Properties of the Motor Unit

Question 1

Functions of the motor system

Answer 1

• Set muscle tone of body
• Bring about voluntary movements

Question 2

Structural components of the motor system

Answer 2

• Motoneurones
• Skeletal muscles
• Neuromuscular junctions

Question 3

What does a motor unit comprise of?

Answer 3

• 1 alpha-motoneurone
• All extrafusal muscle fibres it supplies

Question 4

What is a single cell of a muscle called?

Answer 4

Myocyte

Question 5

Structure of muscle (from myofibril to muscle)

Answer 5

• Myofibrils are sub-components in myocytes
• Myocytes collect to form fascicles
• Fascicles collect to form a muscle

Question 6

3 tissue envelopes of skeletal muscle

Answer 6

• Endomysium
• Perimysium
• Epimysium

Question 7

What does the endomysium surround?

Answer 7

Myocytes

Question 8

What does the perimysium surround?

Answer 8

A fascicle

Question 9

What does the epimysium surround?

Answer 9

All fascicles of a muscle (and neurovascular bundle)

Question 10

Where does the neurovascular bundle of a muscle run?

Answer 10

In between and in parallel with fascicles

Question 11

What is a tendon?

Answer 11

Organised tough band of fibrous connective tissue mass that forms a point of confluence of contraction by single myocytes of a muscle

Question 12

Common assembles of fascicles of skeletal muscle

Answer 12

• Convergent muscle
• Strap muscle
• Circular muscle
• Fusiform muscle
• Pennated muscle

Question 13

Types of pennated muscle

Answer 13

• Unipennate
• Bipennate
• Multipennate

Question 14

2 types of motoneurone

Answer 14

• Upper motoneurone
• Lower motoneurone

Question 15

What characteristics are shared by muscle fibres of the same motor unit?

Answer 15

• Contraction speed
• Susceptibility to fatigue

Question 16

3 classes of muscle fibres

Answer 16

• Fast twitch (type FF)
• Intermediate twitch (type FR)
• Slow twitch (type S)