Visual system Flashcards
What is the part of the retina that is most sensitive to light?
Pigment epithelium
What does the inner segment of the rod contain?
cell nucleus and mitochondria
The outer segment of the rod contains discs that contain light sensitive _________.
rhodopsin
What does the inner segment of a cone contain?
cell nucleus and mitochondria
The outer segment of the cone contents the discs that contain light sensitive _______.
iodopsin
Refraction occurs tat the _________ and at the _______.
cornea; lens
Refractive power of the _______ is greater, but the ______ can change its shape.
cornea; lens
At the _____, interring cell layers are pushed aside.
fovea
Rods and cones are found at the fovea (T/F).
FALSE; just cones
At the _____ ____ there is a blind spot due to emerging retinal arteries.
optic disc
More ________ in the central retina = better visual acuity.
cones
More ______ in the peripheral retina = better for movement.
rods
How many rods are located in the retina?
120 milion
How many cones are located in the retina?
6 million
Cones are sensitive to what 3 colours of the visible spectrum?
red, green and blue
Trace the visual pathway, starting from the retina.
Retina; optic nerve; optic chiasm; optic tract; lateral geniculate nucleus of the thalamus; optic radiation; occipital lobe
Left visual field projects to the _______ cortex, and vice versa.
right
The ________ stream= where, how, and spatial vision
dorsal
The ______ stream - what, object vision
ventral
What muscle causes elevation of the eye?
superior rectus
What muscle causes depression of the eye?
inferior rectus
What muscles cause adduction and abduction of the eye, respectively?
medial rectus; lateral rectus
What muscle is innervated by CN IV?
superior oblique
What nerve innervates inferior oblique?
CN III
What nerve causes lateral eye movements?
CN VI
The _______ _______ muscle is aligned with the axis of the eyeball in the adducted eye.
superior oblique
Contraction of the superior oblique will lead to _______ of the adducted eyeball.
depression
The ______ ______ muscle is perpendicular to the axis of the eyeball in the abducted eye.
superior oblique
Contraction of the superior oblique muscle in an abducted eye will lead to _______ of the eyeball.
intorsion
Oculomotor nerve (CN __) innervates all extraocular muscles except what two?
- Superior oblique
2. Lateral rectus
What nerve is the superior oblique muscle innervated by?
trochlear nerve (CNIV)
What nerve is the lateral rectus innervated by?
Abducens (CN VI)
Where is the oculomotor nucleus found in the brainstem?
midbrain
Where is the trochlear nucleus found?
rostral pons
Where is the abducens nucleus found?
Caudal pons
Motor cranial nerves receive input from the primary motor cortex via the ____________ tract.
corticobulbar
What is the specialized area of the cortex that controls eye movements?
frontal eye fields
In a horizontal eye movement, what two muscles and thereby what two nerves need to work together?
medial and lateral rectus; CN III and VI
The ________ _______ connect the abducens nucleus and the oculomotor nucleus, and is critical for coordinate gaze.
ascending MLF
The ascending MLF is critical for what reflex?
vestibulo-ocular
The descending MLG is the _______ __________ tract.
medial vestibulospinal tract
The aMLF connects the vestibular nuclei (CN VII) to the nuclei of what three CN?
III, IV, and VI
What are the three types of eye movements?
- saccades
- pursuit
- vestibule-ocular reflex
What are the two types of saccades?
- volitional
2. reflexive
What are the 3 types of volitional saccades?
- anti-saccade
- memory saccade
- predictive saccade
Information for reflexive saccades comes from the _______ _______.
superior colliculus
Before moving ones gaze, both reflexive and volitional saccades must synapse were?
paramedian pontine reticular formation
A saccade to the left comes from the _______ side of the cortex.
right
Pursuit to the left comes from the ______ side of the cortex.
left
Vertical gaze requires coordination of what two nerves?
CN III and IV
Where is the vertical gaze center located?
rMLF pretectal area
Horizontal gaze centre in the _____, vertical gaze center in the _______.
pons; midbrain
________ gaze = eyes move in different directions.
disconjugate
What two things does disconjugate gaze include?
- convergence
2. divergence
A dilated pupil may indicated ________ pathology.
parasympathetic
A constricted pupil may indicated a __________ pathology.
sympathetic