The Muscular System Functions Anatomy Functions of the

The Muscular System Functions & Anatomy

Functions of the Muscular System

Movement • Movement of bones • Actions of muscles – Work like rubber bands – Depends on attachment points on the bones

Posture • Maintain body position • Tonic Contraction – Produces no movement – Maintain muscle tone

Heat Production • Contraction produces heat required to maintain normal body temp.

Types of Muscle Tissue • Skeletal • Smooth • Cardiac

Skeletal Muscle • • • Striated Voluntary “Red Meat” Attached to bones Perform contractions that lead to movement of bones – Joints

Smooth Muscle • Non-striated (smooth) • Involuntary • Found in hollow walls of organs – Intestine – Blood vessels – Etc. • Movement of materials through tubes

Cardiac Muscle • Striated – intercalated discs • Involuntary • Heart – Contraction

Structure of Skeletal Muscle • Organs = muscles • Extend from bone to bone – Attached by tendons • Origin – fixed point • Insertion – moves during contraction

Microscopic Structure • Contractile fibers grouped in bundles • Contain Proteins (filaments) – Actin – Myosin • Filaments slide toward each other during contraction

Stimulus • Muscle contracts when stimulus reaches certain intensity • All on none • Motor Unit – Nerve + Muscle – Neurotransmitter crosses gap between

Muscular System Actions

Actions are based on…. • Origin – Fixed point of muscle attachment • Insertion – Moveable point of muscle attachment • Insertions move toward origins – Direction of muscle fibers

Actions • Flexion (lateral*) – Decreasing the joint angle • Extension – Increasing the joint angle • Hyperextension

Actions… • Abduction (Hz*) – Moving away from body • Adduction (Hz*) – Moving toward body • Circumduction – Cone-like movement

Actions… • External Rotation – lateral • Internal Rotation – Medial • L/R Rotation

Actions… • Plantar Flexion – Pointing toes • Dorsi Flexion – Bringing toes toward shins • Inversion – Soles sweep toward each other • Eversion – Soles sweep away

Actions… • Pronation – Palms downward • Supination – Palms upward • Opposition – Thumb moves across palm • Reposition – Thumb returns

Actions… • Depression – Lowering shoulders • Elevation – Shoulders shrug upward • Protraction – Jutting forward • Retraction – Jutting back