Wk 3: myology Flashcards
Muscle characteristics
Excitability
Contractibility
Elasticity
Extensibility
Excitability (muscle characteristics)
tissue responds to a stimulus
Contractility (muscle characteristics)
tissue can shorten & generate force
Extensibility (muscle characteristics)
tissue can be stretched
Elasticity (muscle characteristics)
tissue can return to original length
Muscle types
- Smooth: non-striated and involuntary
- Cardiac: striated and involuntary
- Skeletal: striated and voluntary
Gross anatomy of skeletal muscle
- Belly: the bulk of the muscle
- Attachments: to the skeleton
- Muscles CROSS joints
Types of attatchments
- Proximal attachment (origin usually): least mobile bone
- Distal attachment (insertion usually): most mobile bone
Tendon Sheaths
- Surround tendons as they pass through tunnels or over other structures
- Reduce friction (contain synovial fluid)
- Common at distal ends of limbs
- Allow efficient ‘action’ long distances from muscle belly: prevent tendons pulling away from skeleton
Skeletal muscle attachments
Fleshy
Tendon
Raphe
Fleshy (muscle attatchment)
muscle fibres attach directly to bone with a small amount of connective tissue
Tendon (muscle attachment)
muscle fibres attach to a cord of connective tissue that attaches to bone
fibre-> connective tissue -> bone
Raphe (muscle attachment)
muscle fibres attach to a sheet of connective tissue that attaches to bone
fibres-> sheet of connective -> bone
Parallel skeletal muscle types
Strap
Fusiform
Triangular/convergent
Flat/quadrilateral
Strap
long and flat
Fusiform
classic type
Triangular/convergent
broad origin and narrow insertion
Flat/quadrilateral
fibres in same axes as tendon
Oblique skeletal muscle types
Unipennate
Bipennate
Multipennate
Unipennate
muscle fibres attach to one side of tendon only
Bipennate
fibres attach to both sides of tendon and central septum
Multipennate
group of several bipennate ‘units’
Sliding filament theory:
- Actin (thin) & myosin (thick) filaments slide over one another
- Produce muscle shortening
Parallel muscles
maximum shortening of muscle belly
- Larger range of movement but with less force/power
Oblique muscles
**less shortening **of muscle belly
- Less range of movement BUT more force/power
Muscle action what to describe
what JOINT is MOVED
name of MOVEMENT
Functional anatomy
is taking the knowledge of the body structures that we learn and applying it to live, moving bodies
Action
the movement produced when a muscle contracts concentrically in isolation
Action is dependant on
- Site of attachments
- Type of joint
- Relationship of line of pull to joint
Isometric contraction
- Occurs when tension is generated in a muscle
- Muscle length and angle of joint DOES NOT change
- Produces no movement
Isotonic contraction
- Muscle contraction that changes the length
Eccentric and concentric
Eccentric
muscle lengthening
Cocentric
muscle shortening
Functions/roles of skeletal muscles
- Agonist
- Antagonist
- Fixator (stabiliser)
- Synergist (neutraliser)
Agonist
muscle producing the desired movement by contracting
- Concentric, eccentric or isometric
Antagonist
muscle which must relax to allow the desired movement to occur
- Usually the opposite muscle to the agonist
Cannot have another role
Fixator/stabiliser
stabilises a body segment so that another muscle can perform an action
- Acts to eliminate the unwanted movement of an agonist’s origin
Synergist/neutraliser
assists the agonist to produce the desired movement by cancelling the unwanted action of the agonist
External forces
Gravity: force acting on every object
Momentum: can produce movement
Two joint muscles
passes over two joints
- Implications for recruitment: increased requirement for synergism
- Implications for joint range testing: must consider 2 joint muscles when testing range of motion
Length-Tension relationship
direct relationship between the tension a muscle fibre can produce and the length of the sarcomeres in that muscle fibre
Passive insufficiency
max passive length is insufficient to allow full range of movement at both joints together
Active insufficiency
max length change insufficient to produce full range of movement at both joints together
Axis/fulcrum
pivot point
Force/load
external force (gravity/weight, friction)
Resistance/effort
generated by the muscle pulling
Types of levers
ARF