Structure and Movement

The Muscular System

Figure 6.2Slide 6.1

The Muscular System

The Muscular System• A. A muscle is an

organ that can relax and contract, and provides the force to move your body parts.

• 1. Voluntary muscles – muscles that you are able to control

• 2. Involuntary muscles – muscles that you cannot control

The Muscular System• B.  There are 3 types of

muscle tissue• 1.    Skeletal muscle

moves bones• a.   Most common type

of muscle• b.   Tendons are thick

bands of tissue that attach muscle to bone

• c.   Voluntary muscles• d.   Contract quickly

and tire more easily• e.   Look striped, or

striated

The Muscular System• 2.    Smooth

muscles – found in the internal organs

• a.   Example: intestines

• b.   Smooth muscles are involuntary muscles

• c.Contract and relax slowly 

 

The Muscular System

• 1.    Cardiac muscle • a. Found only in the

heart• b.Cardiac muscle

is striated, like skeletal muscle 

MUSCLE FACTS• Smallest muscle in the body?

Stapedius: the muscle that activates the stirrup, the small bone that sends vibrations from the eardrum to the inner ear. It measures just 0.05 inch (0.13 centimeter) in length.

• Largest muscle in the body?Latissimus dorsi: the large, flat muscle pair that covers the middle and lower back.

• Longest muscle in the body?Sartorius: the straplike muscle that runs diagonally from the waist down across the front of the thigh to the knee.

• Strongest muscle in the body?Gluteus maximus: the muscle pair of the hip that form most of the flesh of the buttocks.

• Fastest-reacting muscle in the body?Orbicularis oculi: the muscle that encircles the eye and closes the eyelid. It contracts in less than 0.01 second.

• Number of muscles used to make a smile?Seventeen.

• Number of muscles used to make a frown?Forty-three.

• There are more than 630 muscles in your body. On average, your body weight is 40% muscle. Out of the 630 muscles, 30 of them are facial muscles, which help you create all those different faces of happiness, surprise, joy, sorrow, sadness, fright, etc.

• The muscles surrounding your eye are the busiest muscles in your body. Research indicates that you probably blink them more than 100,000 times a day.

• And the biggest muscle in your body is the gluteus maximus (your butt).

The Arms

1. Deltoid abducts arm

2. Biceps brachii flexes forearm supinates forearm from neutral

3. Triceps brachii extends forearm

The Legs

4. Sartorius flexes hip and knee

5. Rectus femoris extends knee

6. Gluteus maximus extensor of hip

rotates thigh

7. Biceps femoris

flexes knee

8. Gastrocnemius

flexes ankle

stabilizes ankle and knee when standing

The Trunk

9. Pectoralis major

adducts humerus

10. Rectus Abdominus

produces trunk motions

11. Trapezius

elevates and rotates scapula

12. Latissimus dorsi

rotates humerus

• Head Muscles

• frontalis

• orbicularis oculi

• orbicularis oris

• Etc.