The Muscular System

1. The Muscular System

2. How many muscles do you have in the body? Approximately 640 muscles! Muscles make up approximately 40% of your body weight

3. Types of Muscles Voluntary muscles – muscles you can control by will or thinking What is an example? Involuntary muscles – muscles you cannot control at will, but work automatically What is an example?

4. Different Kinds of Muscles • Skeletal muscle (voluntary) • Smooth (involuntary) • Cardiac (involuntary)

5. Skeletal • Striated muscles • Holds the skeleton together • Gives the body shape • Helps with everyday movements

6. Smooth • Controlled by nervous system automatically • Examples of smooth muscles are the walls of the stomach and intestines, which help break up food and move it through the digestive system. • Smooth muscle is also found in the walls of blood vessels, where it squeezes the stream of blood flowing through the vessels to help maintain blood pressure

7. Cardiac • Found in the heart • The walls of the heart's chambers are composed almost entirely of muscle fibers. • Its rhythmic, powerful contractions force blood out of the heart as it beats.

8. How does movement occur? • The motor cortexsends an electrical signal through the spinal cord and peripheral nerves to the muscles, causing them to contract • The motor cortex on the right side of the brain controls the muscles on the left side of the body and vice versa

9. The cerebellumcoordinates the muscle movements ordered by the motor cortex

10. Movement continued • Sensors in the muscles and joints send messages back through peripheral nerves to tell the cerebellum and other parts of the brain where and how the arm or leg is moving and what position it's in • Muscles move body parts by contracting and then relaxing. Your muscles can pull bones, but they can't push them back to their original position. • They work in pairs of flexors and extensors

11. What is the longest muscle? Sartorius (Quadricep muscle)

12. What is the smallest muscle? Stapedius (Inside the ear)

13. What is the widest muscle? External oblique (Runs around the side of the upper body)

14. What is the biggest muscle? Gluteus maximus (In your buttock)

15. Sternocleidomastoid • Location:Side of the neck • Function:Pulls head back and rotates head

16. Pectoralis Major • Location:Chest • Function:Brings arms toward chest

17. Trapezius • Location:Upper back and neck • Function:Moves shoulders up and down • Notes:Shrugs shoulders

18. Deltoid • Location:Surrounds the shoulder joint • Function:Lifts arm away from body

19. Biceps • Location:Front of the upper arm • Function:Pulls lower arm up (flexion)

20. Triceps • Location:Back of upper arm • Function:Pulls lower arm down (extension) • Notes:extends arm back

21. Latissimus Dorsi • Location:Down the spine and across the back • Function:Pulls arm toward the back

22. External Oblique • Location:Outside part of trunk • Function:Trunk rotation

23. Rectus Abdominus • Location:Center of stomach • Function:Stabilize the trunk area

24. Gluteus Medius • Location:Hip area • Function:Lift leg out to the side

25. Gluteus Maximus • Location:Buttocks • Function:Straightens hip • Notes: Sitting to standing

26. Sartorius • Location:Inner side of upper thigh • Function:Pulls leg inward

27. Rectus Femoris • Location:Front center thigh • Function:Straightens knee and bends hip

28. Vastus Lateralis • Location:Front outside part of thigh • Function:Straightens knee

29. Vastus Medialis • Location:Front inner part of thigh • Function:Straightens knee

30. Biceps Femoris • Location:Back outside thigh • Function:Bends knee and straightens hip

31. Semitendonosus • Location:Back inside thigh • Function:Bends knee and straightens hip

32. Gastrocnemius • Location:Outside lower back of leg • Function:Raises heel

33. Soleus • Location:Inside back of lower leg • Function:Raises heel

34. Tibialis Anterior • Location:Front of lower leg • Function:Pulls toes up