Motor Tracts

Question 1

Upper motor neurons

Answer 1

Arise and contained within cerebral cortex or brain stem
Axons travel in descending trapes
Synapse with LMN or interneurons
-Corticospinal/corticobulbar tract

Question 2

Lower motor nuerons

Answer 2

Directly innervate skeletal muscle
Cell body in spinal cord or brain stem
Gamma motor neuron- medium sized, myelinated, project to intrafusal fibers in spindle
Alpha motor neuron- large cell bodies and myelinated, project to extrafusal skeletal muscle
-Peripheral nerves and cranial nerves

Question 3

Corticospinal tract

Answer 3

UMN arise in cortex and synapse with LMN
Medial corticospinal tract- postural muscles- not clinically significant
Lateral corticospinal tract- limb muscles, fractionation (ability to move fingers precisely)
Send collaterals to indirect pathway

Question 4

Pathway of corticospinal tract

Answer 4

Descends from cortex through posterior limb of internal capsule
Passes through cerebral peduncles, anterior pons, pyramids in medulla, fibers cross in the pyramids/lower medulla
Descends in lateral column, synapse with LMN

Question 5

Voluntary motor control

Answer 5

Primary motor cortex initiates voluntary movement via corticospinal tract
Right side controls left side of body, visa versa

Question 6

Vascular supply to internal capsule

Answer 6

Lenticulostriate arteries

Question 7

What supplies corticospinal tract in midbrain

Answer 7

P1 branch of posterior cerebellar

Question 8

What supplies corticospinal tract in the pons

Answer 8

Paramedian branches of the basilar artery

Question 9

What supplies corticospinal tract in medulla

Answer 9

Anterior spinal artery

Question 10

What supplies corticospinal tract in spinal cord

Answer 10

Legs supplied by posterior spinal artery

Arms supplied by anterior spinal artery

Question 11

Orientation of hands vs legs in midbrain/pons/medulla

Answer 11

Legs are lateral, hands are medial (opposite of brain)

Question 12

Corticobulbar tract

Answer 12

Arises from ventral part of cortical area 4
Comprised of UMN
Descends into brain stem and influences muscles innervated by CN V, VII, IX, X, XI, XII- does not move eyes

Question 13

Corticobulbar tract pathway

Answer 13

Same as corticospinal tract except when descending it travels through the genu of the internal capsule instead of posterior limb
Stops at specific motor nuclei of CNs it works with

Question 14

Corticobulbar inputs to each nuclei

Answer 14

In pons, it gives bilateral input to both trigeminal motor nuclei (each nuclei receives input from both sides of brain)
For facial nucleus in lower pons- it gives bilateral input for areas of forehead, but contralateral input for lower face areas
In medulla- hypoglossal and nucleus ambiguous (CN IX/X) receive bilateral input, but muscles of palate and tongue muscles seem to receive contralateral input in clinical assessment
For spinal accessory- receives ipsilateral input

Question 15

Lesion to corticobulbar tract above the pons- effects to mastication, forehead, lower face, palate muscles, tongue

Answer 15

No difference to muscles of mastication because of bilateral input
Forehead will have no change because of bilateral input
Lower face will have contralateral drooping
Contralateral palate muscles weak, uvula deviates to side of lesion
Tongue deviates to contralateral side because contralateral muscles are weakened

Question 16

LMN organization

Answer 16

Found in anterior horn
Medial LMN project to axial muscles (biceps)
Lateral LMN project to limb muscles (forearm/hand)
LMNs innervating extensors lie ventrally
LMNs innervating flexors lie dorsally

Question 17

Lateral UMN tract indirect pathways

Answer 17

Rubrospinal

Lateral reticulospinal

Question 18

Medial UMN tract indirect pathways

Answer 18

Tectospinal
Medial reticulospinal
Lateral vestibulospinal
Medial vestibulospinal

Question 19

Medial LMNs are receive input from which tracts which are located where

Answer 19

Located in anterior funiculus
Tectospinal tract
Medial vestibulospinal
Medial reticulospinal
Medial corticospinal
Lateral vestibulospinal

Question 20

Lateral LMNs receive input from which tracts which are located where

Answer 20

Located in
Rubrospinal
Lateral reticulospinal
Lateral corticospinal (know location of these in SC)

Question 21

How much detail do we need to know on these tracts

Answer 21

Not a ton, but know where they start and where they are going

Question 22

Lateral vestibulospinal tract

Answer 22

Starts in lateral vestibular nucleus in medulla
Projects to ipsilateral LMNs innervating postural muscles and limb extensors
Gets info about your body and gravity to influence its muscle actions

Question 23

Medial vestibulospinal tract

Answer 23

Starts in medial vestibular nucleus in medulla
Goes to cervical and thoracic levels- neck/shoulder muscles
Interprets what head movements and relation to gravity

Question 24

Medial reticulospinal tract

Answer 24

Starts in pontine reticular formation

Goes to ipsilateral LMN innervating postural muscles and limb extensors

Question 25

Lateral reticulospinal tract

Answer 25

Starts in medullary reticular formation in medulla | Facilitates flexor motor neurons and inhibits extensor motor neurons

Question 26

Rubrospinal tract

Answer 26

Starts in the red nucleus in midbrain | Innervates upper limb flexors

Question 27

Tectospinal tract

Answer 27

Starts in superior colliculus in midbrain Innervates neck muscles If you hear something, tectospinal will help you turn head to look at stimulus

Question 28

Lower motor neuron lesion

Answer 28

Flaccid paralysis Wasting or atrophy Hyporeflexia or areflexia due to denervation Hypotonia- decreased muscle tone Denervation or hypersensitivity seen as fasciculations (random contractions) ALL IPSILATERAL!!**

Question 29

UMN syndrome

Answer 29

Combination of the loss of corticospinal tract and the loss of regulation from the indirect brainstem motor control pathways

Question 30

Direct pathway/corticospinal tract effects of UMN syndrome** important

Answer 30

``` Loss of distal extremity strength/dexterity Babinski sign (inverted plantar reflex) Pronator drift (not sure if this is direct or indirect path) ```

Question 31

Indirect tract effects of UMN syndrome** important

Answer 31

Hypertonia- collapse of resistance at the end of range of motion Rigidity- basal ganglia disease- shows constant resistance throughout full PROM Hyperreflexia- may be seen as clonus Clasp-knife phenomenon (faster you try to move patients arm, more resistance you get. At end of PROM resistance suddenly gives out) and spasticity (spastic paralysis)

Question 32

Spinal level in relation to where the dysfunction is- C5-C8, T1, L2-L5, S1

Answer 32

``` C5 shoulder extension C6 arm flexion C7 arm extension C8 wrist extensors T1 hand grasp L2 hip flexion L3 knee extension L4 knee flexion L5 ankle dorsiflexion S1 ankle plantarflexion (these are not perfect but will get you close to the level) ```

Question 33

Spinal cord lesions give UMN/LMN signs where

Answer 33

UMN signs below level of the lesion | LMN signs at the level of the lesion

Question 34

UMN contralateral vs ipsilateral

Answer 34

Lesion above lower medulla- clinical signs will be CL | Lesion in spinal cord- clinical signs are ipsilateral

Question 35

Decorticate posture/rigidity

Answer 35

Lesion is above the level of the red nucleus Thumb tucked under flexed fingers in fixed position, pronation of forearm, flexion at elbow with the lower extremity in extension with foot inversion

Question 36

Decerebrate posture/rigidity

Answer 36

Lesion below red nucleus, but above reticulospinal/vestibulospinal nuclei UE in pronation and extension and the LE in extension

Question 37

Lesion in what location will give you contralateral UMN probems (spasticity/hyper reflexia) and contralateral face droop

Answer 37

Cortex Internal capsule Cerebral peduncles

Question 38

Damage above pyramidal decussation will give what signs/symptoms

Answer 38

Contralateral UMN signs

Question 39

What issue will mask other problems

Answer 39

LMN problem will mask other problems because its the final pathway

Question 40

Complete SC transection

Answer 40

All sensation lost 1 or 2 levels below lesion Bladder/bowel control lost Spinal shock- lost of tendon reflexes- looks like LMN issue UMN signs at levels below lesion about 6 weeks post accident LMN signs at level of lesion

Question 41

Hemisection of spinal cord

Answer 41

Pain and temp from contralateral side 2 levels below lesion Discriminative touch and conscious proprioception ipsilaterally LMN signs at level of lesion UMN signs on ipsilateral side This pattern of loss is called Brown-Sequards syndrome

Question 42

Syringomyelia

Answer 42

Formation of cysts within spinal cord Pain and temp first affected- Anterior white commissure Resulting pattern is cape distribution May have LMN signs if ventral horns affected May have UMN signs if lateral corticospinal tract is affected Syringomyelia is highly correlated with Chiari type I

Question 43

Anterior cord syndrome

Answer 43

Compression/damage to anterior spinal cord Usually due to spinal cord infarction, intervertebral disc herniation, and radiation myelopathy, anterior spinal artery blockage ALS Corticospinal LMN signs at level of lesion UMN signs below level Everything bilateral

Question 44

Central cord syndrome

Answer 44

Syringomyelia is an example of central cord syndrome Can be caused by cervical hyperextension Same symptoms as syringomyelia

Question 45

Medial medullary syndrome

Answer 45

Anterior spinal artery is cause Hypoglossal nucleus Medial lemniscus Contralateral UMN signs from pyramid damage Contralateral loss of proprioception/vibratory sense Tongue deviation toward side of lesion

Question 46

Lateral medullary syndrome

Answer 46

PICA is cause ALS- loss pain and temp contralaterally Spinal trigeminal nucleus/tract- loss of pain/temp to ipsilateral face (If you see these two symptoms- you know the lesion is in the medulla or lower pons. You can tell b/w pons or medulla because nucleus ambiguous is in medulla and damage will cause hoarseness. CN VI and VII nuclei are in pons) Vestibular nuclei- vertigo/nausea/nystagmus Restiform body- ataxia, wide gait, pt looks drunk Hypothalamospinal tract- Ipsilateral horners syndrome

Question 47

Corticobulbar tract lesion

Answer 47

Central seven palsy Lesion of corticobulbar tract involving CN VII Contralateral face droop To distinguish b/w bells palsy and CN VII issue just look and see if patient can wrinkle forehead

Question 48

Weber syndrome

Answer 48

P1 segment of posterior cerebral artery Corticospinal tract- CL hemiplegia, CL UMN signs Corticobulbar tract- CL face droop CN III- down and out, ptosis, dilated pupil

Question 49

Spastic cerebral palsy

Answer 49

Abnormal supraspinal influences Failure of normal neuronal selection- failure to reach developmental milestones Consequent aberrant muscle development Paresis/weakness Abnormal tonic stretch reflexes at rest and during movement Reflex radiation Lack of postural preparation prior to movement Abnormal cocontraction of muscles Inverted legs, scissor walk, up on the toes

Question 50

Amyotrophic lateral sclerosis ALS

Answer 50

Destroys only somatic motor neurons - UMN and LMN Leads to paresis, myoplastic hyperstiffness, hyperreflexia, babinskis sign, atrophy, fasciculations CN involvement leads to difficulty breathing, swallowing and speaking

Question 51

Polyneuropathy

Answer 51

Involvement of sensory, motor and autonomic Progressing from distal to proximal Impaired axonal transport Demyelization may also contribute