Sensory And Motor Pathways Flashcards
Three main sensory tracts
Dorsal column
Spinocerebellar
Spinothalamic
How many neurons in Dorsal column pathway
3
Is information contralateral in Dorsal column
Yes
Difference between gracilis and cuneatus
Gracilis - lower body/ limb
Cuneatus- upper body/ limb
When does the dorsal column pathway decussate
Decussates in the medial lemniscus in brainstem( medulla)
Where does first and second order neuron in DC pathway synapse
In grey matter in medulla ( nucleus gracilis/cuneatus)
Where do the axons in spinal cord run in DC pathway
Fasciculus gracilis or cuneatus
Where does the second order nucleus run from/till
Medulla till VPL NUCLEUS in THALAMUS in DIENCEPHALON
What fibres do 2nd order neurons in the DC pathway travel in
Internal arcuate fibres
Where do the nerves in DC pathway decussate
Medial lemniscus in medulla
Where does the 2nr order neuron in DC pathway synapse with 3rd order
VPL nucleus in DIENCEPHALON
Where do the 3rd order DC nerves go to and through what
Post central gyrus/ primary sensory cortex through posterior limb of internal capsule
Difference and similarities in pathway of DC and ST
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
How to find ST tract in spinal cord
White matter immediately ventral if ventral grey horn
Where does 1* neurone of ST tract synapse with 2* neurone
At substantia gelatinosa of dorsal horn
What is substantia gelatinosa also called
Nucleus proprius
Where does the 2* neuron of ST tract decussate
Ventral white commissure (white matter)
Where does the STP run in the brain stem
Spinal lemniscus (rather than medial lemniscus)
Where does 2* STP neuron synapse
Also in VPL nucleus in thalamus
Where do fibres in STP travel after internal capsule
Corona radiata and then PCG
What information does spinocerebellar pathway receive
Information about relative stretch in muscles
Stretch in tendons
Output from joint receptors
Information about pressure on skin and superficial fascia
Difference between spinocerebellar pathway and other 2 pathways
Only 2 neurons and ipsilateral
Is there decussation in scp
Yes
Dorsal doesn’t cross but ventral does
Where does synapsing occur in scp
Grey matter between dorsal and ventral horn
Where does decussation occur in scp
Ventral white commissure
Which peduncle does information enter cerebellum through
Dorsal enters through inferior and ventral through superior
What is the nucleus for sensory pathways for head and neck and what is the nerve?
Trigeminal nerve , VPM nucleus of thalamus
Important dermatomes
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
Are Upper motor neurones pyramidal or extra-pyramidal
Can be both
What do UMNs do
Regulate firing pattern of LMN
Where are lower motor neurones found and where do they connect to . Where are the cell bodies found
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
Fibre type of LMNs
Aa (motor to skeletal muscle) and A gamma(muscle spindle)
How many neurons in corticospinal pathway
2
Is there decussation of CST
Yes, 99% of UMN innervate contralateral LMN
Where are UMN mainly found in
Primary motor cortex
Where are the cell bodies and axons at the start of CST
Cell bodies in cortical grey matter, axons in Corona radiata and then internal capsule
Where does CST pass through midbrain
Crus cerebri/ basis pedunculi
Where is the CST in the pons
Pontine corticospinal tracts
Where does the CST pass through in the medulla
PYRAMIDS of medulla
Lateral Vs ventral CST
Lateral runs contralateral, ventral runs ipsilateral
Where do the UMN axons in CST decussate
Pyramids
Where are the cell bodies of LMN primarily located in
Ventral grey horn
What is the role of the corticobulbar pathway
UMN corticobulbar pathways control the LMNs located in the cranial nerve nucleinof the brainstem
Bilateral UMN innervation of cramial nerve nuclei except CNVII
What is the role of the Extra-pyramidal pathways
Involuntary control of movement
What are the four main EP pathways
UMN cell bodies in‽
Receive information from
Activates?
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
Differentiating between upper motor and lower motor neuron loss
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
Where does the basal ganglia connect to
Cortex and thalamus (esp VA nucleus)
What is the neostriatum
Caudate + putamen
Where does information from cortex pass in basal ganglia loop
Cortex to basal ganglia to putamen to thalamus and back to cortex
What us the lentiform nucleus
Putamen and globus pallidus
Where does striatum signal to in indirect and direct pathway respecituveky
Indirect- gpe then subthalamic nuclei then gpi
Direct- gpi
Both end at thalamus after gpi
Which tract is involved in proprioception
Spinocerebellar tract
Are UMN pyrarmidal or EP
both
What does anterior cerebral stroke and middle cerebral stroke result in
Problems with CL lower limb and CL upper limb
What are the UMNs for CST and CBT
Betz cells- Layer V
Does the posterior limb contain sensory or motor fibres
Both
