Nervous System Physiology Pat 9 Flashcards
What is the primary function of the stretch reflex?
To ensure that the muscle stays at a specific length.
Where is the stretch reflex most important?
: In large extensor muscles that support upright posture and in postural trunk muscles.
What is the main function of the tendon reflex?
To prevent excessive tension on the muscle.
How does the tendon reflex work?
Golgi tendon organs detect increased tension, sending inhibitory signals via the spinal cord to reduce muscle tension.
What kind of mechanism is the tendon reflex and why?
is a negative feedback mechanism to prevent excessive muscle tension.
What activates the withdrawal reflex?
Painful stimulation of the skin, such as stepping on a tack.
What happens during the withdrawal reflex?
Flexor muscles contract and ipsilateral extensor muscles are inhibited, moving the limb away from the painful stimulus.
What is the crossed-extensor reflex?
It’s a reflex where the opposite leg responds to a painful stimulus by extending (activating extensors and inhibiting flexors) to support body weight as the injured leg withdraws.
What is the purpose of the crossed-extensor reflex?
To maintain balance by supporting the body’s weight on the opposite leg when one leg withdraws due to pain.
What is the role of the cerebral cortex in motor control?
It plans and controls voluntary movements, functioning at the highest and middle levels of the motor control hierarchy.
What does the cerebral cortex do in terms of action?
: It is responsible for designing and programming action.
What areas make up the sensorimotor cortex?
The premotor, supplementary motor, primary motor, somatosensory, and parietal-lobe association cortices.
What is the sensorimotor cortex?
A term referring to all parts of the cerebral cortex involved in controlling muscle movement.
What is the function of the motor cortex?
: It controls muscle groups through neurons arranged in a somatotopic map.
What is a somatotopic map in the motor cortex?
It is an anatomical organization of neurons corresponding to specific body parts.
Where are subcortical and brainstem nuclei located?
In the brainstem and cerebrum beneath the cortex.
How do subcortical and brainstem nuclei influence motor neurons?
A: Indirectly via ascending pathways to the cortex and descending pathways from the brainstem nuclei.
What is the role of basal nuclei in motor control?
They are part of looping circuits that transmit motor activity between the sensorimotor cortex, thalamus, and back to the cortex.
What is the effect of basal nuclei circuits?
Some circuits facilitate movement; others suppress it.
