Myology Flashcards
Muscle Characteristics
4 characteristics of mucsles
1. excitability:
- respond to stimulus
2. contractility
- shorten + gen force
**3. extensability **
- can be stretched
4. elasticitity
- return to its original length
Muscle Types
3 types of muscle tissue
- smooth
- cardiac
- skeletal
Muscle types
Characteristics of smooth muscle
- non-striated
- involuntary
Muscle types
Characteristics of cardiac muscle
- straited
- involuntary
Muscle types
Characteristics of skeletal muscle
- striated
- involuntary
Skeletal muscle
Label the skeletal muscle
What is it function?
Structure:
1. muscle organ
2. fasicle / bundle of myofibres
3. myofibre (muscle cell)
4. myofibril
5. myofilaments (actin and myosin)
Function:
- contractile cells -> where ‘work’ occurs
Skeletal Muscle
Function of muscle attachment points
- Proximal attachment: least mobile bone
- Distal attachment: most mobile bone
Skeletal Muscle
Structure and function of CT w in skeletal muscle
1. perimysium:
- surrounds each fasicle (bundle of musc fibres)
2. endomysium:
- surrounds each muscle fibre
3. epimysium/fascia:
- surrounds entire muscle
Skeletal muscle
Action
movement produced when muscle contracts _____ in isolation eg.
depends on which 3 things?
- movement produced when muscle contracts concentrically in isolation eg. ext/flex, abd/add, rotation
depends on:
- site of attach
- type of joint
- line of pull to the joint
Muscle Belly structure
Structure and function of the fasicle
structure:
- (bundle of musc fibres)
- perimysium
- endomysium
- epimysium
function:
- force production
Muscle tissue
Structure and function of the 4 types of muscle tissues
**1. muscle cells/fibres: **
- do the work
2. capillary network:
- rich blood supply -> rapid deliv of nutr + remove wastes
3. nerve supply:
- stimulates musc -> contract
4. fibrous connective tissue:
- consists of perimysium, epimysium, endomysium
Skeletal muscle attachments
3 types of skeletal muscle attachments
- fleshy
- tendon
- raphe
Skeletal muscle attahcments
Structure and function of Raphe
eg. obliques
Structure:
- musc fibres attach to a CT sheet -> connects to bone
**Function: **
- DCR frict, distrib force
eg. obliques
Skeletal muscle attahcments
Structure and function of Tendon
eg, semitendinosus
Structure:
- musc fibres connect to a cord-like tendon -> connect to bone
Function:
- DCR frict, distr force
eg, semitendinosus
Skeletal muscle attahcments
Structure and function of Fleshy
eg, glute max
**Structure: **
- musc fibres attach directly to bone w min CT
**Function: **
- prov stable force transmission
eg. glute max
Myofibres (msucle cells)
Structure and function of myofibres
structure:
- Actin (thin) & myosin (thick) filaments slide over one another
function:
- product muscle shortening
Sliding Filament Theory
Steps
1. muscle shortening
2. formation of CBs
3. power stroke
4. release + reset
5. repeat cycles
Step 1- muscle shortening
- Actin and myosin filaments slide over each other, causing the sarcomeres to shorten, which leads to muscle contraction
Step 2 - Formation of Cross-bridges
- myosin attach to actin
- **CB’s ** formed
Step 3 - Power Stroke
- myosin (thick) heads pivot, pulling the actin filaments toward the center of the sarcomere, which causes the muscle to contract
Step 4 - Release and Reset
- ATP binds to the myosin (thick) head, causing it to detach from the actin (thin). The myosin head then resets to its original position, ready for the next cycle.
Step 5 - Repeated Cycles
- as long as calcium ions are present and ATP is available, the process repeats, causing continuous contraction.
Classifiying skeletal muscle fibre oritenations
structure and function of Parallel fibres
fibres run in a ____ line bw attachments
structure:
- fibres run in a straight line between attachments
- long and flat
function:
- shorten muscle belly (up to 50%)
- greater ROM but LESS force
Classifiying skeletal muscle fibre oritenations
structure and function of Oblique fibres
structure:
- fibres run on an angle between attachments
function:
- less shortening of musc belly
- less ROM but MORE force
Classifiying skeletal muscle fibre oritenations
structure and function of circular fibres
structure:
- fibres run around an opening
function:
- contraction of narrow openings
Classifiying skeletal muscle fibre oritenations
Egs of parallel skeletal msucles
- flat/quadrilateral eg. quadratus femoris
- strap eg. sartorius
- triangular eg. pirifemoris
- fusiform eg. bicep
Classifiying skeletal muscle fibre oritenations
Egs of oblique skeletal msucles
- unipennate eg. flexor pollicius longus
- bipennate eg. rectus femoris
- multipennate eg. deltiod
Classifiying skeletal muscle fibre oritenations
Egs of circular skeletal msucles
- circular muscle eg. sphincters
Skeletal muscle contractions
Isometric contraction
- musc gen force without changing its length, meaning there’s no movement at the joint.
- eg. plank
Skeletal muscle contractions
Isotonic contraction
- musc changes its length while generating force, causing movement at the joint.
There are two types of isotonic contractions:
Concentric contraction:
- The muscle shortens as it contracts (e.g., lifting a weight).
**Eccentric contraction: **
The muscle lengthens while contracting (e.g., lowering a weight).
Muscle roles
Agonist
- muscle that contracts and generates force.
Example: In a bicep curl, the biceps are the agonist.
Muscle rolls
Antagonist
- muscle that opposes the agonsit
- it relaxes to let the agonist move and controls the movement.
Example: In a bicep curl, the triceps are the antagonist.
Muscle rolls
Stabiliser/Fixator
- muscles that stabilse one part of the body while another part moves
- Example: In a push-up, the core muscles stabilize the body.
Muscle rolls
Neutraliser
- muscle that stops unwanted movement during an action.
Example: In a shoulder press, the posterior deltoid helps prevent shoulder rotation.
What happens when a muscle crosses 2 joints?
active and passive insufficiency
-
limit ROM and force production.
Active insufficiency: - when the muscle is too short to generate full force across both joints.
Passive insufficiency: - when the muscle is **too stretched **to allow full ROM.
Biomechanics
1st Class Lever
1- EL
- The fulcrum is between the effort and load.
Example: Neck movement (fulcrum = atlas, effort = neck muscles, load = head).** - Balance
Biomechanics
2nd Class Lever
2 - FE
- The load is between the fulcrum and effort.
Example: Standing on tiptoe (fulcrum = ball of foot, load = body weight, effort = calf muscles).** - force/heavy loads
Biomechanics
3rd Class Lever
3 - FL
- The effort is between the fulcrum and load.
Example: Bicep curl (fulcrum = elbow, effort = biceps, load = hand weight). - Speed and range of motion but requires more effort.
Classifying muscles
6 things
- size
- shape
- location
- attachment
- action
- no. of heads
Length - tension r/ship
- tension a muscle fibre can produce vs the length of a sarcomere
Accessory structures of Skeletal muscles
Structure and function of bursae
structure:
- sacs of syn membrane containing syn fluid
function:
- allow muscles to slide over other struct w out frict
Accessory structures of skeletal muscles
Structure, function and location of tendon sheaths
structure:
- contain synovial fluid -> lubrication
function:
- DCR friction
- help tend transmit force
- keep tendons att to bone dur movem
location:
- distal ends of limbs
Accessory structures of skeletal muscles
Structure and function TFL
structure:
- dense firbous CT surrounding muscles of the thigh
function:
- venous return
- knee stability
Accessory structures of skeletal muscles
Structure and function of iliotibial tract
structure:
- band of CT
- continuation of TFL
function:
- flex + abd
- knee stabilisation
location:
- distal ends of limbs
Functional roles of muscles that move the hip
- hip flexors: lifting leg/drive movem
- glute musc: hip ext
