Cranial Nerves And Of The Eye And Orbit Flashcards
What are the CN that innervate the eye and ocular structures?
CNII: optic CNIII: oculomotor CNIV: trochlear CNV: trigeminal: ophthalmic CN V: trigeminal: max CNVI: abducens CNVII: facial
Afferent pathway
Orbital sensory innervation
Away from target organ
Sensations that affect eye
Pain, touch, reassure, warmth, cold,
Sensations from the cornea, iris, conj, and sclera consist of primarily ____
Pain
Light touch of the cornea
Registered as irritation or pain
The fibers of the trigeminal nerve serving the ocular structures are _____ and originate in the innervated structures
Sensory
What is the first branch of the trigeminal nerve
Ophthalmic branch
What is the first branch of the ophthalmic nerve
Nasociliary N
Sensory fibers form the structures of the medial canthal area-caruncle, canaliculi, lacrimal sac, medial aspect of the eyelids, and skin at the side of the nose-join to form
Infratrochlear nerve
The infratrochlear nerve penetrates the orbital septum and enters the orbit where
Below the trochlea
Where does the infratrochlear nerve run before it joins the next branch
Along the upper border of the medial rectus muscle
Where does the infratrochlear nerve become the nasociliary nerve?
As it runs across the upper border of the medial rectus muscle and other branches join it
Sensory fibers from the skin along the center of the nose, the nasal mucosa, and the ethmoid sinuses form the _______
Anterior ethmoid nerve
Fibers from the ethmoid sinuses and the sphenoid sinus form the _____
Posterior ethmoid nerve
Where do the ethmoid N enter the orbit and with what
With their companion arteries through the foramina within the frontoethmoid suture
Both ethmoid nerves join the _____ as it runs along the medial aspect of the orbit
Nasociliary nerve
Corneal sensory innervation is estimated to be _____ times as dense as other epithelial tissue innervation
4oo times
Where is the corneas sensory innervation?
In the epithelium, anterior stroma, and mid stroma. None in posterior stroma, Decemets membrane or endothelium
How do the long ciliary nerves course?
Between the choroid and sclera to the back of the eye where they leave the globe at points appx 3mm on each side of the optic nerve
What makes up the nasociliary nerve
- Infratrochelar
- Anterior and posterior ethmoid
- long ciliary nerve
How do the short ciliary nerves run to the back of the eye where they emerge?
From limbus of cornea, join other sensory nerves from ant set, enter choroid, join choroidal nerves, course to back of eye, leave as 6-10 short ciliary nerves
Where do the short ciliary nerves exit the sclera
In a ring around the optic nerve in company with the short post ciliary arteries.
After the short ciliary nerve leaves the back of the eye, what is the next structure that it PASSES THROUGH?
Ciliary ganglion, does not synapse here!
After the short ciliary nerves leave the ciliary ganglion, what do they join
Nasociliary nerves
What kind of fibers does the short ciliary nerve carry?
Symp and parasympathetic in addition to sensory
Structures that exit the posterior of the eyeball
- vortex veins (4)
- long ciliary arteries (2)
- long ciliary nerves (2)
- short ciliary arteries (many)
- short ciliary nerves (many)
The nasociliary nerve is formed by the joining of..
- infratrochlear nerve
- anterior and posterior ethmoid nerves
- long ciliary nerves
- sensory root of ciliary ganglion
How does the nasociliary nerve exit the orbit?
Passing through the oculomotor foramen WITHIN the common tendinous ring, and the superior orbital fissure into the cranial cavity
Does the nasociliary nerve run inside or outside the common tendinous ring?
Inside
____ of all cases of herpes zoster (shingles) will affect the ophthalmic division of trigeminal.
10%
What indicates that the nasociliary nerve has been affected by herpes zoster via the infratrochlear nerve?
Rash on the side or tip of the nose
Why is the cornea almost always affected in herpes zoster that presents with rash on side or tip of nose?
Nasociliary nerve is affected via the infratrochlear nerve, thus the corneal will effected by way of the short/long ciliary nerves coming off of the nasociliary
What is the rash on the side/tip of nose called in herpes zoster (shingles)
Hutchinsons sign
Sensory fibers from the skin and muscles of the forehead and upper eyelid come together and form the
Supratrochlear nerve
How does the supratrochlear nerve enter the orbit
By piercing the superior medial corner of the orbital septum
Sensory fibers from the skin and muscles of the forehead and upper eyelid form a second nerve called the
Supraorbital nerve
How is the supraorbital nerve in relation to the supratrochlear nerve
Lateral
How does the supraorbital nerve enter the orbit
As one or two branches
-one branch enters through the supraorbital notch, accompanying the supraorbital artery
Where does the supraorbital nerve join the supratrochlear nerve and what does it form at that point?
Midway in the orbit , forms frontal nerve
How does the frontal nerve course?
Back through the orbit between the levator muscle and the periorbita
How does the frontal nerve exit the orbit
Through the superior orbital fissure above the common tendinous ring
Is the frontal nerve inside or outside the common tendinous ring?
Outside
What is the 3rd branch of the ophthlamic division of trigeminal
Lacrimal nerve
Sensory fibers from lateral aspect of the upper eyelid and temple area come together and enter the lacrimal gland. They join the sensory fibers hat serve the gland itself to form the
Lacrimal nerve
How does the lacrimal nerve leave the gland and run in the orbit?
Runs posteriorly along the upper border of the lateral rectus muscle where it receives a branch from the zygomatic nerve containing autonomic innervation from the lacrimal gland
Where does the lacrimal nerve exit the orbit?
Through the superior orbital fissure above the muscle cone
What is the most important sensory nerve of the orbit?
Ophthalmic nerve
After exiting the orbit, the nasociliary nerve, lacrimal nerve, and frontal nerve join and form the
Ophthalmic division of the trigeminal nerve
After all of the nerves come together to form the ophthlamic nerve, where does it go?
Enters the lateral wall of the cavernous sinus where it receives sensory fibers from the oculomotor, trochlear, and abducens
The infraorbital nerve, formed by the sensory fibers from the cheek, upper, and lower eyelid enters the maxillary bone though the
Infraorbital foramen
How does the infraorbital nerve run through the maxillary bone?
It runs posteriorly through the infraorbital canal and groove; while it is isn the maxillary bone, branches join it from the upper teeth and maxillary sinus
As the infraorbital nerve leaves the infraorbital groove it exits the orbit through the _____________
Inferior orbital fissure
After the infraorbital nerve passes through the inferior orbital fissure what happens
Joins other fibers in forming the maxillary nerve
Sensory fibers from the lateral aspect of the forehead enter the orbit through a foramen in the zygomatic bone as the ____________
Zygomaticotemporal nerve
Fibers from the lateral aspect of the cheeks and lower eyelid enter the orbit through a Forman in the zygomatic bone as the __________
Zygomaticofacial nerve
What do the zygomaticotemporal and zygomaticofacial nerve join to become?
Zygomatic nerve
How does the zygomatic nerve course?
Courses along the lateral orbital wall
How does the zygomatic nerve exit the orbit?
Through the inferior orbital fissure and joint with the maxillary nerve
The maxillary nerve traverses the area between the __________
Maxilla and the sphenoid bone
As the maxillary nerve passes near the pterygopalatine fossa, it receives ____
Some autonomic fibers from the pterygopalatine fibers from the pterygopalatine ganglion
Where are the autonomic fibers from the pterygopalatine fossa that run through the maxillary nerve destined?
Lacrimal gland
How does the maximally nerve enter the skull
Through the foramen rotundum
What is the most superior nerve in the cavernous sinus
Oculomotor
What is the most inferior nerve in the cavernous sinus
Maxillary
What is the most medial nerve in the cavernous sinus
Abducens
Order of the CN from superior to inferior in the cavernous sinus
Oculomotor Trochlear Abducens (medial) Ophthalmic Maxillary
What artery runs through the cavernous sinus
Internal carotid
Cranial nerves that supply striated muscles of the orbit and adnexa
Oculomotor
Trochlear
Abducens
Facial
How does the oculomotor nerve run in the cavernous sinus
Pierces the roof of the cavernous sinus and runs within the two dural layers of the its lateral wall above the trochlear nerve
While in the cavernous sinus, the oculomotor nerve sends __________ to the ophthalmic nerve
Small sensory branches
Where does the oculomotor nerve enter the orbit?
Through the superior orbital fissure, having divided into superior and inferior divisions
Where are both divisions of the oculomotor nerve located
Within the oculomotor foramen
How does the superior oculomotor branch run
Medically above the optic nerve
After coursing with the optic nerve, how does the superior division of oculomotor go?
Enters the superior rectus on its inferior surface
How does the superior oculomotor branch innervate the levator palpebrae superioris through the superior rectus?
Additional fibers either pierce the muscle or pass around its border to innervate the levator palpebrae superioris
How does the inferior branch of he oculomotor run in relationship to optic nerve
Runs below the optic nerve and divides into three branches
What does the first branch of the inferior oculomotor nerve do
Enters the medial rectus on its lateral side
What does the second branch of the inferior oculomotor nerve do
Enters the inferior rectus on its upper surface
What does the theirs branch of the inferior oculomotor nerve
Gives off parasympathetic fibers that form the parasympathetic root extending to the ciliary ganglion
How does the inferior oculomotor branch run after it gives off its three branches?
Runs along the lateral border of the inferior rectus, crossing it to enter the inferior oblique muscle near its midpoint
What kind of innervation is trochelar
Motor only
What does the trochlear nerve innervate?
Superior oblique muscle
The trochlear nerve and hte cavernous sinus
Enters the wall of the cavernous sinus and lies abtween the oculomotor nerve and the ophthalmic division of the trigeminal nerve
While in the cavernous sinus, what does the trochlear nerve do
Sends sensory fibers to the ophthalmic nerve
How does the trochelar nerve enter the orbit
Through the superior orbital fissure above the common tendinous ring OUTSIDE the muscle cone
How does the trochlear muscle run
With the frontal nerve to the medial side of the orbit above the levator and superior rectus muscles and enters the upper surface of the superior oblique muscle
Within the cavernous sinus, the abducens lies near the _____
Lateral wall of the internal carotid artery
How does the abducens nerve enter the orbit?
Through the superior orbital fissure WITHIN the common tendinous ring
What does the abducens nerve innervate
The lateral rectus muscle on the medial side
This gives motor supply to the frontalis, procerus, corregator, and orbicularis oculi muscles
The temporal and zygomatic branches of the facial nerve (upper two)
What are the roots of the facial nerve?
Large motor root that innervates the facial muscles and the smaller root contains sensory and parasympathetic fibers
What do the sensory fibers of the smaller root of the facial root carry?
Taste sensations from tongue
What do the parasympathetic fibers from the smaller root of the facial nerve do
Supple secretomotor fibers to various glands of the face including the lacrimal glands
