Topic 4 - Anatomy of the Nervous System

Question 1

Motor Unit

Answer 1

1. Muscle fibre
2. Motor end plate
3. Efferent neuron

Question 2

4 Types of Somatosensory Receptors

Answer 2

Movement Related:

1. Muscle Spindles (muscle)
2. GTO (tendons)
3. Cutaneous receptors (skin)

Nocireceptors:
- heat, chemicals, touch -> pain

Question 3

Fxn of MUSCLE SPINDLES and neurons associated

Answer 3

Tell us about muscle length

Ia and II afferent neurons

Question 4

Fxn of GTOs and neurons associated

Answer 4

Tell us about muscle FORCE / rate of change in length

Ib afferent neurons

Question 5

Fxn of cutaneous receptors

Answer 5

Tell us about skin deformation / stretch

Question 6

Fxn of NOCIREDEPTORS

Answer 6

Tell us about pain

Question 7

2 Types of Efferent Neurons

Answer 7

1. Alpha MNs

2. Gamma MNs

Question 8

Alpha MNs

Answer 8

Innervate extrafusual muscle fibres

Main contributer to movement

Question 9

Gamma MNs

Answer 9

Innervate intrafusal muscle fibres

Tune somatosensory information from muscle spindles (Ia afferent)

Even though they’re efferent, large role in sensory info

Question 10

Grey Matter

Answer 10

Cell bodies & unmyelinated axons

Communication & synapses

Question 11

White Matter

Answer 11

Myelinated axons

Neural tracts & pathways (where info ascends & descends)

Question 12

3 Components of Brain Stem

Answer 12

1. Midbrain
2. Pons
3. Medulla

Question 13

Corpus Callosum

Answer 13

Interhemispheric communication

Lots of myelinated axons (tracts) -> white matter

Question 14

Layers of the Cerebral Cortex

Answer 14

1. Molecular
2. External Granular
3. External Pyramidal
4. Internal Granular
5. Internal Pyramidal
6. Multiform

Question 15

Molecular Layer

Answer 15

Local communication

Lots of basket cells (multipolar neurons w/ lots of axonal & dendritic trees)

Question 16

External Granular Layer

Answer 16

INPUT from other cortical areas

Ex. Somatosensorty cortex to motor cortex

Other hemispheres or the same one

Question 17

External Pyramidal Layer

Answer 17

OUTPUT to cortical areas (layer 2) and layers 4&5

Question 18

Internal Granular Layer

Answer 18

Input from thalamus (especially sensory)

Question 19

Internal Pyramidal Layer

Answer 19

Output to SC, BG and brain stem (leaves cortex)

Descending pyramidal neurons

Question 20

Mulitform Layer

Answer 20

Output to thalamus

Question 21

Monosynaptic Relay

Answer 21

One synapse

Ex. Tendon tap reflex

Direct activation of alpha motor neuron

Question 22

Oligosynaptic Relay

Answer 22

2-3 synapses

Slight longer latency that monosynaptic

Question 23

Polysynaptic Relay

Answer 23

4+ synapses

Voluntary movements are always polysynaptic

Question 24

Where do synapses occur? Whitenor grey matter?

Answer 24

Grey

Question 25

What kind of cells are in the dorsal root ganglion

Answer 25

Cell bodies of pseudo-unipolar cells

Question 26

Cerebellum

Answer 26

Receives sensory input from SC and motor information from cerebrum Planning, timing, and adaptation/learning of movement Role in posture and coordination of eye and hand movements

Question 27

Midbrain

Answer 27

Smaller role in limb movements Larger role in eye movements via superior colliculus

Question 28

Pons

Answer 28

Involved in relay between cerebrum and cerebellum Role in movement, especially posture

Question 29

Medulla

Answer 29

Influenses postural responses and reflexes Potential role in startile-elicited responses - ex. Pre-programmed responses (not entirely voluntary or involuntary)

Question 30

Somatotopic Organization of SC from lat to med

Answer 30

``` Cervical (neck and arms) Thoracic (trunk and arms) Lumbar (hips and legs) Sacral (legs and genitals) Cauda equina (horse tail) ```

Question 31

2 parts of Dorsal Column

Answer 31

1. Gracile Fasciculus (medial) - lower body somatosensory 2. Cuneate Fasciculus - upper body somatosensory