Bodies in Motion

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 biceps Is the agonist The triceps is the antagonist

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…. (Peroneus longus)  Origin / Insertion: The sternocleidomastoid originates on the sternum and inserts on the mastoid

Muscles you should know: Origin, insertion, and action  Orbicularis oculi (234)  Orbicularis oris (234)  Zygomaticus (major/minor) (234)  Temporalis (237)  Massester (237)  Sternocleidomastoid (240)  Trapezius (240)

… More Muscles …  Latissimus dorsi (248)  Pectoralis major (248)  Biceps brachii (251)  Triceps brachii (251)  Gluteus maximus (256)  Sartorius (258)  Biceps femoris (258)