Tracts Of The Nervous System

Question 1

List all the Ascending tracts.

Answer 1

1. Fasciculus cuneatus (posterior or dorsal column)
2. Fasciculus gracilis (posterior or dorsal column)
3. Spinocerebellar tract (dorsal)
4. Spinocerebellar tract (ventral)
5. Spino-olivary tract
6. Spinoreticular tract
7. Spinotectal tract
8. Spinothalamic tract (anterior)
9. Spinothalamic tract (posterior)

Question 2

List all the descending tracts.

Answer 2

1. Cortiocspinal tract (anterior)
2. Corticospinal Tract (Lateral)
3. Reticulospinal tract
4. Rubrospinal tract
5. Tectospinal tract
6. Vestibulospinal tract

Question 3

What is the purpose of the ascending tracts?

Answer 3

Relay SENSORY feedback to the cerebrum and cerebellum.

Question 4

What do sensory tracts ascending in the WHITE matter of the spinal cord arise from?

Answer 4

Either from cells of spinal ganglia or form intrinsic neurons within the gray matter that receive primary sensory input

Question 5

Fasciculus cuneatus (posterior or dorsal)

Answer 5

1. Sensory tract for trunk, neck, and UE proprioception
2. Vibration
3. Two-point discrimination
4. Graphesthesia

Question 6

Fasciculus gracilis (posterior or dorsal)

Answer 6

1. Sensory tract for trunk and LE proprioception
2. Two-point discrimination
3. Vibration
4. Graphesthia

Question 7

Spinocerebellar Tract (dorsal)

Answer 7

1. Sensory tract that ascends to the cerebellum for IPSILATERAL subconscious proprioception
2. Tension in muscles
3. Joint sense
4. Posture of the trunk and LE

Question 8

Spinocerebellar tract (ventral)

Answer 8

1. Sensor tract that ascends to the cerebellum, some fibers crossing w/ subsequent recrossing at the level of the pons for IPSILATERAL subconscious proprioception
2. Tension in the muscles
3. Joint sense
4. Posture of the trunk, UE, LE

Question 9

Spino-olivary tract

Answer 9

Ascends to cerebellum and relays information from cutaneous and proprioceptive organs

Question 10

Spinoreticular tract

Answer 10

Afferent pathway for the reticular formation that influences levels of consciousness

Question 11

Spinotectal tract

Answer 11

Sensory tract providing afferent information form spinovisual reflexes and assists with movement of eyes and head towards a stimulus

Question 12

Spinothalamic tract (anterior)

Answer 12

Sensory tract for light touch and pressure

Question 13

Spinothalamic tract (lateral)

Answer 13

Sensory tract for pain and temperature sensation

Question 14

Corticospinal tract (anterior)

Answer 14

Pyramidal motor tract responsible for ipsilateral voluntary, discrete, skilled movements

Question 15

What are tracts descending to the spinal cord involved in?

Answer 15

Voluntary motor function

Muscle tone

Reflexes and equilibrium

Visceral innervation

Modulation of ascending sensory signals

Question 16

Where does the largest descending tract (corticospinal tract) originate? Where do the other descending tracts originate from?

Answer 16

Cerebral cortex

Others originate in the midbrain, pons and medulla Oblongata

Question 17

Corticospinal tract (lateral)

Answer 17

Pyramidal motor tract responsible for CONTRALTERAL voluntary fine movement

Question 18

What may damage to the corticospinal (pyramidal) tracts resut in?

Answer 18

(+) babinski sign—toes in flexion

Absent superficial abdominal reflexes and cremasteric reflex

Loss of fine motor or skilled voluntary movements

Question 19

Reticulospinal tract

Answer 19

Extrapyramidal motor tract responsible or facilitation nor inhibition of voluntary and reflex activity through the influence of alpha and gamma motor neurons

Question 20

Rubrospinal tract

Answer 20

Extrapyramdial motor tract responsible for motor input of gross postural tone, facilitating activity of flexion muscles and inhibiting the activity of extensor muscles

Question 21

Tectospinal tract

Answer 21

Extrapyramdial motor tract responsible for CONTRALATERAL postural muscle tone associated with auditory/visual stimuli

Question 22

Vestibulospinal tract

Answer 22

Extrapyramidal motor tract responsible for IPSILATERAL gross postural adjustments subsequent to head movements, facilitating activity of the extensor muscles and inhibiting activity of the flexor muscles

Question 23

What does damage to the extrapyramdial tracts result in?

Answer 23

• Significant paralysis
• Hypertonicity
• Exaggerated DTR
• Clasp-knife reaction

Question 24

What is brown-sequard’s Syndrome typically caused by?

Answer 24

Incomplete lesion typically caused by a stab wound which produces hemisection of the spinal cord

Question 25

What are the consequences of brown-sequard’s Syndrome ?

Answer 25

Paralysis and loss of vibratory sense and position sense on IPSILATERAL side as the lesion due to the damage to the CORTICOSPINAL tracts and dorsal column

Loss of PAIN and TEMPERATURE on the CONTRALATERAL side of the lesion from damage to the lateral spinothalmaic tract