L12. Movement Flashcards
Primary motor cortex?
- The primary motor cortex has an ordered map of the body (somatotopy)
- It regulates the spinal cord motor systems via the corticospinal (pyramidal) tract
- Located in the pre-central gyrus
Somatotopy in primary motor cortex?
- Body parts represented roughly sequentially across cortex
Area devoted to each part is:
- dependent on level of fine control
- dependent on extent of use
Damage causes problems with movement, particularly with fine voluntary control in specific parts of the body
Stimulation activates movements in specific parts of the body
Corticospinal pathway?
Output from motor cortex to the spinal neurons that carries signals to control movement (crosses to opposite side at the medulla)
- Most input is to interneurons
Brainstem pathway?
Output from the brainstem to the spinal neurons
Coordinated activity in large muscle groups for posture and balance
Mostly ipsilateral
Stretch reflex?
- Maintains muscle length
- Monosynaptic arc causes contraction of stretched muscle
- Polysynaptic arc cause relaxation of opposing muscle
Tension reflex (Golgi tendon reflex)?
- Polysnaptic arc causes relaxation of muscle responsible for causing high tension on the tendon
- Polysnaptic arc causes contraction of opposing muscle
- Regulates muscle force and protects tendon from rupturing
Withdrawal reflex?
- Pain is detected by sensory neuron
- Causes motor reflex to move away from the pain stimulus
Crossed extensor reflex?
- Stabilises the body when one limb withdraws
- Compensates for loss of support to maintain balance
Do these reflexes get relayed to the brain?
No, they are contained within the spinal cord alone however, the brain can over-ride the reflex (when anticipating the outcome/response)
The tension reflex maintains muscle length BECAUSE sensory neurons can synapse directly onto motor neurons
A. If both statements are true, and the second causes the first
B. If both statements are true, but the second does not cause the first
C. If the first is true and the second is false
D. If the first is false and the second is true
E. Both statements are false
D
