Central Somatosensory System

Question 1

What is managed at the spinal level in local neural circuits or by cerebellum to adjust movements and posture

Answer 1

Somatosensory Information

Question 2

Where does perception (interpretation of sensation) take place?

Answer 2

Thalamus and cerebral cortex

Question 3

Why is sensory feedback important?

Answer 3

Goal-directed movement

Question 4

Why are patients with somatosensory deficits more prone to injury?

Answer 4

They are unable to percieve excessive pressure, temperature, or stretch due to joint damage

Question 5

What is the following disorder called?

Individual is not able to percieve physical pain in any part of the body when injured

Answer 5

Congenital Insensitivity to pain

Question 6

What do pathways with high accuracy signals transmit?

Answer 6

Acurate signals about location, size, and intensity of stimulation

Question 7

In high-accuracy pathways a ____ of information similar to anatomic organization of the body is established

Answer 7

Somatotopic arrangement

Question 8

What is the following a definition of?

When a specific part of the body is associated with a distinct location in the central nervous system

Answer 8

Somatotopic arrangment

Question 9

Where in the body do we see somatotopic arrangment?

Answer 9

In the spinal cord

Question 10

What is somatotopically organized where it recieves information form the hands in a specific location and information from the feet in another location?

Answer 10

primary somatosensory cortex

Question 11

Where is the map of the parts of the somatosensory cortex that corresponds to specific parts of the body created and represented?

Answer 11

Sensory homunculus

Question 12

Are low-accurary pathways organized somatotopically?

Answer 12

No they are not well localized

Question 13

In the 3-neuron pathway where does the first neuron bring information from?

Answer 13

From a peripheral receptor into the central nervous system

Question 14

In a 3-neuron pathway what does the second neuron do?

Answer 14

Signals information to the thalamus

Question 15

In a 3-neuron pathway what does the third neuron do?

Answer 15

Conveys information from the thalamus to the somatosensory cortex

Question 16

What is the following a definiton of?

bundle of axons with the same origin and common termination

Answer 16

tract, column, leminscus, or fasicle

All the same thing

Question 17

What are somatosensory pathways named after?

Answer 17

Origin and termination of the tract that contains the second neuron in the sequence

Question 18

What is the following somatosensory information pathway called?

This pathway conveys information about location and type of stimulation to conscious awareness in the cerebral cortex

Answer 18

Conscious Relay Pathway

Question 19

What is the following somatosensory information pathway called?

This pathway transmits information to many locations in the brainstem and cerebrum and use pathways with variable numbers of nuerons

Answer 19

Divergent Pathway

Question 20

Which pathway transmits information with high accuracy?

Answer 20

Conscious Relay Pathway

Question 21

What is the following somatosensory information pathway called?

This pathway transmits nonconscious proprioceptive and other movement-related information to the cerebellum

Answer 21

Nonconscious Relay Pathway

Question 22

What Conscious Relay Pathway is this?

• Light touch and conscious proprioception
• Terminates in the primary somatosensory cortex

Answer 22

Dorsal Column Medial Leminscus

Question 23

What Conscious Relay Pathway is this?

• Fast nocicpetion and temperature
• Terminates in the primary somatosensory cortex

Answer 23

Spinothalamic

Question 24

What Divergent Pathway is this?

• Slow nociception
• Terminates in the periaqeductal gray of midbrain, superior colliculus

Answer 24

Spinomesencephalic

Question 25

# What Divergent Pathway is this? - Slow nociception - Terminates in the reticular formation

Answer 25

Spinoreticular

Question 26

# What Divergent Pathway is this? - Slow nociception - Terminates in the amygdala, ventral striatum of basal ganglia, insular cortex

Answer 26

Spinolimbic

Question 27

# What Nonconscious Relay Pathway is this? - Movement-related information - Terminates in the cerebellum

Answer 27

Spinocerebellar

Question 28

What type of information does the dorsal columns in conscious relay pathways carry?

Answer 28

Light touch and conscious proprioception

Question 29

What type of information do the anterolateral columns of the conscoius relay pathway carry?

Answer 29

Nociceptive, temperature, and crude touch

Question 30

Tracts with information for discriminative percption of stimuli localized with fine resolution are processed by what?

Answer 30

Cerebral cortex

Question 31

In the DCML pathway what happens when the sensory receptor is stimulated by light touch or conscious perpeption? ## Footnote DCML: dorsal column medial leminscus

Answer 31

the receptor depolarizes generating an axon potential that is transmitted along distal axon and then proximal axon in the PNS

Question 32

Where does the proximal axon go when it is stimulated by DCML pathway?

Answer 32

It enters the spinal cord via the dorsal root and ascends in the ipsilateral dorsal column

Question 33

Where do axons from the lower limb and lower trunk (below T6) reside in?

Answer 33

Medial section of the dosral column

Question 34

# What is the following a defintion of? Medial section of the dorsal column

Answer 34

Fasciculus Gracilis

Question 35

Where do axons from the upper trunk, upper limb, and neck (above T6) reside?

Answer 35

Lateral section of the dorsal column

Question 36

# What is the following a defintion of? Lateral section of the dorsal column

Answer 36

Fasciculus Cuneatus

Question 37

Axons that enter in fasciculus gracilis synapse with what?

Answer 37

Second-order neurons in the nucleus gracilis of the medulla

Question 38

Axons in the fasciculus cuneatus synapse with what?

Answer 38

second-order neurons in the nucleus cuneatus of the medulla

Question 39

# Where are these axons from? These axons decussate as internal arcuate fibers, then ascend to the thalamus as the contralateral medical lemniscus tract

Answer 39

axons from second-order neuron

Question 40

Where do second-order neurons synapse?

Answer 40

Area of the thalamus called ventral posterolatral nucleus

Question 41

What do third-order neurons connect?

Answer 41

Ventral Posterolateral nucleus to the thalamus to the somatosensory cortex

Question 42

What is the pathway that the sensory information of light touch and conscous proprioception take?

Answer 42

Ascends and synpases in the ventral posterior lateral nucleus of the thalamus on third order neurons to the primary somatosensory cortex

Question 43

Where is the primary somatosensory cortex located?

Answer 43

In the postcentral gyrus

Question 44

# Which area of the brain as the following function? Analyzing information from the primary somatosesory cortex and the thalamus to provide sterogenesis and memory of the tractile and spatial environment

Answer 44

Secondary somatosensory area

Question 45

Where is the secondary somatosensory area located?

Answer 45

Located posterior to the primary somatosensory cortex

Question 46

# What is the following a defintion of? The area of the primary somatosensory cortex devotes to a specfic part of the body; surrounds the cortex

Answer 46

Homunculus

Question 47

What does the homunculus illustrate?

Answer 47

Proportions and arrangement of cortical areas that contain representation of the surface of the body

Question 48

Which two pathways ascend together in the anterolateral spinal cord?

Answer 48

- Conscious Relay Pathway - Divergent Pathway

Question 49

What do the free nerve endings in first-order neurons respond to?

Answer 49

Noxious mechanical stimulation or to noxious meachnothermal stimulation

Question 50

How do the peripheral axons of the A(delta) fibers transmit information?

Answer 50

From free nerve endings along lightly myelinated axons to the cell body

Question 51

# Which axon is this? Enters spinal cord then branches to several levels of the spinal cord in the dosrolateral tract before entering and terminating inthe dorsal horn

Answer 51

Central axon

Question 52

# Which axon is this? This axon crosses the midline in the anterior commissure, then ascends to the thalamus in the spinothalamic trat

Answer 52

Axon of the second-order neuron

Question 53

# Which neuron is this? This axon arises from ventral posterolateral nucleus and projects to the primary and secondary somatosensory cortices

Answer 53

Third-order neuron

Question 54

# What is the following somatosensory information called? Conveys nondiscriminative tractile information and is transmitted by C fibers

Answer 54

Crude touch

Question 55

Where does crude touch project?

Answer 55

Anterior and posterior insula

Question 56

What is discriminative temperature information detected by?

Answer 56

Specialized free nerve endings of small myelinated and unmyelinated neurons

Question 57

A(delta) fibers carry impulses produced by ___

Answer 57

cooling

Question 58

C fibers carry information regarding ____

Answer 58

Heat

Question 59

In the spinothalamic tract fibers carrying information from the lower body are found ____

Answer 59

laterally

Question 60

In the spinothalamic tract fibers from higher levels are found ____

Answer 60

Medially

Question 61

Ascending axons in the spinothalamic tract are ____ neurons and most ascend ____

Answer 61

second order; contralaterally

Question 62

Where do the second-order neurons in the dorsal column and spinothalamic tracts end?

Answer 62

Ventral posterolateral nueclus of the thalamus

Question 63

Third-order neurons from dorsal column and spinothalamic pathways project from the ____ to the ____ cortex,

Answer 63

Thalamus; Primary Somatosensory Cortex

Question 64

Responses the nociception depend on a divergent ascending group of neurons called the ____

Answer 64

Medial nociception system

Question 65

Where do medial nociception system projection neurons synapse?

Answer 65

Medial locations in the CNS

Question 66

What are the first-order neurons of the slow nociceptive pathways?

Answer 66

Small, unmyelinated C fiber that transmits information to the spinal cord the same way it does as first-order neuronin spinothalamic pathway

Question 67

Aching, poorly localized pain is which slow nociceptive tract?

Answer 67

Spinolimbic

Question 68

Which two areas of the midbrain does spinoemesencephallic tract transmit slow nocicpetive information?

Answer 68

Superior colliculus and peraqueductal gray

Question 69

What is the role of superior colliculus?

Answer 69

Visual reflexes

Question 70

What is the role of periaqueductal gray?

Answer 70

Activiates descending tracts that moduclated incoming nocieptive signals and is part of descending nociceptive control system

Question 71

Where does spinoreticular ascending tract terminate?

Answer 71

Brainstem Reticular Formation