PHYSIOLOGY - somatic motor system

Question 1

where are upper motor neurons (UMN)

Answer 1

in the brain

Question 2

what do UMN do

Answer 2

supply input to LMN

Question 3

where are lower motor neurons (LMN)

Answer 3

in the brain stem/ventral horn of spinal cord

Question 4

what do LMN do

Answer 4

command muscle contraction

Question 5

which horn of the spinal cord do LMNs leave via

Answer 5

anterior/ventral horn

motor = want to be need the action = anterior

Question 6

what happens after LMN leaves anterior/ventral horn

Answer 6

joins posterior/dorsal horn nerve (sensory) to form a mixed spinal nerve

Question 7

what do the medial LMNs supply

Answer 7

axial/proximal muscles

eg shoulder

Question 8

what do the lateral LMNs supply

Answer 8

distal muscles

Question 9

what do the dorsal (posterior) LMNs supply

Answer 9

flexor muscles

think: elbow flexion moves the arm posteriorly

Question 10

what do the ventral (anterior) LMNs supply

Answer 10

extensor muscles

think: elbow extension moves the arm anteriorly

Question 11

what are synergistic muscles

Answer 11

muscles that work together

eg biceps brachii and brachialis

Question 12

what do alpha motor neurons supply/innervate

are these intra/extrafusal muscle fibres

Answer 12

muscles that provide a force

intrafusal muscle fibres

Question 13

what do gamma motor neurons supply/innervate

are these intra/extrafusal muscle fibres

Answer 13

sensory muscles eg organs

extrafusal muscle fibres

Question 14

what is a motor unit

Answer 14

1 alpha motor neurone and all the skeletal fibres that it innervates

Question 15

what is a motor pool

Answer 15

all the alpha motor neurons that supple one skeletal muscle (collection of motor units)

Question 16

for type I and IIa muscle fibres where does ATP come from

Answer 16

oxidative phosphorylation

Question 17

for type IIb muscle fibres where does ATP come from

what does this mean

Answer 17

glycolysis

when you are fatigued = wont make ATP

Question 18

what type of muscles fibres are slow oxidative fibres

Answer 18

type I

Question 19

what type of muscle fibres are fast

Answer 19

type II

Question 20

why is it important to have a mix of type I, IIa and IIb fibres in each muscle

Answer 20

for different functions eg walking, running, jumping

Question 21

what is the myotatic reflex

Answer 21

when a skeletal muscle is pulled it pulls back = reflex (eg knee jerk)

Question 22

what do golgi tendon organs do

what sensation do they contribute to

Answer 22

reverse the myotatic reflex

proprioception

Question 23

where are golggi tendon organs

Answer 23

the junction of muscles and tendons

Question 24

where are joint receptors

what are they important for

Answer 24

the connective tissue of joints (eg ligaments, joint capsule)
proprioception