Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

202: Theme 1, Fundamental neuroscience and the brain > Physiology of spinal cord > Flashcards

Physiology of spinal cord Flashcards

You may prefer our related Brainscape-certified flashcards:
The Brain flashcards
1
Q

Functions of spinal cord

A

Initial processing of somatosensory input by the CNS.

Final processing of motor output by the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mechanoreceptors

  • Modality
  • Afferent fibre type
  • Conduction velocity
  • Examples
A

Detects touch, pressure and vibration.

A-beta fibre type

Wide diameter= fast conduction velocity

Examples:

  • Merkell’s cells
  • Ruffini end organs
  • Pacinian corpuscles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Bare nerve ending for pain

A

Fast pricking pain

  • A-delta fibres
  • medium diameter
  • Medium speed conduction velocity.

Slow burning pain/itch

  • C-fibres
  • Thin diameter
  • Slow conduction velocity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Meissner’s corpuscle

A

Cutaneous mechano-sensory receptor

  • Sensitive to shear forces/ light touch
  • On smooth skin [hairless] like the hands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Merkel disk

A

Cutaneous mechanosensory receptors

  • Sensitive to contact
  • Appears on smooth skin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ruffini’s corpuscle

A

Cutaneous mechanosensory receptor-

- Sensitive to tension, folding and stretching on smooth skin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pacinian corpuscle

A

Cutaneous mechanosensory receptor
- Sensitive to deep pressure and vibrations in the skin

  • Transmits afferent signal to the dorsal root ganglion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Two point discrimination

A

Measurement in the variation of sensitivity to tactile discrimination.
- High density of mechanoreceptors = the smaller the distance tactile stimuli can be discrimination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Density of mechanoreceptors throughout the body

A

Greatest on the hand and face

Detection of stimuli here has a much greater spatial resolution than the rest of the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Lower motor neurones

A

Final common path for all signals from CNS to skeletal muscles

Longitudinal organised columns

  • Alpha and gamma axons
  • Supply one muscle of functionally similar muscles
  • Extends through more than one spinal cord segments

Muscles
- Receive motor inout from more than one ventral root and spinal nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Alpha and gamma axons

- Longitudinal organised columns

A

Alpha- thick axons with high conduction velocity

Gamma- thin axons with low conduction velocity

Organised in columns to supply a muscle or a group of functionally similar muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Paresis

- Organised columns

A

Results from the destruction of a single ventral root or single spinal nerve
- Each muscle receives motor input from more than one ventral root and spinal nerve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

A motor unit

A

A single alpha motor neurone and the muscle fibres it innervates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Prioproceptive sensory organs

A

Muscle spindles

  • Negative feedback regulation of muscle length
  • Due to passive stretch

Golgi tendon organs

  • Negative feedback regulation of muscle tension
  • Due to contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Stretch reflex circuit

A

Monosynaptic

  1. Muscle spindle initiates the reflex
    - Sensory receptor
  2. Stretch increases la afferent activity
    - Increases alpha motor neurone activity
    - Contracts the same muscle
  3. Stretch reflex
    - Negative feedback loop
    - Regulates muscle length via descending tracts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Flexion reflex

- Pain in foot example

A

Polysynaptic pathway
- Spinal cord circuit

  1. Stimulation of cutaneous pain receptors in foot [i.e stepping on sharp object]
  2. Activation of spinal cord circuits= flexion at stimulated extremity
    - Extension at other extremities for support.
17
Q

Anterior cord syndrome

A

Lesion to the anterior spinal cord

Damage of lower motor neurones

  • Bilateral lower motor neurone paralysis
  • Muscular atrophy in segment of lesion

Loss of anterior descending tract
- Bilateral spastic paralysis below the level of lesion

Loss of anterior and lateral spinothalmic tracts
- Bilateral loss of pain, temperature and light touch below level of lesion.

Dorsal column still preserved so:
- Tactile discrimination and proprioception still preserved

18
Q

Brown- Sequard/ Cord hemisection syndrome

A

Lesion to the spinal cord

Damage to lower motor neurones
- Ipsilateral lower motor neurone paralysis and muscular atrophy in segment of lesion

Loss of anterior descending tract
- Ipsilateral spastic paralysis below level of lesion

Loss of dorsal root
- Ipsilateral band of cutaneous anesthesia in segment of lesion

Loss of ascending tract in the dorsal white column on the side of lesion

  • Ipsilateral loss of tactile discrimination
  • Ipsilateral loss of vibratory and proprioceptive sensations
  • Below level of lesion

Loss of crossed lateral spinothalmic tracts on same side of lesions
- Contralateral loss of pain, temperature and light touch

19
Q

Functions preserved in Brow-Sequard/ Cord hemisection syndrome

A

Ascending tracts in the contralateral dorsal white column intact
- Discriminative touch pathways remain

20
Q

Functions preserved in the anterior cord syndrome

A

Dorsal white columns on both sides intact

  • Tactile discrimination
  • Proprioceptive sensations
  • Both preserved
21
Q

Complete cord transection syndrome

A

Complete loss of sensation and voluntary movement below level of lesion

Bilateral lower motor neurone paralysis and muscle atrophy in segment of lesion

Loss of descending tracts
- Bilateral spastic paralysis below level of lesion

Loss of ascending tracts
- Bilateral loss of all sensations below the level of lesion

Loss of descending autonomic fibres
- Bladder and bowel functions no longer under voluntary control,

22
Q

3 mechanisms of sensory stimulus discrimination

- Include examples

A
  1. Different types of receptors for the same modality of stimulus
    - Such as cutaneous mechanoreceptors
  2. Different spatial distribution of receptors
    - Seen with the distribution of cutaneous mechanoreceptors on skin
  3. There are different windows of response intensity
    - Example: cold receptors only response to specific temperatures, same with ‘hot receptors’

4.

23
Q

Clasp-knife reflex

A

Reflex that prevents muscle damage [prevents tearing]

  1. Contraction of muscle detected by tendon organ— stimulates 1-beta afferent neurone
  2. Afferent neurone synapses with the inhibitory interneurone and excites it.
  3. This inhibits the alpha motor neurone, causing the same muscle to relax.
24
Q

Somatrophic organisation of lower motor neurones

A

Proximal muscles are arranged more medially
- I.e trunk

Distal muscles for laterally
- I.e hands and feet

202: Theme 1, Fundamental neuroscience and the brain (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions