Module 14 Flashcards
Name the two components of conscious proprioception (DGS) ?
Static (perception in body/position sense)
Dynamic (sense movement & balance/kinesthetic sense)
What are the discriminative general senses?
2 point discrimination Size perception Texture perception Stereognosis Conscious proprioception
What makes the movement awareness?
Kinesthsia(static) & position(dynamic) sense
How are receptors stimulated?
Environmental stimuli (inside/outside of body)
What is the role of the receptors?
Function as transducers
Covert environmental stimuli into nerve impulses
How are sensory AP initiated?
Adequate stimulus (depolarizes the receptor membrane)
Where do the APs go to after being initiated by the receptor potential (generator potential)?
Spinal cord or brainstem
The receptor potential is similar to which type of stimulus? Action or generator?
Generator because it’s not an all or nothing response to the stimulus
How do receptor adapt?
Rapidly
Slowly
Before eventually stopping
How do rapidly adapting receptors respond?
Strong response at first then RAPIDLY adapts to the stimuli
I.e putting on clothes
How do slow adapting receptors respond?
Weaker initial response but the response is maintained for as long as the stimuli is presented!
CALLED: Tonic receptor
How is somasensory data transmitted?
Peripheral nerves (cranial and spinal nerves)
Where does somatosensory data go?
To nuclei in spinal cord and brainstem
Reflexive sensory data: stays at SC or BS level
Other sensory data: go to the thalamus then to the cerebral cortex
Unconscious proprioceptive data: from muscle spindles/joint receptors to cerebellum then cortex
What are the 4 main ASCENDING sensory pathways?
Dorsal column/medial lemniscus
Anterolateral spinothalamic
Trigeminal/trigeminothalamic
Spinocerebellar
What does the dorsal column pathway carry?
General discriminatory senses (conscious proprioception
What does the anterolateral spinothalamic pathway carry?
Sensory data from body and BACK of the head
Anterior (crude touch)
Lateral (pain & temp.)
What information does he trigeminal sensory pathway carry?
Pain & temperature
Crude touch
GDS from face
What information does the Spinocerebellar pathway Carry?
Unconscious proprioception
Are receptors equally sensitive to all stimuli?
No!!
Sensory receptors detect different types of sensory stimuli
Each receptor is highly sensitive to specific sensations it’s designed for.
HOW do we know this( what tells us)?
Doctrine of specific nerve energies
What is the labeled line principal?
Explains how different nerve fibers transmit different modalities of sensation
EACH nerve terminates at a specific part in the CNS
SENSATION stimulated based on location of nerve fiber (ie optic nerve fibers to visual cortex)
How are receptors classified?
Physiological/functional (location/modality)
Type of stimulus (type of stimulus it responds to)
What are the 5 main sensory modalities?
Crude (light) touch Pain Temperature Discriminative general senses Unconscious proprioception
What are the psychological/function receptors?
Exteroceptors-near body surface (touch/pain/temp/smell/sound/taste/light)
Interceptors- in viscera (sense feelings of pain/fullness/cramping)
Proprioceptors- deep within walls (balance/position/movement)
What are the receptors classified by the type of stimulus received?
Mechanoreceptors-detect deformation (crude/fine touch)
Thermoreceotors- detect temperature
Nociceptors- detect pain
Electromagnetic receptors- detect light on retina
Chemoreceptors-detect chemical stimuli (taste buds/smell receptors)
How does sensory from back of the head enter?
Through dorsal root ganglia
How does sensory data from head/face (minus back of the head) enter?
CN ganglia and goes into Trigeminal system
What type of pathway does a somatic sensation constitute?
3 neuron pathway from peripheral to cortex
What type of nerve is the 1st order neuron for somatic sensation? Where does it go?
Peripheral (from receptor to SC or BS)
Where does the 2nd order neuron for the somatic sensation go?
From nucleus to thalamus
CROSSES midline to opposite side
Where does the 3rd order neurons for somatic sensation go?
From thalamus to the cerebral cortex (parietal lobe)
What type of pathway was unconscious proprioception have?
Spinocerebellar pathway
2-neuron pathway
Where does the 1st order neuron from the Spinocerebellar system go?
Receptor to SC nucleus
Where does the 2nd order neuron from the Spinocerebellar system go?
From the nucleus to the cerebellum
Describe the dorsal column/medial lemniscus
Discriminative general senses
Back of the head/body
Rapidly adapting
Dorsal column has their cell bodies for 1st order neurons where?
In the dorsal root ganglia
What are the first order neurons of the dorsal column?
Fasciculus cuneatus (upper body/travels laterally to medulla)
Fasciculus gracilis (lower body/travels medically to medulla)
Where do the 1st order neurons for the dorsal column meet the 2nd order neurons? What are they called after they meet?
At the nucleus of gracilis and cuneatus.
Cross at above point of decussation then form medial lemniscus
Where do the 2nd order neurons the medial lemniscus go?
To the VPL nucleus of the thalamus
Where do the 3rd order neurons of the medial lemniscus go?
To the upper 2/3 of 3-1-2 via POSTERIOR limb of internal capsule and corona radiate
What is tactile anesthesia?
Loss of tactile sensibility
What is tactile hypoesthesia?
Reduction in tactile sensibility but NOT completely loss
What is tactile hyperesthesia?
Exaggerated tactile sensibility
A lesion to the dorsal column call impair what?
Any of the discriminative general senses
TO ASSESS: 2point discriminative
Tactile object recognition
Body part position sense
Graphesthesia
Why is the anterolateral spinothalamic sensory pathway important?
For light touch, pain and temperature
FROM: body and back of the head
Which pathway has faster conduction, the anterolateral spinothalamic or dorsal column?
The dorsal column
What are the two pathways of the anterolateral spinothalamic? What do they do?
Anterior spinothalamic- light touch
Lateral spinothalamic- pain & temperature
Where do the lateral spinothalamic 1st order neurons receive input?
From pain and temp receptors
If there is a lesion to the dorsal root/nucleus of termination on the lateral spinothalamic pathway, what happens?
Ipsilateral impairment in pain/temp sensation
If the lateral spinothalamic pathway has crossed, the impairment will be contralateral
What is neuralgia?
Severe pain
Name the 3 categories of altered pain response
Analgesia-no response
Hypoalgesia-reduced response
Hyperalgesia-increased response
Where does anterior spinothalamic pathway receive input from?
Touch receptors.
Mediates light and crude touch
What happens if there’s a lesion to the anterior spinothalamic pathway?
TRICK QUESTION!!
no lesion will occur because DORSAL COLUMN WILL COMPENSATE
Lesion to SC kills light touch below lesion
What is the trigeminal system responsible for?
ALL general sensory modalities (DGS, pain/temp/crude touch/taste from tongue)
Where does the trigeminal system receive its input from?
Anterior scalp, head & next structures
Which CN send input to the trigeminal system?
CN V
CN IX
CN X
How is GSA sent to trigeminal system from CN V?
All 3 branches
Maxillary
Mandibular
Ophthalmic
How is GSA sent to trigeminal system from CN IX?
From tongue, soft palate, pharynx
Cell bodies in inferior petrosal
How is GSA sent to trigeminal system from CN X?
From trachea, larynx, pharynx
Cell bodies in superior [ jugular] ganglion
Which pathway of the trigeminal system is crossed? Which is uncrossed?
Anterior (ventral) trigeminothalamic is crossed
Posterior (dorsal) trigeminothalamic is uncrossed & crossed
Unlike the other sensory pathways, where do the 2nd order neurons of the anterior trigeminothalamic (pain/temp/crude touch) ascent to?
Contralateral VPM of thalamus
Where do the 3rd order neurons travel to?
The LOWER 1/3 of the 3-1-2
What happens if there’s a lesion to the ganglion of the Trigeminal system?
Ipsilateral sensory loss
The 1st order neurons synapse with spinal trigeminal nucleus for pain/temp/crude touch) T/F
T
Where do the 1st order neurons of the trigeminal system (discriminative general senses) synapse with?
Main sensory nucleus
where do the 2nd order neurons of the trigeminal system (discriminative general systems) ascend to?
Some: CROSSED anterior trigeminothalamic pathway. Contralateral VPM of thalamus
Others: posterior trigeminothalamic pathway. REPORT to: IPSILATERAL VPM nucleus
If there is a lesion to the anterior pathway, what happens?
Contralateral sensory loss
What type of lesion causes mild effects on DGS (due to bilateral/ipsilateral/contralateral/projection)?
Lesion to posterior pathway
What does the Spinocerebellar pathways mediate?
Unconscious proprioception
Where does the Spinocerebellar pathway get input from?
Muscle spindles and GTO
What type of conduction is the Spinocerebellar pathway have?
Rapid
Name the 4 pathways of the Spinocerebellar pathway.
Dorsal Spinocerebellar
Cuneocerebellar
Ventral Spinocerebellar
Rostral Spinocerebellar
What does the dorsal Spinocerebellar pathway do?
Get input from lower half of body and limbs (keeps cerebellum informed)
What does the cuneocerebellar tract do?
Get input from upper half of body and limbs.
Informs cerebellum about muscle contraction and tension in tendons
What do the ventral Spinocerebellar system do?
SOME input from lower limbs
EXCITED by motor signals
What does the rostral Spinocerebellar do?
SOME input from upper limbs
Excited by DESCENDING motor signals
When do the ventral Spinocerebellar pathways inform the cerebellum?
When motor signals have arrive. Also informs of intensity
Out of the 4 pathways of the Spinocerebellar pathways, which one is crossed and ipsilateral?
The ventral pathway.
ALL other pathways are uncrossed and ipsilateral
Where does the Spinocerebellar pathway send input to?
The MESENCEPHALIC nucleus of CN V
T/F: does the cerebellum act as a feedback mechanism?
True!
T/F: do the cerebral cortex and basal ganglia coordinate motor behavior?
FALSE! they INITIATE the motor behavior
What coordinates motor behavior?
The cerebellum
If there is a lesion to the cerebellum, what happens?
Ataxia “without order”
Movements are poorly coordinated, awkward and unsteady
