Anatomy & Physiology

Muscular System

Muscles

• Bundle of muscle fibers held together by connective tissue

• All muscles have:– Excitability (responsive)– Contractibility (becomes short, thick)– Extensibility (stretched)– Elasticity (return to it original shape)

Types of Muscle

1. Cardiac– Involuntary– Contracts heart

2. Smooth– Involuntary– Lines hollow organs

3. Skeletal– Voluntary– Causes body movement

Muscle Movements• Muscle attach to bones by tendons

1. Adduction Moving a body part toward the midline

2. Abduction Moving a body part away from the midline

3. Flexion Bending a body part

4. Extension Straightening a body part

5. Rotation Turning side to side

6. Circumduction Moving a joint in a circle

Major Muscle Groups

• Sternocleidomastoid (turns & flexes neck)• Trapezius (extends head & moves shoulders)• Deltoid (moves arms; injection site)

• Biceps (flexes lower arm)• Triceps (extends lower arm)

• Pectoralis major (moves & flexes upper arm)

Major Muscle Groups

• Intercostal muscles {Not on diagram} (Moves ribs for breathing)

• Rectus abdominus (compress abdomen)• Latissimus dorsi (extends & moves upper

arms)• Gluteus maximus (extends thigh; injection

site)

Major Muscle Groups

• Sartorius (moves thighs & flexes leg)• Quadriceps (extends leg)

• Tibialis anterior (moves foot)• Gastrocnemius (moves foot)