Muscular System

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ad- to, toward or nearab- from, awaycircum- aroundinter- between, among

General Info

• Consists of 650 muscles

• Muscles are bundles muscle fibers held together by connective tissue

Properties

• Excitability– Ability to respond to a stimulus such as a

nerve impulse• Extensibility

– Ability to be stretched• Elasticity

– Allows the muscle to return to its original shape after it has contracted or stretched

●Contractibility -Muscle fibers stimulated by

nerves contract or become shorter and thicker which

causes movement

Types of Muscles

• Skeletal– Attached to bones and

causes movement

Cardiac Muscle

• Found only in the heart

• Contracts to circulate blood

Visceral Muscle

• Also called smooth• Found in all internal

organs

Functions of Muscles

• Attaches to bones to provide voluntary movement

• Produces heat and energy• Helps maintain posture• Protects internal organs

Tendons

• Strong, tough, connective tissue

• One way skeletal muscles attach to bones

• Ex: Achilles →

Fascia

• Tough sheet-like membrane that covers and protects tissue

• Ex: back

Muscle Actions

• Origin– End of the muscle that

does not move• Insertion

– End of the muscle that does move

Muscle Movements

• Adduction– Moving a body part

toward the midline

Abduction

• Moving a body part away from the midline

Flexion

• Decreasing the angle between 2 bones or bending a body part

Extension

• Increasing the angle between 2 bones or straightening a body part

Rotation

• Turning a body part around it’s own axis

Circumduction

• Moving in a circle at a joint while the other end stays stationary

Muscle Tone

• State of partial contraction

• Muscles have some tone at all times

Atrophy

• Lack of muscle tone• Occurs when muscles

are not used for a long period of time they shrink in size and lose strength

Contracture

• A severe tightening of a flexor muscle resulting in a bending of a joint

• Ex: Foot drop

Diseases• Muscular Dystrophy

– Group of inherited diseases that lead to chronic progressive muscle atrophy

• Fibromyalgia– Widespread pain in specific muscle sites– S/S muscle stiffness, numbness, tingling, pain

• Muscle Spasms– Cramps– Sudden involuntary muscle contraction

• Strain– Overstretching of or injury to a muscle or tendon