EOM innervation Flashcards
Yoke muscles definition
Equal and simultaneous innervation
Yoke muscle questions
Draw EOM diagram
EOMs muscle to nerve ratio
Low muscle fiber to nerve fiber ratio
Pupillary reflex route
Retinal gang cell- pretectal nucleus - ew - ciliary ganglion - short ciliary nerves - sphincter
Oculomots - parasympathetic
Mitosis
CNIII afferent fibers
Propioceptive
Nerves passing through SOF
Throchlear Lacrimal Frontal Abducen Inferior + sup oculomotor Nasociliary 7
Angela tiene la nariz fea, super intelligente obvio
How many oculomotor nucleus do we have
And where are they located
R and L
In the midbrain ( within gray matter that surrounds cerebral aqueduct, anterior to superior colliculus
Components of each CNIII nucleus
Oculomotor nuclear complex
Parasympathetic nucleus = EW
Input into CNIII nuclei includes
Cerebral cortex : motor and sensory
Midbrain nuclei: MLF ( CNIV, CNVI, CNVIII nuclei)
Pretectal nucleus
Supraoculomotor area
Cerebellum
CNIII input motor cortical regions
Voluntary horizontal gazes
Saccades
FEF
Pursuits
Occipitoparietal cortex
CNIII input sensory cortical region
Visual cortex for accommodation and visual reflexes ( superior colliculus)
Visual association areas
CNIII CN 4, 6, 8 nuclei input come via
MLF
CNIII pretectal nucleus input
Light reflex and vertical gazes
CNIII supraoculomotor area input
Acc reflex
Each oculomotor nucleus has
Medial subnucleus
3 lateral subnuclei
Medial subnucleus of oculomotor controls
Contralateral SR
3 lateral subnuclei of oculomotor nucleus controls
3 ipsilateral EOMS
IO, IR, MR
Parts of CNIII nucleus
Common central nucleus
Then each oculomotor nucleus (L and R ) - has 1 medial subnucleus, and 3 lateral subnuclei
EW receives
Corticonuclear fibers for accommodation
Pretectal fibers (midbrain) for pupillary reflexes
Where is EW located
Posterior to the main motor nucleus in the midbrain
Preganglionic fibers from EW path
Synapse in ciliary ganglion- enter short ciliary nerves - sphincter and ciliary muscle- pupil contraction/accommodation
Oculomotor nerve emerges from
Anterior aspect of midbrain medial to the cerebral peduncles and b/w posterior cerebral and superior cerebellar arteries
Oculomotor nerve passes through which arteries
Posterior cerebral and superior cerebellar arteries
Posterior cerebral artery
Superior cerebellar artery
CNIII nerve passes through
CNIII progresses anteriorly parallel to
Posterior communicating artery
Where does CNIII pierce the dura
At the level of the posterior chinoid process of the sphenoid bone and runs in the lateral wall of the cavernous sinus superiorly to CNIV
Where are the parasympathetic fibers of CNIII located
On the surface of the nerve and migrate down towards orbit
What’s incorporated into the oculomotor nerve as it progresses anteriorly
Sensory branch from ophthalmic
Sympathetic fibers from carotid plexus
When does the CNIII nerve divide into sup and inferior
When they enter the orbit through SOF/ inside annulus of Zin
Superior division of CNIII
SR and levator
Inferior division of CNIII
3 branches for Other CNIII muscles (except SR) MR,IR, IO
and parasympathetic fibers for Ciliary ganglion
Where is the nucleus of the trochlear nerve
Inferiorly to oculomotor nucleus at the level of inferior colliculus
Exit of SO4/ trochlear muscle
Leave in posterior direction and decussate before exiting the dorsal aspect of the midbrain
Where does the trochlear nerve pierce the dura
It goes around the cerebral peduncle and pierces the dura close to the posterior chinois process and enters cavernous sinus
Where does trochlear nerve pass through after going along the lateral wall of the cavernous sinus
Between CNIII superiorly and ophthalmic nerves inferiorly
How does the trochlear nerve enter the orbit
It becomes medial to oculomotor nerve and enter orbit through SOF above the tendinous ring
Where is the nucleus of abducens nerve located
In the pons beneath the floor of the 4th ventricle
Where does abducens nerve exit
Within the sulcus located between the pons and the medulla
Where does the abducens pierce the dura
Level of the dorsal of the sella truck a
How does CNVI enter the orbit
Through SOF between the inferior and superior divisions of CNIII (inside the oculomotor foramen
Most frequent CN palsy
CNVI
Least common CN palsy
CNIV
EOMs during Graves
Thyroid disease
Enlargement of EOM causes defective ocular motility and exothalmus
Proptosis
Palsies that cause head tilt
6 and 4
Do pts experience diplopia during CNIII palsies
Yes
What happens if pt with CNIII palsy try’s to look down
SO would cause it to move inward
What happens to pupil during CNIII palsy
Mydryasis
Opthalmoplegia
Paralysis or weakness of EOMS
External ophthalmoplegia
EOMS affected, ptosis
Internal ophthalmoplegia
Paresis of ciliary body and mydryasis
Nuclear lesion of CNIII
Involves contralateral superior rectus muscle
What happens when you look nasally with a CNIV palsy
Affected eye goes up
What does pt experience during CNIV palsy
Vertical diplopia
Fixed by tilting head to opposite side of the affected muscle
What happens to eye when we have CNVI palsy
Eye is turned inward
