motor units and movement

Question 1

biceps branchii and what work together

Answer 1

branchialis

Question 2

biceps and triceps working with and against each other

Answer 2

Biceps brachii and brachialis (as flexors) oppose-triceps brachii and anconeus (as extensors),these groups are antagonists to each other

Question 3

what does axial muscle control

Answer 3

movements of the truk

Question 4

What are proximal muscles found

Answer 4

in the shoulder, elbow, pelvis and knee

Question 5

what do distal muscles move

Answer 5

hands, feet and digits

Question 6

Motor neurons of the somatic nervous system

Answer 6

→ Upper motor neurons
→ Lower motor neurons

Question 7

upper motor neurons

Answer 7

→ Arise in the cerebral cortex
→ Use glutamate as a neurotransmitter

Question 8

Lower motor neurons

Answer 8

→ Arise from the spinal cord
→ Use acetylcholine as a neurotransmitter

Question 9

what do lower motor neurons exiting the spinal cord in the spinal nerves do

Answer 9

→ Provide both motor and sensory supply to skeletal muscle (and sensory input from skin, visceral receptors, too)

Question 10

motor unit

Answer 10

a motor neuron and all of the skeletal muscle innervates

Question 11

Motor pool

Answer 11

single muscle innervated by group of α motor neurons

Question 12

A force of contraction from α motor neuron influenced by

Answer 12

→ Motor unit recruitment
→ Frequency of action potentials generated

Question 13

what do small motor units control

Answer 13

finer movements (i.e. extraocular muscles of the eye)

Question 14

what do larger motor units control

Answer 14

postural muscles (i.e. pictorials and erector spine)
like posture

Question 15

properties of fast-fatiguing muscles

Answer 15

• Very high tension
• Fast fatiguing
• Large α-MN,high threshold
• Type IIx fibres

Question 16

properties of fatigue-resistant muscles

Answer 16

• High tension
• Slow fatiguing
• Intermediate α-MNand threshold
• Type IIa fibres

Question 17

properties of slow muscles

Answer 17

• Low tension
• Fatigue resistant
• Small α-MN,low threshold
• Type I fibres

Question 18

what can increase the force of contraction that a muscle can produce

Answer 18

greater number of motor units

Question 19

Fixed order of recruitment in response to increased activity of the lower motor neurons stimulating the muscle (the motor pool)

Answer 19

→ Starts with slow motor units
→ Then, Fast Fatigue-Resistant units
→ Finally, Fast Fatigable units

Question 20

summary

Answer 20

The somatic nervous system is responsible for motor control of skeletal muscle

That control is facilitated by upper motor neurons which synapse on and drive lower motor neurons which act as the final common pathway in initiating skeletal muscle contraction

Lower motor neurons exit the spinal cord as spinal nerves and are organized into motor units with skeletal muscle fibres

The force of contraction of skeletal muscle can be modulated by:
→ Motor unit recruitment
→ Changes in the frequency of action potentials generated