spinal cord topography

UMN lesion presentation

hyperreflexia

spastic paralysis/ weakness (LMN intact, but NOT coordinated/voluntary way)

Not much atrophy: muscles still receive stimulation from LMN

LMN lesion presentation

Areflexia: lack of reflexes + atonia (lack of muscle tone); UMN intact, but nothing to excite

Flaccid paralysis: muscles can’t contract, not even reflexively

Atrophy! - no neural stimulation = muscles waste away

Which levels is the lateral horn (aka IML: intermediolateral) present in?

T1-L2

Pre-ganglionic SYMPAthetics

Somatotropy

concept of mapping

regions of CNS → correlate to regions of body

ex. ventral side of horn = “extensors” ; dorsal side =”flexors”

Medial: medial muscles/regions

Lateral: more distal muscles/regions

White matter increases as you…

ascend the spinal cord

-more white in cervical region

Cervical segments

lots of white/gray

-largest spinal cord segment

thoracic segements

less gray + white matter compared to cervical

-less gray: no limbs to innervate

-less white: some axons exited at the cervical level (fewer axons running up/down)

Contains the LATERAL HORN (IML) (T1-L2): pregang sympathetics

lumbar segments

L1/L2- contain lateral horn (IML-intermediolateral nucleus)

-moderate amount of gray matter: innervates lower limbs

-reduced amount of whtie matter

sacral segments

small

lateral horn (IML) - can be found in S2-S4 segments: but contain PARAsympathetic preganglion nuerons

UMN relation to LMN

UMN control LMN DIRECTLY or via interneurons

-descend from cerebral cortx/brainstem → synapse on LMN dendrites in VENTRAL HORN

reflexes have ..

sensory + motor components

contraction/firing of muscle AND inhibtion of antagonist muscles

Somatotropy pattern for lateral corticospinal tract :

Cerebrum Pyramids Cross Lateral Down

Medial → Lateral

Cervica, Thoracic, Lumbar

(higher spinal levels = more MEDIAL)

where does the anterior corticospinal tract corss?

in the spinal cord

Ants sometimes cross, they STay in

Corticobulbar Tract: which cranial nerve crosses completely?

CN 11

“ Cortical bulbs go to the brainstem!”

Note: CN 7 - some cross completely (below eyes); others do/don’t cross (above eyes)

what are the 2 types of reticulospinal tracts

Pontine (medial): postural muscles (facilitates spinal extensors) +

Medullary (Lateral) (inhibits the spinal extensors)

Where does the pontine (medial) reticular formation tract go?

ventral tract

Where does the medullary (lateral) reticular formation tract go?

ventral tract + some ventral portion of the lateral tract

what is the function of the lateral vestibulospinal tract?

postural control of Legs + trunk

what is the medial vestibulospinal tract responsible for + where does it end?

neck muscles

ends in cervical spine

What is the role of the rubrospinal tract?

Red Racoons Run More Laterally

-excite FLEXORS; inhibit extensors (modulate reflexes)

where does the rubrospinal tract decussate?

Red Racoons Run More Laterally

The midbrain- ventral tegmentum

where does the tectospinal tract decussate?

Tecto turns more ventral

midbrain - dorsal tegmentum

role of tectospinal tract

head/neck muscles for eye positioning

originates - superior collucili

“Tecto turns more ventral”