1. The Muscular System Key Facts The ability to move is an essential activity of the human body The ability to move is an essential activity of the human body ½ our body weight comes from muscles ½ our body weight comes from muscles Consists of over 600 individual muscles. Consists of over 600 individual muscles. 3 purposes: 3 purposes: –Body movement –Body shape –Body heat (maintain temp.)

2. The Muscular System Muscle: a general term for all contractile tissue. - comes from the Latin word mus which means “mouse” because the movement of muscles looks like mice running around under our skin

3. The Muscular System Body movements are determined by three types of muscles Body movements are determined by three types of muscles –Smooth (involuntary) – cannot be controlled by will. –Cardiac – control the contractions of the heart. –Skeletal (Voluntary) – can be controlled by will.

4. 1. Skeletal Muscles Skeletal Muscles - attached to bones, provide movement for your body - tendons are fibrous tissues that usually attach skeletal muscle to bones - skeletal muscle is known as voluntary muscle because its movement can be controlled by conscious thought - skeletal muscles found throughout the body are responsible for movement, maintaining our body posture, and heat generation

6. Skeletal Muscles Skeletal Muscle Movement: Skeletal Muscle Movement: –Contraction and relaxation Contraction – shortening of muscles -Muscles, either by themselves or in muscles groups that cause movement, are known as agonists or primary movers -Point of origin: end of the muscle attached to the stationary bone -Point of Insertion: muscle end that is attached to the moving bone -Muscles that assist the primary mover are called synergistic

7. Function of Skeletal muscles Attach to bones to provide voluntary movement Attach to bones to provide voluntary movement –Tendons: strong, tough connective cords –Fascia: tough, sheet-like membrane Produce heat and energy for the body Produce heat and energy for the body Help maintain posture Help maintain posture Protect internal organs Protect internal organs Called striated (striped) because they have striations of alternating light and dark band Called striated (striped) because they have striations of alternating light and dark band

8. Functions cont’d. Fleshy body parts are made of skeletal muscles Fleshy body parts are made of skeletal muscles Provide movements to the limbs, but contract quickly, fatigue easily and lack the ability to maintain contraction for long periods Provide movements to the limbs, but contract quickly, fatigue easily and lack the ability to maintain contraction for long periods –Blinking eyes, talking, breathing, eating, dancing and writing all produced by these muscles

9. 2. Visceral or Smooth Muscle Found in all organs (except the heart) of your body, such as your stomach and other digestive organs, uterus, blood vessels and bronchial airways Found in all organs (except the heart) of your body, such as your stomach and other digestive organs, uterus, blood vessels and bronchial airways These are involuntary muscles and do not contract as rapidly as skeletal muscles These are involuntary muscles and do not contract as rapidly as skeletal muscles “smooth” muscle, not striped like skeletal muscles “smooth” muscle, not striped like skeletal muscles Use: facilitates the movement of blood by changing the diameter of blood vessels, internal movement of food in digestive system Use: facilitates the movement of blood by changing the diameter of blood vessels, internal movement of food in digestive system

10. Function of Smooth Muscle Called smooth muscle because they are unmarked by striations, small spindle shaped Called smooth muscle because they are unmarked by striations, small spindle shaped Unattached to bones, act slowly, do not tire easily and can remain contracted for a long time Unattached to bones, act slowly, do not tire easily and can remain contracted for a long time Not under conscious control so they are also called involuntary muscles Not under conscious control so they are also called involuntary muscles Found in walls of internal organs (intestines, bladder, stomach, uterus, blood vessels) Found in walls of internal organs (intestines, bladder, stomach, uterus, blood vessels)

11. 3. Cardiac Muscle Specialized muscle, found only in the heart Specialized muscle, found only in the heart Makes up the walls of the heart and causes it to contract, which causes the internal movement (circulation) of blood in the body Makes up the walls of the heart and causes it to contract, which causes the internal movement (circulation) of blood in the body Involuntary muscle, happens without conscious control Involuntary muscle, happens without conscious control Because of the amount of work these muscles do, they receive a generous blood supply to get enough oxygen and nutrition Because of the amount of work these muscles do, they receive a generous blood supply to get enough oxygen and nutrition Cardiac muscle does not regenerate after severe damage Cardiac muscle does not regenerate after severe damage

12. Function of cardiac muscle Found only in the heart Found only in the heart Involuntary muscle Involuntary muscle Requires a continuous supply of oxygen to function Requires a continuous supply of oxygen to function Cardiac muscle cells begin to die after 30 seconds of oxygen cut-off Cardiac muscle cells begin to die after 30 seconds of oxygen cut-off Striated and branched Striated and branched

13. Characteristics of Muscles All muscles have 4 common characteristics All muscles have 4 common characteristics –Excitability – ability to respond to a stimulus (ie: nerve impulse) –Contractibility – muscle fibers that are stimulated by nerves contract (become shorter) and causes movement –Extensibility – ability to be stretched –Elasticity – allows the muscle to return to its original shape after it has been stretched

14. MUSCLES YOU NEED TO KNOW THE FUNCTIONS OF: Biceps – flexes lower arm Biceps – flexes lower arm Deltoid – abducts arm; injection site Deltoid – abducts arm; injection site Sternocleidomastoid – turns head Sternocleidomastoid – turns head Gastrocnemius – flexes sole of feet Gastrocnemius – flexes sole of feet Latissimus dorsi – extends & adducts upper arm Latissimus dorsi – extends & adducts upper arm Pectoralis major – adducts and flexes upper arm Pectoralis major – adducts and flexes upper arm

15. Trapezius – extends head, moves shoulder Trapezius – extends head, moves shoulder Triceps – extends lower arm Triceps – extends lower arm Gluteus maximus – extends thigh; injection site Gluteus maximus – extends thigh; injection site Sartorius – abducts thigh, flexes leg Sartorius – abducts thigh, flexes leg Rectus abdominus – compresses the abdomen Rectus abdominus – compresses the abdomen Rectus femoris – flexes thigh & extends lower leg Rectus femoris – flexes thigh & extends lower leg Tibialis anterior – flexes and inverts foot Tibialis anterior – flexes and inverts foot