Spinal Movement Flashcards
How are motor systems organized?
Hierarchically
What are coordinated movements produced by?
Spatial and temporal patterns on muscle contractions ordered by the brain and spine
What are the two parts of motor control?
1) Spinal cord -> contains motor programs
2) Brain -> controls spinal motor programs
What are spinal nerves?
Mix of sensory and motor
What are the two types of muscles?
Smooth (inner gated by ANS fibers) and Striated
Do muscles pull or push on a joint?
Pull
What direction to flexors and extensors pull on a joint?
Opposite directions in order to antagonize each other
What are the 3 groups of muscles that act on joints?
Axial, proximal, distal
What do axial muscles control?
Trunk movement, posture
What do proximal muscles control?
Shoulder, elbow, pelvis, knee
What do distal muscles control?
Hands, feet, and digit movements
What are somatic muscles innervated by?
Somatic motor neurons (pretty tricky huh?)
Where are somatic motor neurons found?
Ventral horn of the spinal cord (lower motor neurons)
What do lower motor neurons do?
Directly command muscle contraction
Where are somas of upper motor neurons?
The brain
What do upper motor neurons provide?
Input to lower motor neurons
What does damage to UMNs cause?
Spasticity/Hypertonia
What does damage to LMNs cause?
Paralysis
What is meant by “limb enlargements”?
The spinal cord sections of muscles in the ventral horn are not even and are bigger the more skeletal muscle there is somewhere (ex. Lumbar section of spine has much larger ventral horns for the legs)
Where do motor neurons controlling flexors lie relative to extensors?
Dorsal
Where do motor neurons that control axial muscles lie relative to distal muscles?
Medial
What are two categories of LMNs?
Alpha and gamma
What do alpha neurons innervate?
Extrafusal muscle fibers
What do gamma LMNs innervate?
Intramural muscle fibers
What do alpha motor neurons do?
- branch and innervate many fibers over a wide area
- triggering generation of force by muscles