Lopez- control of motor vision and visual reflexes Flashcards
spastic hemiparesis in R upper and lower limb; + babinski sign
right-sided lower facial weakness
forehead movement preserved
unable to stand or walk
Pupillary Reflex: Rt eye: normal direct reflex, no consensual pupillary response. Lt eye: no direct but normal right consensual pupillary response. No convergence is present
lesion in the midbrain
coordinated direction of both eyes to look at a specific point or follow a target
key function of oculomotor system
gaze
Refers to higher-level centers in the brain responsible for planning and initiating eye movements
supranuclear control of eye movements
Frontal Eye Fields (FEF)
Parietal Eye Fields (PEF)
Rostral Interstitial Nucleus of the Medial Longitudinal Fasciculus (riMLF)
Horizontal Gaze Center (Pontine)
supranuclear control of eye movements
Oculomotor Nucleus (CN III)
Trochlear Nucleus (CN IV)
Abducens Nucleus (CN VI)
Vestibular Nuclei
nuclear control of eye movements
Medial Rectus: Adduction (CN III).
Lateral Rectus: Abduction (CN VI).
Superior Rectus: Elevation (CN III).
Inferior Rectus: Depression (CN III).
Superior Oblique: Depression and intorsion (CN IV).
Inferior Oblique: Elevation and extorsion (CN III)
extraocular muscles for eye movements
adduction of eye and innervated by CN III
medial rectus
abduction of eye and innervated by CN VI
lateral rectus
elevation of eye and innervated by CN III
superior rectus
depression of eye and innervated by CN III
inferior rectus
depression and intorsion of eye and innervated by CN IV
superior oblique
elevation and extorsion of eye and innervated by CN III
inferior oblique
recti muscles align to orbital axis and since it is pulled out, the eye needs to be slightly ___
adducted
Keep a viewed object stable as the head is tilted side to side
intorsion and extortion
primary muscle for extorsion (outward rotation)
inferior oblique
secondary muscle for extorsion (outward rotation)
inferior rectus
primary muscle for intorsion (inward rotation)
superior oblique
secondary muscle for intorsion (inward rotation)
superior rectus
2 main muscles for upward vertical eye movement
superior rectus and inferior oblique
2 main muscles for downward eye movement
inferior rectus and superior oblique
refer to the coordinated movement of both eyes in the same direction to focus on an object
conjugate movements
Rapid, ballistic movements to shift gaze from one object to another.
Controlled by frontal eye fields (FEF) and superior colliculus
saccades
slower movements that allow the eyes to follow moving targets [Parietal lobe]
smooth pursuit
Both eyes move medially (toward the nose) to focus on a near object
convergence
Both eyes move laterally (away from the nose) to focus on a far object
divergence
_______ movements help maintain binocular vision and depth perception, adjusting the focus so that both eyes align properly on a target
vergence
reflexive eye movement that stabilizes vision during head movements by adjusting the position of the eyes in the opposite direction of head movement. This ensures that the image remains steady on the retina, even when the head moves rapidly
Vestibulo-Ocular reflex (VOR)
reflexive eye movement that allows the eyes to track a moving object smoothly and then quickly reset to the original position, ensuring continuous visual tracking of a moving scene (ex. Watching trees move past while riding in a car)
Optokinetic reflex
The eyes smoothly track a moving object in one direction.
This is controlled by the parietal-occipital visual cortex and the extraocular motor nuclei (CN III, IV, VI)
Slow phase (smooth pursuit) of optokinetic reflex
Once the eyes reach their limit of movement, a rapid, jerky eye movement resets them to the original position.
This phase is controlled by the brainstem gaze centers (PPRF - paramedian pontine reticular formation)
Fast phase (Saccade reset) of optokinetic reflex
lies near the midline the rostral midbrain
Somatic motor
oculomotor nucleus (red)
Parasympathetic preganglionic fivers
synapse in the ciliary ganglion
Postganglionic motor neurons to ciliary and pupillary muscle
Edinger-Westphal nucleus (yellow)
CN III
right by L internal carotid a.
Somatic motor
Innervates superior oblique muscle
CN IV trochlear
caudal membrane
trochlear n
_____muscle (which depresses and intorts the eye) is weakened due to CN IV palsy
superior oblique muscle
in CN IV palsy, the unopposed action of the ______ muscle elevates and extorts the eye.
inferior oblique
As a result of _____, the affected eye (right eye in this case) rests in an abnormally high position (hypertropia) when looking straight ahead.
CN IV palsy
________ away from the affected side (leftward tilt in this case) compensates for the lack of intorsion from the superior oblique muscle
tilting the head
________slightly downward shifts the gaze into a position where the superior oblique muscle is less needed
tucking the chin
This helps reduce the hypertropia and improves binocular vision in CN IV palsy
head tilt and chin tuck
Affected eye fails to intort but the ____ help to compensate
head tilt
CN IV palsy
pons
Somatic motor
Innervates lateral rectus
Abducens (CN VI)
CN VI
left and down of posterior part of internal carotid
L eye cant move laterally or extort
CN VI affected
coordinated movement of both eyes in the same direction
conjugate gaze
cortical control, initiating eye movement
(R_____) controls leftward gaze
frontal eye fields (FEF)
parietal lobe, smooth pursuit movements for tracking moving objects
parietal eye fields (PEF)
for descending signals of conjugate gaze to brainstem, ____ sends contralateral signals via the corticobulbar tract to the Paramedian Pontine Reticular Formation (PPRF), the horizontal gaze center in the brainstem
FEF (frontal eye field)
key center in brainstem for horizontal gaze
Pons (paramedian pontine reticular formation)
mechanism for horizontal gaze by the pons to move ipsilateral eye laterally
abducens nucleus (CN VI) gets signal from PPRF
mechanism for horizontal gaze by the pons to move contralateral eye medially
oculomotor nucleus (CN III) gets signal from medial longitudinal fasciculus (MLF)
control contralateral frontal eye field
UMNs
oculomotor nucleus and abducens nucleus controlled by
LMNs
_____ gaze center in the pons (PPRF)
horizontal
_____ gaze center in midbrain
vertical (rostral interstitial nucleus of the medial longitudinal fasciculus—-riMLF)
control the movements of the lens and pupil and thus participate in the accommodation of vision
intrinsic muscles
dilates pupil
dilator pupillae
innervation by sympathetics
T1 superior cervical ganglion
dilator pupillae
constricts pupil
sphincter pupillae
innervated by parasympathetic
oculomotor n.; ciliary ganglion
sphincter pupillae
rounds lens (accommodation for near vision)
ciliary muscle
innervated by parasympathetic
oculomotor n. and ciliary ganglion
ciliary muscle
light shone in R eye elicits pupillary constriction in the same eye (direct response) and in opposite eye (consensual response)
pupillary light reflex
refers to a condition where one eye shows a reduced or absent response to light
Marcus Gunn Pupil (relative afferent pupillary defect)
optic neuritis or optic nerve compression can cause what
Marcus Gunn pupil
central retinal artery or vein occlusion and retinal detachment can cause what
Marcus Gunn pupil
condition characterized by a dilated pupil that reacts sluggishly to light but more strongly to near accommodation (unilateral dilated pupil)
Adies Pupil (Tonic pupil)
Adie’s pupil is caused by damage to _______(parasympathetic ganglion supplying the sphincter pupillae muscle).
Postganglionic parasympathetic fibers regenerate abnormally, leading to tonic (slow) and aberrant pupil constriction
ciliary ganglion
Interruption of the sympathetic pathway responsible for innervating the eye and facial structures
Horner’s syndrome
Pupil: Causes miosis (constricted pupil).
Eyelid: Causes mild ptosis (drooping eyelid).
Sweat Glands: Causes anhidrosis (loss of sweating) on the affected side of the face
Horner’s syndrome
Eye movements:
When asked to look to the right:
The right eye abducts normally with associated nystagmus.
The left eye fails to adduct.
When asked to look to the left:
The left eye abducts normally with associated nystagmus.
The right eye have difficulty adducting.
Convergence is preserved
Internuclear opthalmoplegia
Why would L eye be pulled laterally
oculomotor n injured and abducens unopposed
contralateral weakness of body and face and ipsilateral eye pulled laterally
weber’s syndrome
diagonal movements up controlled by what
lateral rectus and superior rectus
diagonal movements down controlled by what
lateral rectus and inferior rectus
in and up (extort) eye movements controlled by what
medial rectus and inferior oblique
in and down (intort) eye movements controlled by what
medial rectus and superior oblique
