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Functional Anatomy and Embryology > Anatomy of skeletal muscles > Flashcards

Anatomy of skeletal muscles Flashcards

(49 cards)

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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

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A

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

21
Q

Types of contraction

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A

Isotonic (dynamic)
Isometric
Isotonic (eccentric)

22
Q

Isotonic (dynamic)

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A

Concentric muscle shortens during force production

23
Q

Isometric

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A

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

24
Q

Isotonic (eccentric)

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A

Muscle produces force but length increases

25
General structures and connective tissue in skeletal muscle
``` CT holds fibres in position in skeletal muscle Epimysium Perimysium Endomysium Vessels and nerves embedded in CT ```
26
Epimysium
Tough outermost layer, surrounds entire muscle
27
Perimysium
Surrounds muscle fibre bundles, create fascicle
28
Endomysium
Surrounds each fibre with fascicles
29
Architecture and shape of skeletal muscles
``` Circular Fusiform Flat parallel Bipennate Unipennate Digastric Multipennate Convergent Tendinous intersections Thin parallel ```
30
Formation of skeletal muscle
Myoblasts fuse into myotubes to form syncytial cells
31
Satellite cells and properties
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
Importance of satellite cells
Muscle growth after birth Muscle maintenance Muscle hypertrophy Muscle repair and regeneration
33
Composition of myofibrils
Sarcomere, contractile unit of skeletal muscle Myofibrils made up of 2 protein filaments Myosin and actin
34
Sarcomere organisation
H bands, myosin only A band, length of myosin Z, center of actin I band, actin only
35
What happens when the sarcomere contracts
Z lines move closer together I and H bands narrow A band does not change
36
Subtypes of muscle fibres
According the speed of contraction Speed of contraction depends on myosin heavy chain isoform T1 slow T2 fast IIa, IIb, IIx
37
Metabolic properties of fast fibres
Found in white fibres, small amount of myoglobin
38
Metabolic properties of slow fibres
Found in red fibres, large amount of myoglobin
39
Fibre specification
I slow oxidative IIa fast oxidative IIb fast glycolytic Iix super fast glycolytic
40
Fibres in 1 motor unit
All the same
41
How are muscles innervated
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
Muscle circuit diagram
Motor neurone to muscle Muscle to sensory afferent neurone to dorsal root Dorsal root in spinal cord to motor neurone
43
What happens when you don't use your muscles
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
Definition of aponeurosis
Large flat tendon
45
Definition of raphe
Tendons between small groups of muscle that have fused together
46
Definition of intermediate tendon
Tendon that breaks up digastric muscle
47
Describe a 1st class lever
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
Describe a 2nd class lever
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
Describe a 3rd class lever
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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