Neuro Block 3 Week 3

Front 1

What are the names of the lateral motor pathways?

Back 1

The corticospinal tract and the rubrospinal tract

Front 2

What do the 2 lateral motor pathways achieve?

Back 2

Movement of the contralateral limbs

Front 3

What are the 5 Medial Motor Pathways?

Back 3

Anterior Corticospinal tract, Medial vestibulospinal tract, lateral vestibulospinal tract, reticulospinal tract, tectospinal tract

Front 4

What is the function of the anterior corticospinal tract?

Back 4

Moves axial and girdle muscles

Front 5

What is the function of the medial vestibulospinal tract?

Back 5

VOR and coordinates eyes together

Front 6

What is the function of the LVST?

Back 6

Balance, posture

Front 7

What is the function of the reticulospinal tract

Back 7

Controls posture, gait, decerebrate posture

Front 8

What is the function of the tectospinal tract?

Back 8

Upward gaze
Reflexive movements of head and eyes

Front 9

Which tract is most important for fine motor movement?

Back 9

Lateral Corticospinal tract

Front 10

A typical lateral corticospinal tract injury involves what symptoms

Back 10

No flexion. Loss of fractionated movements

Front 11

What action does the lateral corticospinal tract have on extensors and flexors

Back 11

Inhibits extensors. Excites flexors

Front 12

What is the pathway of the lateral corticospinal tract?

Back 12

Descends from cortex in the corona radiata -> posterior limb of internal capsule-> cerebral peduncle (midbrain) -> anterolateral pons -> medullary pyraminds (decussation) -> lateral white matter columns of SC -> lateral motor nuclei

Front 13

What are the 3 places in the cortex where the lateral corticospinal tract can start from

Back 13

Primary motor cortex, SMA/premotor, parietal lobe

Front 14

Are lesions ipsilateral or contralateral for the lateral corticospinal tract?

Back 14

They are ipsilateral above the medullary pyramids. They are contralateral below this decussation

Front 15

If there is a lesion in the cortex that damages the lateral corticospinal tract, what symptoms result?

Back 15

Contralateral paresis/paralysis
Loss of fine motor movement
spasticity
hyperrelfexia
Babinski

Front 16

If there is a lesion to the posterior limb of the internal capsule, what deficits will occur in the lateral corticospinal tract?

Back 16

Contralateral hemiplegia

Front 17

What is Weber's syndrome?

Back 17

Weber's syndrome is a cerebral peduncle lesion (midbrain) usually accompanied by occlusion in the PCA.

The symptoms of Weber's include contralateral paralysis of lower face, tongue, UE, and LE.

If CN III is involved, ptosis, mydriasis, lateral strabismus

Front 18

The medial medullary syndrome is a lesion in which tract? What causes it and what are the symptoms?

Back 18

Lesion in the lateral corticospinal tract. It is caused by and vertebral or PICA occlusion. It results in contralateral hemiplegia (FACE SPARED), contralateral loss of sensory info (pain, temp, vibration etc). CNXII injury results in ipsilateral tongue paralysis.

Front 19

What is the function of the rubrospinal tract?

Back 19

Excites proximal limb flexors in the upper extremity.

Front 20

What are the inputs to the rubrospinal tract?

Back 20

Ipsilateral cerebral cortex
Contralateral cerebellar nuclei

Front 21

What is the pathway of the rubrospinal tract?

Back 21

Inputs -> red nucleus -> decussation in the ventral tegmentum -> lateral funiculus -> LMN of ventral horn

Front 22

Are deficits in the rubrospinal tract ipsilateral or contralateral

Back 22

Lesions below the midbrain are ipsilateral. Lesions above the midbrain are contralateral.

Front 23

What is decorticate posturing? In what tract does this pathology occur.

Back 23

Decorticate posturing occurs in the rubrospinal tract when input from the CORTEX is removed (red nucleus and cerebellar input still intact). This causes flexed upper limbs (hands to de cor)

Front 24

What is Bendekits syndrome? In which tract does this pathology occur and why

Back 24

Bendekits occurs due to a unilateral red nucleus lesion in the midbrain. This results in CNIII issues, contralateral tremor and hemianesthesia. This is in the rubrospinal tract

Front 25

What is the function of the lateral vestibulospinal tract?

Back 25

Balance posture -> autonmatic postural adjustments

Front 26

What muscles are excited in the lateral vestibulospinal tract?

Back 26

LMNs of neck, trunk, and limb extensors (antigravity)

Front 27

What is the pathway of the lateral vestibulospinal tract?

Back 27

Lateral Vestibular nuclei (sense linear, angular accel; take input from CN VIII) -> ipsilateral LMN.

Front 28

What structures modify input to the lateral vestibulospinal tract

Back 28

the flocculus and nodulus as well as sensory receptors

Front 29

Lesions to the lateral vesibulospinal tract result in falling to which side

Back 29

The ipsilateral side because you've lost extensor input to that side

Front 30

The Lateral Medullary Syndrome of Wallenberg occurs in which tract

Back 30

The lateral vestibulospinal tract

Front 31

What causes the lateral medullary syndrome of wallenberg? What are the symptoms?

Back 31

Vertebral or PICA occlusion causes lateral medullary syndrome.

Ipsilaterally there are 5 symptoms:
1) Loss of NAc (CN IX, X) leads to dysphagia, dysarthria, reduced gag reflex
2) Loss of pain/temp from face (spinal tract of V)
3) Loss of vestibular nuclei (vertigo, vomiting, nystagmus)
4) Horners syndrome (ptosis, miosis, anhydrosis)
5) stumble toward side of lesion.

Contralaterally - loss of pain/temp from body

Front 32

What does the medial vestibulospinal tract do?

Back 32

Coordinates the eyes together. VOR (coordinates eye movements to compensate for head movements),
adjust head in response to changes in posture

Front 33

What is the pathway of the medial vestibulospinal tract?

Back 33

Medial vestibular nucleus -> bilateral projection to LMN in spinal cord and spinal accessory nuclei via the medial longitudinal fasciculus.

The point of this is to inhibit LMN that control neck and axial muscles.

There is also some superior projection to the CN III, IV, and VI -> VOR

Front 34

What is the function of the VOR?

Back 34

The VOR allows you to keep your eyes focused when the head moves. It is supressed when watching a moving object (cerebellum, vermis). Interruption of the MLF will result in VOR loss (eyes move with the head).

Front 35

What is internuclear opthalmoplegia

Back 35

INO results from a unilateral MLF lesion often caused by MS/pontine infarct/tumor/trauma.
The eye on the side of the lesion cannot adduct fully. The eye on the opposite side exhibits nystagmus.
Test by Dolls test- move the head to one side- the eyes should turn in the opposite direction. If not some brainstem dysfunction could be present.

Front 36

What is the function of the tectospinal tract (corticotectal)

Back 36

Reflexive head turning movements of head/eyes

Upward Gaze

Front 37

What is the pathway for the corticotectal tract/tectospinal tract?

Back 37

visual cortex/retinal/inferior parietal lobe -> superior colliculi-> tectospinal fibers -> decussate at dorsal tegmentum -> MLF (medulla) ->cervical spinal cord (CN XI nuc)

o Visual cortex -> superior colliculi -> PPRF -> MLF -->extraocular muscles (upward gaze)

Front 38

What are some names for Parinauds? In which tract does this lesion occur

Back 38

Dorsal midbrain/collicular syndrome occuring in the corticotectal tract.

Front 39

What are the symptoms of Parinauds

Back 39

Loss of upward gaze, large irregular pupils (pupils will not constrict with light but will with accomodation), eyelid ptosis, convergence retraction nystagmus when trying to look up.

Front 40

Causes of Parinauds syndrome

Back 40

Pineal gland tumor, hydrocephalus (increased ICP-> aqueductal stenosis)

Front 41

What does the reticulospinal tract do?

Back 41

Helps maintain upright posture by influencing voluntary/reflexive movement.The reticulospinal tracts also convey ANS information (circulation, breathing, UG, pupils).

Front 42

What is the core difference between the Medial Reticulospinal tract and Lateral Reticulospinal tract

Back 42

Lateral reticulospinal tract inhibits motor neurons related to posture (inhibits spinal motor neurons related to extensor spinal reflex). Medial reticulospinal tract excites motor neurons related to posture (excite spinal neurons that innervate axial muscles and leg extensors)

Front 43

The Lateral RST is also called what? Is it Mellow or Pump up.

Back 43

The lateral RST is also called the medullary. hence mellow.

Front 44

The Medial RST is also called what? Is it Mellow or pump up

Back 44

The Medial RST is also called the pontine. hence pump up.

Front 45

Is the LRST usually stimulated or inhibited by the cortex?

Back 45

LRST is usually stimulated by the cortex

Front 46

Is the MRST usually stimulated or inhibited by the cotex?

Back 46

MRST is usually inhibited by the cortex

Front 47

In which tract does arousal/sleep fibers ascend to the thalamus?

Back 47

LRST has ascending arousal/sleep fibers to the thalamus.

Front 48

What is decerebrate posturing and in what tract does this occur. Whats the cause

Back 48

Decerebrate posturing is a lesion in the reticulospinal tract. It involves the arms and legs extended, toes in, back arched. It is caused by a lesion caudal to red nuclei (transection btwn superior and inferior colliculi)

Front 49

What is the explanation as to why decerebrate posturing occurs?

Back 49

You are removing excitatory coritcal input to the inhibitory LRST.
With only the MRST -> exciting motor neurons -> increases tone.

Front 50

What is locked in syndrome? Why can they maintain eye opening and vertical movements?

Back 50

Locked in syndrome occurs when you have a ventral pons infarct (stroke at the level of basilar artery). This results in a loss of bilateral corticospinal tracts, with no corticul input to CN nuclei or SC. These individuals maintain sensory function and cognition. They can move eyes vertically because the rostral midbrain tegmentum is spared. Horizontal eye movements are lost because they are based in the pons.

Front 51

What is the function of the corticonuclear/corticobulbar tract?

Back 51

UMN for cranial nuclei

Front 52

What is the pathway of the corticonuclear/corticobulbar tract?

Back 52

Corticonuclear fibers originate in the precentral gyrus (primary motor cortex) -> pass with corticospinal tracts through the corona radiata -> internal capsule (genule)

• terminate in brainstem motor nuclei

Front 53

Describe the arrangement of the corticonuclear/corticobulbar tract (bilateral, contralateral, ipsilateral etc)? Which nuclei relay through the reticular formation?

Back 53

o CN V, IX, X, XI = bilateral
o CN XII = contralateral
o CNVII = top 1/3 = bilateral innerv & bottom 2/3 = contralateral innerv

• Most relay through the reticular formation
o V, VII & XII do NOT relay through reticular formation

Front 54

In what tract does an Internal capsule lesion occur?

Back 54

An internal capsule lesion occurs in the corticobulbar tract.

Front 55

What does the internal capsule lesion involve?

Back 55

Affect the corticospinal and corticonuclear tracts
• Contralateral hemiplegia accompanied by CN signs:
o CNVII: contralateral lower 2/3 deficits = can’t smile
o CNXII: tongue deviates toward & atrophies on contralateral side

Front 56

In what tract does the pseudobulbar palsy occur?

Back 56

The Corticobulbar tract

Front 57

What are the symptoms of pseudobulbar palsy? What are the causes of the pseudobulbar tract?

Back 57

• Bilateral lesion of corticobulbar tract
• Dysphagia, dysarthria, paresis of the tongue, loss of emotional control
• Causes: brainstem infracts, ALS, MS

Front 58

Whats Bells palsy? In what tract does Bells palsy occur?

Back 58

Bells palsy occurs in the corticobulbar tract?

• Peripheral CN VII lesion
• Can’t wrinkle forehead or smile on ipsilateral side
o Loss of forehead wrinkle = pathognomonic of peripheral lesion because with central lesion of CNVII forehead innervation is intact d/t bilateral innervation of peripheral nerves

Front 59

What is Peripheral CNXII lesion? What tract does it occur in?

Back 59

Corticobulbar tract
• Tongue deviation toward side of injury (side of injury is weak so healthy side can deviate tongue toward side of injury)
• Compared with corticonuclear tract lesion: tongue deviates away from side of injury