Week 2 Vocab Flashcards
Lens
a piece of glass or other transparent substance with curved sides for concentrating or dispersing light rays, used singly (as in a magnifying glass) or with other lenses (as in a telescope)
Fovea
a small depression in the retina of the eye where visual acuity is highest. The center of the field of vision is focused in this region, where retinal cones are particularly concentrated
Macula
an oval yellowish area surrounding the fovea near the center of the retina in the eye, which is the region of keenest vision
Optic disc
the raised disk on the retina at the point of entry of the optic nerve, lacking visual receptors and so creating a blind spot
Optic nerve
each of the second pair of cranial nerves, transmitting impulses to the brain from the retina at the back of the eye
Photoreceptors
a structure in a living organism, especially a sensory cell or sense organ, that responds to light falling on it
Rods
a thin straight bar, especially of wood or metal
Cones
a solid or hollow object which tapers from a circular or roughly circular base to a point
Receptive field
The area which when stimulated elicits a particular response, such as a reflex, the firing of a sensory neuron, or the activation of a ganglion cell
Parvocellular layers
cell layers of the lateral geniculate nucleus of the thalamus that relay information about motion and spatial analysis
Magnocellular layers
cell layers of the lateral geniculate nucleus of the thalamus that relay information about detailed form and color vision
Lateral geniculate nucleus (LGN
a nucleus of the thalamus which in part of the visual pathway in receiving information from the optic tract and sending information to the primary visual cortex
Optic chiasm
the X-shaped structure formed at the point below the brain where the two optic nerves cross over each other
Optic tract
the pathway between the optic chiasma and the brain.
Homonymous visual field defects
the defect occurs in the same portion of the visual field of each eye with a lesion posterior to the optic chiasm
Bitemporal visual field defects
the defect occurs in the bilateral visual fields when there are lesions to the optic chiasm
Monocular visual field defects
the defect occurs in one visual field when there are lesions anterior to the optic chiasm
Contralateral superior quadrantanopia
pie in the sky” a visual field defect caused by a lesion to the temporal lobe
Contralateral inferior quadrantanopia
- ”pie on the floor” a visual field defect caused by a lesion to the parietal lobe
Optic radiation
- a wide range of white matter axons that fan out as they leave the lateral geniculate nucleus of the thalamus and travel back towards the primary visual
Primary visual cortex
Brodmann’s area 17 located in the banks of the calcarine fissure in the occipital lobe
Visual acuity
sharpness of vision, measured by the ability to discern letters or numbers at a given distance according to a fixed standard
Ophthalmic artery
the artery which supplies the retina and originates just above the internal carotid artery
Optic neuritis
an inflammatory demyelinating disorder of the optic nerve often related to multiple sclerosis
Extraocular muscles
each of six small voluntary muscles controlling movement of the eyeball within the socket
Nuclear and infranuclear pathways
involve the brainstem nuclei of cranial nerves III, IV, and VI; the peripheral nerves arising from these nuclei; and the eye movement muscles
Supranuclear pathways
involve the brainstem and forebrain circuits that control eye movements through connections with the nuclei of cranial nerves III, IV, and VI
Torsional
movements that involve the eye rotating slightly about its axis
Lateral rectus
an extraocular muscle, innervated by cranial nerve VI, that abducts the eye
Medial rectus
an extraocular muscle, innervated by cranial nerve III, that adducts the eye
Superior rectus
an extraocular muscle, innervated by cranial nerve III, that elevates and intorts the eye
Inferior rectus
an extraocular muscle, innervated by cranial nerve III, that depresses and extorts the eye
Inferior oblique
an extraocular muscle, innervated by cranial nerve III, that elevates and extorts the eye
Superior oblique
an extraocular muscle, innervated by cranial nerve IV, that depresses and intorts the eye
Intorsion
movement of the upper pole of the eye inward
Extorsion
movement of the upper pole of the eye outward
Oculomotor nuclei
located in the upper midbrain at the level of the superior colliculi and the red nuclei, just ventral to the peri aqueductal gray matter
Trochlear nuclei
located in the lower midbrain at the level of the inferior colliculi and the decussation of the superior cerebellar peduncle
Abducens nuclei
located on the floor of the fourth ventricle under the facial colliculi in the mid-to-lower pons
Diplopia
double vision
Hypertropia
elevation of the eye from the vertical axis; vertical strabismus
Anisocoria
pupillary asymmetry
Ptosis
upper eyelid drooping
Miosis
decreased pupillary size
Anhidrosis
decreased sweating of the ipsilateral face and neck
Reticular formation
a diffuse network of nerve pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum, and mediating the overall level of consciousness
Consciousness
the state of being awake and aware of one’s surroundings
Alertness
being awake and depends on normal functioning of the brainstem and diencephalic arousal circuits and cortex
Attention
uses the same circuits as alertness together with additional processing in frontal parietal association cortex
Awareness
knowledge or perception of a situation or fact
Non-REM sleep
non-rapid eye movement phases of sleep which begin the sleep process
REM sleep
rapid eye movement phase of sleep which is where most dreaming typically occurs
Narcolepsy
a condition characterized by an extreme tendency to fall asleep whenever in relaxing surroundings
Coma
a state of deep unconsciousness that lasts for a prolonged or indefinite period, caused especially by severe injury or illness
Vegetative state
a stage after coma where patients may enter a perplexing state in which they regain sleep-wake cycles and other primitive orienting responses and reflexes mediated by the brainstem and diencephalon, but remain unconscious
Persistent vegetative state
a term used if a vegetative state persists longer than one month
Minimally conscious state
a stage of recovery from a vegetative state where patients have some minimal or variable degree of responsiveness including following simple commands, saying a single word, or holding onto an object
