Head Neck Movement Muscles What about muscles Myology

Head Neck Movement Muscles

What about muscles • Myology – study of muscles • Characteristics – – Excitability – receive and respond to stimuli Contractility – actively shorten and thicken Extensibility – able to be stretched Elasticity – return to its original state • Function – Movement – reflex and voluntary – Maintenance of posture – Heat production • Types – Skeletal – striated, voluntary – Cardiac – striated, involuntary – Smooth – nonstriated, involuntary

Skeletal Muscle • Fascia (bandage) – fibrous connective tissue lines/surrounds beneath skin and around muscles and organs. And carries nerve, lymph and blood vessels – Epimysium – whole muscle – Perimysium – bundles of muscle fibres fasciculi/fascicles – Endmysium –muscle fibre • Extend beyond muscle fibres to form tendon

Muscle Fibre • Fibres - lie parallel – Myofibrils • Myofilaments – Thin/actin – Thick/myosin • Sarcomere • Contraction – Myofilaments overlap – Striated appearance – Sarcomere shortens

Types of fibre • Structure/Colour – Red • high myoglobin content – stores oxygen • Smaller in diameter – White – lower myoglobin content • Function/Speed – Fast/slow – Generate/use Adenosine Triphosphate (ATP) – biochemical energy source • Types – combine above – Type I – slow twitch – predominant in postural muscles • • Red -high myoglobin High ATP generation Slower ATP use Resistant to fatigue – Type II – fast twitch – faster contraction, fatigue more quickly • Type IIA – red, high ATP generation, high ATP use (infrequent) • Type IIB – white, lower ATP generation (anaerobic), fast ATP use

Types of muscle fibre

Muscle tone • State of resting tension in a muscle • Helps maintain posture, balance and prepares for action/response to danger e. g. pull on muscle increases • Range of normal • Maintained by muscle spindles and golgi tendon organs • Low tone/hypotonia – flaccidity, reduced stretch reflex • High tone/hypertonia – increased stretch reflex – Spasticity – velocity dependent resistance – Rigidity – velocity independent • Cogwheel – jerky resistance • Lead pipe – same throughout • Butter!!!

Muscles Spindles and Golgi Tendon Organs • Muscle spindles – Modified muscle fibres – Parallel to muscle fibres – Sense length/stretch in muscle • Golgi tendon organs – Situated at muscle-tendon junction – Detect tension

Muscle contraction • Isotonic – same strength, changes length – Concentric – gets shorter – Eccentric – gets longer • Isometric – same length, changes strength

Levers • Lever – Rigid rod moving from a fixed point – fulcrum/joint – Acted on at 2 different points by resistance/weight of body part and effort/muscle pull – 3 types dependent on arrangement of fulcrum, resistance and effort