Ocular: Orbital And Ocular Innervation I Flashcards
Superior division of the oculomotor nerve motor innervation:
-superior rectus
-lavatory palpabrae superioris
Inferior division of oculomotor nerve motor innervation:
-medial rectus
-inferior rectus
-inferior oblique
Trochlear nerve motor innervation:
Superior oblique
Abducent nerve motor innervation:
-lateral rectus
Facial nerve motor innervation:
-orbicularis oculi
-frontalis
-corrugator
-procerus
Optic nerve sensory innervation:
-transmits visual information (sight)
Ophthalmic nerve sensory innervation:
-globe
-superior eyelid
-medial regions of both eyelids
Maxillary nerve sensory innervation:
-lower eyelid
At the level of superior colliculus in the midbrain:
Oculomotor nucleus
At the level of the inferior colliculus in the midbrain:
Trochlear nucleus
Both oculomotor nucleus and Trochlear nucleus are located..
Ventral to cerebral aqueduct
Pons contains the:
Abducens, facial, and vestibular nuclei
Medial longitudinal fasciculus (MLF):
-myelinated tract enabling nerve fibers to cross over
-connects nuclei on each midline side
Central caudal nucleus (CCN):
-single, centrally located
-controls both lavator palpebrae muscles
Lesions at the brain stem are rare. True or false?
True
Edinger-Westphal nuclei (EWN):
-parasympathetic
-on each side of midline of oculomotor nucleus complex
-controls ciliary muscle and pupillary sphincter
Where does superior rectus sit in oculomotor nucleus complex?
Caudal/medial
Where does medial rectus sit in oculomotor nucleus complex?
3 different locations centrally
Where does inferior rectus sit in oculomotor nucleus complex?
Towards upper border
Where does inferior oblique subnuclei sit in oculomotor nucleus complex?
Between other nuclei
What fibers from oculomotor nucleus continue ipsilateral?
Inferior rectus, medial rectus, inferior oblique
What fibers decussate and continue contralateral from oculomotor nucleus complex?
Superior rectus sub nuclei
Both levator palpebrae muscles come from a ____________________in oculomotor nucleus complex
Single sub nucleus
CN 3 palsy:
-nerve damage including ischemia and compression (aneurysm)
-parasympathetic fibers from EWN travel peripherally relative to oculomotor fibers
-microvascular supply is more rich towards the surface (more superficial)
Ischemic etiology in CN 3 palsy are less likely to affect..
parasympathetic pupillary fibers
Aneurysm in CN 3 palsy affects…
Both fibers, sympathetic and parasympathetic
Main feature of CN 3 palsy in patients
One eye of pt goes down and out
Clinical features of CN 3 palsy:
-ptosis
-EOM deviation
-compressive causes fixed dilated pupil
-diplopia
Trochlear nucleus is located at…
The midbrain at the level of inferior colliculus
Trochlear nucleus is located:
-Anterior to cerebral aqueduct
-dorsal to medial longitudinal fasiculus
-inferior to oculomotor nucleus
CN IV palsy:
-nerve damage including ischemia as well as compression
-motor fibers only!
CN 4 is the only cranial nerve that emerges from…
Dorsal aspect of the brainstem
CN 4 supplies the ________________ side as it decussates
Contralateral
CN 4 is responsible for what movements of the eye?
Intorsion, depression, and abduction
Which nerve have the longest intracranial course?
Trochlear nerve
Clinical features of CN 4 palsy:
-torticollis (abnormal head posture)
-facial asymmetry
-strabismus (hypertropia, excyclotorsion, esotropia)
-diplopia
Why does torticollis occur in CN 4 palsy
To compensate for the diplopia, pt may adopt head tilt and face turn to opposite side
Abducens nuclei are located…
In the pons, lateral to the medial longitudinal fasciculus
What nerve arcs around Abducens nerve?
Facial nerve (so damage here can affect both facial and Abducens nerve)
CN 6 supplies the…
Ipsilateral lateral rectus
CN 6 palsy
-inability to abduct the eye leading to horizontal diplopia and eye sitting inward
-increased intracranial pressure
Increased intracranial pressure can cause…
Downward herniation of the brainstem that can compress the nerve as it course over petrous ridge
Cavernous sinus is located posterior to the…
Superior orbital fissure
What courses through the cavernous sinus?
-CN 3, 4, and 6
-V1 and V2
CN 2 travels superior to ____________________
Pituitary gland (above where nasal fibers decussate)
How would CN 6 be the first nerve affected by an internal carotid artery aneurysm?
Located the closest to the internal carotid artery within the cavernous sinus
Carotid-cavernous fistula (CCF)
-Abnormal connection between the carotid artery and/or its branches with the cavernous sinus
-can be direct (high-flow) or spontaneous (indirect/low flow)
Symptoms of CCF:
-chemosis
-pulsatile proptosis
-ocular bruit (blood flow sounds coming from eye)
Cavernous sinus receives venous blood from the…
Brain, orbit, and pituitary gland
