Motor Systems: Musculoskeletal System + Neural Mechanisms

Question 1

the heirarchy of motor control systems

Answer 1

muscle
spinal cord - contains motor neurons innervating the muscle
brainstem - nuclei project to spinal cord
motor cortex - primary and supplementary areas
subcortical regions - basal ganglia and thalamus
cerebellum

Question 2

characteristics of the musculoskeletal system

Answer 2

skeleton, tendons, ligaments, agonist/antagonist pairs, flexor and extensor

Question 3

skeleton

Answer 3

bodily movements constrained by joints. muscles use bones as levers around joints

Question 4

degrees of freedom

Answer 4

number of directions possible in articulation

Question 5

tendons

Answer 5

connect muscle to bone

Question 6

ligaments

Answer 6

connect bone to bone

Question 7

synergists

Answer 7

muscles that team up to move in one direction

Question 8

agonist/antagonist pairs

Answer 8

pairs of muscles are coordinated to either side of a joint, producing movement in opposite directions

Question 9

flexor

Answer 9

muscle that flexes joint usually toward body

Question 10

extensor

Answer 10

muscle that straightens joint usually away from body

Question 11

striate muscle

Answer 11

skeletal muscle, made up of many muscle fibres, up to 100 microns in diameter. each fibre consists of myofibrils which make up myofilaments and wher eteh contractile action occurs

Question 12

myofilament

Answer 12

consists of regularly arranged, overlapping molecules of myosin and actin, which make up a molecular motor that runs on calcium. myosin and actin ratchet each otehr to produce contractions

Question 13

innervation of muscle

Answer 13

supplied by ventral horn motor neurons. theyre sometimes called the final common pathway

Question 14

neuromuscular junction

Answer 14

highly specialized synapse where the ACh binds to receptors on the motor endplate and produce endplate potential

Question 15

endplate potential

Answer 15

where ACh produces a large depolarization as Na and Ca ions rush in

Question 16

motor unit

Answer 16

one motor neuronand all of the fibres which it innervates. the basic unit of movement

Question 17

motor pool

Answer 17

all neurons that innervate a single muscle in the muscles motor pool. usually close aggregated in the spinal cord

Question 18

integration

Answer 18

motor neuron must integrate information from a large variety of sources

Question 19

simple relfexes

Answer 19

at any level of the cord, reflect processing and integration of corresponding sensory info from that level. usually involve only oneor a couple of synapses between input and output side

Question 20

projections from the brain

Answer 20

modulate the activity of motor neurons either causing them to fire or inhibiting them. 2 major divisions: pyramidal system and extrapyramidal system

Question 21

pyramidal system

Answer 21

projection from cortical motor neurons whose axons pass through the pyramdis of the medulla.

Question 22

betz cells

Answer 22

extra large, fast cotrical motor neurons which are importnat for lower limbs

Question 23

extrapyramidal system

Answer 23

axons from cells other than the pyramidal cells, especially from subcortical regions. play a special role in movement initiation, gait and error corection

Question 24

motor cortex

Answer 24

major source of pyramidal tract and executive control which is the conscious decision to move in some way

Question 25

basal ganglia

Answer 25

recieves inputs from substantia nigra and thalamus. the pattern of innervation differs amongst the basal ganglia

Question 26

caudate

Answer 26

intergrates info from frontal lobes, lesions affect complex behaviour, especially dealing with spacial relations

Question 27

putamen

Answer 27

integrates inputs from sensorimotor cortical areas, lesions have straightforward motor effects

Question 28

cerebellum

Answer 28

3 layers - mole cular, purkinje and granule layers. the cells of the 3 layers form a highly complex set of parallel circuits that act as comparators

Question 29

what do they compare in inputs

Answer 29

from motor system: efference copy of the planned motor behaviour. termed as a corollary discharge from sensory system: inputs from a variety of senses. reafference from proprioceptive system

Question 30

what do they compare in outputs

Answer 30

all output is via the purkinje cells and inhibitory