Lecture 15 - Motor Systems Pyramidal System Flashcards
Corticospinal motor tracks are 2-neuron tracks that begin with Primary Motor Neurons in the ______Gyrus (Primary motor cortex) which synapse with Secondary Motor Neurons in the ______ horn of the Spinal cord. 90% of Primary motor neurons decussate in the ______ of the ______.
Precentral Gyrus
Ventral (Anterior) horn
Pyramids
Medulla
In the Corticobulbar track, Primary motor neurons synapse with Lower motor neurons in the ______. What are these Lower motor neurons that innervate the head and neck known as?
Keep in mind Corticobulbar track Primary motor neurons decussate at the level of Origin of the Cranial Nerves they synapse with (should make sense).
Brainstem
Cranial Nerves
While the area of the Primary Motor cortex that controls the Lower limbs is most _____ and the area that controls the Face is most _____, the fibers twist in the Corona Radiata and down into the Internal Capsule such that the “Leg” fibers become most ______ and the “Face” fibers become most _____.
Medial
Lateral
Lateral
Medial
Similar to the Cerebral cortex, there is Somatotopy of the Ventral Horn. Motor neurons that innervate more Proximal muscles are more ______ (medial or lateral?) and those that innervate Distal muscles are more _______ within the horn. Also, Neurons that innervate Flexor muscles are more _____ (dorsal or ventral?) while Extensors are more ______.
Medial
Lateral
Dorsal
Ventral
______ ______ is the term used to describe how neurons that innervate muscles that synergistically move body parts in a particular direction are grouped close together.
Directional Tuning
Notice in the image how movement to the yellow area causes a group of neurons to become more active (darker lines) and those same neurons become completely Inactive (absent lines) when the movement is to the opposite (purple) direction.
The ______ cortex, located just anterior (ventral) to the Primary Motor Cortex, is involved with motor planning. ______ area for speech production and ______ _____ fields for conjugate eye movements are both located in this cortex.
It communicates directly with the Primary Motor Cortex, and it receivs input from the _____ _____ cortext, which it then communicates with the Primary Motor Cortex.
Premotor cortex
Broca’s Area
Frontal Visual fields
Posterior Parietal Cortex
Because inputs from the Thalamus, Cerebellum, and Posterior Parietal Cortex help coordinate movements, lesions here may result in ______ (keep in mind this means the strength and basic motor function is there, but coordination is not.)
Apraxia
The Medial Vestibulospinal tract controls _____ movement with ______ (what kind of directional movement?)
The Lateral Vestibulospinal tract controls ______ (proximal or distal?) limb movements and Antigravity _______ (flexor or extensor?) movements.
Head
Rotation
Proximal
Extensor
The ________ tract originates in the Red nucleus and modulates motor neuron activity in the Ventral horn.
Rubrospinal tract
Neurons in the Reticulospinal tract help to modulate muscle ______. The Medial Reticulospinal tract originates in the ______ and is ______, while the Lateral Reticulospinal tract originates in the ______ and is ______.
Tone
Pons
Excitatory
Medulla
Inhibitory
A lesion anyhwere along the Pyramidal pathways will cause muscle weakness. UPPER motor neuron lesions will result in ______, ______, and potenially _______ reflex (Big toe goes up with plantar stimulation - which is pathological if present in patients > 2years of age).
Spasticity
Hyperreflexia
Babinski’s sign
For lesions in the UPPER motor neurons of the Corticobulbar tract, look for exaggerated Brainstem reflexes/primitive reflexes like ____ reflex, Rooting reflex, Jaw Jerk, and Snouting reflex. It can also result in _______ affect, characterized by affect that doesn’t reflect mood (e.g. laughing when angry).
Gag
Pseudobulbar affect
