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There are two types of muscle contractions: isontonic and isometric. In osotonic the tension rises and the skeletal muscle's length changes. The isometric contraction, differentiates from the isotonic, it does not change length. The tension never rises above the resistance. In isotonic contraction the skeletal muscle remains constant and just exceeds the resistance as the muscle shortens. For instance lifting, running and walking are isotonic contraction. Pushing against something or holding something above around. .
The bones and muscles have direct physical connections. The attachment sites of skeletal.
muscle and connective tissue surround individual muscle fibers are continuous with those that form the organic framework of an attached bone. Muscles and bones are linked though mutual dependence on calcium ion concentrations in body fluids. Bone abnormalities can have a direct effect on the muscle. The bones are directly affected by muscular activity.
Each muscle contracts to produce a specific action or movement. Almost all skeletal muscles either originate or insert on the skeleton. When a muscle moves a portion of skeleton, that movement may involve flexion, extension, adduction, protraction, retraction, elevation, depression, rotation, circumduction, pronation, supination, inversion, eversion, lateral flexion, or opposition. .
Actions are described by two methods: "Flexion of the forearm," such as the biceps brachii muscle. The action of the biceps brachii muscle would be "flexion at (or of) the elbow." pg. 315.
The head and neck muscles are axial muscles. The muscles of facial expressionare.
obricularis oris, buccinator, and epricranius muscles and the platysma. The extrinsic eye muscles control eye movements: the inferior and superior rectus muscles, the lateral and medial rectus muscles and the inferior and superior oblique muscles.
