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Functional Anatomy and Embryology > Anatomy of skeletal muscles > Flashcards

Anatomy of skeletal muscles Flashcards

1
Q

Definition of myofibre

A

Skeletal muscle fibre

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2
Q

Definition of myonucleus

A

Nucelus in syncytial muscle fibre

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3
Q

Definition of myofibril

A

Rodlike structure of many sarcomeres in series

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4
Q

Definition of myogenesis

A

Process of making skeletal muscle

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5
Q

Definition of myoblast

A

Proliferative cell committed to making skeletal muscle

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6
Q

Definition of myocyte

A

Mononucleated differentiated muscle cell

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7
Q

Definition of myotube

A

Immature muscle fibre with centrally located nuclei

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8
Q

Definition of satellite cell

A

Resident stem cell of skeletal muscle

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9
Q

Definition of prime mover

A

Agonist in muscle movement, concentric contraction such as gravity

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10
Q

Definition of antagonist

A

Opposite agonist/prime mover

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11
Q

Definition of synergist

A

Complements prime mover action either with same movement of by acting as fixator of intervening joint

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12
Q

Definition of fixator

A

Movement that stabilizes position through isometric contraction

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13
Q

Function of skeletal muscle

A

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

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14
Q

Type of muscles

A

Skeletal muscle
Cardiac muscle
Smooth muscle

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15
Q

Properties of skeletal muscle

A

Striated
SNS, voluntary
Multinucleated, unbranched

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16
Q

Properties of cardiac muscle

A

Striated
ANS, involuntary
Branched, joined by intercalated discs

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17
Q

Properties of smooth muscle

A

Not striated
ANS, involuntary
Not branched, spindle single cells

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18
Q

Characteristics of muscle fibres

A

1 fibre=1 muscle cell
40-100um in diameter, cms long
Larger for power, smaller for coordination
Myonuclei on periphery, controls syncytial cell
Cytoplasm packed with myofibrils and mitochondria

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19
Q

Structures and properties of skeletal muscles and tendons

A

Move skeleton
Muscles attach to skeleton by tendon
Endo, peri and epimysium merge with dense CT of tendon at myotendinous junction
Tendons transmit muscle force to bone
Tendons made of collagen, strong and stiff

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20
Q

Muscle arrangements

A

Generate force by contracting
Only pull in antagonistic pairs
Flexors and extensors

21
Q

Types of contraction

A

Isotonic (dynamic)
Isometric
Isotonic (eccentric)

22
Q

Isotonic (dynamic)

A

Concentric muscle shortens during force production

23
Q

Isometric

A

Muscle exerts force without changing length
Pulling against immovable object
Postural muscles

24
Q

Isotonic (eccentric)

A

Muscle produces force but length increases

25
Q

General structures and connective tissue in skeletal muscle

A 
CT holds fibres in position in skeletal muscle
Epimysium
Perimysium
Endomysium
Vessels and nerves embedded in CT
26
Q

Epimysium

A

Tough outermost layer, surrounds entire muscle

27
Q

Perimysium

A

Surrounds muscle fibre bundles, create fascicle

28
Q

Endomysium

A

Surrounds each fibre with fascicles

29
Q

Architecture and shape of skeletal muscles

A 
Circular
Fusiform
Flat parallel
Bipennate
Unipennate
Digastric
Multipennate
Convergent
Tendinous intersections
Thin parallel
30
Q

Formation of skeletal muscle

A

Myoblasts fuse into myotubes to form syncytial cells

31
Q

Satellite cells and properties

A

Type of stem cell on muscle fibre surface, dormant in mitosis, but can self renew, maintain stem cells population
Can be activated, enter cell cycle, become my oblasts
Myoblasts proliferate, differentiate, become new myonuclei
Myonuclei cannot divide

32
Q

Importance of satellite cells

A

Muscle growth after birth
Muscle maintenance
Muscle hypertrophy
Muscle repair and regeneration

33
Q

Composition of myofibrils

A

Sarcomere, contractile unit of skeletal muscle
Myofibrils made up of 2 protein filaments
Myosin and actin

34
Q

Sarcomere organisation

A

H bands, myosin only
A band, length of myosin
Z, center of actin
I band, actin only

35
Q

What happens when the sarcomere contracts

A

Z lines move closer together
I and H bands narrow
A band does not change

36
Q

Subtypes of muscle fibres

A

According the speed of contraction
Speed of contraction depends on myosin heavy chain isoform
T1 slow
T2 fast IIa, IIb, IIx

37
Q

Metabolic properties of fast fibres

A

Found in white fibres, small amount of myoglobin

38
Q

Metabolic properties of slow fibres

A

Found in red fibres, large amount of myoglobin

39
Q

Fibre specification

A

I slow oxidative
IIa fast oxidative
IIb fast glycolytic
Iix super fast glycolytic

40
Q

Fibres in 1 motor unit

A

All the same

41
Q

How are muscles innervated

A

Myofibre innervated from 1 motor neuron
Nerve in contact with NMJ on fibre membrane
1 neurone contacts motor unit (many fibres)
Motor unit size increases degree of muscle control

42
Q

Muscle circuit diagram

A

Motor neurone to muscle
Muscle to sensory afferent neurone to dorsal root
Dorsal root in spinal cord to motor neurone

43
Q

What happens when you don’t use your muscles

A

Mature muscles normally grow by hypertrophy
Skeletal muscle fibres cannot self renew
New fibres replaced by satellite cells, activated in repair
Ability to repair/build muscle decreases with age
Can be replaced by adipose, fibrous tissue, impedes function

44
Q

Definition of aponeurosis

A

Large flat tendon

45
Q

Definition of raphe

A

Tendons between small groups of muscle that have fused together

46
Q

Definition of intermediate tendon

A

Tendon that breaks up digastric muscle

47
Q

Describe a 1st class lever

A

Force is on one side of the pivot, weight is on the other side of the pivot

Pivot=top of spine
Weight=head
Force=splenius capitus

Muscle that can pull your head back (splenius capitus)

48
Q

Describe a 2nd class lever

A

The force is more distal from the pivot than the weight

Pivot=ball of foot
Weight=body weight
Force=calves

The calf muscles. 2nd class levers often used for power

49
Q

Describe a 3rd class lever

A

The weight is more distal to the pivot than the force

Pivot=elbow
Weight=arm
Force=bicep brachii

3rd class levers used more for control than power

Functional Anatomy and Embryology (28 decks)

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