-affects UMN & LMN

LMN

- weakness

- atrophy

- fasciculations at rest

- depressed reflexes 

UMN

- umn pattern of weakness

- spastic bulbar & limb muscles

- hyperreflexia & extensor plantar responsiveness

- unknown cause

- slow progression degeneration of UMN & LMN

- Bublar symptom (slurring of words or chocking during a meal)

- arm weakness or wrist drop

- leg weakness or foot drop

- cyst (syrinx) forms in spinal cord, expanding & destroys the center of the spinal cord

- dissociated sensory loss -> syrinx block decussating spinothalamic fibers mediating pain & temp but light touch, vibration, & position are preserved

- syrinx into posterior column -> loss of position and vibration in feet

- syrinx into anterior horn - damage to moto neurons, atrophy of upper limbs (distal - proximal)

• degenerate of large diameter neurons in the dorsal root ganglia
• bilateral dorsal column signs below lesion
• late-stage neurosyphillia
• positive rhomberg sign

• selective destruction of LMN in ventral horn
• poliovirus
• flaccid paralysis
• hyporeflexia
• hypotonicity
• may result in progression or recovery

• decreased strength
• increased muscle tone
• increased stretch reflex
• mild atrophy
• clonus
• Babinski Sign

• decrease strength
• decrease muscle tone 
• decrease stretch reflexes
• severe atrophy
• fasiculations
• fibrillations

• hemisection of cord
• lesion may be in ...
• corticospinal tract
• spinothalamic tract
• dorsal column

Brown-Sequared Syndrome

Lesion of corticospinal tract

Brown-Sequared Syndrome

Lesion to dorsal column

Brown-Sequared Syndrome

lesion to spinothalamic tract

1 anterior spinal artery

2 posterior spinal arteries

segmental arteries

(upper cervical)

- comes from --> vertebral arteries

-forms --> anterior median fissure

(upper cervical)

- arises: vertebral aa or PICA

remain separate

- reinforcement vessel

-originates: thoracic or abdominal aorta

-distribution: anterior 2/3 & postioer 1/3

Dorsal Column/Medial Lemniscal System 

contains info

Dorsal Column/Medial Lemniscal System/Posterior Column

T6 and below

- ascending tract

-Fasciculus gracilis

-->

nucleus gracilis in caudal medulla (1st synapse)

-->

decussation in ventral medulla (medial lemniscus tract)

--->

VPL of thalamus (2nd synapse)

-->

post central gyrus

Posterior Column/Dorsal Column/Medial Lemniscus

pathway 

(T6 & above)

Fasciculus Cuneatus 

-->

nucleus cuneatus in caudal medulla (1st synape)

-->

decussation in ventral medulla (medial lemniscus tract)

VPL of thalamus (2nd synapse)

--->

post central gyrus 

- ascending 

- unconscious proprioception to cerebellum

help maintain posture and coordinated movement 

Contains:

Posterior Spinocerebellar (lower limb)

Cuneocerebellar Tract (upper limb)

Anterior Spinocerebellar

DRG from T8-S3

-->

dorsal nucleus of Clark (T1-L2) (synapse)

-->

enter cerebellum via inferior peduncle

Cunceocerebellar Tract

DRG (C2-T7)

-->

lateral cuneate/accessory cuneate nucleus in medulla oblongata (synapse)

-->

enter cerebellum via inferior peduncle

DRG (L2-S2)

-->

spinal border cells of ventral horn (synapse)

-->

decussates in anterior white commisure

-->

enters cerebellum via superior cerebellar peduncle

-->

decussate in cerebellum 

Spino thalamic Tract

Anterolateral System

-fibers enter Lissauer's tract & synapse in 1 or multiple places in dorsal horn

-->

cross anterior white commisure/decussate

-->

out of grey matter & into anterolateral feniculus (spinothalamic tract)

-->

VPL in thalamus

-->

post central gyrus

Anterolateral system includes collaterals

1. spinoreticulothalamic Tract

2.  spinomesencephalic Tract

3. Spinohypothalamic Tract

• changes in level of attention to pain
• multisynaptic (slower)

lateral Corticospinal tract

cortex

-->

internal capsule

--> 

cerebral peduncle in midbrain

-->

pons

-->

pyramids in caudal medulla

-->

pyramidal decussation & go to lateral feniculous as lateral corticospinal tract

(goes to all levels)

cortex

-->

internal capsule

-->

cerebral peduncle in midbrain

--> 

pons

-->

pyramids in the caudal medulla

--> form anterior corticospinal tract

-->

enter ventral horn and synpase with interneurons and LMN

Lateral Corticospinal Tract

anterior vs lateral

anterior = axial

lateral = distal limbs

controls voluntary skilled motor movements

cortex 

-->

synapse and project to red nucleus in midbrain

-->

decussate in midbrain 

-->

lateral feniculus and terminate in cervical region

maintains extension in lower limb

flexion in upper limb

cell bodies in lateral vestibular nucleus (pons and medulla)

-->

axon goes ipsilaterally to spinal cord

Medial Vestibulospinal Tract

Pathway

cell bodies in medial vestibular nucleus (pons & medulla)

-->

axons go ipsilaterally to cervical regions of spinal cord

medullary reticular formation 

-->

lateral feniculus 

Medial Reticulospinal Tract

Pathway

pontine reticular formation 

-->

forms part of medial longitudinal fasciculus (MLF)