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The muscular system plays a vital role in the human body, facilitating motion, posture, respiration, and heat production. It also enables communication through body language and expressions and regulates the constriction of organs and blood vessels. Muscle tissues possess unique properties, including contractility, excitability, extensibility, and elasticity. There are three types of muscles: skeletal, smooth, and cardiac. Understanding each muscle's origin, insertion, and action helps appreciate how muscles work in pairs (agonists and antagonists) to create movement.
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Bodies in Motion The Muscular System
Functions of the Muscular System • Motion • Posture (tone) • Respiration • Production of body heat • Communication by expressions and body language • Constriction of organs and blood vessels • Heartbeat (pulse)
Properties of muscle tissue • Contractility: Ability to shorten with force. Muscles can only pull, not push.
Excitability: The ability of a muscle to respond to a stimulus, usually a nerve signal
Extensibility: Muscle fiber can stretch beyond its normal length and still contract Elasticity: A muscle can return to its original shape after being stretched
3 Types of Muscles • Skeletal • Smooth • Cardiac
Skeletal Muscle:` • Cells are called fibers • Long, parallel cylinders with striations and multiple nuclei • Voluntary • Also control reflexes • Move the body
Gross Anatomy of Skeletal Muscle: Chapter 9 • Muscles can only pull – never push • Muscles must work in pairs to move body parts • The pairs are called agonists and antagonists The triceps is the antagonist The biceps Is the agonist
Origin and insertion: • The origin is the fixed (immobile) end of the muscle • The insertion is the movable end of the muscle
Muscles are named for… • Location: posterior/anterior, brachial (arm), pectoral (chest), etc…. (Tibialis anterior) • Number of heads: bi (2), tri (3), etc…. • Size:maximus, minimus, longus, major, minor, etc…. (Peroneuslongus) • Origin / Insertion: The sternocleidomastoidoriginates on the sternum and inserts on the mastoid
Muscles you should know: Origin, insertion, and action • Orbicularisoculi (234) • Orbicularisoris (234) • Zygomaticus (major/minor) (234) • Temporalis (237) • Massester (237) • Sternocleidomastoid (240) • Trapezius (240)
… More Muscles … • Latissimusdorsi (248) • Pectoralis major (248) • Biceps brachii (251) • Triceps brachii (251) • Gluteus maximus (256) • Sartorius (258) • Biceps femoris (258)