Mechanic of Movement

1. Mechanic of Movement • Tissues and Structures Involved • Muscle • Nerve • Bone • Cartilage • What are Tendons & Ligaments? • Types of Joints • Mechanics of Joints

2. Nerve and Muscle--the Motor Unit • Motor Unit is one motor neuron plus the muscle cells it synapses • “Action potential”--controlled conduction of electrical messages in neurons and muscle by depolarization of cell membrane

3. Neuro-Muscular Junction Action potential in nerves triggers chemical release at synapse which triggers action potential in muscle

4. Bone and Cartilage • Bone as tissue • Bones as structures formed from bone, cartilage and other tissues • Location of cartilage in skeleton and relation to joints

5. HOW DOES MOVEMENT HAPPENS? Muscles Pull on Tendons to Move Bones at Connections called Joints or Articulations

6. Tendons • Made up of tendon tissue (connective tissue) • Can have various shapes • Typical is cord-like tendon of biceps • Tendons are structures that connect bone to muscle, muscle to muscle, or bone to bone Frolich, Human Anatomy, Mechanics of Movement

7. Ligaments connect bone-to-bone or reinforce joints--they are made up of tendinoustissue as well • Typical are knee ligaments Ligaments Frolich, Human Anatomy, Mechanics of Movement

8. Joints or Articulations • Connections between bones • Usually, but not always allow for movement • Formed from various connective tissues • Fibrous • Cartilaginous • Synovial (most complex--typical limb joints) • Functions of joints • Hold bones together • Allow for mobility • Ways joints are classified • Functionally • Structurally Frolich, Human Anatomy, Mechanics of Movement

9. Functional Classification The amount of movement the joint allows • Synarthroses • immovable joints • Amphiarthroses • slightly moveable joints • Diarthroses • freely moveable joints Frolich, Human Anatomy, Mechanics of Movement

10. Structural Classification • Fibrous joints • Generally immovable • Fibrous tissue separate the boney region at the joint • Cartilaginous joints • Immovable or slightly moveable • Cartilage separates the boney regions at the joint • Synovial joints • Freely moveable • The boney regions of the joint are separated by a space Frolich, Human Anatomy, Mechanics of Movement

11. Fibrous Joints • Bones united by fibrous tissue – synarthrosis or largely immovable. • Skull • Bones tightly bound by minimal fiber • Syndesmoses • Longer connecting fibers • Joint has more give Frolich, Human Anatomy, Mechanics of Movement

12. Cartilaginous Joints • Mostly amphiarthrosis • Bones connected by cartilage • Pubic symphysis • Intervertebral joints • Hyaline cartilage unites bones • Epiphyseal growth plates • Costal cartilage-sternum Frolich, Human Anatomy, Mechanics of Movement

13. Synovial Joints • Diarthroses – movable joint • Most common joint in the body • Articulating ends of bones are covered with hyaline cartilage • Enclosed by a capsule of fibrous connective tissue lined with synovial membranes • Joint cavity is filled with synovialfluid for lubrication • Ligaments reinforce the joint Frolich, Human Anatomy, Mechanics of Movement

14. Typical Synovial Joint Frolich, Human Anatomy, Mechanics of Movement

15. Structures Associated with the Synovial Joints • Bursae – flattened fibrous sacs • Lined with synovial membranes • Filled with synovial fluid • Not actually part of the joint • Tendon sheath • Elongated bursa that wraps around a tendon

16. Types of Synovial Joints The type of joint, in part, determines the range and direction of movement

17. Types of Synovial Joints The type of joint, in part, determines the range and direction of movement

18. Upper arm bone - humerus Capsule (ligaments) Synovial membrane Cartilage Cartilage Synovial fluid tendon Triceps muscle HOW DOES MOVEMENT HAPPEN? The elbow joint - a hinge joint allowing movement in 1 plane The Capsule. Holds the bones of the joint in place. The synovial membrane. Secretes synovial fluid The synovial fluid. Lubricates the movement of the cartilage surfaces against each other – reducing friction and preventing arthritis (inflammation and joint damage). Cartilage. Lubricates the movement of the cartilage surfaces against each other – reducing friction and preventing arthritis (inflammation and joint damage).

19. HOW DOES MOVEMENT HAPPEN? The elbow joint - how the bicep and triceps control movement When the biceps contracts the elbow joint flexes (its joint angle decreases). humerus biceps (flexor muscle), contracts When the triceps contracts the elbow joint extends (its joint angle increases). Triceps (extensor) relaxes The biceps and triceps are called antagonistic muscles because they have the opposite effect on the same joint. radius ulna Remember that for this to work properly the biceps must relax when the triceps contracts, and vice versa. THE BICEPS AND TRICEPS ARE AN ANTAGONISTIC PAIR

20. Inflammatory Conditions Associated with Joints • Bursitis– inflammation of a bursa usually caused by a blow or friction • Tendonitis– inflammation of tendon sheaths • Arthritis– inflammatory or degenerative diseases of joints • Over 100 different types • The most widespread crippling disease in the United States

21. Clinical Forms of Arthritis • Osteoarthritis • Most common chronic arthritis • Probably related to normal aging processes • Rheumatoid arthritis • An autoimmune disease – the immune system attacks the joints • Symptoms begin with bilateral inflammation of certain joints • Often leads to deformities Frolich, Human Anatomy, Mechanics of Movement

22. X-ray of hand affected by arthritis Frolich, Human Anatomy, Mechanics of Movement

23. Frolich, Human Anatomy, Mechanics of Movement

24. Artificial Hip Joint Frolich, Human Anatomy, Mechanics of Movement

25. Click on the picture for the web sports injury clinic Dislocation The bones move out of position, causing pain and preventing joint movement Tendons strain or tear Making movement of the joint painful and difficult Cartilage damage Movement becomes painful or impossible and the joint becomes inflamed. Antagonistic muscle damage due to too overloading Making movement of the joint painful and difficult Lots of problems with joints result from sports injuries What can go wrong with joints