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PHYS2
Control of Body Systems--MOTOR FUNCTION
| Question | Answer |
|---|---|
| What is a motor neuron pool? | All motor neurons that control a given muscle |
| NEURAL SYSTEMS THAT CONTROL BODY MOVEMENT | NEURAL SYSTEMS CONTRLLING BODY MOVEMENT |
| Highest level: | Determine intention of an action |
| What are some of these structures? | Association cortex |
| Middle Level: | Specifies postures and movements needed to carry out intended action |
| Structures: | Primary cortex, cerebellum, basal ganglia, and brainstem |
| Lowest level: | Determine which motor neurons will be activated |
| Structures: | Brainstem or spinal cord |
| Where do motor neurons exit? | Brainstem and spinal cord |
| What happens as the muscles are doing an action; Where do we send updates about what we're doing? | Motor control centers, which make needed program corrections |
| What determines if an action is voluntary? | We are aware of what we are doing and why, and our attention is directed toward the action of its purpose |
| Do we only control motor movements using conscious thought? Give an exception: | NO! When we move our calf msucles,, so we don't trip when we shift our center of gravity |
| LOCAL CONTROL | LOCAL CONTROL |
| Interneurons: | Where most input to motor neurons comes from |
| Where do they receive input from? | Peripheral receptors, descending pathways, and other interneurons |
| What do muscle spindle stretch receptors do? | Monitor muscle length and changes in length |
| What are they broken into? | Extra fascial and interfascial? |
| What's extrafascial? | They have a large diameter, so long tension and do work |
| Interfascial? | In capsule, interneurons;; innervate others |
| What does activation of the muscle spindle stretch receptors lead to? | Stretch reflex |
| What is the stretch reflex? | ipsilateral antagonists are inhibited and those of synergists are activated |
| What happens there? | You lengthen muscle fiber-->tell brain muscle is stretched-->stretch reflex |
| What is an example of the muscle spindle stretch receptor mechanism? | The knee jerk |
| What do gamma efferent activation of the spindle muscle fibers do? | Maintains muscle contraction in stretch receptors |
| How do we prevent stretch receptors from going slack during voluntary contraction? | Activate alpha and gamma motor neurons |
| What are you aactivating in doing so? Which shortens more quickly? | Interfusal and extrafusal fibers; extrafusal fibers shorten more quickly |
| What does this allow? | Lets motor control system ignore voluntary movements, but still keeps muscle spindles poised to detect if there is a change in the intention |
| What is an example of when this would hapen? | If you pick up a carton of milk you thought is heavy but is empty, you activate alpha and beta, muscle spindles go slack, but you reduce level of excitation |
| MUSCLE TENSION | MUSCLE TENSION |
| Where does muscle tension occur? | In tendons |
| What is it monitored by? | Golgi tendon organs |
| What do the golgi tendon organs do? | Activate inhibitory synapses on motor neurons of the contracting muscle and excitatory synapses on motor neurons of ipsilater antagonists |
| So what neurons do they inhibit? | Alpha neurons |
| FLEXION OR WITHRRDRAWL REFLEX | Withdrawl reflex |
| What does this reflex do? | Excites ipsilateral flexor muscles and inhibits ipsilateral extensors |
| Crossed extensor reflex? | Excites contralateral extensor muscles during excitation of the pisilateral flexors |
| MEAT AND POTATOES | MEAT AND POTATOES |
| What happens when you step on a nail? | Withdrawl: You relax your ipsilateral extensor muscles and contract your flexor (withrdawl) ipsilateral muscles; Crossed-extensor reflex: Excite contralateral extensors during flextion of ipsilateral muscles |
| BRAIN MOTOR CENTERS | BRAIN MOTOR CENTERS |
| Sensorimotor cortex: | parts of the cerebral cortex that act together in control of muscle movement |
| What are the two primary areas? | Primary motor cortex and pre-motor area |
| Which areas get greater control in the brain? How do you decide? | MOTOR HAL!! |
| What do subcortical and brainstem nuclei determine? | determine direction, force, and speed of movements |
| Cerebellum: | Coordinates posture and movement and plays a role in learning |
| What is the corticospinal pathways? | From motor cortex to neurons in spinal cord to interneurons |
| What kind of movmeent does the corticospinal pathway control? | Specific/fine |
| What are non-corticospinal pathways doing? | From brainstem and are invovled in coordination of large groups of musces in posture and movement |
| Is there any overlap between the two? | Yep |
| MUSCLE TONE | MUSCLE TONE |
| Define muscle tone? | Resistance of skeletal musce to passive stretch when an individual is attempting to relax |
| What is muscle tone due to? | Alpha motor neuron ad viscoelastic properties |
| ABNORMAL MUSCLE TONE | abnormal |
| Hypertonia: | Too much tone/ activation |
| Hypotonia: | Too little tone |
| Where does hyptonia arise from? | Alpha motor neuron disuse |
| Where does hypertonia arise? | Disorders of efferent pathways |
Created by:
talkglitter2486