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MECHANICS 1122 > Muscles > Flashcards

Muscles Flashcards

1
Q

What are the types of muscle tissues?

A
  • Cardiac (found only in the heart and are involuntary)
  • Smooth (walls of abdominal organs, blood vessels and airways and are also involuntary)
  • Skeletal (moves the bones of the skeleton and are mostly voluntary)
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2
Q

What are muscle fibers?

A
  • Muscle cells
  • Elongated tubes that have incredible movement potential
  • Could not create movement without other surrounding tissues and muscles
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3
Q

What are myofascial units?

A
  • The “muscle” that is separate in whole from fibers and tissues
  • If you were to build a myofascial unit, first a single muscle fiber needs to be placed onto fascia, then rolled up in connective tissue, then repeat this process several hundred times
  • Tendons will form at either end, and then it will be sheathed in a final layer of fascia
  • Lastly, nerves and blood vessels are added
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4
Q

What are muscle contractions?

A
  • Muscles with the arrangement of 2 contact points can contract or shorten
  • This action produces movement and maintains postural support
  • Pulls fascial elements toward it’s center which includes its attaching tendons
  • If the contraction is strong enough, the tendons pulling force will move the attaching bone and its general body part
  • Muscle contracts, tendon is pulled, bone pivots around a joint, body part moves
  • Overlapping of thick and thin filaments in the sarcomere of a muscle
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5
Q

What is the origin?

A
  • The muscles attachment to the more stationary bone
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6
Q

What is insertion?

A
  • The muscles attachment to the more mobile bone
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7
Q

What are the components of skeletal muscle?

A
  • Muscle belly, fascia profunda, epimysium, perimysium, endomysium, tendon, fascicles, myofibrils, myofilaments, sarcomere
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8
Q

What is a muscle belly?

A
  • Portion between tendons
  • Bound together with neighboring muscles by a layer of fascia profunda (deep fascia)
  • Composed of chunky fascicles which are formed by tubular muscle fibers
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9
Q

What is fascia profunda?

A
  • Binds the muscle belly between tendons
  • Type of dense, irregular connective tissue
  • Also binds together muscle groups
  • Allows movement of the muscles while providing space for nerves and blood/lymph vessels to pass and fill the space between muscles
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10
Q

What is epimysium?

A
  • Layer of connective tissue beneath fascia profunda
  • Outer fascial layer
  • Found just beneath the deep fascia and swaths the entire muscle belly
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11
Q

What is perimysium?

A
  • Layer of connective tissue beneath fascia profunda
  • Middle fascial layer
  • Separates the muscle belly into compartments (fascicles)
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12
Q

What is endomysium?

A
  • Layer of connective tissue beneath fascia profunda
  • Deepest fascial layer
  • Within the fascicles of the muscle belly
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13
Q

What are myofibrils?

A
  • Each muscle fiber contains cylindrical contractile organelles called myofibrils
  • Contain myofilaments
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14
Q

What are myofilaments?

A
  • Chain-like protein structures found in myofibrils

- Pull against each other to generate force in the muscle

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15
Q

What are sarcomeres?

A
  • Where myofibrils are grouped into sections containing multiple adjacent myofilaments… forms a sarcomere structure
  • The muscles base unit of contraction
  • Made up of thick and thin myofilaments (to form these it needs myosin, actin, tropomyosin, troponin and titin)
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16
Q

What is the sliding filament theory?

A
  • How the contraction unit functions
  • Process by which the myosin heads at both ends of the thick filament attach to actin and progressively pull the thin filaments toward the M-line (middle of the sarcomere)
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17
Q

What are the general functions of muscles?

A
  • Produce movement
  • Stabilize posture
  • Assist in circulation
  • Produce body heat through thermogenesis
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18
Q

What is excitability?

A
  • Capacity for muscles and nerve cells to respond to stimuli

- Chemical, electrical and mechanical stimuli can all lead to muscle activation

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19
Q

What is contractility?

A
  • A muscle’s ability to develop tension when stimulated
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20
Q

What is extensibility?

A
  • The capacity of muscle tissue to stretch without being damaged
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21
Q

What is elasticity?

A
  • A muscles tendency to return to its original length after being stretched
22
Q

What are parallel muscle bellies?

A
  • Comprised of relatively long muscle fibers and are usually in a straightforward design
  • 5 common types of parallel bellies: Flat, sphincter, fusiform, strap and triangular
  • Usually have 2 short tendons
  • Has a larger range of motion than pennate
23
Q

What are pennate muscle bellies?

A
  • Bird’s feather like design (fibers at an oblique angle to a central tendon)
  • Requires one or more of the muscles tendons to extend most of the length of the muscle
  • Unipennate (tibialis posterior), Bipennate (rectus femoris), Multipennate (deltoid)
  • Need many muscle fibers, but of shorter length
  • Is stronger than parallel
24
Q

What is excursion?

A
  • The degree that a muscle can change in length
25
Q

What are muscle motor units?

A
  • The attachment of a motor neuron to the muscle fibers it will innervate
  • The quantity of muscle fibers to which a motor unit connects depends on the type of movement that is required of that muscle
26
Q

What is the all-or-none law?

A
  • When the motor neurons electrical stimulation is sufficient enough to engage its muscle fibers simultaneously and completely
  • Total commitment within motor units is necessary so we can activate our muscles predictably and systematically
27
Q

What is first recruitment?

A
  • The number of a muscles motor units that are activated to generate enough tension to produce movement in the body
28
Q

What is wave summation?

A
  • The pace at which nerve signals are fired through a motor unit
29
Q

What are slow contractile fibers?

A
  • Constructed with endurance in mind

- Slower contractions but perform with greater efficiency

30
Q

What are fast contractile fibers (Type IIA)?

A
  • Larger and produce faster contractions than slow fibers

- Fatigue more rapidly

31
Q

What are fast contractile fibers (Type IIB)?

A
  • Biggest and most powerful fibers

- Flame out the quickest of all 3 types of fibers

32
Q

What are isotonic contractions?

A
  • When a muscle changes length, either shortening (concentric) or elongating (eccentric)
33
Q

What are isometric contractions?

A
  • When the length of the muscle does not change
  • Works against the forces of gravity to hold and maintain contractions of “equal length”
  • No joint movement occurs during this contraction
34
Q

What is the difference between concentric and eccentric isotonic contractions?

A
  • Concentric moves towards the body, shortening the muscle length
  • Eccentric moves away from the body, elongating muscle length
35
Q

What is reverse muscle action?

A
  • When the origin and insertion of the muscle swaps roles
  • Example: within the brachialis when doing a chin-up because the ulna (insertion) is stationary and the humerus (origin) must move towards the hand
36
Q

What is a agonist muscle?

A
  • Also known as prime mover

- Muscle that produces the main action

37
Q

What is a synergist muscle?

A
  • Any muscle that assists the agonist in producing the main action
  • Less effective than agonist but still needed to produce movement
38
Q

What is a antagonist muscle?

A
  • Executes the action opposite of the agonist when it shortens
39
Q

What is a neutralizer muscle?

A
  • Stops the agonist from pulling both of its ends simultaneously (gives it direction)
  • Is a fixating force to prevent undesired action and dictate which end of the agonist’s bony attachments will move
40
Q

What is a supporter muscle?

A
  • Often does not function near the main action, but supports another part of the body in position while the main action occurs
  • Often neighboring muscles to the agonist are supporters
41
Q

What factors affect a muscles role?

A
  • Size affects its part in joint motion
  • Shape and design of a joint determine the muscles role
  • Muscles location in relationship to the joint axis
  • The muscles line of pull (the direction of force exerted on a joint by a muscle)
42
Q

What is passive insufficiency?

A
  • When a bi- or multi-articular muscle is in a position of maximum length
  • Example: can’t fully clench fist when maximally flexing your wrist
43
Q

What is active insufficiency?

A
  • Occurs when an action is weakened or incomplete due to excessive shortness of the multi-joint agonist
  • Example: cannot fully flex your fingers back when extending your wrist
  • Biarticular muscles (cross 2 joints) are more susceptible to active insufficiency
44
Q

What are postural muscles?

A
  • Designed to perform for long periods of time in a semi contracted state
  • stabilize the body and keep it in an upright stance (for long term kinesiological health)
45
Q

What are phasic muscles?

A
  • Perform movement quickly and strongly

- Fatigue quickly and need more recovery time then postural muscles

46
Q

What is the force-length muscle relationship?

A
  • The length of a muscle, relative to its resting length during an isometric contraction, will determine the maximum force it can produce
47
Q

What is the force-velocity muscle relationship?

A
  • Asserts the speed of a muscles contraction will dictate its maximal force production
48
Q

What does muscle length determine?

A
  • It’s tension
49
Q

What does a muscles contractile speed affect?

A
  • The force it can generate
50
Q

What is active tension?

A
  • The muscle is actively producing tension by pulling itself toward its center
51
Q

What is passive tension?

A
  • The muscle is like a rubber band

- When stretched beyond its resting length it builds tension (wants to return to its original resting length)

MECHANICS 1122 (6 decks)

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