Anatomy & Embryology Of Skeletal Muscle

Question 1

Roughly how many skeletal muscles do we have?

Answer 1

639

Question 2

Roles of skeletal muscle

Answer 2

Force generation for movement and breathing
Force generation for postural support
Heat production
Metabolism

Question 3

Types of muscle tissue

Answer 3

Striated skeletal muscle
Striated cardiac muscle
Non striated smooth muscle

Question 4

Striated skeletal muscle

Answer 4

Voluntary
Controlled by somatic nervous system
Multi nucleated cells
Unbranched

Question 5

Striated cardiac muscle

Answer 5

Found in the heart
Involuntary
Controlled by autonomic nervous system
Single branched cells joined by intercalated disk

Question 6

Non striated smooth muscle

Answer 6

Involuntary
Controlled by autonomic nervous system
Spindle shaped single cells

Question 7

Properties of muscle fibres

Answer 7

Each muscle fibre is a single muscle cell
Giant cells have myonuclei located on the periphery controlling a common cytoplasm
Cytoplasm is packed with myofibrils that contain contractile proteins and many mitochondria

Question 8

How does skeletal muscle move the skeleton?

Answer 8

Muscles attach to the skeleton by tendons
Tendons transmit muscle force to the bone
Tendons are made of collagen fibres and are strong and stiff

Question 9

Antagonistic muscle pairs

Answer 9

Muscles that work in pairs, in opposite motions to each other
Flexor muscle - muscle that bends the joint (decreases joint angle)
Extensor muscle - muscle that straightens the joint (increases the joint angle)

Question 10

2 types of muscle contraction

Answer 10

Isotonic
Isometric

Question 11

Isotonic muscle contraction

Answer 11

Two types:
Concentric - muscle shortens during force production
Eccentric - muscle lengthens

Question 12

Isometric contraction

Answer 12

Muscle exerts force without changing length
Postural muscles

Question 13

Prime mover

Answer 13

Agonist
Concentric contraction

Question 14

Antagonist

Answer 14

Opposes the action of the prime mover/agonist

Question 15

Fixator

Answer 15

Holds a position through isometric contraction

Question 16

Synergist

Answer 16

Complements the action of a prime mover

Question 17

3 layers of connective tissue

Answer 17

Epimysium - tough outermost layer surrounding the entire muscle
Perimysium - surrounds bundles of muscle fibres to create a fascicle
Endomysium - Surrounds each muscle fibre within the fasciculus

Question 18

Formation of skeletal muscle

Answer 18

Single cell (myoblast)
Proliferation
Fusion (myotube)

Question 19

Satellite cells

Answer 19

Resident muscle stem cells
Proliferate and differentiate to produce new myonuclei
They also self renew to maintain stem cell population

Question 20

Protein filaments in myofibrils

Answer 20

Thick filaments - myosin
Thin filaments - actin

Question 21

What happens during muscle contraction to the sliding filament model?

Answer 21

Sarcomere shortens - Z lines move closer
I and H bands narrow
A band stays the same length

Question 22

H band

Answer 22

Myosin filament with no actin overlap

Question 23

A band

Answer 23

Actin and myosin overlap

Question 24

I band

Answer 24

Actin filaments only

Question 25

Types of muscle fibres

Answer 25

Slow
Fast

Question 26

Fast fibres

Answer 26

3 types - IIa, IIb, and IIx
Found in white muscle fibres, only contain small amount of myoglobin

Question 27

Slow fibres

Answer 27

Found in red muscle fibres - contain a lot of myoglobin

Question 28

Somites

Answer 28

All trunk and limb muscles are derived from these embryonic structures
Contain progenitors of many tissues

Question 29

What determines muscle pattern?

Answer 29

Extrinsic signals

Question 30

Myocyte

Answer 30

Mononucleated muscle cell

Question 31

Myogenesis

Answer 31

Process of making skeletal muscle