Spinal Cord-- Descending Systems Flashcards
Corticospinal tract
Neuronal pathway which originates in motor cortex, travels down brainstem, crosses the midline and eventually ends up in the anterior horn of the spinal cord gray matter.
Where does the cortical spinal tract originate?
In Cells of Broadman’s area 4 (precentral gyrus of the central culcus-bates/pyramidal cells)
Where does the cortical spinal tract mainly terminate?
The ventral horn, though their are some axons which
Anterior cortical spinal tract
10% of the cortical spinal tract axons which do not cross the midline
What does area 4 receive/send out?
Sends out motor information
Internal capsule
White fiber bundle between thalamus and some basal ganglia where axons travel after leaving area 4
Destruction of substantia nigra gives you…
Parkinson’s disease
Where does the decussation occur?
The lower part of the medulla where it meets the spinal cord. 90% of fibers go this route, pile up in the Lateral funiculus and become the lateral corticospinal tract.
The pyramids, specifically.
What does the cortical spinal track control?
Fine digital motor movement (playing piano) and other detailed movements.
What happens clinically if the CST is damaged via stroke or legion.
Spasticity and hemiplegia. Muscles will become weak and spastic and person will be hyper reflexive. There will be NO muscle wasting.
Stroke will affect things on the opposite side of part of brain where it occurred.
Legion in the spinal cord will affect things on same side.
Motor neuron (small vs large)
DEFINITION: Alpha motor neuron plus the skeletal muscle fibers it innervates.
SMALL- Result in precise movements
LARGE- Results in coarser movements
Distribution of alpha motor neurons
Alpha motor neurons which control distal muscle control are located LATERALLY while the nerves which control the trunk are most MEDIAL
