Muscular System

Muscular System

• Muscles use chemical energy to exert a pulling force

• Many functions– Movement of body

parts– Propel body fluids

and food– Heartbeat– Distribute heat– Protects body

Muscular System

• Smooth Muscle

• Cardiac Muscle

• Skeletal Muscle

Types of Muscle

• Peristalsis, vasoconstriction• No Striations• Single nucleus• No Transverse Tubules• No Intercalated Discs• Involuntary• Tapered

Smooth Muscle

• Heartbeat• Striations• Single nucleus• Transverse Tubules• Intercalated Discs• Involuntary• Branched

Cardiac Muscle

• Movement of bones at joints• Striations• Multiple nuclei• Transverse Tubules• No Intercalated Discs• Voluntary• Non-Branched

Skeletal Muscle

• Skeletal muscles act as levers

• Levers are simple mechanical devices consisting of a– Rod– Fulcrum– Weight (Resistance)– Force Applied

Levers

• Fulcrum located between resistance and force• Ex. Extending the arm at the elbow

1st Class Lever

• Resistance located between fulcrum and force• Ex. Opening mouth at mandible

2nd Class Lever

• Force located between resistance and fulcrum• Ex. Flexing arm at the elbow

3rd Class Lever

• Origin – The head of the muscle, usually superior, relatively immobile

• Insertion – The end of the muscle, usually inferior, relatively mobile

• When a muscle contracts, the insertion is moved towards the origin

Features of Muscle

• Agonist – A muscle that causes an action– Ex. Deltoid is the agonist for abduction of arm

• Antagonist – A muscle that opposes an action– Ex. Pectoralis Major is the antagonist for

abduction of arm• Synergist – Muscles that work together• Prime Mover – The muscle that does most of

the work in synergistic relationships

Muscle Interactions

• Flexion – Moving parts at a joint, angle decreases

• Extension – Moving parts at a joint, angle increases

• Hyperextension – Extension beyond anatomical position

Types of Movements

• Dorsiflexion – Moving ankle closer to shin• Plantar Flexion – Moving ankle further from

shin

• Abduction – Moving a body part away from the midline of the body

• Adduction – Moving a body part towards the midline of the body, think ADDuction= ADDing to body

• Medial Rotation – Turning a limb on its axis towards the midline of the body

• Lateral Rotation – Turning a limb on its axis away from the midline of the body

• Circumduction – Moving a body part so that it follows a circular path

• Pronation – Rotation of forearm so that the palm is facing downward

• Supination – Rotation of forearm so that the palm is facing upward, think “holds soup”

• Eversion – Turning the foot so the bottom faces laterally

• Inversion – Turning the foot so the bottom faces medially

• Protraction – Moving a body part forward• Retraction – Moving a body part backward

• Elevation – Raising a part of the body• Depression – Lowering a part of the body