Chapter 8: Control of Movement Flashcards
The ones that move us around and thus are responsible for our actions; most of them are attached to bones at each end and move the bones when they contract.
Skeletal muscles
Strong bands of connective tissue.
Tendons
Moving a limb toward the body; produced by contraction of a flexor muscle.
Flexion
Opposite movement or moving a limb away from the body; produced by contraction of extensor muscles.
Extension
Muscles that we use to stand up.
Antigravity muscles
2 types of muscle fibers.
Extrafusal muscle fibers
Intrafusal muscle fibers
Are served by axons of the alpha motor neurons; contraction of these fibers provides the muscle’s motive force.
Extrafusal muscle fibers
Are specialized sensory organs that are served by two axons, one sensory and one motor; sensitive to stretch.
Intrafusal muscle fibers
Its efferent axon causes the intrafusal muscle fiber to contract.
Gamma motor neuron
The synapse between the terminal button of an efferent neuron and the membrane of a muscle fiber.
Neuromuscular junction
Located in grooves along the surface of the muscle fibers; where the terminal buttons of the
neurons synapse on.
Motor endplates
When an axon fires, acetylcholine is liberated by the terminal buttons and produces a depolarization of the postsynaptic membrane.
Endplate potential
Where the tendons are that the stretch receptors are also located within.
Golgi tendon organ
The animal’s back is arched, and its legs are extended stiffly from its body.
Decerebrate rigidity
A region of the brain stem, which greatly facilitates all stretch reflexes, especially of extensor muscles, by increasing the activity of
the gamma motor system.
Reticular formation
Function to control limb movements when weight is applied or removed quickly and to maintain upright posture.
Monosynaptic stretch reflex
2 regions adjacent to the primary motor cortex.
Supplementary motor area
Premotor cortex
Region that is located on the medial surface of
the brain, just rostral to the primary motor cortex; damage to this region disrupts the ability to execute well-learned sequences of responses in which the performance of one response serves as the signal that the next response must be made.
Supplementary motor area
Region that is located primarily on the lateral surface, also just rostral to the primary motor cortex.
Premotor cortex
Consists of the corticospinal tract, the corticobulbar tract, and the rubrospinal tract; primarily involved in control of independent limb movements, particularly movements of
the hands and fingers.
Lateral group
Consists of the vestibulospinal tract, the tectospinal tract, the reticulospinal tract, and the ventral corticospinal tract; control more automatic movements: gross movements of
the muscles of the trunk and coordinated trunk and limb movements involved in posture and locomotion.
Ventromedial group