1. Muscular System

2. Muscles: Designed for Motion
How Muscles are Classified
Muscles – The three main types of muscles are skeletal, smooth, and cardiac
Voluntary Muscles – Muscles that are generally under conscious control (usually skeletal)
Involuntary Muscles – Muscles that not under conscious control (smooth and cardiac)

3. Skeletal Muscles – Primary function is to move the skeleton, made of muscle fibers
Muscle Fibers (Cells) – Bound together in parallel bunches, the contracting mechanism causes the muscle to be striated or striped.
Striated Muscle – Another name for skeletal muscle

5. Smooth Muscle – Shorter, wider cells in a looser arrangement, specialized for long, slow, powerful contractions, used in circulatory and digestive systems, in the iris, and in women during birth

7. Cardiac Muscles – Similar to skeletal muscle but designed to contract continually, only found in the heart and is self stimulating

10. Important Muscles
Sternocleidomastoid – Connect the temporal bones to the sternum and clavicle, Allows for movement of the head

11. Temporalis – Moves the lower jaw when it is chewing or talking
Masseter – Located near your lower jaw and works with the Temporalis

12. Trapezius – Connected to the spine, head, and scapula, moves shoulders back and up, raises the head

13. Intercostal Muscles – Muscles between the ribs, used to raise the rib cage and expand the thoracic cavity when they contract
Pectoralis Major – Connected to the sternum, extends across the chest and connects to the humerus, used when you push your hands in front of your body

14. Deltoid – Connected to your clavicle and humerus (shoulder), used in raising your arm away from your body

15. Latissimus Dorsi – Connects each humerus to the lumbar region, used for drawing your arms toward your body

16. Biceps Brachii – Located on the front of each upper arm, used to bend your forearm toward your body
Triceps Brachii – Located on the back of each upper arm, used to straighten the arm

17. Fingers Flexed/Extended – Muscles in the forearm connected to tendons that run to the hands allow the fingers to be flexed and extended

18. Rectus Abdominus – (6-pack Abs) Extend from the bottom of the sternum to the top of the pelvic girdle, used when you sit up from reclining
External Oblique – Connect the ribs to the pelvis, used for bending sideways (Laterally)

19. Erector Spinae – Extend vertically along the spine from the upper back to the pelvis, used to hold your body upright
Gluteus Maximus – (butt) Largest and strongest muscle in the whole body, connected to pelvis and femur, used to move the leg downward and to the rear

20. Quadriceps Femoris – A group of four muscles on the front of the upper leg, used to straighten the leg
Sartorius – Connects the outside of the pelvic bone to the inside of the tibia, used to lift the lower leg and turn it inward

21. Hamstrings – A group of three muscles on the back of the upper leg, used to bend the leg at the knee
Gastrocnemius – Largest muscle on the back of the lower leg, used to extend the foot downward

22. 1 4 2 5 3 6

23. 7 9 8 10

24. Engineered for Power The Design of Skeletal Muscle
Fascia (8) (Epimysium) – The tough translucent sheath that covers the entire muscle
The fascia tapers at each end into tendons (7) that connect the muscle to the bone

25. Fascicle (9) – Inside the muscle there are bundles of muscle cells called fascicles
Perimysium (1) – The outer covering of a fascicle made of connective tissue
Nerves and vessels (2) run between the fascicles to supply food and oxygen and signal the muscle to contract

26. Muscle Fiber (Cell) (4) – Inside the fascicle there are many muscle fibers that are made of many microfibrils
Each muscle is made of millions of muscle fibers (cells)
Each muscle cell has many nuclei and an unusually large amount of mitochondria

27. Microfibril (6) – Long tubes bunched together to make each muscle fiber; they are made of many sarcomeres
Endomysium (3) – Tough connective tissue between the muscle fibers
Sarcolemma (Cell Membrane) (5) - The outer covering of the muscle fiber (cell)

28. Sarcomere (12) – Overlapping protein fibers made of thick (myosin) and thin (actin) filaments that work together to contract the muscle (this is why skeletal muscles have a striated appearance)

29. 7 8 4 3 2 9 1

30. 5 6 12

31. Muscle contraction
Neuromuscular Junction – Where the nerve connects to the muscle, triggers the muscle to contract
On average one nerve can stimulate 100 muscle cells

32. The group of muscle cells stimulated by a nerve cell is called a motor unit
A motor unit allows there to be less nerve cells for every muscle cell

33. If there are less muscle cells per nerve cell, those muscles are more precise
If there are more muscle cells per nerve cell, those muscles are less precise
Each muscle has thousands of motor units, when you use a muscle some of the units contract while others are relaxed
All-or-none Principle – When motor units are stimulated, they completely contract and completely relax until stimulated again

34. Muscles in Strength and Weakness
Exercise is Healthy for Muscles
Hypertrophy – The enlargement of muscles through use

35. Atrophy – The degeneration of muscles through the lack of use

36. Red Fibers – Muscle fibers that contain a large amount of mitochondria and myoglobin; have a pronounced red color
Contract more slowly, but have more endurance, are called slow-twitch fibers
Myoglobin – A protein that stores oxygen

37. White Fibers – Muscle fibers that contain smaller amounts of mitochondria and myoglobin; do not have a pronounced red color
Have more myofibrils and contract faster and more strongly, are called fast-twitch fibers
You can train your muscles to perform a certain task

38. A weightlifter and marathon runner have about the same amount of muscle cells, they are just trained for a different task.
Weight Lifter Has more White Fibers

39. Marathon Runner Has more Red Fibers

40. Exercise
We need to continue to exercise so the muscle will at least remain in the same condition
If we do not exercise our muscles will deteriorate

41. Warming up – Allows muscle contraction and cellular respiration to occur more efficiently
Cooling down – Allows excess lactic acid to be removed from the muscle to reduce soreness

42. If a muscle is strained, there is usually no noticeable strength loss after healing
Muscle Fatigue – When a muscle becomes stiff, sore, and difficult to contract
Caused by a build-up of waste products in the muscle
Cramp – A sudden , painful, involuntary contraction, caused by a lack of ATP

43. Muscle Tone – A state of slight tension in a relaxed muscle, which a small number of cells are contracted
Allows your muscles to be ready for action
Needed for good posture

44. A Functioning Unit
Both skeletal and muscular systems need all the other systems to be working together with them.
Skeletal system gives the muscular system a support
Nervous system sends electrochemical signals to the muscular system to contract

45. Muscle Sense – Sensors in the muscle tissue relay messages to the brain, informing it of location and tension