Spinal Cor - DESCENDING systems Flashcards
Describe the pathway of the Corticospinal tract starting from the Betz cells:
- Betz Cells/ Pyramidal cells in AREA 4 (pre-central=motor)
- Corona Radiata
- Posterior Internal Capsule
- Crus Cerebri (Cerebellar Peduncle of Midbrain)
- Pons
- Medullary Pyradis - DECUSSATE
- Lateral corticospinal & Anterior Tract (mostly in LATERAL)
What tract is responsible for fine movement?
Corticospinal Tract
Where does the Corticospinal tract synapse?
LATERAL FUNICULUS (dorsal horn, IG, and ventral horn)
–> ANTERIOR HORN CELLS
What areas are found in the pre-central gyrus? Post-central?
pre-central = AREA 4
post-central AREA 312 (sensory)
Which area does the CST start?Where does the CST decussate/cross?
AREA 4
- MEDULLARY PYRAMIDS
- synapse in ANTERIOR HORN CELLS
Most fibers of the CST cross and descend as which tract?
Lateral Corticospinal Tract
10% = Anterior COrticospinal Tract
Where is area 4?
Pre-central gyrus of the Cerebral Cortex
Frontal, post-central = parietal
Where do axons from the Cerebral Cortex converge for CST? Where do they descend through?
Corona Radiata
- descend through INTERNAL CAPSULE
- -> Crus Cerebri in midbrain
- pons
- medulla
What type of motor neurons are termed “lower motor neurons”
Alpha Motor neurons (innervate skeletal muscle)
Where is the phrenic nucleus found? Spinal Accessory nucleus?
C3,4,5
C1-C6
Which nuclei occupy the same area as the CST anterior horn cells?
Phrenic & SPinal Accessory Nuclei in cervical cord
have upper motor neurons
Where does CST terminate? Where else are fibers found? Where do the remaining fibers go up into?
- VENTRAL horn
- Intermediate Gray (gross movements)
- Dorsal Horn
- terminates mainly in VENTRAL HORN
A stroke of the right cortex of the CST affects which side? What about a cut in the CST in the spinal cord?
Stroke = affect opposite side
Cut = affect SAME SIDE
(similar to DCP)
Cells of origin of the CST are called what?
Bet cells (pyramidal cells)
When the CST axons first leave the pyramidal cells/betz cells, what do they form? Where do these cells descend?
Corona Radiata
- Internal Capsule
(between thalamus & putamen & globes pallidus)
Where does the CST travel after it descends from the internal capsule?
Crus Cerebri (Cerebellar Peduncle) of Midbrain
What are the black cells between the crus & central portion of midbrain (mickey mouse)?
SUBSTANIA NIGRA
Damage to Substantia Nigra, which contains dopamine cells, leads to which neurologic condition?
Parkinson’d Disease
After the crus of the midbrain, where do axons travel?
BASE OF PONS
The CST proper, after descending in the lateral funicular, synapses where?
ANTERIOR HORN CELLS (ventral)
What type of lesion results in spasticity, exaggerated reflexes, and hemiplegia?
UPPER MOTOR NEURON
What type of lesion causes flaccid paralysis, hypo reflexivity, and fasciculations?
LOWER MOTOR NEURON
anterior horn cells + axons = lower motor neurons
Small motor unites result in _____ movements, large motor units in ____ movements.
- Fine
2. Coarse movements (Ex; gluteus maximus)
Somatotopy, or medial & lateral divisions of the ventral horn, show that lateral divisions & medial divisions are responsible for which parts of the body?
LATERAL = Arm, hand, forearm
Medial = trunk, leg
Where is the size of the ventral horn in C8 compared to T10?
C8 = much larger
ALS or Polio both wipe out which cells?
ANTERIOR HORN CELLS
What is unique about pyramidal cells?
Have LARGE apical dendrites
In ALS, which motor neuron signs dominate? What is destroyed?
- LOWER MOTOR NEUROn (flaccid paralysis, hyporeflexivity, fasciculations)
- ANTERIOR HORN CELLS destroyed
A stroke of area 4 is sign of what motor neuron lesion?
UPPER MOTOR NEURONLESION
- Spacticity
- Exaggerated Reflexes
- Hemiplegia
WILL AFFECT OPPOSITE SIDE
What is a normal & abnormal Babinski sign?
1. Hallux Dorsiflex, toes fan out
2. Toes curve inward, foot everts
What does the Babinski sign show?
- ABNORMAL
- Normal
- shows you are an infant or a CENTRAL NERVOUS SYSTEM LESION
= UPPERMOTOR NEURON
(spasticity, ex. reflexes, hemiplegia)
What is destroyed in the following:
- Anterior SPinal A. Occlusion
- Subaccute Combined Degeneration
- ALS
- Tobes Dorsalis
- Wipe out CST & Ventral horn
- Posterior Column & CST
- CST & Ventral Horn
- POSTERIOR COLUMB
The nucleus Proprius is a part of which tract?
Spinothalamic Tract
Area 312 is responsible for what two tracts?
STT & DCP
Which area is CTT? (Corticospinal tract)
4
Which pathways are crossed in the cord?
- STT (spinothalamic)
- VSCT (twice)
- ACST
The medial lemniscus is part of which pathway?
DCP
Nucleus DOrsalis is in which tract?
DSCT
Dorsospinocerebellar Tract
Medullary Pyramids are in which tract?
CST
corticospinal (descending)
Which tracts are crossed in the medulla?
- CST
2. DCP
Where is Clark’s Nucleus?(which tract)
Dorsospinocerebellar Tract
DSCT
Which tract uses both medial & lateral motor nuclei?
CST
What is in the IML?
sympathetics
Where does the CST synapse?
ANTERIOR HORN
What are the cells of origin of CST?
PYRAMIDAL CELLS
