Motor Tracts Flashcards
(31 cards)
What are the three subareas of the motor cortex?
- Primary motor cortex
- Premotor area
- Supplementary motor area
What does the primary motor cortex control?
It controls specific movements, especially of the hands and speech muscles.
Where is the primary motor cortex located?
It is located in area 4, starting in the sylvian fissure and dipping into the longitudinal fissure.
What is the function of the premotor area?
It creates a motor image and organizes complex movement patterns.
What type of contractions are caused by the supplementary motor area?
Often bilateral contractions for body-wide and positional movements.
What happens if Broca’s area is damaged?
The person can vocalize but cannot form full words.
What does the voluntary eye movement field control?
Voluntary eye movements and eyelid blinking.
What is the function of the head rotation area?
Controls head rotation, often in coordination with eye movement.
What condition results from lesions in the hand skills area?
Motor apraxia – uncoordinated and purposeless hand movements.
Where does the corticospinal tract originate?
30% from primary motor cortex, 30% from premotor/supplementary areas, and 40% from somatosensory areas.
What are Betz cells?
Large pyramidal cells in the primary motor cortex involved in the corticospinal tract.
What is the course of the corticospinal tract?
From internal capsule → brainstem → medullary pyramids → mostly cross to form lateral corticospinal tracts.
Where does the corticospinal tract terminate?
On interneurons, sensory relay neurons, and some directly on anterior motor neurons.
What do the rubrospinal, reticulospinal, and vestibulospinal tracts do?
They help control posture and body movements via the brainstem and cerebellum.
What is the function of the corticorubrospinal pathway?
Accessory motor control for small muscle groups, not fine finger movements.
Which part of the red nucleus receives input from the corticorubral tract?
The magnocellular portion.
What structures are involved in the extrapyramidal system?
Basal ganglia, reticular formation, vestibular and red nuclei.
What motor functions does the brainstem control?
Respiration, cardiovascular system, GI function, equilibrium, stereotyped movements, eye movements.
What is the function of pontine vs. medullary reticular nuclei?
Pontine: excitatory to axial/extensor muscles. Medullary: inhibitory to same muscles.
What do vestibular nuclei do?
Send excitatory signals to antigravity muscles to help maintain equilibrium.
How can you explain stroke symptoms variation in a patient like TJ?
Stroke symptoms depend on which brain area is affected—motor, sensory, or consciousness-related.
Which area of the motor cortex is mainly responsible for fine motor control of the hands?
Primary motor cortex
What cells are large pyramidal neurons in the primary motor cortex involved in voluntary movement?
Betz cells
Which tract crosses at the medullary pyramids to form the lateral corticospinal tract?
Corticospinal tract
