Pt 612 Quiz 5


Terms in this set (...)

Cutaneous senses include?
-touch- pressure and vibration
Musculoskeletal system includes?
-Proprioception- static joint position in space and kinesthesia
What is Kinesthesia
Sensory information about movement
What is the purpose of the somatosensory system?
-To provide the individual with a conscious experience of the internal and external environment
- To initiate, shape and adjust motor behavior in response to changes in the internal and external environment
How does the somatosensory system work?
energy forces (aka stimuli) activate specific receptors at the end of the peripheral neurons which generates an action potential beginning an impulse transmission towards the CNS
where are the cell bodies of the peripheral sensory neurons located?
DRG or the cranial nerves that have a sensory function
What are the two types of peripheral sensory neurons?
Proximal - either send it to the DRG --> to the spinal cord, or from DRG to the CNS
Distal- conducting info from the receptor to the cell body (DRG)
Sensory Receptors
A subset of all of the other somatosensory receptors = Nociceptors
active when we have a mechanical change or change in the formation in the receptor by touch, pressure, by stretch, by vibration
-will fire action potential when anything changes the shape of them
-they live in the skin- dermis some are more superficial than others
responding to different chemical processes- responding to substances released by cells- including damaged cells following injury or infection
Ex- bee sting- body releases histamine- sensory receptors would become more active with a chemical change
become active in hot to cold scenarios
not a category on their own
-burning sensed by temp- -will likely be sending signals of pain, triggered to sense the feeling of pain over the feeling of hot
Pulling away with withdrawal or secondary affect going to the cortex saying it hurt but how much did it hurt- higher level of thinking
Sensory receptors are classified as..??
-Type of information they are sensitive to
-Unencapsulated versus Encapsulated
-Adaptation rate (slow vs. fast)
Rapidly adapting (phasic) receptors
Slowly adapting (tonic) receptors
external closest to the outside of the body, sense info coming from the outside environment
transmit info about what's going on inside- muscles, tendons, joints
sensory info concerning the internal environment- what's going on with BP, HR, gas exchange - taking in with oxygen and expiring with CO2- internal regulation
Encapsulated types
Muscle spindles
Ruffini end organs-respond when it comes to stretch, helping with proprioception input primarily in the joints
Pacinian corpuscle- sense pressure and vibration
Raffini end organs
- located in joint capsules, dermis, and underlying hypodermis of hairy skin
- respond to stretching of collagen bundles (providing proprioceptive info)
What is the difference between peripheral nerve roots and dermatomes?
Area of the skin innervated by the bundle of axons coming from the cell body - dorsal root - is going to be supplying a dermatome
vs. ulnar nerve supplies a particular portion of that arm- peripheral nerve distribution
What are the two conscious somatosensory pathways
Antrerior-lateral system
Dorsal columns/ medial lemniscal system
Anterior - lateral system conveys?
Non-discriminative (crude or poorly localized) touch
Dorsal Column/Medial Lemniscal System
Discriminative Touch
Joint Position Sense - static
Kinesthesia - with movement
Compound sensations: (graphaesthesia, stereoagnosis)
what is steroagnosia?
interpreting an object by feel
What is Graphestheais?
the ability to recognize writing on the skin purely by the sensation of touch.
What is the pathway for the spinothalamic tract?
Information from body enters the DRG
synapses in SC Lamina 1-4 --> decussates at level of entry into SC--> ascends in the contralateral lateral funiculus --> synapses in VPL of thalamus ---> Post central gyrus (AKA primary sensory cortex/Broadmans 1-3)
Spinthalamic tract- Face pathway
Info from face enters Semilunar ganglion --> Spinal trigeminal nucleus ---> contralateral VPM of thalamus --> Primary sensory cortex
What is the 1st, 2nd and 3rd neuron cell body?
1st= DRG
2nd= substantia gelatinosa
3rd = thalamus VPL
What are the unconscious collaterals for the spinothalamic?
Spinoreticular-RF has something to do with our consciousness which is influenced by pain
Spinomesencephalic-going to the superior colliculus- turns the head and eyes away from noxious input- painful stimulus our eyes and head are directing away from it
Spinolimbic- going to limbic system and hypothalamus -
-limbic- we have an emotional response to pain
And when were in pain we have an autonomic response - HR BP increases
automatic and emotional response to pain
what is the pathway for the DCML
Information from body enters the DRG--> ascends ipsilaterally in fasciculus--->cuneatus/gracilis, until it synapses in N. cuneatus (>T6) or N. Gracilis (<T6) at the level of the closed medulla where it decussates (now called medial lemniscus) --> contralateral VPL of thalamus --> Primary Sensory Cortex
Pathway for the face of the DCML
Info from face enters the semilunar ganglion --> chief/main trigeminal in pons --> contralateral VPM of thalamus --> Primary Sensory Cortex
primary, secondary, and third neuron cell body
1st- DRG
2nd- <T6 Nucleus Gracilis in closed medulla
>T6 Nucleus Cuneatus in closed medulla
3rd - VPL of the thalamus
Why does sensation matter?
sensory info informs how we move!
Primary sensory and somatosensory association cortices have extensive connections with the primary motor cortex...why?
Need that info to inform/adapt our movement
Lesion to the Primary Sensory Cortex will result in what?
Inability to sense/feel something touching us (contralateral)
Not just touch-->proprioception, pain, temp; everything is logged in here
Lesions to the Association cortex will result in what?
Lose compound cortical ability of sensing (stereoagnosis, graphasthesia)
What would happen if you had a lesion to the Thalamus
loss of sensation to the contralateral side!
What would happen if you had a lesion to the lateral pons or lateral medulla?
involves the anterolateral pathways and the spinal trigeminal nucleus on the ipsilateral side, causing loss of pain and temperature sensation in the body opposite the lesion and loss of pain and temperature sensation in the face on the same side as the lesion.
What would happen if you had lesion in the medial medulla
The lesion will therefore involve the medial lemniscus and will cause contralateral loss of vibration and proprioception
What happens if their is a lesion in the nerve roots or peripheral nerves
Distal symmetrical polyneuropathies can cause bilateral sensory loss in a stocking and glove pattern in all modalities.
What happens if their is damage to posterior cord (dorsal column)
all sensory info in fasciculus gracilis and cuneatus below lesion is affected-->complete loss of proprioception
what happens if their is an isolated nerve root lesion?
the sensory loss is in specific territories related to the nerves' innervation.
what happens with a Brown-sequard-spinal cord hemisection
Interruption of dorsal column on right side--> loss of proprioception on the right side (ipsilateral loss below level of lesion)
Damage ipsilaterally from corticospinal tract
Loss of pain and temp on opposite side (contralateral loss) below level of lesion (b/c this info crosses at each level immediately when it enters the spinal cord)
Ipsilateral loss AT THE LEVEL OF THE LESION b/c it is coming in here and attempting to cross
What is paraesthesia
"an abnormal positive sensory phenomena"
Description of this abnormal sensation might help us with localization of lesion