M2-C2-Review For Somatic Sensory Systems

Front 1

Each somatic sensory system contains what three neurons?

Back 1

1. Ganglion cell synapse
2. Projection cell synapse
3. Thalamic cell synapse

Front 2

Briefly describe a ganglion cell synapse.

Back 2

Unipolar neuron with a receptor

Front 3

What happens with a projection cell synapse?

Back 3

Axon decussates

Front 4

Where does the thalamic cell synapse project to?

Back 4

Sensory cortex

Front 5

All neurons of the somatic sensory system contains what?

Back 5

Contains a receptive field

Front 6

Define Receptive Field.

Back 6

Area of a skin which when stimulated either increases or decreases the firing rate of that cell.

Front 7

All receptive field has what two things?

Back 7

Excitatory center

Inhibition surround

Front 8

Define lateral inhibition.

Back 8

A mechanism by which neurons determine more specifically the origin of stimulus. A stimulated neuron will suppress the stimulation of neighboring neurons.

Front 9

Define Receptor.

Back 9

Sensory terminal whose membrane response to stimulus producing a local, graded, usually depolarizing potential (increased Na+ & K+ conductance)

Front 10

Define adequate stimulus.

Back 10

Unique for each type receptor,

it is the minimum stimulus needed to cause the receptor membrane to be depolarized.

Front 11

What allows each type of receptor to make a unique contribution to somatic sensation.

Back 11

Adequate stimulus

Front 12

Define adaptation

Back 12

Decrease in receptor potential with continued stimulation.

Front 13

List all the slowly adapting receptors. x7

Back 13

Meckels Disk
Ruffini Ending
Golgi Tendon Organ
Muscle Spindle
Warm & Cold
Free nerve endings
Pain

Front 14

List all the rapidly adapting receptors.

Back 14

Meissner Corpuscle
Pacinian Corpuscle
Peritrichial ending

Front 15

List the Axonal categories including:
- AKA
- Thickness
- Speed
- Myelination

Back 15

Type I: A alpha - Large, fastest, and myelinated
Type II: A beta - Medium, faster, and myelinated
Type III: A delta - Small, fast, and myelinated
Type IV: C - Small, slow, and UNmyelinated

Front 16

Afferents to the spinal cord form what two divisions in the dorsal root?

Back 16

Medial division
Lateral division

Front 17

The medial division contains what type of nerve fibers?

Back 17

Type I & II

Fast

Front 18

The medial division mediates what type of sensory modalities?

Back 18

Discriminative touch
Pressure
Proprioception

Front 19

The lateral division mediates what type of sensory modalities?

Back 19

Pain
Temperature

Front 20

The lateral division contains what type of nerve fibers?

Back 20

Type III & IV

Slow

Front 21

Crude (light) touch is mediated by what nerve fibers?

Back 21

II & III

Front 22

Peripheral nerves carry which type of modalities and fibers?

Back 22

All sensory modalities + motor fibers

Front 23

During nerve fiber segregation in the medial and lateral divisions, the large fibers enter what?

Back 23

Dorsal Funiculus

Front 24

During nerve fiber segregation in the medial and lateral divisions, the small fibers enter what?

Back 24

Lissauer's Tract

Front 25

Nerve fibers entering either the Dorsal funiculus or Lissauer's Tract have what three functions?

Back 25

1. Reflexes
2. Muscle Coordination
3. Conscious sensation

Front 26

Nerve fibers responsible for reflexes do what?

Back 26

Make reflex connections with motor neurons

Front 27

Nerve fibers responsible for muscle coordination provide input to where?

Back 27

Cerebellum

Front 28

Nerve fibers responsible for conscious sensation provide input to where?

Back 28

Cerebral Cortex

Front 29

Define protopathic.

Back 29

General, nondiscriminating, poorly-localized responsiveness to stimuli

Front 30

Define epicritic.

Back 30

Precise, well-localized responsiveness to stimuli

Front 31

Most protopathic senses are mostly conveyed where?

Back 31

Spinothalamic tract

Front 32

Most epicritic senses are mostly conveyed where?

Back 32

Dorsal Column Medial Lemniscus tract (DCML)

Front 33

Both the Spinothalamic tract and the DCML tract go where via where?

Back 33

Somatosensory cortex

via Thalamus

Front 34

What are the categories of Thalamic nuclei?

Back 34

1. Specific Sensory Nuclei
2. Specific Motor Nuclei
3. Nonspecific Nuclei
4. Association Nuclei

Front 35

What are the two functional states of the cerebral cortex due to the interplay of thalamocortical activity?

Back 35

Synchronized (Slow sleep wave)

Desynchronized (Awake or REM sleep)

Front 36

The two functional states of the cerebral cortex is due to what?

Back 36

Interplay of the thalamocortical activity.

Front 37

The lateral surface of the thalamus, covered by GABA neurons comprise what?

Back 37

Reticular nucleus

Front 38

Axons of tertiary (thalamic) neurons terminate mainly in? which is where? in which gyrus?

Back 38

In layer IV

of the Primary Somatosensory Cortex (Area SI)

in the Postcentral gyrus

where sensations are perceived.

Front 39

Name the Brodmann's cytoarchitectonic areas of the Primary Somatosensory cortex (Area SI)

Back 39

1
2
3a
3b

Front 40

Which Brodmann's areas are responsible for Tactile sensory?

Back 40

1
3b

Front 41

Which Brodmann's areas are responsible for Proprioceptive sensory?

Back 41

2
3a

Front 42

Our subjective sensations result from the integration of what two areas?

Back 42

Area SI (primary somatosensory cortex)

Sensory Association areas

Front 43

Unlike Protopathic, Epicritic is highly dependent on which area?

Back 43

Cerebral cortex

Front 44

Describe a dermatome's association with adjacent dermatomes.

Back 44

One will overlap the adjacent one by one-half.

Front 45

What does it mean for something to be somatotopically organizaed?

Back 45

Adjacent parts of the dermatome are represented in adjacent parts of the cortex. Neighborhood relationships are preserved.

Front 46

Neurons in DCML have receptive fields of what size and density?

Back 46

Small and high density

Front 47

What are the five epicritic sensations conveyed in the DCML?

Back 47

1. Discriminative Touch
2. Stereognosis
3. Graphesthesia
4. Vibratory sense
5. Proprioception

Front 48

All epicritic sensations of the DCML require high degrees of what? x2

Which is made possible by what? x2

Back 48

1. Spatial resolution
2. Temporal resolution

Small receptive fields
Large, rapidly-conducting axons

Front 49

Dorsal column axons synapse where?

Back 49

Medullary dorsal column nuclei

Front 50

DCML senses from the upper body (T6 and above) ascend in where?

Back 50

Fasciculus Cuneatus

Front 51

DCML senses from the lower body (T7 and below) ascend in where?

Back 51

Fasciculus Gracilis

Front 52

What is the exception to the rule for a DCML sense that ascends in the spine?

Back 52

Some proprioception ascends in the dorsal part of the lateral funiculus

Front 53

Axons in the Nucleus Cuneatus and Nuclues Gracilis cross the midline in the what? and form the what?

Back 53

Sensory Decussation

Medial lemniscus

Front 54

What type of orientation does the medial lemniscus have in the midline of the medulla?

Back 54

Vertical orientation

Front 55

Nerve fibers of the medial lemniscus terminate where?

Back 55

Ventral Posteriolateral (VPL) thalamic nucleus.

Front 56

In order to get to the postcentral gyrus, the axons of the VPL must project through what?

Back 56

Posterior limb of the Internal Capsule.