Musculoskeletal Anatomy

1. Musculoskeletal Anatomy Toby J. Brooks, PhD, ATC, CSCS

2. Anatomical Kinesiology: Foundations What the heck is it? “The study of muscles as they are involved in the science of movement” Who needs to learn about it? Why do I need to take it?

3. Overview Directional terminology Planes of motion Axes of rotation Types of bones Types of joints

4. Foundations Directional terminology Must be familiar with directional terms…we will use them everyday and it is assumed you learned these terms in prerequisite courses (namely A & P) Review terms on pages 3-5

5. Foundations Group assignment Start at the belly button. Move laterally about one hand width to the right. Then move inferiorly and distally until you reach a hinge joint. Move to the posterior side of the joint and travel distally until you reach a large tendon. Move to the contralateral side (continued)

6. Foundations Travel superiorly past a hinge joint and a ball and socket joint, up the dorsal surface until you reach another ball and socket joint. Move to the anterior side and medially about two hand widths. You are now over a large flat bone. Move superiorly approximately two hand LENGTHS, then move to the right, lateral-most aspect of this structure.

7. Foundations Where are you? Right ear

8. Foundations Planes Frontal or Coronal Divides body into anterior and posterior portions Sagittal Divides body into left and right portions Transverse or horizontal Divides body into inferior and superior portions

9. Planes

10. Axes of Rotation Sagittal/AP Lateral Vertical

11. Types of Bones Long Ex.- Femur Short Ex.- calcaneus Flat Ex.- Scapula

12. Types of Bones Irregular Ex.- Spine Sesamoid Ex.- Patella

13. Types of Joints Synarthroidial (immovable) Example: Cranial sutures

14. Types of Joints Amphiarthroidial (slightly movable) Syndesmosis Ex.- tib./Fib Synchondrosis Ex.- symphysis pubis

15. Types of Joints Diarthrodial Arthrodial (gliding) Condyloidal (ball & socket) Enarthodial (multiax. ball & socket) Ginglymus (hinge) Sellar (saddle) Trochoidal (pivot)

16. Types of Joint Movements 2 classifications General Can occur at multiple joints Specific Only occur at one joint Measurement & quantification Goniometery

17. General Movements Abduction Move away from midline Occurs in frontal plane on AP axis

18. General Movements Adduction Movement toward midline Occurs in frontal plane on AP axis

19. General Movements Flexion Movement that results in decreased joint angle Usually occurs in sagittal plane on frontal axis

20. General Movements Extension Movement that results in increased joint angle Usually occurs in sagittal plane on frontal axis

21. General Movements Circumduction Circular movement that forms an arc in the shape of a cone

22. General Movements Internal rotation Rotary movement around the longitudinal axis toward the midline of the body Occurs in the transverse plane

23. General Movements External rotation Rotary movement around the longitudinal axis away from the midline of the body Occurs in the transverse plane

24. Specific Movements Ankle Inversion Turn sole inward Occurs in frontal plane on AP axis Eversion Turn sole outward Occurs in frontal plane on AP axis

25. Specific Movements Ankle Dorsiflexion “Toes up” Occurs in sagittal plane on lateral axis Plantarflexion Actually an extension “Gas pedal” Occurs in sagittal plane on lateral axis

27. Specific Movements Radioulnar joint Pronation Internally rotating radius in transverse plane on longitudinal axis “Palm down” Supination Externally rotating radius in transverse plane on longitudinal axis “Hold your soup”

28. Specific Movements Shoulder girdle & shoulder joint Depression Inferior movement in frontal plane Elevation Superior movement in frontal plane

29. Specific Movements Shoulder girdle & shoulder joint Horizontal abduction Mvmt. Of humerus in transverse plane away from midline Horizontal adduction Mvmt. Of humerus in transverse plane toward midline

30. Specific Movements Shoulder girdle and shoulder joint Protraction In horizontal plane Retraction In horizontal plane Downward rotation (scapula) In frontal plane Upward rotation (scapula) In frontal plane

31. Specific Movements Spine Lateral flexion Sidebending in the frontal plane

32. Specific Movements Wrist & hand Radial deviation Abduction movement of wrist Occurs in frontal plane on AP axis

33. Specific Movements Wrist & hand Ulnar deviation Adduction movement of wrist Occurs in frontal plane on AP axis Thumb opposition

34. Muscle Terminology Origin Usually refers to the proximal, more fixed attachment point Insertion Usually refers to the distal, more moveable attachment point

35. Muscle Terminology Intrinsic Works only where it is…usually too little to do much else! Extrinsic Usually originate proximal to where they act

36. Types of Muscular Contraction Get into six small groups. Try to come up with the four types of muscular actions. Discuss what they are, and give an example of one use of that action during sport performance.

37. Types of Muscular Contraction Isometric “Iso”=same, “metric”=length No change in length, but force developed is equal to resistance Example: arm wrasslin’, flexin’

38. Types of Muscular Contraction Isotonic “Iso”=same, “tonic”=tension Change in length and force developed may be < or > resistance

39. Types of Muscular Contraction Concentric Force developed > resistance, therefore movement occurs Also known as “positive” contraction Example: acceleration phase of kicking

40. Types of Muscular Contraction Eccentric Force developed < resistance, therefore movement occurs Also known as “negative” contraction Example: defensive lineman who gets pancaked

41. Role of Muscles Agonist Antagonist Stabilizer Synergist Neutralizer

42. Role of Muscles For each role listed, answer the following questions: What is it? What does it do? What is an example?

43. Agonist What is it? Prime mover What does it do? Most (or all) of the work What is an example? Biceps brachii in a biceps curl

44. Antagonist What is it? Opposite of prime mover What does it do? Provides control; Opposes motion What is an example? Triceps brachii in a biceps curl

45. Stabilizer What is it? Dynamic support; Fixator What does it do? Establishes fixed points to provide movement What is an example? Peri-scapular muscles (trapezius I, II, III, rhomboids, teres major, etc.) in UE exercise

47. Synergist What is it? Guiding muscle(s) What does it do? Assists prime mover and refines motion What is an example? Brachioradialis in biceps curl

48. Neutralizers What is it? Muscle that counteracts another muscle What does it do? Prevents unwanted motion or movement What is an example? Hip adductors & abductors during kicking motion

49. Neuromuscular Concepts “All or none” principle of motor units (not nerve cells!) Refers to the motor unit (motor neuron & all innervated sarcomeres), NOT the muscle itself Force produced depends on RECRUITMENT Recruitment depends on both the # of motor units called into action & their INNERVATION DENSITY Example: hand & fingers= high density (precision & control); Trunk= low density (power & speed)

50. Length-tension Relationship

51. Single Joint Vs. Multi-joint Muscles Single joint Cross only one joint, therefore can produce only one action Example: soleus Multi-joint Cross multiple joints, therefore action at one joint depends on position of other Example: gastrocnemius Important clinical/training implications

52. Reciprocal Inhibition Agonists & antagonists “wired”oppositely If brain is telling agonist “contract maximally” then antagonist is told to “contract minimally” This results in inability to produce maximal force in force couple (agonist/antagonist pair) simultaneously

53. Active Insufficiency Muscle contracts maximally, its structural limits (myosin available to form cross-bridges) are reached Cannot generate or maintain contraction due to the limited contractile capacity of the sarcomere

54. Passive Insufficiency Antagonist muscle becomes taut before agonist can fully contract (or vice versa) Multi-joint muscles most affected Example: finger flexion w/ wrist flexion Squeeze your neighbor’s fingers w/ your wrist in neutral Now fully flex your wrist and try again…what happens? Why?