Eye & Eye Movements (Part 1) Flashcards
What bones make up the eye orbit?
Frontal Zygomatic Sphenoid (Greater Wing) Ethmoid Lacrimal Palatine Maxilla
What are the sinuses and their location in relation to the eye orbit?
Frontal Sinus – Superior and Medial
Ethmoid Sinus – Medial
Maxillary Sinus – Inferior and Medial
If there is an infection within the Ethmoid Sinus and it goes to the eye orbit, what can occur?
Optic Neuritis
***This is damage and swelling to the Optic N. (CN II). Ethmoid Sinus is very close to Optic Canal and thus the Optic N.!!!
An orbital ________ fracture is a fracture of the orbital walls usually caused by indirect trauma.
Blowout
In an orbital “blowout” fracture, the “blowout” usually occurs medially and inferiorly involving the _________ bone.
Maxillary
In an orbital “blowout” fracture, orbital contents may prolapse and become entrapped in which sinus?
Maxillary Sinus
What are symptoms of an orbital “blowout” fracture?
Diplopia
Globe Ptosis (eye sinking down into Maxillary Sinus)
Exophthalmos (protrusion of eyeball)
What passes through the Optic Canal?
CN II (Optic N.) Ophthalmic A.
The (LATERAL/MEDIAL) walls of the orbit are nearly parallel to each other, while the (LATERAL/MEDIAL) walls are approximately at right angles to each other.
Medial
Lateral
The orientation of the medial and lateral walls of the orbit cause the axes of the orbit to diverge at ______ and the optical axes (axes of gaze) to be _______.
45 degrees
Parallel
What are the movements of the eye around the three axes?
Vertical Axis – Abduction or Adduction
Horizontal Axis – Elevation or Depression
AP Axis – Intorsion (Medial Rotation) or Extorsion (Lateral Rotation
What nerve opens the eye, and what nerve closes it?
Opens Eye = Facial N. (CN VII) – via Orbicularis Oculi M.
Closes Eye = Oculomotor N. (CN III) – via Levator Palpebrae Superioris M.
***Specifically, it is the Superior branch of CN III
What muscle elevates the eyelid?
Levator Palpebrae Superioris
What is the origin and insertion for the Levator Palpebrae Superioris?
Origin – Lesser Wing of Sphenoid
Insertion – Superior Tarsus and skin of eyelid
What passes through the Inferior Orbital Fissure?
Maxillary N. as it transitions to Infraorbital N.
Zygomatic N.
T/F. The muscles of the eye are oriented based on the Orbital Axis, not the Optical Axis.
True
This muscle is located just inferiorly to Levator Palpebrae Superioris.
Superior Rectus
This muscle is located superiorly and goes through trochlea, which changes the direction of its muscle fibers.
Superior Oblique
This muscle is located inferiorly and attaches anteriorly to posteriorly on the eye.
Inferior Oblique
What are the movements of the Superior Rectus on the horizontal axis?
Elevate eye
What are the movements of the Inferior Rectus on the horizontal axis?
Depress eye
What are the movements of the Superior Rectus on the vertical axis?
Adduct eye
***Because it lies medial to the vertical axis, so it pulls inward
What are the movements of the Inferior Rectus on the vertical axis?
Adduct eye
***Because it lies medial to the vertical axis, so it pulls inward
What are the movements of the Superior Rectus on the AP axis?
Intorsion (medially rotate) eye
What are the movements of the Inferior Rectus on the AP axis?
Extorsion (laterally rotate) eye
What is the innervation of the Levator Palpebrae Superioris M.?
Superior branch of Oculomotor N. (CN III)
The actions of this muscle include eye abduction, depression, and medial rotation.
Superior Oblique
***Depresses the eye because it attaches below the horizontal axis
What is the origin and insertion of the Superior Oblique?
Origin – Body of sphenoid
Insertion – Tendon passes through trochlea, changes direction, and inserts onto sclera deep to Superior Rectus
What is the innervation of the Superior Oblique?
Trochlear N. (CN IV)
The actions of this muscle include eye abduction, elevation, and lateral rotation.
Inferior Oblique
***Elevates the eye because it attaches above the horizontal axis
What is the origin and insertion of the Inferior Oblique?
Origin – Anterior part of floor of orbit
Insertion – Sclera deep to Lateral Rectus
What innervates the Inferior Oblique?
Oculomotor N. (CN III)
The actions of this muscle include eye adduction, elevation, and medial rotation.
Superior Rectus
Which muscles share the origin of common tendinous ring, and insertion of the sclera just posterior to corneoscleral junction?
Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus
The actions of this muscle include eye adduction, depression, and lateral rotation.
Inferior Rectus
The actions of this muscle include eye adduction.
Medial Rectus
The actions of this muscle include eye abduction.
Lateral Rectus
What is the innervation of the Inferior Rectus?
Oculomotor N. (CN III)
What is the innervation of the Superior Rectus?
Oculomotor N. (CN III)
What is the innervation of the Medial Rectus?
Oculomotor N. (CN III)
What is the innervation of the Lateral Rectus?
Abducent N. (CN VI)
How are the Inferior Oblique and the Superior Rectus able to elevate the eye?
Their other actions are cancelled out –
SR = Adduction, Intorsion IO = Abduction, Extorsion
How are the Superior Oblique and the Inferior Rectus able to depress the eye?
Their other actions are cancelled out –
SO = Abduction, Intorsion IR = Adduction, Extorsion
Go over binocular movements and the muscles (Slide 12)!
Go over for 5 minutes
To test the Superior Rectus and Inferior Rectus, you have to (ADDUCT/ABDUCT) the eye.
Abduct
***Opposite of what their muscle action is, which is adduct!
To test the Superior Oblique and Inferior Oblique, you have to (ADDUCT/ABDUCT) the eye.
Adduct
***Opposite of what their muscle action is, which is abduct!
If I want to test elevation of the eye, how can I make sure I’m only testing the Superior Rectus or the Inferior Oblique separately?
You have to “trap” one of the two muscles by putting the eye into abduction or adduction. Muscles are trapped from performing their function when the visual gaze axis (optical axis) is perpendicular to the muscle fiber direction.
When the eye is abducted by the lateral rectus, only which muscles can produce elevation and depression?
Superior Rectus
Inferior Rectus
When the eye is adducted by the medial rectus, only which muscles can produce elevation and depression?
Superior Oblique
Inferior Oblique
When I’m testing the Superior Rectus, what muscle do I have to trap?
Inferior Oblique
***Have to abduct eye
When I’m testing the Inferior Oblique, what muscle do I have to trap?
Superior Rectus
***Have to adduct eye
When I’m testing the Inferior Rectus, what muscle do I have to trap?
Superior Oblique
***Have to abduct eye
When I’m testing the Superior Oblique, what muscle do I have to trap?
Inferior Rectus
***Have to adduct eye
This lies on the lateral side of the eye (not a muscle) and has sensory innervation by the Lacrimal N., which is a branch off CN V1 (Ophthalmic N.) and Zygomatic N. (from V2).
Lacrimal Gland
The Frontal N. branches off the Ophthalmic N. (V1) and branches into what?
Supratrochlear N.
Supraorbital N.
This nerve provides sensory innervation to the forehead and vertex. It exits the skull via the Supraorbital Foramen.
Supraorbital N.
This nerve branches off of the Ophthalmic N. (V1) and branches into Anterior and Posterior Ethmoidal Ns.
Nasociliary N.
These are branches off the Nasociliary N. that provide innervation to the nasal cavity and sinuses.
Anterior Ethmoidal N.
Posterior Ethmoidal N.
This branch off the Nasociliary N. will provide sensation to the cornea. Carrying sympathetics.
Long Ciliary Ns.
This comes out of the Ciliary Ganglion (from branch of V1), and is carrying sympathetics and parasympathetics. Also provides sensation to the cornea.
Short Ciliary Ns.
This nerve is motor and carries parasympathetics. It pierces the dura near the Diaphragm Sellae and comes through the Cavernous Sinus then the Superior Orbital Fissure.
Oculomotor N. (CN III)
This nerve is very susceptible to damage from falls or hitting your head. It pierces the dura near the Tentorium Cerebelli, then through Cavernous Sinus and the Superior Orbital Fissure.
Trochlear N. (CN IV)
This nerve pierces the dura near the clivus, and is also found in the Cavernous Sinus more central near the ICA. Exits via Superior Orbital Fissure.
Abducents N. (CN VI)
The Oculomotor N. (CN III) branches into a Superior branch and an Inferior branch. What do these branches innervate?
Superior branch = Superior Rectus and Levator Palpebrae Superioris
Inferior branch = Inferior Oblique, Inferior Rectus, and Medial Rectus
The rectus muscles of the eye create a tendinous ring that some nerves pass through. What are these nerves?
Oculomotor N. (Superior and Inferior branches)
Nasociliary N.
Abducent N.
Optic N.
What nerves that pass through the Superior Orbital Fissure do NOT go through the tendinous ring?
Frontal N.
Lacrimal N. (V1)
Trochlear N.
Describe the path of a pre-ganglionic sympathetic fiber.
Fiber begins in lateral horn of thoracic vertebrae (T1-T3/4) and exits via White Rami. From here it hooks onto the Sympathetic Trunk and travels up to the Superior Cervical Ganglion where it synapses with the post-ganglionic sympathetic fiber.
T/F. The Superior Cervical Ganglion is very close to the bifurcation of the Common Carotid A., so the post-ganglionic sympathetic fibers use the arteries as a highway to travel where they want to go (called Internal Carotid Plexus and External Carotid Plexus).
True
Where do the post-ganglion sympathetic fibers travel to via the External Carotid Plexus?
Salivary Glands – Make mucous saliva (dry mouth)
Sweat Glands – Make you sweat
Blood Vessels – Make them constrict
This is a sympathetic nerve that jumps off the Internal Carotid Plexus. It meets with the Greater Petrosal N., which is parasympathetic, and enters the Pterygoid Canal.
Deep Petrosal N.
When the Greater Petrosal N. (parasympathetic) and the Deep Petrosal N. (sympathetic) come together and enter the Pterygoid Canal, what nerve do they form?
N. of Pterygoid Canal
The N. of Pterygoid Canal will exit and reach the Pterygopalatine Ganglion. Here, the parasympathetic portion will synapse (Greater Petrosal N.) but the sympathetic portion will just travel straight through (Deep Petrosal N.) and go to…
Blood Vessels
What muscle opens the eyelid, and which one keeps the eyelid open?
Opens eyelid – Levator Palpebrae Superioris M.
Keeps open – Superior Tarsus M.
Some sympathetic fibers continue from the ICA up the Ophthalmic A. to get to the orbit. Some sympathetic roots will go through the Ciliary Ganglion (do NOT synapse there, it is parasympathetic) and continue on via Short Ciliary Ns. to what muscle?
Dilator Pupilae
Other sympathetic fibers will catch rides on the Nasociliary N. (V1) and Long Ciliary Ns. to the ________ ________, as well as along the Superior branch of Oculomotor N. to the ________ _________.
Dilator Pupilae
Superior Tarsus
What are the main functions of sympathetics on the eye orbit?
Dilate pupil
Aids in keeping eye elevated
This disease is caused by damage to the Sympathetic Trunk or the Superior Cervical Ganglion. This causes sympathetic responses to not be able to occur, and parasympathetics will take over. Symptoms include constricted pupils, ptosis, anhidrosis, and fleshing of the skin from dilated blood vessels.
Horner’s Syndrome
The parasympathetics traveling with Oculomotor N. are going to come off and synapse in the ________ Ganglion. From here they go out with the Short Ciliary Ns. and go to the pupillary constrictor.
Ciliary
What other fibers pass through the Ciliary Ganglion that do NOT synapse?
Sensory fibers
Sympathetic fibers
This is due to an injury to the Trochlear N. This nerve innervates the Superior Oblique, so without it the eye laterally rotates and the head will be tilted away from the lesion. Diplopia can occur, especially when depressing the eye.
Trochlear Palsy
***Superior Oblique usually medially rotates and depresses the eye!
This is the term for when patients cannot look laterally with the affected eye.
Abducents Palsy
This type of Oculomotor Palsy is caused by the loss of innervation to the ocular muscles, yet leaving Superior Oblique (CN IV) and Lateral Rectus (CN VI) intact.
Down and Out Eye
***Eye is going down (SO) and out (LR)
This type of Oculomotor Palsy is caused by the loss of innervation to the Levator Palpebrae Superioris muscle.
Complete Ptosis
***This muscle raises the eyelid!
This type of Oculomotor Palsy is caused by the loss of parasympathetic innervation to the pupil (parasympathetics traveled on Oculomotor to Ciliary Ganglion).
Pupil Dilation
ANY reflex has what two components?
Sensory
Motor
Describe the Pupillary Light Reflex.
1) Light sensed by CN II and will synapse in pretactal nucleus. (SENSORY PORTION)
2) Cells from pretactal nucleus will synapse in Edinger-Westphal nucleus.
3) Pre-ganglionic parasympathetic neurons will travels with CN III and will synapse in the Ciliary Ganglion. (MOTOR PORTION)
4) Post-ganglionic parasympathetic neurons will synapse in the pupillary constrictor muscle. (MOTOR PORTION)
***Remember, this is a 4 neuron arch pathway!
Describe the Corneal Reflex.
1) Receptors in cornea detect touch or irritation, travel in CN V (V1), and synapse in spinal Trigeminal nucleus. (SENSORY PORTION)
2) Cells from the Trigeminal nucleus project to the Facial nucleus.
3) Neurons in the Facial N. will cause eye to blink. (MOTOR PORTION)
***Remember, Facial N. closes eye and Oculomotor N. opens eye
