Sensory And Motor Pathways

Question 1

Three main sensory tracts

Answer 1

Dorsal column
Spinocerebellar
Spinothalamic

Question 2

How many neurons in Dorsal column pathway

Answer 2

3

Question 3

Is information contralateral in Dorsal column

Answer 3

Yes

Question 4

Difference between gracilis and cuneatus

Answer 4

Gracilis - lower body/ limb
Cuneatus- upper body/ limb

Question 5

When does the dorsal column pathway decussate

Answer 5

Decussates in the medial lemniscus in brainstem( medulla)

Question 6

Where does first and second order neuron in DC pathway synapse

Answer 6

In grey matter in medulla ( nucleus gracilis/cuneatus)

Question 7

Where do the axons in spinal cord run in DC pathway

Answer 7

Fasciculus gracilis or cuneatus

Question 8

Where does the second order nucleus run from/till

Answer 8

Medulla till VPL NUCLEUS in THALAMUS in DIENCEPHALON

Question 9

What fibres do 2nd order neurons in the DC pathway travel in

Answer 9

Internal arcuate fibres

Question 10

Where do the nerves in DC pathway decussate

Answer 10

Medial lemniscus in medulla

Question 11

Where does the 2nr order neuron in DC pathway synapse with 3rd order

Answer 11

VPL nucleus in DIENCEPHALON

Question 12

Where do the 3rd order DC nerves go to and through what

Answer 12

Post central gyrus/ primary sensory cortex through posterior limb of internal capsule

Question 13

Difference and similarities in pathway of DC and ST

Answer 13

Also 3 neuron pathway
Also contralateral
But 2nd order neuron is in spinal cord at same level rather than in nucleus in medulla
Also decussates in same level in spinal cord

Question 14

How to find ST tract in spinal cord

Answer 14

White matter immediately ventral if ventral grey horn

Question 15

Where does 1* neurone of ST tract synapse with 2* neurone

Answer 15

At substantia gelatinosa of dorsal horn

Question 16

What is substantia gelatinosa also called

Answer 16

Nucleus proprius

Question 17

Where does the 2* neuron of ST tract decussate

Answer 17

Ventral white commissure (white matter)

Question 18

Where does the STP run in the brain stem

Answer 18

Spinal lemniscus (rather than medial lemniscus)

Question 19

Where does 2* STP neuron synapse

Answer 19

Also in VPL nucleus in thalamus

Question 20

Where do fibres in STP travel after internal capsule

Answer 20

Corona radiata and then PCG

Question 21

What information does spinocerebellar pathway receive

Answer 21

Information about relative stretch in muscles
Stretch in tendons
Output from joint receptors
Information about pressure on skin and superficial fascia

Question 22

Difference between spinocerebellar pathway and other 2 pathways

Answer 22

Only 2 neurons and ipsilateral

Question 23

Is there decussation in scp

Answer 23

Yes
Dorsal doesn’t cross but ventral does

Question 24

Where does synapsing occur in scp

Answer 24

Grey matter between dorsal and ventral horn

Question 25

Where does decussation occur in scp

Answer 25

Ventral white commissure

Question 26

Which peduncle does information enter cerebellum through

Answer 26

Dorsal enters through inferior and ventral through superior

Question 27

What is the nucleus for sensory pathways for head and neck and what is the nerve?

Answer 27

Trigeminal nerve , VPM nucleus of thalamus

Question 28

Important dermatomes

Answer 28

Anterior arm and Thumb- C6 Middle finger- C7 Little finger- C8 C2/C3- posterior scalp and neck T4- Ant/Post thorax at level of 6th rib at level of nipples T10- Ant/ Post at level of umbilicus l4- front of knee down to medial aspect of ankle/foot

Question 29

Are Upper motor neurones pyramidal or extra-pyramidal

Answer 29

Can be both

Question 30

What do UMNs do

Answer 30

Regulate firing pattern of LMN

Question 31

Where are lower motor neurones found and where do they connect to . Where are the cell bodies found

Answer 31

Spinal cord, peripheral nerves and NMJ Connect CNS to skeletal muscle fibres Cell bodies found predominantly in the ventral grey horn, exit via ventral roots

Question 32

Fibre type of LMNs

Answer 32

Aa (motor to skeletal muscle) and A gamma(muscle spindle)

Question 33

How many neurons in corticospinal pathway

Answer 33

2

Question 34

Is there decussation of CST

Answer 34

Yes, 99% of UMN innervate contralateral LMN

Question 35

Where are UMN mainly found in

Answer 35

Primary motor cortex

Question 36

Where are the cell bodies and axons at the start of CST

Answer 36

Cell bodies in cortical grey matter, axons in Corona radiata and then internal capsule

Question 37

Where does CST pass through midbrain

Answer 37

Crus cerebri/ basis pedunculi

Question 38

Where is the CST in the pons

Answer 38

Pontine corticospinal tracts

Question 39

Where does the CST pass through in the medulla

Answer 39

PYRAMIDS of medulla

Question 40

Lateral Vs ventral CST

Answer 40

Lateral runs contralateral, ventral runs ipsilateral

Question 41

Where do the UMN axons in CST decussate

Answer 41

Pyramids

Question 42

Where are the cell bodies of LMN primarily located in

Answer 42

Ventral grey horn

Question 43

What is the role of the corticobulbar pathway

Answer 43

UMN corticobulbar pathways control the LMNs located in the cranial nerve nucleinof the brainstem Bilateral UMN innervation of cramial nerve nuclei except CNVII

Question 44

What is the role of the Extra-pyramidal pathways

Answer 44

Involuntary control of movement

Question 45

What are the four main EP pathways UMN cell bodies in‽ Receive information from Activates?

Answer 45

Rubrospinal- red nucleus in midbrain, received information from cortex and cerebellum to activate motor neurons of flexor muscles Vestibulospinal- vestibular nuclei in pons, receives information from labyrinthine system and cerebellum, activates extensor motor neurons concerned with maintenance of anti gravity posture Tectospinal- superior colliculi in midbrain- receives information from visual system and activates lower motor neurons reflex response to visual stimuli Reticulospinal- reticular formation- receives information from hypothalamus and activates lower motor neurons concerned with reflex activity, muscle tone, breathing and circulatory system

Question 46

Differentiating between upper motor and lower motor neuron loss

Answer 46

Voluntary movements of affected muscles are weak Vs affected muscles are weak or paralysed No profound muscle atrophy ( slow wasting) Vs profound muscle atrophy Spasticity due to increased muscle tone due to continuous stretch reflex Vs tendon reflexes weak or absent Positive Babinski reflex (abnormal plantar reflec- dorsiflexion of big toe when stroking sole of foot) in UMN loss Vs fasciculation in LmN loss

Question 47

Where does the basal ganglia connect to

Answer 47

Cortex and thalamus (esp VA nucleus)

Question 48

What is the neostriatum

Answer 48

Caudate + putamen

Question 49

Where does information from cortex pass in basal ganglia loop

Answer 49

Cortex to basal ganglia to putamen to thalamus and back to cortex

Question 50

What us the lentiform nucleus

Answer 50

Putamen and globus pallidus

Question 51

Where does striatum signal to in indirect and direct pathway respecituveky

Answer 51

Indirect- gpe then subthalamic nuclei then gpi Direct- gpi Both end at thalamus after gpi

Question 52

Which tract is involved in proprioception

Answer 52

Spinocerebellar tract

Question 53

Are UMN pyrarmidal or EP

Answer 53

both

Question 54

What does anterior cerebral stroke and middle cerebral stroke result in

Answer 54

Problems with CL lower limb and CL upper limb

Question 55

What are the UMNs for CST and CBT

Answer 55

Betz cells- Layer V

Question 56

Does the posterior limb contain sensory or motor fibres

Answer 56

Both