THE MUSCULAR SYSTEMBodies 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)