Tracts/Pathways

Question 1

How many sensory pathways are there?

Answer 1

Five

Question 2

What are the five sensory pathways?

Answer 2

Spinothalamic pathway
Dorsal column medial leminiscal pathway
Spinal tract V
Chief sensory Tract
Spinocerebellar tract

Question 3

What pathways receive information from the body?

Answer 3

Spinothalamic
Dorsal Column medial leminiscal
Spinocerebellar

Question 4

What pathways receive information from the head?

Answer 4

Spinal tract V

Chief sensory tract

Question 5

What are some of the nerve endings that actually receive sensory information?

Answer 5

Free Nerve Endings
Merkels Discs
Pacinian corpuscles
Messiners corpuscles
Ruffini end-organs

Muscle spindle fibres
Golgi tendon organs

Question 6

What are the two ways the brain selectively chooses the sensory information we consciously are aware of?

Answer 6

Accomodation

Selective awareness

Question 7

What is accommodation?

Answer 7

When the brain NO LONGER feels certain sensory inputs that have been present for a long while

Question 8

What is selective awareness?

Answer 8

When the brain chooses TO RECEIVE certain sensory inputs (cocktail party phenomenon)

Question 9

What type of sensory input does the spinothalamic tract receive?

Answer 9

Crude touch/pressure, Pain, Temperature

Question 10

What type of sensory input does the dorsal column medial leminiscus tract receive?

Answer 10

Discriminative touch/vibration, proprioception

Question 11

What type of input does spinal tract V receive?

Answer 11

Crude touch/pressure, pain, temperature

Question 12

What type of input does The chief sensory nucleus V receive?

Answer 12

Discriminative touch/vibration and proprioception

Question 13

What pathway do both Spinal tract V and The chief sensory tract travel in?

Answer 13

The trigemino-thalamic tract (TTT)

Question 14

What cranial nerves contribute to spinal tract V?

Answer 14

Trigeminal (main), Facial, Glossopharyngeal and Vagus

Question 15

What cranial nerves contribute to the chief sensory tract?

Answer 15

Only the trigeminal

Question 16

Where do The spinothalamic and dorsal column medial leminiscal tracts and spinal tract V and chief sensory nucleus tract synapse in the thalamus?

Answer 16

The spinothalamic and dorsal column both synapse in the VPL as they come from the body

Spinal tract V and the chief sensory nucleus synapse in teh VPM as they come from the head

Question 17

What is different about the spino-cerebellar tract to all the other sensory tracts?

Answer 17

It gives it’s input ipsilaterally

Question 18

What kind of input does the spinocerebellar tract give?

Answer 18

Proprioception of muscles to co-ordinate posture and balance

Question 19

Where does the spinocerebellar tract synapse (eventually)?

Answer 19

The cerebellum

Question 20

What are the two different types of motor pathways?

Answer 20

Voluntary - Pyramidal

Involuntary - extra-pyramidal

Question 21

What are the two pyramidal motor pathways? Whats the difference between them?

Answer 21

Corticospinal - body and limbs

Corticobulbar - Head

Question 22

What type of neurones do the extrapyramidal motor pathways act on?

Answer 22

Gamma Lower motor neurones

Question 23

What kinds of actions are extrapyramidal motor pathways involved in?

Answer 23

Inhibition of muscles:

• Reflexes
• Posture

Question 24

Where are the UMN cell bodies located in the cortico-spinal tract?

Answer 24

Mostly in the primary motor cortex, but also importantly in the:

Association motor cortex AND sensory cortex

Question 25

UMN of the cortico-spinal tract that originate in the primary sensory cortex synapse where, what is their use?

Answer 25

Synapse on the Dorsal medial leminiscal pathway and are involved in the proprioceptive functions of muscle

Question 26

What are the differences in the lateral and the anterior corticospinal tracts?

Answer 26

The Lateral corticospinal tract (90% of fibres): - Cross at the decussation point - Descend on the contralateral side - Distal muscles and fine motor control The Anterior corticospinal tract: - Do not cross - Descend on the ipsilateral side - Axial Muscles (around spine) and posture/balance

Question 27

What is the route from the UMN of the lateral corticospinal tract?

Answer 27

UMN passes through the internal capsule Pass down into the brainstem and through the crus cerebri, through the pons to the medulla where they form the pyramids Cross at the decussation point and descend in the lateral funiculus Then go to ventral horn of grey matter and then onto a mixed spinal nerve

Question 28

What route from the UMN will the anterior corticospinal tract take?

Answer 28

UMN passes through the internal capsule Pass down into the brainstem and through the crus cerebri, through the pons to the medulla where they form the pyramids Will not cross but will continue down the anterior funiculus Will then cross at the anterior white commisure

Question 29

If there is a lesion to the corticospinal tract at the level of the brain where will the effects be seen

Answer 29

Contralateral side (assume it is the lateral corticospinal tract).

Question 30

What is spinal shock?

Answer 30

Occurs when there is damage to the spinal cord and all spinal functions stop for a period of time after the trauma.

Question 31

Classic signs of UMN lesion?

Answer 31

Spastic paralysis (pen-knife response) Clonus (rythmic contractions) Hypereflexia/hypertonia (extrapyramidal damage) Positive babinski's sign

Question 32

Classic signs of a LMN lesion?

Answer 32

Flaccid paralysis - weakness/reduced tone Positive atrophy (permanent) Fasciculations Hyporeflexia

Question 33

What path does the corticobulbar pathway take?

Answer 33

UMN is in cortex and then synapses onto interneurone and then onto a cranial nerve

Question 34

What does damage to the corticobulbar tract usually cause? | Exceptions?

Answer 34

Usually causes slight weakness (palsy) not full blown as there is usually bilateral innervation CNVII and CNXII do not give out bilateral innervation.

Question 35

If there is a lesion to the corticobulbar pathway to the hypoglossal nerve affecting the UMN what will the effects be?

Answer 35

Tongue will deviate to the opposite side

Question 36

If there is a lesion to the corticobulbar pathway to the hypoglossal nerve affecting the LMN what will the effects be?

Answer 36

Tongue will deviate to the same side

Question 37

Damage to the corticobulbar pathway to the facial nerve will cause what?

Answer 37

Paralysis on the lower part of one side of the face.