GSA, Vestibular/Auditory, Vision Flashcards
Exteroception
ways that the nervous system receives information about the external environment
What are examples of exteroception?
touch, temperature, paint, etc.
Interoception
ways the nervous system receives information about the internal environment (GVA)
Examples of interoception:
visceral pain, sensory for pain within body
Proprioception
ways the n.s. receives info about the position and movement of teh body (where the limbs are in space)
GVA (general visceral afferent)
sensory from autonomic ns
afferent info from teh viscera
GSA (gneral sensory afferent: somatosensation(
Sensory from teh skin and skeletal mm
What does GSA (somatosensation) sens?
touch, pain, temperautre, position of the body
Mechanoreception
physical deformation
Thermoreceptors
heat and cold
nociceptors
noxious stimuli (potentially injurious)
Photoreceptors
vision
Chemoreceptors
chemical change (taste, smell, O2/CO2 in blood)
Destinations for afferent neurons
cortex, cerembellum, individual spinal cord segments or ARAS
ARAS
wakefulness- noxious stimulus that will help keep you awake
pinching urself to stay awake in lecture
Divergence
same sensory info. sent to multiple destinations for different purposes
Parallel processing
different aspects of the same sensory experience are perceived in different parts of the brain at the same time
Receptors (receptor cell)
transduction of neuronal activity
Action potentials in primary neuron
goes from periphery to CNS
Axons ascend the to brain in somatosensory pathways in
fiber tracts
Thalamus to the Cortex
relay processing point for all sensations destined for conscious perception
**Vision, audition, somatosensation
Somatosensory inputs go to the (blank) thalamus and cortex
contralateral
somatotopy
the spot in the brain corresponding to a specific area on the body
Sensory pathways exhibit?
somatotopy
The receptor density in the periphery is equal
to the amount of space in the thalamus and the cortex dedicated to that sensation (mapping)
Why does the startle reflex occur?
protection from physical impact, interrupt behavioral patterns, facilitate flight response
Where does the descending pathway of the startle reflex go to?
LMNs of skeletal muscles of limbs
What does the start reflex cause?
flexion of almost all skeletal muscle
Auditory pathway is responsible for?
conscious perception of sound
What is the auditory pathway?
- cochlear nuclei
- caudal colliculi
- medial geniculate nucleus
- auditory cortex for conscious perception of sound
conduction deafness
sound can’t get from the ear to the vestibular window due to damage, disease or obstruction
Sensorineural deafness
sounds get to the vestibular window but can’t transmit the sound to the auditory cortex
–> damage to cochlea, cochlear neves or auditory cortex
Inherited deafness is classified as?
sensorineural deafness
What kind of testing can be done for congenital deafness?
BAER testing
Vestibular System is involved in?
motor pathways that are complex and concerned with maintaining a stable orientation to gravity and motion
The vestibular system is a special form of proprioception because
it is sense balance and acceleration which are varieties of body position
Vestibular nerve is formed by:
axons from the utricle, sacule and semicircular canals
Vestibular pathway
vestibular portions of CN VIII to vestibular nuclei in teh hind brain
What is the vestibulo-ocular reflex?
When information goes from the vestibular nuclei to the motor nuclei of 3, 4, 6 for control of eye movements
Vestibular pathway effects what part of the brain for posture and balance modifications?
cerebellum
Vestibulo-spinal reflex involves
vestibular pathway and the trunk
Vestibulocollic reflexes involves
vestibular pathway and the head n neck
What does the thalamus coordinate for the vestibular pathway?
conscious perception of movements
What part of the vestibular pathway is involved with control of eye movement in response to vestibular input?
medial longitudinal fasciulus (in brain stem)
Vestibulo-ocular reflex is
the slow movement of the eyes as they catch up to teh movement of the head (tracking)
Are resting nystagmus or positional nystagmus a normal vestibulo-ocular reflex?
NO
Estropia
crossed eyes can cause a type of physiological nystagmus in Siamese/Himalayan cats
Unilateral lesion
vestibulo-ocular reflex
one side fires and the other does not (partially or not at all )
Peripheral vestibular lesion
nystagmus is either horizontal or rotary and does NOT change in when the head position is changed
Central Vestibular Lesion
Horizontal, rotary, vertical and MAY change when patient is put into dorsal or lateral recumbency
Lesion to the vestibulo-collic reflex
decreased/absent firing ont eh side of the lesion, wit h the other side firing at a normal rate
**head tilts TOWARDS the side of the lesion
Vestibulospinal Reflex prevents falling when
the head shifts in position
Vestibulospinal reflex lesion
patient only senses movement toward the intact side
**move balance towards the lesioned side
What are clinical signs of a vestibulospinal reflex lesion?
rolling, circle, leaning TOWARDS the side of the lesion
OS refers to
the left eye
OD refers to
the right eye
Prey animals eyes are located laterally for:
increased peripheral vision (poor depth perception) and decussation compared to predators
Where does the optic nerve go after they penetrate the optic disc?
optic nerve, optic chiasm, hypothalamus, lateral geniculate nucleus, pretectum, superior colliculus
Retinogeniculostriate pathway is involved in:
conscious perception of vision
- menace response pathway
Retinogeniculostriate pathway occurs via what nerve after optic nn?
lateral geniculate nucleus (LGN)
Retinopretectal Pathway is involved in which reflex?
PLR
Retinopretectal pathway occurs via what nerve?
pretectal nucleii
Retinotectal pathway occurs via which nerve?
rostral colliculi
Retinotectal pathway is involved in what reflex?
ocular fixation
Retinohypothalamic pathway is involved in
circadian rhythms
Retinohypothalamic pathway occurs via which nerve
suprachiasmatic nucleus
80% of your optic tract axons follow which nerve?
LGN in the thalamus
How do you test the retinogeniculostriate pathway?
maze, drop a cotton ball, roll ball, visual placement test, menace response
Retinopretectal pathway is going to synapse at the
rostral colliculus
The retinopretectal pathway after projecting on the rostral colliculus synapses on
teh edinger-westphal nucleus
**para nucleus of CN3
What kind of clinical sign is common with brainstem trauma?
pupillary abnormalities
What ocular pathway is involved processing visual information without conscious awareness (blindsight)?
Retinotectal pathway
What pathway is involved in reflex orientation of the eyes towards visually interesting stimuli?
Retinotectal pathway
From the rostral colliculi the retinotectal pathway nerves travel to
CN nuclei (3, 4, 6), spinal mm., thalamus and cerebellum
Which ocular pathway is involved in light input for circadian rhythm (photoperiod for breeding)
Retinohypothalamic pathway
In the retinohypothalamic pathway where to nerves travel to after optic n?
to teh superchiasmatic nucleus (craniomedial hypothalamus)
What is Horners?
Sympathetic denervaton
What causes horners (pre-ganglionic)?
neck trauma or disc rupture, brachial plexus avulsion, axillary lesion, cranial thoracic disease, neck tumor, traumatic venepuncture
What causes horners (post-ganglionic)?
otitis, orbital disease
What is the most common type of horners?
idiopathic
