Somato & Neruo 2

Question 1

Dorsal root ganglion

Answer 1

Location of cell bodies (ncb) of first order sensory neurons
Support cells = satellite cells (sc)
Unmyelinated and myelinated axons (ma)

Question 2

Spinal cord organization for sensory pathways

Answer 2

Dorsal column (funiculus)
2 divisions
Faciculus Gracilis - carries info abt caudal body & hindlimb
Faciculus cuneatus - carries info abt cranial body & forelimb

Question 3

Grey matter organization

Answer 3

Rexed laminae 1-9
1 - pain & temp
2 - modulation
3 - touch
4 - touch
5 - pain
6 - position
7 - motor to viscera
8 - modulation
9 - motor to skeletal muscle

Question 4

Dorsal Somatosensory pathways

Answer 4

Dorsal column system
Relays in for abt touch, position, vibration

Question 5

First order neurons in dorsal SS pathway

Answer 5

Cell bodies in DORSAL root ganglion
Axon ascends in dorsal funiculus (dorsal columns
- hindlimb in Fas Gracilis (medial)
- forelimb in Fas cuneatus (lateral)
Synapses in nucleus Gracilis & cuneate nucleus in medulla

Question 6

2nd order neuron Dorsal SS pathway

Answer 6

Cell body in brainstem nuclei
Axon crosses midline in medial lemniscus
Synapses in thalamus

Question 7

3rd order neuron in dorsal SS pathway

Answer 7

Cell bodies in thalamus
Synapses in sensory cortex

Question 8

Where 1st, 2nd, 3rd dorsal SS pathway synapse

Answer 8

1st - nucleus Gracilis & cuneate nucleus in medulla
2nd - thalamus
3rd - sensory cortex

Question 9

Where orders cross in dorsal SS pathway

Answer 9

1st - axon ascends in dorsal funiculus
2nd - axon crosses at midline in medal lemniscus
3rd - cell bodies in thalamus

Question 10

Lateral Spinothalamic tract

Answer 10

Relays information abt pain and temperature
Three neuron pathways

Question 11

First neurons in lateral Spinothalamic tract

Answer 11

Cell body in dorsal root ganglion
Synapses in dorsal root of spinal cord

Question 12

2nd neuron in lateral Spinothalamic tract

Answer 12

Cell body in dorsal horn of spinal cord
Axon crosses midline
Ascends in lateral funiculus
Synapses in thalamus

Question 13

3rd neuron of lateral Spinothalamic tract

Answer 13

Cell body in thalamus
Synapses in sensory cortex

Question 14

Where neurons synapse in lateral Spinothalamic tract

Answer 14

1st - dorsal horn of spinal cord
2nd - in thalamus
3rd - sensory cortex

Question 15

Where axon crosses in lateral Spinothalamic tract

Answer 15

1st - cell body in dorsal root ganglion
2nd - crosses at midline
3rd - cell body in thalamus

Question 16

Ventral Spinothalamic tract

Answer 16

Relays info abt light touch (non painful touch)
Three neuron pathways

Question 17

First neuron in ventral spinolthalamic tract

Answer 17

Cell body in dorsal root ganglion
Synapses in dorsal horn of spinal cord

Question 18

2nd neurons in ventral spinolthalamic tract

Answer 18

Cell body in dorsal horn of spinal cord
Axon crosses midline
Ascends in lateral funiculus
Synapses in thalamus

Question 19

3rd order neuron in ventral spinolthalamic tract

Answer 19

Cell body in thalamus
Synapses in sensory cortex

Question 20

Where neurons synapse in ventral spinolthalamic tract

Answer 20

1st - dorsal horn of spinal cord
2nd - in thalamus
3rd - sensory cortex

Question 21

Where axon crosses in ventral spinolthalamic tract

Answer 21

1st - cell body in dorsal root ganglion
2nd - axon crosses midline
3rd - in thalamus

Question 22

What tract handles touch, position, vibration

Answer 22

Dorsal somatosensory pathways

Question 23

What tract handles pain & temperature?

Answer 23

Lateral Spinothalamic tract

Question 24

What tracts handles light undiscriminated touch?

Answer 24

Ventral Spinothalamic tract

Question 25

Other synapses in the spinal cord

Answer 25

Axons in the first order sensory neuron branch Also synapse in local Interneurons Basis of spinal reflexes Modulation of ascending signals

Question 26

Descending tracts

Answer 26

Motor Lateral corticospinal tract (motor) Ventral corticospinal tract (motor)

Question 27

Ascending tracts

Answer 27

Sensory Dorsal columns - Fine touch, Proprioception, vibration Lateral Spinothalamic tract - pain, temperature Ventral Spinothalamic tract - light touch

Question 28

Spinoreticular tract

Answer 28

Pain modulation and response to pain

Question 29

Spinovestibular tract

Answer 29

Information about posture and balance

Question 30

Spinocerebellar tract

Answer 30

Unconscious proprioception

Question 31

Thalamus

Answer 31

Diencephalon Relay station for input to cerebral cortex - all sensory information except olfaction Located rostral to midbrain Two halves join in midline at the inter thalamus adhesion (3rd ventricle)

Question 32

Thalamic nuclei

Answer 32

Specialized for different sensory modalities Also involved in motor system Ventral nuclei = relay for somatosensory information

Question 33

Primary somatosensory cortex

Answer 33

Located caudal to primary motor cortex Areas of cortex correspond to body parts on opposite side of the body Head - lateral Tail - medial Limbs - rostral

Question 34

Somatotropic map

Answer 34

Areas with more sensory receptors have a larger area within the cortex

Question 35

Function of an itch

Answer 35

Receptors: pruriceptors Axons: C and A gamma TRP receptors respond to chemical stimuli Information ascends to the brain in the lateral Spinothalamic tract