Muscles Flashcards
Excitability
- respond stimli
Contractility
-shorten and pull
Extensibility
- contract over diff. lengths
Elasticity
-back to original length
Skeletal Muscles -characteristics
- Somatic (VOLUNTARY)
- innervated by spinal/cranial nerves
-Contractile - produce motion of body
Skeletal Muscle -Functions
- mvmt at joints
-maintain posture - support soft tissue
- regulate orifices
-maintain body temp
SM structure
Muscle(epimysium)–> muscle fascicle (perimysium) –> Muscle fibre (Endomysium)
-myofibril
myofibril and sacromere
myofibril made up of sarcomere
- boundaries = z-line
-centre = M-line
-contractile unit
Sarcomere Bands (3)
H band: THICK filament -during contraction width DECREASES
I band: THIN filament -during contraction width DECREASES
A band: ZONE OF OVERLAP-during contraction width CONSTANT
Muscle contraction
- Innervated by motor neuron
- all or nothing
-controlled by single MN or motor unit
Types of SM fibres
Slow fibres: red, narrow, less fatigue + less power
Fast Fibres: white, large, powerful +more fatigue, rapid
Parallel Muscles
- parallel to long axis
- flat or spindle shaped
-contraction: short and wide - exert great force
Convergent Muscles
- fan shaped
- coverage at common attachment site
- exert less force
Circular Muscles
- Form sphincters
- contraction: reduce opening diameter
Pennate Muscles
- form oblique angle relative to body tendons
- Generate most force
Unipennate: fibers on one side of tendon (forearm)
Bipennate: fibers on both sides of tendon (thigh)
Multipennate: tendon branches within muscle (shoulder)
