebral parts) -> EyE BLINKS!
eye has
fibrous
vascular and
inner layer
what are the components of each
Fibrous (sclera and cornea)
Vascular (choroid, ciliary body, iris)
Inner layer (retina)
the OPTIC nerve is covered with what?
ALL THREE MENINGEAL LAYERS
What is found WITHIN the optic nerve?
- Central retinal A
2. Central retinal V
Tarsal m. is innervated by ____ and does what?
sympathetics
keeps eye open
Orbicularis oculi M
I:
Axn:
I: CN 7
Axn: gently. closes eyelid
_______ can cause subconjunctival hemorrhage, BELOW BULBAR LEVEL OF CONJUNCTIVA AND SCLERA
valsalva maneuvers (coughing, committing)
What is complete PTOSIS is d.t
d/t damage of CN3
destruction of CN3 or one of the branches -> paralysis of LPS -> cannot open eye
Partial ptosis
Partial ptosis is due to damage of the sympathetics (tarsal muscle) such as in Horner Syndrome:
INNERVATED BY POSTGANGLIONIC SYMPATHETICS
What is papilledema
increase pressure on optic nerve -> increases in cranial pressure (ICP) -> bulging optic disk.
What is the MAIN arterial supply. of the eye?
Ophthalmic a from the ICA
The eye STILL WERKS if there are SLOW occlusions. how?
has a shit ton of anastomoses.
- Ethmoidal arteries ↔ Sphenopalatine As
- Supratrochlear A ↔ Angular A (Facial)
- Supraorbital A ↔ Superficial temporal A. (Facial)
The eye STILL WERKS if there are SLOW occlusions. how?
has a shit ton of anastomoses.
- Ethmoidal arteries ↔ Sphenopalatine As
- Supratrochlear A ↔ Angular A (Facial)
- Supraorbital A ↔ Superficial temporal A. (external carotid)
SUDDEN occasion of ophthalmic A. what happens
blind
Why is the central retinal artery so important?
Because it is the only artery to the retina, and if it is occluded, you will end up blind.
What sorts of things can cause central retinal vein occlusion?
Hardening or hypertension of the central retinal artery.
Increased intracranial pressure.
What are the causes discussed for a central retinal artery occlusion?
Atherosclerosis or embolism.
What are the causes discussed for a central retinal artery occlusion?
Atherosclerosis
embolism.
what does CRA occlusion look like
pale and red spot
retina looks white
cherry red spot
how can infections from face go to cavernous sinus?
Supraorbital vein and infraorbital vein drain to cavernous sinus AND pterygoid plexus > INFECTIONS TO face
Will damage to the lacrimal nerve cause an inability to produce tears?
Damage to the lacrimal nerve will only lose tears if it happens near to the lacrimal gland - after the communicating branch attaches.
SO if we lesion anything trigeminal: no.
Describe the flow of tears from start to finish.
CN 7 via greater petrosal: Lacrimal gland -> eye -> lacrimal canaliculus -> lacrimal sac -> nasolacrimal duct -> inferior meatus of nose (reason why nose waters when we cry
describe tear production
- Facial nerve arises off the brainstem.
- Enters the internal acoustic meatus with CN VIII.
- Gives off muscular branch.
- Joins tympanic plexus.
- Gives off a branch called the greater petrosal nerve.
- Greater petrosal nerve comes out of the hiatus for the greater petrosal nerve.
- Runs along the foramen lacerum and meets up with the deep petrosal nerve, forming the N. of the pterygoid canal.
- Dives under the sphenoid bone and travels thur
- comes our of pterygopalatine fossa
Joins the pterygopalatine ganglion and synapses.
10 Hops onto the zygomatic branch of V2 (maxillary branch of the trigeminal nerve) which runs in the inferior orbital fissure. - Sends a communicating branch to the lacrimal branch of V1.
12 Travels to and joins the lacrimal gland in the superolateral area of the orbit.
What cranial nerve carries parasympathetics for tear production?
Facial nerve.
Via greater petrosal.
what is the ciliary. body>
ring of tissue inside eye made up of ciliary muscles and ciliary processes
what. is ciliary rocesses
secrete. aqueous humor, which fills anterior and posterior chamber
what. is ciliary processes
secrete. aqueous humor, which fills anterior and posterior chamber
what is poster chamber
space between iris and lens/CB
Describe the flow of aqueous humor in the eye.
The ciliary process creates the aqueous humor into the posterior chamber, and it flows into the anterior chamber. From there it flows into a structure called the scleral venous sinus to drain (Schlemm’s Canal).
what happens if we block schemes canal (scleral venous sinus)
glaucoma
what is hyphema
rupture of BS in anterior chamber d/t trauma or direct hit in orbit
rupture of BS in anterior chamber d/t trauma or direct hit in orbit
what is this
hyphema
le forte fracture 1
horizontal maxillary fx separating the teeth from upper face
A Le Fort fracture of the skull is a classic transfacial fracture of the midface, involving the maxillary bone and surrounding structures in either a horizontal, pyramidal or transverse direction.
le forte fracture 1
horizontal maxillary fx separating the teeth from upper face
palate
le forte fracture II
pyramidal fx with the teeth at the pyramid base and nasofrontal suture at the apex.
nose and palate
Le forte fraction III
craniofacial disjuntion
entire face
