3. Extensibility : is the ability of muscular tissue to stretch without being damaged. Smooth muscle is subjected to the greatest amount of stretching (Ex: stomach filling with food, cardiac muscle stretches each time the heart fills with blood).
4. Elasticity : is the ability of muscular tissue to return to its original length and shape after contraction or extension.
Skeletal Muscle
Each skeletal muscle is a separate organ composed of hundreds to thousands of cells called muscle fibres (muscle cell = muscle fibre). Skeletal muscle is surrounded by connective tissue and is penetrated by nerves and blood vessels.
Fibre arrangement of Skeletal Muscle
1. Parallel – fibres are parallel to the force-generating axis. These muscles are used for fast or extensive movements. Strap, fan-shaped & fusiform are subtypes. 2. Pennate – fibres are at an angle to the force-generating axis & fibres insert into a central tendon. These muscles will create more force than parallel. Subtypes include uni-, bi- & muti- pennate.
Components of a Skeletal Muscle Fibre
A mature skeletal muscle fibre is composed of many immature mesoderm cells called myoblasts that have been fused together. For this reason, a single skeletal muscle cell has many nuclei. A muscle fibre is composed of many basic contractile units called myofibrils , and myofibrils are composed of many structural units called sarcomeres .
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