Lecture 7- Somatosensory Flashcards
1
Q
SOMATOSENSORY OVERVIEW
A
SOMATOSENSORY OVERVIEW
2
Q
Somatosensation is divided into _____ sensation and __________ sensation.
A
- skin sensation
- musculoskeletal sensation
3
Q
What are the 3 components of skin sensation?
A
- touch
- pain
- temperature
4
Q
What are the 2 components of musculoskeletal sensation?
A
- proprioception (muscle and tendon stretch, joint position, vibration)
- pain
5
Q
Describe the somatosensory pathway.
A
- sensory stimulus
- receptor
- threshold stimulation
- AP on peripheral (distal) axon/process of pseudounipolar sensory neuron in perpheral nerve
- pseudounipolar neuron soma located in dorsal root ganglia
- central (proximal) axon/process in dorsal root
- brainstem/spinal cord
1. withdraw reflex or
2. ascending tract- lower brain (REFLEX)
- cerebral cortex (VOLUNTARY RESPONSE)
6
Q
- The sensory pathway involves a _____ of neurons.
- Signal movement through the pathway is dependent on what 2 things?
- Signals often ____ to the other side.
A
- series
- diameter of axons, degree of axon myelination
- cross
7
Q
PERIPHERAL SOMATOSENSORY SYSTEM
A
PERIPHERAL SOMATOSENSORY SYSTEM
8
Q
What are the 6 types of receptors located in the Peripheral Somatosensory System and their function?
A
- ) Mechanoreceptors (stretch)
- respond to stimuli such as touch, pressure, stretch, vibration - ) Chemoreceptors
- detects changes in normal environment - ) Thermoreceptors
- detect temperature - ) Nociceptors
- detect pain - ) Tonic Receptors
- SLOW adapting to stimulus - ) Phasic Receptors
- RAPID adapting to stimulus
9
Q
What is the difference between tonic and phasic receptors?
A
- Tonic= slow adapting
- Phasic= rapid adapting
10
Q
What are the 3 types of sensory neurons and what signals do they carry?
A
- viscerosensory (general visceral afferent; GVA)- carry unconscious signals
- somatosensory (general visceral afferent; GSA)- carry conscious signals
- special sensory (special sensory afferent; SSA)
11
Q
Sensory neurons are ___________ in structure.
A
pseudo-unipolar
12
Q
What is the structure of a pseudo-unipolar neuron?
A
- peripheral (distal) axon
- soma
- central (proximal) axon
13
Q
Where are the soma of sensory neurons located?
A
- dorsal root ganglia (DRG)
- cranial nerve sensory ganglia
14
Q
If a sensory neuron is classified as a Aα it has a ______ conduction velocity.
If a sensory neuron is classified as a Ia it has a ________ fiber diameter.
A
- fast
- large
15
Q
- Most sensory neurons will be type __-__ nerve fibers.
- Pain is type __ neuron.
A
- II-III
- IV
16
Q
Skin sensation is ______sensory
A
somato
17
Q
- What is the receptive field?
- Are they the same as dermatomes?
A
- Area of skin innervated by a single sensory neuron
- No
18
Q
______ receptor fields and ________ density of sensory neurons give some body regions (finger tip) greater 2 point discrimination.
A
- smaller
- greater
19
Q
What are the fine touch receptors from superficial skin to deep?
A
- Merkel’s (touch)
- Meissner’s (touch, vibration)
- Pacinian (touch, vibration)
- Hair follicle receptor
- Ruffini (skin stretch)
20
Q
_______ receptor is the most sensitive to things touching the skin while _______ is the least.
A
- Merkel’s
- Ruffini
21
Q
Fine touch receptors allow good _________ of stimuli.
A
resolution
22
Q
All fine touch receptors transmit signals on ___ axons; so what can you conclude about the speed of transmission?
A
- Aβ
- generally quick conduction velocity in regards to sensory neurons
23
Q
- Course touch are ____ nerve endings.
- Course touch involves _______ localization. What is this?
A
- free
- crude, crude touch allows the subject to sense something has touched them without them being able to localize it
24
Q
Course touch receptors transmit signals on ___ axons, so are they faster or slower than fine touch receptors?
A
- Aδ
- slower
25
Pain (tissue damage) are carried by ________ which have ____ nerve endings that detect extremes of mechanical, chemical, and temperature stimuli.
- nociceptors
| - free
26
Pain receptors transmit signals on ___ and ___ neurons, are they fast?
- Aδ and C
| - No, they are the slowest signals
27
Proprioception is primarily determined by __________ receptors from stretch (_______) and pressure changes associated with changing the position of body segments.
- musculoskeletal
| - Ruffini
28
What is a dermatome?
area of skin with sensory innervation by a particular dorsal root
29
Muscle spindle fibers are __________ located inside muscle _______ to muscle fibers= intrafusal fibers.
- proprioreceptors
| - parallel
30
What are the 2 fibers that make up muscle spindles?
- nuclear chain muscle fiber
| - nuclear bag muscle fiber
31
The annulospiral receptor/group Ia sensory neurons detect ____________=rate of change. They are associated with both the nuclear chain and bag intrafusal fibers.
-dynamic length/stretch
32
The flower spray/ group II sensory neurons detect ____________. They are associated with ______ fibers more that ______.
- static length/stretch
| - chain, bag
33
What causes motor stimulation of intrafusal fibers
gamma motor neuron
34
Brain takes signals from muscle spindles in ALL muscles crossing a given joint to determine whether the body part at that joint is moving and where it is in space=___________.
proprioception
35
When whole muscle (_________ fibers) contracts via ________ motor neurons the muscle spindle fibers (__________ fibers) may also contract via ________ motor neurons to keep the spindle stretched/tense so it will remain _________ even when the whole muscle is shortening during contraction.
- extrafusal fibers
- alpha
- intrafusal
- gamma
- sensitive
36
Muscle spindles are capable of ________ and ____ signaling via Type Ia (annulospiral) and II (flower spray) afferent sensory neurons.
phasic and tonic
37
Golgi tendon organs are __________ organs located inside ________. These organs are very sensitive to ______ of the tendon.
- proprioceptive
- tendon
- tension (stretch)
38
Golgi tendon organs are Type ___ afferent neurons. They are part of a reflex that ________ muscle contraction to reduce stretch on muscle tendon.
- Ib
| - inhibit
39
Joint receptors respond to ________ deformation of joint capsule and ligaments= mechanoreceptors responding to stretch
-mechanical
40
What are the 4 joint receptors and their function?
- Paciniform- movement
- Ruffini- indicate end range; and passive movement
- Free nerve endings- pain from inflammation
- Ligament receptors- tension (stretch) receptors (golgi tendon organs)
41
What is proprioception and what are the 3 things it is a result of?
Awareness of joint position and movement
- muscle spindles
- joint receptors
- cutaneous mechanoreceptors
42
PATHWAYS OVERVIEW
PATHWAYS OVERVIEW
43
What is a tract?
bundle of axons in CNS with a common origin and destination
44
Pathway includes the _________ neuron that delivers information to the CNS tract and carries information from the tract to its final destination.
peripheral
45
Only neurons with long axons (___________ neurons) are included in pathway descriptions; pathways also contain __________ that interconnect pathways.
- projection
| - interneurons
46
What are the 3 types of pathways and where do they end?
- Conscious- pathways end in the cerebral cortex
- Divergent- pathways branch to end at many CNS locations for both conscious and unconscious perception
- Unconscious- pathways end at brain locations below the cerebral cortex ie. brainstem, cerebellum, diencephalon, limbic
47
A loop is the neural connection between a ________ and _______; it includes ______ pathway, ______ control center, and ________ pathway.
- receptor, effector
| - sensory, CNS, motor
48
What describes the location that a signal originates from?
fidelity
49
What is the difference between high and low fidelity?
- High fidelity- can pinpoint location of origin
| - Low fidelity- signals have a general origin
50
What allows precise identification of stimuli?
discriminative
51
Somatotopic organization is required for ______ fidelity signals
high
52
CONSCIOUS PATHWAYS
CONSCIOUS PATHWAYS
53
Typically, sensory pathways are _ neuron pathways.
3
54
Conscious pathways carry touch, pain, proprioception, and temperature signals to ________ gyrus of __________ lobe where _________ awareness of the body is generated.
- postcentral
- parietal
- conscious
55
Tracts of conscious pathways are arranged _______________ and end in the ________ which relays information to the homunculus of the somatosensory cortex.
- somatotopically
| - thalamus
56
The dorsal column/medial lemniscus tracts carry __________ touch (localization of stimulus and 2 point discrimination), and ________ proprioception (relative position and movement of body parts) information from the body to the __________ cortex postcentral gyrus.
- discriminative
- conscious
- contralateral
57
The cortex processes discriminative touch and proprioception together to facilitate __________, what does this mean?
stereognosis- identification of object based on touch and proprioception
58
The primary first order neuron of DCML tracts are _______-________ neurons that carries signals from the __________ to the medulla of the brain stem.
- pseudo-unipolar
| - periphery
59
The distal (peripheral) axon of the primary first order neuron of DCML tracts has discriminative _______ and _______ receptors and is located ______ to the DRG.
- touch and proprioception
| - distal
60
The soma of the primary first order neuron of DCML tracts is located in the ____________.
dorsal root ganglion (DRG)
61
The proximal (central) axon of the primary first order neuron of DCML tracts is ________ to the DRG. It carries the fasciculus _________ and _______ through the __________ column.
- proximal
- cuneatus and gracilis
- dorsal
62
The proximal (central) axon of the primary first order neuron of DCML tracts synapses in the _______ with the ____________ neuron in the nucleus __________ and __________.
- medulla
- second order neuron
- cuneatus and gracilis
63
Collaterals of the proximal (central) axon of the primary first order neuron of DCML tracts influence motor (refine motor signals for fine motor control), and other sensory signals both ___________ and __________
conscious and unconscious
64
The secondary second order neuron of DCML tracts carries signals from the _________ to the ___________ and has its soma in ____________ and ___________.
- medulla to the thalamus
| - nucleus gracilis and nucleus cuneatus
65
What is the path of the secondary second order neuron of the DCML?
- cross midline in decussation of medial lemniscus
- ascend in medial lemniscus through brain stem to the thalamus
- synapse in ventral posterolateral (VPL) nucleus of thalamus
66
The tertiary third order neuron carries from the _________ to the _________ and has its soma in ____________ of the thalamus.
- thalamus to the cortex
| - ventral posterolateral (VPL) nucleus
67
What is the path of the tertiary third order neuron?
- internal capsule (thalamocortical radiation)
| - synapse in postcentral gyrus of parietal lobe (somatotopic)
68
The trigeminal nerve carries discriminative touch and conscious proprioception information from the ______ to the __________ cortex.
- face
| - contralateral
69
The trigeminal nerve is divided into a _______, _________, and ________ neuron.
primary,secondary,tertiary
70
The distal axon of the primary neuron of the trigeminal nerve is located in the ________, _________, or ____________ nerve
opthalmic, maxillary, mandibular
71
The soma of the primary neuron of the trigeminal nerve is located in the __________ ganglion.
trigeminal/semilunar
72
The proximal axon of the primary neuron of the trigeminal nerve synapses in the main __________ of CN5 in the metencephalon of brain stem.
main sensory nucleus or mesencaphalic nucleus of CN5
73
The secondary neuron of the trigeminal neuron has its soma in the __________ nuclei or ________ nuclei for prooprioception from the jaw. The axon of the secondary neuron crosses to the contralateral side in the _____. It then ascends in ___________________ part of the medial lemniscus and synapses at the _______________ nucleus of the thalamus.
- main sensory or mesencephalic nucleus of CN5
- pons
- trigeminal lemniscus
- ventroposterior medial (VPM)
74
The tertiary neuron of the trigeminal nerve projects from the VPM of the thalamus to the ______________ via the internal capsule.
-postcentral gyrus
75
The spinothalamic tracts carries discriminative ____, _________, and _______ touch sensation to the contralateral cortex.
pain, temperature, crude
76
The spinothalamic tract is divided into 2 seperate tracts, what are they?
temperature and pain
77
The temperature spinothalamic tract is divided into __ neurons.
3
78
The temperature primary neuron of the spinothalamic tract has its soma in the ______. Its distal axon carries signals from ___________ via the peripheral sensory pathway. The proximal axon synapses in the _________ of the spinal cord.
- DRG
- free nerve endings
- dorsal horn (laminae I and II; substantia gelatinosa)
79
The temperature secondary neuron of the spinothalamic tract has its soma in the ________. Its axon crosses at the level of the ___________ and ascends via the _______________ tract of the spinal cord white matter. It synapses at the ____________ nucleus of the thalamus.
- dorsal horn
- spinal cord
- spinothalamic/ contralateral posterolateral
- ventroposterior lateral (VPL)
80
The temperature tertiary neuron of the spinothalamic tract has its soma at the __________ and the axons project to the ___________.
- ventroposterior lateral (VPL) nucleus of thalamus
| - postcentral gyrus
81
- Spinothalamic pain is fast pain that is _________.
| - The pain spinothalamic tract is divided into __ neurons.
- localized
| - 3
82
The pain primary neuron of the spinothalamic tract has its soma in the ______. Its distal axon carries signals from ___________ from the body to the DRG via peripheral sensory pathway. The proximal axon synapses in the _________ of multiple spinal cord levels.
- DRG
- nociceptors
- dorsal horn
83
What are the levels that the pain proximal axon synapses at and what NT stimulates it?
- lamina I, II, and IV
- substantia gelatinosa (I and II)
- nucleus proprius (V)
glutamate
84
The pain secondary neuron of the spinothalamic tract has its soma in the ______. The axon crosses to the ________ side (spinal cord ventral white commissure) and ascends in the _____________ column of the spinothalamic tract. It synapses in _________ nucleus of the thalamus.
- dorsal horn
- contralateral
- anterolateral
- ventroposterior lateral (VPL)
85
The pain tertiary neuron of the spinothalamic tract has its soma in the ________. The axons project to _______ and _________ somatosensory cortex.
- ventroposterior lateral (VPL)
| - primary and secondary
86
Fast pain from the face comes from what nerve?
Trigeminal
87
The pain primary neuron of the trigeminal tract has its soma in the ______ ganglia. Its distal axon carries signals from ___________ from the face to the trigeminal ganglion. The proximal axon synapses in the ____________ of CN5 in the medulla.
- trigeminal/semilunar
- nociceptors
- spinal nucleus
88
The pain secondary neuron of the trigeminal tract has its soma in the ___________ of CN5 in the medulla. Its axon crosses to contralateral side at the ________ and ascends trigeminal lemniscus to __________ nucleus of the thalamus.
- spinal nucleus
- medulla
- ventralposterior medial (VPM)
89
The pain tertiary neuron of the trigeminal tract has its soma in the _________ nucleus of the thalamus. Its axon projects to ____________ gyrus and ______________ cortex.
- ventralposterior medial (VPM)
- postcentral
- associative
90
Slow pain results from _____ damage and is carried in __ fibers. The destination is the _______ and __________ cortex.
- tissue
- C
- insula and associative sensory
91
DIVERGENT PATHWAYS
DIVERGENT PATHWAYS
92
Divergent pathways carry both _________ and _________ signals.
conscious and unconscious
93
What is the difference between the Lateral and Medial Pain Systems?
The lateral pain system is responsible for the sensory aspects of pain such as its locating the pain, while the medial pain system is responsible for the emotional aspects of pain, such as how unpleasant it feels.
94
The medial pain system does not go to ______, rather synapse on medial located gray of the CNS. This means that they are not ________ or __________. These are pathways with _______ number of neurons.
- cortex
- somatotopic or localizable
- variable
95
The first neuron of the Medial Pain System has its soma at the ______. The distal axon carries signals from _________ to the DRG. The proximal axon branches to multiple spinal cord segments and synapses at the _________ using __________ as the NT.
- DRG
- periphery
- dorsal horn
- substance P
96
The second neuron of the Medial Pain System has its soma at the _________. The axon crosses to __________ side. It then ascends in anterolateral spinal cord white column by 3 main tracts.
- dorsal horn
| - contralateral
97
What are the 3 main divergent neurons of the Medial Pain System diverging pathways?
- Spinomesencephalic
- Spinoreticular
- Spinolimbic
98
The spinomesencephalic tract goes to what 2 structures and for what purpose?
- Superior colliculus- turn head to position eyes on pain source
- Periaquiductal gray- descending pain modulation
99
The spinoreticular tract goes to the __________ to modulate ______ sensation to the ________.
- reticular formation of the brain stem
- pain
- thalamus
100
The spinolimbic tract goes to the anterior cingulated cortex to link pain sensation to ________ response.
emotional
101
Overall, the spinomesencephalic tract is for ____________ to pain, the spinoreticular tract is for ________, and the spinolimbic is for the __________ to pain.
- reflex movement
- intensity
- emotional response
102
UNCONSCIOUS PATHWAYS
UNCONSCIOUS PATHWAYS
103
Unconscious pathways carry proprioceptive and feedback information about activity in motor tracts to _________ to adjuct (refine) conscious movement.
-cerebellum
104
The Posterior Spinocerebellar Pathway is a __ neuron pathway that carries high fidelity, somatopic information from the lower body to the ______________ on the _________ side.
- 2
- cerebellar cortex
- ipsilateral
105
The primary neuron of the posterior spinocerebellar pathway has its soma at the ______. Its distal axon carries afferent signals from proprioreceptors in ______ and ________ toward the CNS. Its proximal axon ascends in the dorsal column to __________, nucleus dorsalis in T_ to L_ region.
- DRG
- legs and lower body
- dorsal horn
- T1-L2
106
The secondary neuron of the posterior spinocerebellar pathway has its soma at the ________. The axon ascends in the spinal cord and brain stem in posterior ___________ tract to the _______ cerebellar peduncle and synapses with the cerebellar cortex __________ to the stimulus.
- nucleus dorsalis (dorsal horn)
- spinocerebellar
- inferior
- ipsilateral
107
The Cuneocerebellar Pathway is a __ neuron pathway that carries high fidelity, somatopic information from the upper body to the ______________ on the _________ side.
- 2
- cerebellar cortex
- ipsilateral side
108
The primary neuron of the Cuneocerebellar Pathway has its soma at the ______. Its distal axon carries afferent signals from proprioreceptors in ______ and ________ toward the CNS. Its proximal axon ascends in the posterior column to synapse with ___________ _________ nucleus in the medulla.
- DRG
- arm and upper body
- lateral cuneate
109
The secondary neuron of the Cuneocerebellar Pathway has its soma at the ________. The axon ascends in the _________ tract, goes to the _________ cerebellar peduncle, and synapses with cerebellar cortex __________ to stimulus.
- lateral cuneate nucleus
- cuneocerebellar
- inferior
- ipsilateral
110
The Anterior Spinocerebellar Pathway is a __ neuron pathway to provide cerebellum feedback from spinal cord ventral interneurons to monitor activity of the __________. It is a ________ pathway.
- 1
- lower body
- crossed
111
The neuron of the Anterior Spinocerebellar Tract has its soma at __________ of spinal cord lateral and ventral horn in the thoracolumbar (lower body) region. Its axon crosses to contralateral side at the __________, ascends in the ___________ tract, goes to the _________ cerebellar peduncle. It then has collaterals to branch to synapse with both _____________.
- interneurons
- spinal cord
- spinocerebellar
- superior
- cerebellar hemispheres
112
The Rostrospinocerebellar Pathway is a __ neuron pathway to provide cerebellum feedback from spinal cord interneurons and motor activity of the ________. It carries to the _________ side.
- 1
- upper body
- ipsilateral
113
The neuron of the Rostrospinocerebellar Tract has its soma at ___________ of spinal cord ventral horn from the cervical (upper body) region. It ascends in the ipsilateral _____________ tract and goes to the _________ cerebellar peduncle, it then synpases with the ____________ cerebellar hemisphere.
- interneurons
- rostrospinocerebellar
- inferior and superior
- ipsilateral
