MUSCULAR SYSTEM

anatomical terminology ? Assume the anatomical position, what do these words mean? Inferior; superior Proximal; distal Medial; lateral Posterior; anterior

TYPES OF MUSCLES 1. SKELETAL : voluntary control striated appearance (alternating dark & light bands) Tendons attach mostly to bone Main function is movement

TYPES OF MUSCLE 2. CARDIAC : Heart muscle, also striated Involuntary control (contracts without thought)

TYPES OF MUSCLE 3. SMOOTH MUSCLE : Lines the walls of blood vessels and hollow organs eg. Stomach and intestines Involuntary movement

MUSCLE FUNCTION Interaction of bones, skeletal muscles & joints = MOVEMENT Muscles move substances within the body eg. Smooth muscles move food through the intestines; cardiac muscle moves blood; skeletal muscle helps venous blood return to the heart

MUSCLE FUNCTION Postural muscles contract to stabilize and maintain body positions Muscles can be active even when there is no movement at a joint

MUSCLE FUNCTION When muscles contract voluntarily or involuntarily (as in shivering) they can generate up to 85% of body heat

MUSCLE PROPERTIES CONTRACTILITY: – Ability of muscle to contract and generate force when stimulated by a nerve – Only muscle tissue can do this – Muscles are usually in pairs: when one contracts the other is stretched.

MUSCLE PROPERTIES EXTENSIBILITY : – The ability of a muscle to be stretched beyond its normal resting length

MUSCLE PROPERTIES ELASTICITY : – The muscles’ ability to return to its original resting length after the stretch is removed ? Give an example Using contractility, extensibility & elasticity together…

SKELTAL MUSCLE STRUCTURE FASCIA: – Connective tissue surrounding tissues (as in bones & muscles) – Made of fibrous tissue, adipose tissue (fat) & fluid – Superficial or deep – Skeletal muscles mostly work in groups – Each group (compartment) is surrounded by fascia

SKELTAL MUSCLE STRUCTURE 3 layers of Fascia in each individual muscle. EPIMYSIUM: the outer layer covering the entire muscle PERIMYSIUM: surrounds bundles of muscle fibres or fascicles ENDOMYSIUM: surrounds the individual muscle fibres

SKELTAL MUSCLE STRUCTURE

TENDONS Layers of Fascia continue beyond muscle to form TENDONS. – Strong, flexible bands of fibrous connective tissue connecting muscle to bone – Various forms: rounded cord or flat sheet – Tendons can be grouped together in a tendon sheath. These contain synovial fluid ? Why? – They play an important role in muscle contraction & joint movement

TENDONS

MUSCLE FIBRE Muscles contain thousands of long, cylindrical fibres lying parallel to each other Inside are small structures called myofibrils – light & dark bands They are arranged into units called Sarcomeres. Sarcomeres contain contractile proteins called Actin & Myosin

MYOFIBRIL/SARCOMERE

MUSCLE FIBRE Muscles have a good nerve & blood supply. Motor neurons send messages from CNS to the muscle Neurons release neurostransmitters into the blood which stimulate the muscle to contract & produce force Muscles have a rich network of capillaries = good damage repair

DEFINE THESE TERMS Define and give an example for each of the following: ATROPHY HYPERTROPHY ORIGIN INSERTION