2.1 Spinal Cord: Sensory (ascending) Pathways

Question 1

What does the sensory system use for sensing the environment

Answer 1

1) External- exteroreceptors
2) Internal- interoreceptors
3) Spatial orientation- proprioceptors

Question 2

List external- exteroreceptors:

Answer 2

• Touch
  * Pain
• Thermal
• Vision
• audition
• olfaction
• gustation

Question 3

List internal- interoreceptors:

Answer 3

• Visceral
• Stretch
• pH
  *CO2

Question 4

List Spatial orientation: proprioceptors & where they’re found on the body:

Answer 4

• Location: head, body, vestibular apparatus
• tactile/pressure receptors
• joints, muscle spindles (stretch)
• golgi tendon organs
• ear (hair cells)

Question 5

Where do proprioceptors​ feed into the brain?

Answer 5

• somatic sensory regions
• cerebellum (unconscious​ propreoception)

Question 6

General Somatic Sensation (GSS) aka Afferent (GSA): Types

Answer 6

• Modality
• Dendritic zone

Question 7

Modality =

Answer 7

what part of the environment is being sensed?

Question 8

Dendritic zone =

Answer 8

on or near the surface of the body
• Pain
• Temperature
• Touch
• Pressure
• Kinaesthesia, sense of motion,
• conscious proprioception

Question 9

What information is received at the somatosensory Cortex?

Answer 9

conscious information

Question 10

What is this diagram showing us?

Answer 10

The lower extremities are mapped at the higher part of the brain at the most dorsal aspect

The higher extremities are mapped at the lateral side of the lower cerebral hemisphere

**inverse mapping

Question 11

If I’m​ typing / usi​ng my fingers what part of the brain is responsible?

Answer 11

Parietal lobe

Question 12

What does the parietal lobe receive​ and process?

Answer 12

All somatosensory input ( touch, pain)

Question 13

Parietal lobe =

Answer 13

homunculus

Question 14

3 key points to remember about the somatosensory cortex?

Answer 14

• inverted image
• disproportionally arranged
• regular somatotopic organization​

Question 15

GSS species differences: disproportional homunculus examples

Answer 15

raccoon​: large forehands
camel: large lips
naked mole rats: (blind) uses teeth to burrow
pig: large snout for rooting

Question 16

What are the 3 sensory pathways /tracks?

Answer 16

1. dorsal column
2. spinothalamic​ tracts
3. spinocervicothalamic tracts

** All merge to join medial lemniscal systems

Question 17

What part of the brain does the medial lemniscal system deal with?

Answer 17

hindbrain

Question 18

Are the tracts that go from the periphery to the higher centers

Answer 18

dorsal column

Question 19

The dorsal​ column splits up the?

Answer 19

gracile tract into hindlimb,

Question 20

The dorsal column governs the hindlimb in terms of ?

Answer 20

touch, pressure, kinaesthesia

Question 21

The spinothalamic​ tract:

Answer 21

• dominate in humans
• important for pain sensation
• superficial “pin-prick” pain, temperature (skin, viscera)

ex: hand on oven

Question 22

spinocervicothalmic tracts

Answer 22

• touch
• pressure
• some superficial pain (skin)

Question 23

The thalamus​ is responsible for​?

Answer 23

prioritizing​ and filtering information to the cortex

Question 24

which tracy is prominent in carnivores ?
ex: cat walking on fence

Answer 24

spine cervical​ tract

Question 25

Medial Lemniscal System origin, termination, & what it runs through

Answer 25

1. Located in the ​medulla oblongata 2. Thalamus relays information to the cerebral cortex which acts as an important filter for information (sorting office) 3. Final site of perception is in general sensory cortex

Question 26

Medial Lemniscal System components, do fibers decussate, & is it ipsilateral or contralateral

Answer 26

- Composed of bundle of heavily myelinated axons - Decussation of fibers - Mainly contralateral (bilateral) relay close to midline

Question 27

which tracts merge to join Medial Lemniscal System

Answer 27

- Dorsal columns - Spinothalamic - spinocervicothalamic **except joint &muscle proprioception

Question 28

Spinal relay tracts are predominately utilized & ​merge for Medial Lemniscal System

Answer 28

A) Dorsal columns gracile-cuneate B) spinocervicothalamic used more than spinothalamic all merge to form a system except joint & muscle proprioceptio

Question 29

Tracts Dorsal Columns (DC) uses

Answer 29

- gracile tract for hindlimb - cuneate tract for forelimb

Question 30

Ascending reticular formation spinoreticular tracts (AscRF) what does deep pain loss indicates

Answer 30

significant bilateral spinal cord lesion

Question 31

Ascending reticular formation spinoreticular tracts (AscRF): information relay process

Answer 31

A) Information at Spinal cord B) Information relayed to reticular formation C) Information relayed to thalamus D) Information relayed to cerebral cortex

Question 32

Ascending reticular formation spinoreticular tracts (AscRF): how does the tract run in relevance to the spinal cord

Answer 32

Bilateral relay close to midline of body

Question 33

Spinocerebellar tract (ScerbT): triggers

Answer 33

* Subconscious proprioception * Used in co-ordination & finetuning motor activity

Question 34

Spinocerebellar tract (ScerbT): how does the tract run in relevance to the spinal cord

Answer 34

* 2-neuron pathway * Ipsilateral relay (stimulated side of body gets sent to symmetrical side of brain)

Question 35

Spinocerebellar tract (ScerbT): how does the tract run in relevance to the spinal cord

Answer 35

* 2-neuron pathway * Ipsilateral relay (stimulated side of body gets sent to symmetrical side of brain)

Question 36

Spinocerebellar tract (ScerbT): What symptoms are expected for a clinical scenario diagnosis:

Answer 36

* Incoordination: Ataxia (cerebellar disturbance, afferent kinesthetic deficit) * Vestibular: loss of balance, wide based stance * Alcohol 'drunken' gait

Question 37

Spinocerebellar tract (ScerbT): Conscious stimuli relay process:

Answer 37

A) Information at Spinal cord B) Information sent to cerebral cortex as proprioception control center

Question 38

Spinocerebellar tract (ScerbT): unconscious stimuli relay process:

Answer 38

A) Information at Spinal cord B) Information sent to cerebellum as proprioception control center

Question 39

Pain transmission &reception: what is the clinical significance, what does it indicate &how does the tract run in relevance to the spinal cord

Answer 39

* Enormous clinical significance * Pain fibers lie throughout cord &are very resilient, indicating loss of ALL pain sensation has very poor prognostic - 2 pathways used

Question 40

Which 2 tracts are utilized for pain transmission &reception

Answer 40

1) Delayed, slow, or true pain sent to SRetT (spinoreticuothalamic tract) 2) Fast, initial, or pin prick pain sent to STT (spinothalamic tract)

Question 41

Explain general principles of lesion localization in sensory pathways within the CNS.

Answer 41

1. presence/ absence of sensory deficit (neurological examination) determining what lesion is 2. Neuroanatomical localization of where lesion is 3. etiological basis of neurological lesion for why it's occurred

Question 42

Ascending reticular formation spinoreticular tracts (AscRF): triggers

Answer 42

* True pain (everything other than "pin-prick") * In superficial & deep tissues * All intensities (itching, aches, agony) * Arousal

Question 43

Visceral pain traits:

Answer 43

* Poor localization * Can be extreme (especially distension) * Can induce skeletal muscle spasm Can be referred to somatic areas served by same spinal nerve (angina)

Question 44

Relay information process if slow, delayed or true pain:

Answer 44

Question 45

Relay information process if fast, initial, or pin prick pain

Answer 45

Question 46

Nociception - key points

Answer 46

- conscious perception of a noxious stimulus + unpleasant emotional response - can stimulate reflex activity or transmitted to brain via sensory pathways found on both sides of spinal cord -hyperalgesia: tissue damage - visceral pain