Just a whole bunch of crap to know... Flashcards
The space between the clear cornea and the opaque iris.
Anterior chamber
T/F There are no structures within the anterior chamber
TRUE
The space between the iris and the vitreous chamber.
Posterior chamber
What lies within the posterior chamber?
The lens and zonular fiber
What is the main function of the anterior chamber?
Light diffraction or bending
What are the zonular fibers responsible for?
They attach the equator of the lens to the ciliary body
What important structure is located on the posterior internal surface of the vitreous chamber?
Retina
What two sets of muscles lie within the iris?
Pupillary constrictor muscle, and pupillary dilator muscle
T/F The two pupillary type muscles are under somatic control.
FALSE. Both are under autonomic control. The constrictor is governed by parasympathetic control and the dilator by sympathetic control
T/F Most diffraction occurs in the pupil.
FALSE. It is just a hole for light to travel through.
What is responsible for focusing the light on the retina?
Lens
T/F Retinal fields are inverted from visual fields
TRUE
Where does initial photo transduction occur as well as the initial steps in visual system processing?
Retina
The two most obvious features of the retina when examined are…
The optic disc and macula
On the opposite pole of the lens in the eye globe lies the…
Macula
Lying inside the borders of the macula, this small spot is exactly where the center of our vision is focused
Fovea
T/F The macula and fovea lack visible blood vessels and appear yellow
TRUE
The “blind spot” coincides with what physical landmark in the eye?
Optic disk
Another name for “blind spot” is…
Scotoma
T/F The optic nerve arises from oligodentrocytes and NOT Schwann cells and is particularly affected by MS
TRUE
Increased ICP within the ____ cranial fossa will be transmitted along the dural sleeve containing the optic nerve and cause papilla edema or the bulging of the optic nerve into the eye
Middle
Lying deep to the sclera (white) and choroid (vascular) layer of the eyes is the ____
Retinal pigmented epithelium
T/F The retinal pigmented epithelium is one cell layer thick and black to absorb light at the expense of sensitivity (in humans)
TRUE
T/F In animals who are nocturnal the retinal pigmented epithelium is reflective to reflect light back and improve night vision.
TRUE
What is responsible for cleaning up and recycling the outer segments of photo receptors?
Retinal pigmented epithelium
Age related macular degeneration and retinitis pigmentosa are thought to be associated with problems with the…
Recycling of photo receptors by the retinal pigmented epithelium
There are no (rods/cones) in the macular region of the retina
Rods
cones are to color as rods are to____
Black and white
What are the two main functions of the interneuron cell layer?
Communicating electrical signals between the photoreceptors and the retinal ganglion and to provide “contrast detection”.
What are the first “true” neurons in the visual system?
Retinal ganglion
T/F All retinal ganglion receive their light energy directly from photo receptors.
FALSE. Though 99% do, there are some on the periphery that have their own photopigment and can detect higher light intensities.
Axons from where form the optic nerve and optic tract?
The retinal ganglion cells
What target of the retinal ganglion cells involve vision.
Lateral geniculate nucleus
A small number of axons don’t make it past the optic chiasm but instead leave and go straight into the ____ nucleus of the ____
Suprachiasmic, hypothalamus
T/F It takes strong light intensities to reset our internal clock because the axons reaching the suprachiasmic nucleus originate in the lateral retinal ganglion cells and have their own photo pigment.
TRUE
The axons responsible for activating the recto-spinal tract in visual reflexes synapse in the ____
Superior colliculus
T/F Most axons of the retinal ganglion cells lead to the lateral geniculate nucleus of the thalamus
TRUE
Where does the “combining” of axons of the retinal ganglion cells take place?
Optic chiasm
T/F Only neurons from the temporal halves of each retina cross over in the optic chiasm.
FALSE. Only those on the nasal half of each retina cross over
T/F The information carried by the optic nerves of each eye are identical to the information carried by the optic tracts of each eye.
FALSE
The right optic tract carries information from ____ and the ____ visual field.
Both eyes, contralateral (left)
A pt is looking at car head on…he sees the entire car with his left eye but nothing with his right eye. He may have a problem with his right optic ____
Nerve
A pt is looking at a car head on…he sees most of the car with both eyes except he can’t see the left side mirror or left front headlight with either eye. He may have a problem with his right optic ____
Tract
Homonymous hemianopsia is associated with damage to the entire optic ____
Tract
Homonymous refers to the same visual field missing in both eyes and is usually associated with damage posterior to the optic ____
Chiasm
Hemianopsia = loss of ____ in ____ the visual field.
Vision, half
Heteronymous visual field deficits are usually associated with damage to the optic ____
Chiasm
Visual field deficits that are opposite in each eye is referred to as ____
Heteronymous
A pt presents with a “tunnel vision” to where he can’t see laterally in either eye. Damage to the optic ____ could cause this.
Chiasm. The nasal portions of each eye (responsible for lateral vision) cross in the optic chiasm. If this is damaged centrally, then the crossing nasal fibers would be affected and lateral perception in each eye would be inhibited.
A tumor where could cause “tunnel vision”.
Pituitary gland lying just inferior to the optic chasm
Each LGN processes information from the ____ half of the ____ retina as well as the ____ half of the ____ retina or in other words the right LGN processes information from the left visual fields of both eyes and the left LGN processes information from the right visual fields of both eyes.
Temporal, ipsilateral, nasal, contralateral
V1 is also known as the ____
Primary visual cortex
Of the brain, visual fibers are NOT found in the ____ lobe
Frontal
T/F Visual fibers are NOT found in the brain stem, cranial nerves (other than CN II), cerebellum, or spinal cord.
TRUE
The upper RETINAL field (inferior visual field) is perceived in the ____ lobe ____ gyrus
Parietal, Cuneus
The lower RETINAL field (superior visual field) is perceived in the ____ lobe ____ gyrus
Meyers loop of the temporal lobe, Lingual
Retinal ganglion cell axons responsible for circadian rhythm go to the ____
Hypothalamus
Retinal ganglion cell axons responsible for vision go to the ____
Lateral geniculate nucleus
Retinal ganglion cell axons responsible for visual reflexes go through the ____
Superior colliculus
Retinal ganglion cell axons responsible for pupillary light reflexes go through the ____
Superior colliculus
Monocular scotoma in the right upper nasal visual field = problem where?
Right lateral retinal field
Monocular blindness in the right eye = problem where?
Right optic nerve
Bitemporal hemianopia (hemianopsia) = problem where?
Optic chiasm
Left sided homonymous hemianopia = problem where?
Right optic tract
Left sided superior quadrantanopia = problem where?
Right Meyer’s loop or lower bank of calcarine fissure.
Left sided inferior quadrantanopia = problem where?
Right optic radiation or upper bank of calcarine fissure.
If the problem is in one eye’s visual field, but not the other eye’s field, then the problem is ____ the optic chiasm
Anterior to
If the problem is in both eyes, and in roughly the same position in both visual fields, then the problem is ____ the optic chiasm
Posterior to
If the problem is in both eyes, but in opposite positions in both visual fields, then the problem is ____ the optic chasm
At
A pt has a lesion in the parietal lobe that is pressing out laterally and into the lower left temporal lobe…this could cause a problem with the ____ pathway and not all to pt to perceive ____
“What”, visual form agnosia or color (achromatopsia)
A pt has a lesion in the parietal lobe that is pressing upward…this could cause a problem with the ____ pathway and not all to pt to perceive ____
“Where”, visual movement agnosia
Raising eyelids = Somatic or Visceral Motor?
Somatic
Constriction of the pupil = Somatic or Visceral Motor?
Visceral
Focusing of the lens = Somatic or Visceral Motor?
Visceral
Extraocular muscle control = Somatic or Visceral Motor?
Somatic
T/F Saccades require a visual target while pursuit movements of the eyes do not.
FALSE. The opposite.
The CNS center for lateral gaze
Pons
The CNS center for vertical gaze
Rostral midbrain
The CNS center for mergence
Rostral midbrain
The CNS center for accommodation
Rostral midbrain
Parasympathetics via the ____ nerve control pupillary ____ muscles, causes pupillary ____ and causes lens ____ and ____ vision
Oculomotor, constrictor, constriction, thickening, near
Sympathetics via the ____ plexus control pupillary ____ muscles, causes pupillary ____ and causes ____ muscle to ____ eyelids
Carotid, dilator, dilation, tarsus, raising
From the lateral geniculate nucleus, information is then sent to the ____, also known as V1, which is housed in the ____ flanking the ____ sulcus of the ____ occipital lobe. But they have to take a round-about way because the the ____ and ____ horn of the ____ ventricles lie in between the LGN and V1.
Primary visual cortex, cerebral cortex, calcarine, medial, atrium, occipital horn
Thalamocortical axons traveling superior to the lateral ventricles pass through the white matter of the ____ lobe and contact V1 cortical neurons ____ to the calcarine sulcus in the ____ gyrus.
Parietal, superior, cuneus
Thalamocortical axons traveling inferior to the lateral ventricles pass through the white matter of the ____ lobe and contact V1 cortical neurons ____ to the calcarine sulcus in the ____ gyrus.
Temporal, inferior, lingual
How would damage to the fibers of the left cuneus gyrus present?
Contralateral (right) inferior quadrantanopsia. The fibers that travel here are associated with the fibers from the inferior visual fields.
How would damage to the fibers of the left lingual gyrus present?
Contralateral (right) superior quadrantanopsia. The fibers that travel here are associated with the fibers from the superior visual fields.
3 L’s = pie in the sky! What are the L’s?
Lower (fields), Meyer’s Loop, Lingual gyrus.
V1
Primary visual cortex
V2
Secondary visual cortex
V3, V4, V5
Form, color, movement
Someone shows you a red cube…you can see that it’s red against the background but can’t perceive that it’s a cube.
V3 problem
Someone shows you a red cube…you can see it’s a cube…but not that it’s red
V4 problem
Someone can see the red object…they can see it’s a red cube…but cannot see the red cube moving fluidly through the air in motion but rather sees it in a series of still images.
V5 problem
Prosopagnosia
Cannot recognize a persons face. Associated with a visual cortex higher than those of V3, V4, or V5
Lateral rectus muscle of the eye is innervated by…
Abducens nerve (CN VI)
Superior oblique muscle of the eye is innervated by…
Trochlear nerve (CN IV)
Inferior oblique, medial rectus, superior rectus, inferior rectus muscles of the eye are innervated by…
Oculomotor nerve (CN III)
Which two eye muscles associated with ocular movement have only one action?
Medial and lateral rectus muscles
On the right eye…to test specific muscle function…looking up and lateral tests ____, looking up and medial tests ____, looking directly lateral tests ____, looking directly medial tests ____, looking down and lateral tests ____, and looking down and medial tests ____.
Superior rectus, inferior oblique, lateral rectus, medial rectus, inferior rectus, superior oblique
The trochlear nucleus associated with the ____ muscle of the eye is located within the ____
SO, midbrain
The abducens nucleus associated with the ____ muscle of the eye is located within the ____
LR, pons
Internuclear neurons are found within the ____ nucleus
Abducens
The LMN’s that innervated the levator palpebrae superioris reside within the ____
Oculomotor nuclear complex
The LMN’s controlling the extraocular muscles receive input from ____ within the midbrain and pons rather than from ____ in the cerebral cortex
Motor pattern generators, UMN’s
There are how many motor pattern generators involved in the coordination of the eyes?
- Two in the midbrain and one in the pons
The “center for vertical gaze” is located within the ____
Midbrain
The “center for horizontal gaze” is located within the ____
Pons
The “center for accommodation” is located within the ____
Midbrain
The highly myelinated fiber tracts that are responsible for coordinating all of the communication between the eyes so that they eyes move together.
Medial longitudinal fasciculi
Asking a person to glance at a stationary object in the distance and to their right will require a convergent ____ eye movement. These are very (fast/slow)
Saccadic, fast
T/F It is possible to carry out a slow pursuit eye movement without a target so long as the movement is slow enough.
FALSE
T/F The center for horizontal gaze is responsible for saccadic and slow pursuit movements in the horizontal plane.
TRUE
Another name for the center for horizontal gaze is the ____
Paramedian pontine reticular formation
What is located directly adjacent to the abducens nucleus in the pons?
Paramedian pontine reticular formation
To move the eyes horizontally to the right in a conjugated way…the 1st pathway of the PPRF neurons is to go to the ____ of the right ____ nucleus which then send their axons to the right ____ nerve to innervate the right ____ muscle causing the right eye to rotate to the right.
LMN’s, abducens, abducens, lateral rectus
To move the eyes horizontally to the right in a conjugated way…the 2nd pathway of the PPRF neurons is to go to the ____ neurons of the right ____ nucleus which then send their axons to the ____ ____ to innervate the left ____ subnucleus within the ____ nucleus. They then innervate the ____ ____ muscle causing the left eye to rotate to the right.
Internuclear, abducens, left MLF, medial rectus, oculomotor, left medial rectus,
____ neurons activated by the PPRF are responsible for deactivating antagonistic muscles of the eyes
Inhibitory
If the right PPRF is activated it causes (right/left) horizontal eye movement.
Right
Right PPRF stimulation of the left abducens nucleus (excites/inhibits)
Inhibits = inhibition of left lateral rectus = moves eye toward right
Right PPRF stimulation of the left oculomotor neuron (excites/inhibits)
Excites = excitation of left eye medial rectus = moves eye toward the right
Right PPRF stimulation of the left PPRF (excites/inhibits)
Inhibits = turns down it’s function of pulling both eyes to the left through the same mechanisms.
