Neuroanatomy: Somatosensory I & Ii (Lundy)

Front 1

Sensory System responsible for transmitting touch, vibration, and conscious proprioception

Back 1

Dorsal Column/Medial Lemniscus Pathway

Front 2

The fine sensation of the dorsal column pathway is detected by _____ ______ that lie in the skin.

Back 2

Meissner's Corpuscles

Front 3

Which part of the dorsal column do axons from the lower body travel in?

Back 3

The more medial fasciculus cuneatus.

Front 4

Which part of the dorsal column do the axons from the upper body travel in?

Back 4

The more lateral fasiculus gracilis (only present at higher spinal levels).

Front 5

The secondary neurons of the Dorsal column pathway cross over where? What are they called?

Back 5

They cross in the medulla and are called internal arcuate fibers.

Front 6

The axons of the secondary neurons in the DCP synapse where?

Back 6

In the Thalamus

Front 7

The third neuron in the DC/ML Pathway travels through what and synapses where?

Back 7

They travel up the posterior limb of the internal capsule and synapse on the primary sensory cortex. The lower body is most medial and upper body is more lateral.

Front 8

Which pathway transmits information to the thalamus about pain, temperature, itch, and crude touch?

Back 8

The spinothalamic pathway.

Front 9

Where does the spinothalamic pathway decussate?

Back 9

At the level of the spinal cord.

Front 10

The cell bodies of the neurons of the spinothalamic pathway are located where?

Back 10

Principally within the dorsal horn of the spinal cord.

Front 11

What are the two divisions of the Spinothalamic tract?

Back 11

Lateral ST and Anterior ST

Front 12

Which senses are located in the Lateral Spinothalamic Tract?

Back 12

Pain and Temperature

Front 13

Which sense is located in the Anterior Spinothalamic Tract?

Back 13

Crude touch

Front 14

The primary axons of the ST tract lead from the skin to the spinal cord where they ascend or descend one or two vertebral levels in _______ ______.

Back 14

Lissauer's Tract

Front 15

The primary neurons of the ST tract synapse with the secondary neurons located where?

Back 15

Substantia Gelatinosa or Nucleus Proprius

Front 16

The secondary axons of the ST tract decussate where? What are they called? Where do they end up?

Back 16

The decussate in the spinal cord, as the anterior white commissure, and end up in the anterolateral part of the spinal cord.

Front 17

The third order neurons in the in ST pathway are located where?

Back 17

In one of several nuclei in the Thalamus (MD, VPL, or VMP)

Front 18

Which three places do the third order neurons in the ST pathway synapse in the higher bain?

Back 18

Cingular, primary somatosensory, and insular cortex

Front 19

A unilateral lesion in the ST pathway usually causes _________ anesthesia and usually begins where?

Back 19

Causes contralateral anesthsia and starts 1-2 segments below the level of the spinal lesion, affecting all lower body areas.

Front 20

Set of axonal fibers originating in the spinal cord and terminating in the ipsilateral cerebellum.

Back 20

Spinocerebellar Tract

Front 21

Which tract conveys information to the cerebellum about limb and joint position?

Back 21

Spinocerebellar Tract

Front 22

The proprioceptive information of the SC tract is obtained by which two things?

Back 22

Golgi Tendon Organ and Muscle Spindles

Front 23

What is the name given to a group of interneurons foudn in lamina VII?

Back 23

Clarke's Nucleus

Front 24

The unconscious proprioceptive information is processed where?

Back 24

Cerebellum

Front 25

Which tract invoves two neurons and remains on one side of the body?

Back 25

Spinocerebellar tract.

Front 26

Where are the second order neurons of the SC pathway located?

Back 26

Clarke's Nucleus

Front 27

Ascending pathway in the nervous system that conveys pain, temperature, and crude touch. Travels from where to where?

Back 27

Anterolateral system. Conveys from the periphery to the brain.

Front 28

What are the three main pathways that make up the anterolateral system?

Back 28

1. Spinothalamic (lateral & anterior)
2. Spinoreticular
3. Spinotectal

Front 29

Which division of the anterolateral system is important for the localization of pain and temperature?

Back 29

Spinothalamic tract

Front 30

Which division of the anterolateral system is responsible for alertness and arousal?

Back 30

Spinoreticular Tract

Front 31

Which division of the anterolateral system is responsible for orienting the eyes and head towards stimuli?

Back 31

Spinotectal Tract

Front 32

What is the destination of the spinothalamic tract?

Back 32

Thalamus

Front 33

What is the destination of the spinoreticular tract?

Back 33

The reticular formation

Front 34

What is the destination of the spinotectal tract?

Back 34

Tectum

Front 35

Damage to the anterolateral system would cause what deficits?

Back 35

deficits in pain and crude touch

Front 36

Pain and temperature information is carried from free nerve endings by which two fibers?

Back 36

1. A delta Fibers (small, myelinated)
2. C Fibers (unmyelinated)

Front 37

A delta fibers and C fibers (transmit pain) are both thought to use which neurotransmitter?

Back 37

P Substance

Front 38

Both A and C fibers in the pain pathway can ascend or descend a few spinal levels in which tract?

Back 38

Lissauer's Tract

Front 39

Which fibers transmit fast pain which is sharp and well localized?

Back 39

A Delta Fibers

Front 40

Which fibers transmit slow pain which is dull, aching, and not well localized?

Back 40

C Fibers

Front 41

The A Delta (fast) pain fibers feed primarily into which tract?

Back 41

The spinothalamic pathway.

Front 42

The C (Slow) pain fibers feed primarily into which tract?

Back 42

The spinoreticular pathway.

Front 43

The cell bodies of the 2nd order neuron in the fast pain pathway are located where?

Back 43

In laminae I and V of the dorsal horn.

Front 44

The cell bodies of the 3rd order neuron in the fast pain pathway is located where? Where do they go from there?

Back 44

In the VPL of the thalamus. They then pass through the post. limb of the internal capsule and terminate in the somatosensry cortex.

Front 45

The cell bodies of the 2nd order neurons in the slow pain pathway are located where? Where do they go from there?

Back 45

In Laminae II (substantia gelatinosa) of the dorsal horn of the spinal cord.
From there they go to the reticular formation bilaterally.

Front 46

Where are the cell bodies of the 3rd order neuron in the slow pain pathway?

Back 46

In the intralaminar nuclei of the thalamus.

Front 47

Thalamic projections from the slow pain pathway go where? (3 places)

Back 47

1. Postcentral Gyrus
2. Insula
3. Anterior Cingulate Gyrus

Front 48

Where does the spinotectal tract terminate?

Back 48

The asceding axons terminate in the tectum of the midbrain (periaqueductal grey and superior colliculus)

Front 49

Why is there a sparing of pain and temperature sensation in the sacral region when the spinothalamic pathway has compromised blood flow?

Back 49

Because the sacral dermatomes are represented laterally and supplied by vessels that run on the surface of the cord. So it is not affected by compromised blood supply or lesions in the internal cord.

Front 50

What is the effect on pain and temperature sensation if a lesion is located in the anterior white commissure?

Back 50

It disrupts pain and temperature sensation bilaterally- meaning an entire ring on the body will be missing these sensations

Front 51

What does hemisection of the cord do to pain and temperature sensation?

Back 51

It causes contralateral loss of pain and temp and ipsilateral loss of discriminative touch.

Front 52

What do medial lesions in the medulla do to sensation? Lateral lesions?

Back 52

Medial lesions in the medulla disrupt contralateral discriminative touch. Lateral lesions disrupt contralateral pain and temp.

Front 53

In the Pons and above the pathways conveying all modalities from the contralateral body travel together in what?

Back 53

They travel in the Thalamus VPL.

Front 54

What is the effect of small lesions in the pons?

Back 54

Hemianesthesia- loss of pain, temp, and touch for the contralateral half of the body.

Front 55

Lesions in the ventral posterior thalamus can cause a period of analgesia followed by chronic pain. What is this called?

Back 55

Thalamic pain syndrome.

Front 56

What is the effect of damage to the somatosensory cortex on the perception of pain?

Back 56

It can reduce the ability to localize pain but doesn't eliminate the ability to feel pain.

Front 57

The activity of non-nociceptive fibers terminating on spinothalamic tract cells can have what effect?

Back 57

It can act to inhibit the tract cells and prevent the transmission of nerve impulses.

Front 58

Pain that originates in the viscera but is perceived in other parts of the body

Back 58

Referred Pain.

Front 59

Why does referred pain happen?

Back 59

Because visceral and somatic information converges on single cells in the pain pathways.

Front 60

What appears to be the mechanism in chronic pain following injury?

Back 60

Damage to the nerves can cause loss of tonic inhibition in central pain pathways. The pain results from the hyperactivity of cells that have had their normal inputs removed.

Front 61

What are the three opiate like substances that are important in the pain pathways?

Back 61

1. Endorphins
2. Enkephalins
3. Dynorphins

Front 62

To modulate pain sensetivity, axons from the periaqueductal gray go to the ______ ______ ______ including a group called the ________ ________.

Back 62

Medullary Reticular Formation, Raphe Nuclei

Front 63

Raphe cells use ________ as a neurotransmitter and activate ________ cells in the spinal cord which supress pain transmission.

Back 63

Serotonin, enkephalin cells.

Front 64

Damage to __________ pathways can lead to severe motor deficits.

Back 64

Spinocerebellar

Front 65

Damage to the spinocerebellar tract does what?

Back 65

Causes loss of unconscious proprioception and thus, uncoordinated movement. It doesn't eliminate conscious proprioception (dorsal column system).

Front 66

All the 2nd order neurons of the spinocerebellar pathway terminate where?

Back 66

In the cerebellum on the same side.

Front 67

Cairres unconsious proprioceptive information from the trunk and leg.

Back 67

Dorsal spinocerebellar tract

Front 68

Carries unconscious proprioceptive information from the arm and neck.

Back 68

Cuneocerebellar tract

Front 69

Where is Clarke's Nucleus (nucelus dorsalis) located? What is found here?

Back 69

In the spinal cord from C8 to L2.
The 2nd order neurons in the dorsal spinocerebellar tract are found here.

Front 70

Axons from the dorsal and cuneo spinocerebellar tracts enter the cerebellum through what?

Back 70

Through the inferior cerebellar peduncle.

Front 71

All trigeminal axons enter the brainstem where?

Back 71

At the mid-pons.

Front 72

What are the three divisions of the trigeminal nucleus?

Back 72

1. Spinal trigeminal nucleus
2. Chief Sensory Nucleus
3. Mesencephalic Nucleus

Front 73

What senses is the Spinal Trigeminal Nucleus and Tract responsible for?

Back 73

Pain and temperature.

Front 74

What is the Chief sensory nucleus of the trigeminal nerve responsible for?

Back 74

Discriminative touch

Front 75

What is the mesencephalic nucleus of the Trigeminal nerve responsible for? How is it unique?

Back 75

Nonconscious proprioception. Its unique because it is the one place in the CNS where the cell bodies of pimary afferent fibers are found.