1. Chapter 11: The Muscular System

2. Origins and Insertions Muscles have 1 fixed point of attachment (origin) and 1 moving point of attachment (insertion) Most muscles originate or insert on the skeleton Origin is usually proximal to insertion

3. Muscle Interactions Muscles work in groups to maximize efficiency Smaller muscles reach maximum tension first, followed by larger, primary muscles

4. Muscle Terminology Based on Function Agonist (prime mover): –produces a particular movement Antagonist: –opposes movement of a particular agonist

5. Muscle Terminology Based on Function Synergist: –a smaller muscle that assists a larger agonist –helps start motion or stabilize origin of agonist (fixator)

6. Muscle Opposition Agonists and antagonists work in pairs: –when 1 contracts, the other stretches –i.e., flexors–extensors, abductors– adductors, etc.

7. Descriptive Names for Skeletal Muscles 1.Location in the body 2.Origin and insertion 3.Fascicle organization 4.Relative position 5.Structural characteristics 6.Action

8. Location in the Body Identifies body regions: –e.g., temporalis muscle

9. Origin and Insertion First part of name indicates origin Second part of name indicates insertion: –e.g., genioglossus muscle

10. Fascicle Organization Describes fascicle orientation within muscle: –i.e., rectus (straight), transversus, oblique

11. Relative Position Externus (superficialis): –visible at body surface Internus (profundus): –deep muscles Extrinsic: –muscles outside an organ Intrinsic: –muscles inside an organ

12. Structural Characteristics Number of tendons: – bi = 2, tri = 3 Shape: –trapezius, deltoid, rhomboid Size

13. Names for Muscle Size Longus = long Longissimus = longest Teres = long and round Brevis = short Magnus = large

14. Names For Muscle Size Major = larger Maximus = largest Minor = small Minimus = smallest

15. Action Movements: –e.g., flexor, extensor, retractor Occupations or habits: –e.g., risor = laughter

16. Axial and Appendicular Muscles Figure 11–3a

17. Axial and Appendicular Muscles Figure 11–3b

18. Divisions of the Muscular System 1.Axial muscles: –position head and spinal column –move rib cage –60% of skeletal muscles 2.Appendicular muscles: –support pectoral and pelvic girdles –support limbs –40% of skeletal muscles

19. The Axial Muscles Divisions based on location and function: –muscles of head and neck –muscles of vertebral column –oblique and rectus muscles –muscles of pelvic floor

20. Muscles of Facial Expression Figure 11–4a

21. Muscles of Facial Expression Figure 11–4b

22. 3 Muscles of Mastication Masseter: –the strongest jaw muscle Temporalis: –helps lift the mandible Pterygoid muscles: –position mandible for chewing

23. Oblique and Rectus Muscles Lie within the body wall Figure 11–11a, b

24. Rectus Group Rectus abdominis: –between xiphoid process and pubic symphysis –divided longitudinally by linea alba –divided transversely by tendinous inscriptions

25. Rectus Group Diaphragmatic muscle or diaphragm: –divides thoracic and abdominal cavities –performs respiration

26. The Appendicular Muscles Figure 11–13a

27. The Appendicular Muscles Figure 11–13b

28. The Appendicular Muscles Position and stabilize pectoral and pelvic girdles Move upper and lower limbs

29. Muscles that Move the Arm Figure 11–15a

30. Muscles that Move the Arm Figure 11–15b

31. The Rotator Cuff Muscles involved in shoulder rotation –supraspinatus, subscapularis, infraspinatus, teres minor,and their tendons

32. Muscles that Move the Forearm and Hand Figure 11–16a

33. Muscles that Move the Forearm and Hand Figure 11–16b

34. Muscles that Move the Hand and Fingers Figure 11–17a, b

35. The Intrinsic Muscles of the Hand Figure 11–18a

36. The Intrinsic Muscles of the Hand Figure 11–18b

37. Muscles that Move the Thigh Figure 11–19a, b

38. Muscles that Move the Thigh Figure 11–19c, d

39. Muscles that Move the Leg Figure 11–20a

40. Muscles that Move the Leg Figure 11–20b, c

41. Hamstrings Made up of: –biceps femoris –semimembranosus –semitendinosus

42. Muscles that Move the Foot and Toes Figure 11–21a, b

43. Muscles that Move the Foot and Toes Figure 11–21c, d

44. The Achilles Tendon The calcaneal tendon (Achilles tendon): –shared by the gastrocnemius and soleus

45. The Intrinsic Muscles of the Foot Figure 11–22a

46. The Intrinsic Muscles of the Foot Figure 11–22b, c