General Organization of the Motor Systems

Reflex arc Neural “wiring” of reflex Requires 5 functional components: 1. sensory receptor, 2. sensory neuron, 3. intergrating center (SC or BS), 4. motor neuron, & 5. effector

curve A, in a normal muscle, and curve B, in a muscle whose muscle spindles were denervated

Muscle Spindle Reflex

Golgi Tendon Reflex

withdrawal crossed extensor

Myogram of the flexor reflex showing rapid onset of the reflex, an interval of fatigue, and, finally, afterdischarge after the input stimulus is over.

Myogram of a crossed extensor reflex showing slow onset but prolonged afterdischarge

Control of voluntary movement

18

The somatosensory cortex homunculus & The motor cortex homunculus

20

Inputs to motor cortex SMA Premotor cortex Primary motor cortex Thalamus Basal ganglia Cerebellum Spinal/sensory inputs Thalamus Primary sensory cortex

24

DECEREBRATION and DECORTICATION

Plantar Response Scrape object on sole of foot. Babinski sign indicative of UMN lesion. Normal in infants up to 1 yr.