The Joints

1. The Joints A Study in Motion

2. Joints Joints are classified by structure and function. These can: • Fibrous Joints

3. Joints Joints are classified by structure and function. These can: • Fibrous Joints • Cartilaginous Joints

4. Joints Joints are classified by structure and function. These can: • Fibrous Joints • Cartilaginous Joints • Synovial Joints

5. Sutures(Fibrous Joints) These can be found connecting the plates of the skull. As the plates fuse in the adult, the sutures are called synostosesand result in immovable joints.

6. Gomphotic Joints(Fibrous Joints) These are a peg and socket joint. The only example is the articulation of the tooth and its socket.

7. Cartilaginous Joints These are joints where the articulating bones are united by cartilage. There is no joint cavity and mobility is limited. Most common examples are the first rib and manubrium and epiphyseal plates of the long bones.

8. Cartilaginous Joints

9. Synovial Joints The articulating bones are separated by a fluid containing cavity. These joints are diarthrotic and provide the greatest movement. They have 6 distinguishing features.

10. 6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.

11. 6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage. 2. Synovial cavity that is a potential space containing a small amount of liquid.

12. 6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage. 2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers.

13. 6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage. 2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers. 4. Synovial fluid occupies the free space of the joint capsule.

14. 6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage. 2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers. 4. Synovial fluid occupies the free space of the joint capsule. 5. Reinforcing ligaments provide additional structure to the joints

15. 6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage. 2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers. 4. Synovial fluid occupies the free space of the joint capsule. 5. Reinforcing ligaments provide additional structure to the joints 6. Nerve and blood vessels supply

16. Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Articular capsule Synovial membrane Periosteum Figure 8.3 General structure of a synovial joint.

17. Associated Structures Other structures commonly associated with synovial joints include fat pads and articular discs of fibrocartilage. They work like “ball bearings” and reduce friction where ligaments, tendons and muscles rub against each other.

18. Associated Structures Tendon Sheaths Bursae of the knee

19. Movement of Synovial Joints All skeletal muscles attach to bone or connective tissue by at least 2 points. • The Origin is the muscle attachment to the less movable bone • The Insertion is the muscle attachment to the movable bone.

20. 3 general types of movement • Gliding • Angular • Rotational

21. Gliding motion is the simplest and consists of one bone sliding over another. This is seen with the intercarpal and intertarsal joints and between vertebrae

22. Gliding (a) Gliding movements at the wrist Figure 8.5a Movements allowed by synovial joints.

23. Angular movements increase or decrease the angle between 2 bones. Movements include: • Flexion • Extension • Hyperextension • Abduction • Adduction • Circumduction

24. a)Flexion is the bending along a sagittal plane; this decreases the angle of the joint and brings the bones closer together. b) Extension is the straightening of bones resulting in the increase angle between bones. c) Hyperextension is the bending of a joint beyond anatomical position.

25. Hyperextension Extension Flexion (b) Angular movements: flexion, extension, and hyperextension of the neck Figure 8.5b Movements allowed by synovial joints.

26. Extension Hyperextension Flexion (c) Angular movements: flexion, extension, andhyperextension of the vertebral column Figure 8.5c Movements allowed by synovial joints.

27. Flexion Extension Flexion Extension (d) Angular movements: flexion and extension at theshoulder and knee Figure 8.5d Movements allowed by synovial joints.

28. d) Abduction is moving away from the midline along the frontal plane. e) Adduction is moving toward the midline. f) Circumduction is moving the limb to describe a cone, for example the motion made by a pitcher. This motion involves the motions described above.

29. Abduction Circumduction Adduction (e) Angular movements: abduction, adduction, andcircumduction of the upper limb at the shoulder Figure 8.5e Movements allowed by synovial joints.

31. Rotation Is the turning of the bone along its axis. This is seen with the first and second vertebrae and the hip and shoulder joint

32. Rotation Lateral rotation Medial rotation (f) Rotation of the head, neck, and lower limb Figure 8.5f Movements allowed by synovial joints.

33. Special Movements Supination is the radius and ulna are parallel and the palms are facing forward. Pronation the radius and ulna form an X and the palms face posterior. (Think 3 P’s-pronation palms posterior).

34. Pronation (radius rotates over ulna) Supination (radius and ulna are parallel) (a) Pronation (P) and supination (S) Figure 8.6a Special body movements.

36. Dorsi flexion and plantar flexion are seen with the bending of the foot up and down. Bending the foot towards the tibia is dorsi flexion. Pointing the toes away is plantar flexion. This latter motion is seen with ballet dancers.

37. Dorsiflexion Plantar flexion (b) Dorsiflexion and plantar flexion Figure 8.6b Special body movements.

39. Inversion/Eversion is medial and lateral movement of the ankle. Overextension or inversion is commonly seen with the sprained ankle.

40. Inversion Eversion (c) Inversion and eversion Figure 8.6c Special body movements.

42. Protraction and Retraction are the anterior and posterior movement of the jaw. Protraction is the jutting out of the jaw.

43. Protraction of mandible Retraction of mandible (d) Protraction and retraction Figure 8.6d Special body movements.

44. Protraction and Retraction are the anterior and posterior movement of the jaw. Protraction is the jutting out of the jaw. Elevation and depression are the movement of the jaw in an inferior superior direction. (Opening and closing)

45. Depression of mandible Elevation of mandible (e) Elevation and depression Figure 8.6e Special body movements.

46. Opposition is seen with touching of the thumb to the tips of the other phalanges.

47. Opposition (f) Opposition Figure 8.6f Special body movements.

48. Questions?