Norden- Cranial Nerves Flashcards
Accomodation reflex / near triad
Controlled by cortex via connections w/ CN III
Increase in curvature of the lens (ciliary muscles)
Pupillary constriction (pupillary sphincter)
Convergence of eyes (medial rectus)
Frontal eye fields
Area 8
Frontal eye fields (area 8) provides innervation to which motor nuclei?
CN III, IV, VI
A lesion in the cortical area 8 will cause what?
Inability to voluntarily conjugately move eyes to the contralateral side of the lesion and there will be baseline bilateral eye deviation to the side of the lesion.
Direct the eyes to a new point of fixation
Gaze centers
Voluntary eye movements are initiated primarily in _
Areas 4 and 8
Where is the vertical gaze center located?
In the periaqueductal gray region of the midbrain reticular formation
Where is the horizontal gaze center?
Paramedian pontine reticular formation
The horizontal and vertical gaze centers have connections to CNs III, IV, and VI through ______
The medial longitudinal fasciculus
The medial longitudinal fasciculus major function is:
To coordinate eye movements
Involuntary jerking or oscillatory movement of the eyes: can be vertical, horizontal, or rotational
Nystagmus
Pathological nystagmus can be caused by lesions:
In medial longitudinal fasciculus, vestibular system, or cerebellum
Palsy
Weakness (paresis)
PERRLA
Pupils equal, round, reactive to both light and accomodation
Mydriasis
Sympathetic
Pupillary constriction (Miosis)
Parasympathetic
Interruption of parasympathetics in eye
Produces dilation bc of unnopposed sympathetic innervation
Interruption of sympathetic fibers of eye
Produces pupillary constriction (unopposed parasympathetic innervation)
The inability to move both eyes so that the image of an object falls on both foveas
Strabismus
Strabismus causes
Diplopia, bc each eye is seeing a slightly different image
What allows the retinal image to remain stationary when you turn your head?
Cycloduction done by inferior and superior oblique
LMN for Cranial nerves are where?
In the motor nuclei of CN’s throughout the brainstem
Projections of LMN to specific muscles (in Cranial nerves) can be ___
Ipsilateral or contralateral
What is the general rule for the laterality of the cranial nerve innervations?
from cortex (UMN ) to CN nucleus is typically bilateral with slightly more coming from contralateral than from ipsilateral.
From the LMN, innervation to specific muscles is ipsilateral