Ascending Pathways

Question 1

Describe the types of spinal tracts?

Answer 1

1. Ascending tracts - Carry sensory information to the CNS
2. Descending tracts - Carry motor information from the CNS
3. Intersegmental tracts - related to intersegmental reflex

Question 2

What are the 2 categories of sensations of the ascending sensory pathways?

Answer 2

1. Conscious - referred to cerebral cortex
2. Unconscious - referred to cerebellum

Question 3

Describe the 2 types of conscious sensations?

Answer 3

1. Exteroceptive - external in nature
   Detected by:
   - somatic receptors on body surface
   > pain, touch, pressure, heat, cold
   - telereceptors - vision and hearing
2. Proprioceptive - from within the body
   - Locomotor system and balance - muscles, joints, bones, vestibular labyrinth
   - Position sense and kinesthetic

Question 4

Name the 3 ascending tracts?

Answer 4

Tracts of the posterior funiculus
Tracts of the lateral funiculus
Tracts of the anterior funiculus

Question 5

Name the 2 tracts of the posterior funiculus and what they detect?

Answer 5

1. fasculus gracilis
2. fasculus cuneatus

> touch
pressure
proprioception
vinration
2 point discrimination

Question 6

Describe the fasculus gracilis?

Question 7

Describe the fasculus cuneatus?

Question 8

Describe the fasciculus gracilis and fasciculus cuneatus pathway?

Answer 8

> Touch, Pressure, Proprioception (position & kinesthetic sense), Vibration, Two point discrimination
DORSAL ROOT GANGLION
(1st order neuron)
NUCLEUS GRACILIS - NUCLEUS CUNEATUS
(2nd order neuron in medulla oblongata)
INTERNAL ARCUATE FIBERS
MEDIAL LEMNISCUS
Ventral Posterolateral (VPL) Nucleus
(3rd order neuron in the thalamus)
CORTEX 3 -2-1 (somatic sensory cortex areas) postcentral gyrus

Question 9

What are the tracts of the lateral funiculus?

Answer 9

Lateral spinothalamic tract
Posterior spinocerebellar tract
Anterior spinocerebellar tract

Question 10

Describe the lateral spinothalamic tract and what it detects?

Question 11

Describe the lateral spinothalamic tract pathway?

Answer 11

> pain and thermal sense
DORSAL ROOT GANGLION
(1st neuron)
REXED LAMINA 6,7,8
(2nd neuron)
DECUSSATION
(anterior white commissure)
VPL nucleus
(3rd neuron in the thalamus)
CORTEX 3 -2-1

Question 12

Describe the posterior spinocerebellar tract?

Answer 12

Located lateral to the lateral corticospinal tract.
Close to surface of the cord
Its fibers are the largest in entire CNS
20 µm diameter
Fast conduction to keep cerebellum informed about ongoing movements

Question 13

Describe the posterior spinocerebellar tract pathway?

Answer 13

(Touch, Pressure, Proprioception, Vibration)

DORSAL ROOT GANGLION
(1st neuron)

CLARKE DORSAL NUCLEUS
(2nd neuron ie thoracic nucleus in Lamina 7 posterior horn)

IPSILATERAL

INFERIOR CEREBELLAR PEDUNCLE

Question 13

Describe the posterior spinocerebellar tract pathway?

Answer 13

(Touch, Pressure, Proprioception, Vibration)

DORSAL ROOT GANGLION
(1st neuron)

CLARKE DORSAL NUCLEUS
(2nd neuron ie thoracic nucleus in Lamina 7 posterior horn)

IPSILATERAL

INFERIOR CEREBELLAR PEDUNCLE

Question 14

Describe the anterior spinocerebellar tract?

Question 15

Describe the anterior spinocerebellar tract pathway?

Answer 15

(Touch, Pressure, Proprioception, Vibration)from the lower limb)



DORSAL ROOT GANGLION
(1st neuron)


LAMINA 5,6,7
(2nd neuron)


DECUSSATION
(anterior white commissure)


SUPERIOR CEREBELLAR PEDUNCLE

Question 16

Describe the anterior spinothalamic tract?