Arthrology

1. Arthrology Ch. 8.

2. Arthrology: Study of joints Joints are classified according to structure and function Structural: 1.  Fibrous joints: composed of fibrous tissue with no joint cavity 2.  Cartilaginous joints: articulating bones are united by cartilage and no joint cavity present. 3.  Synovial joints: articular bones are separated by a fluid-filled joint cavity.

3. Functional: 1.  Synarthroses: immovable joints 2.  Amphiarthroses: slightly movable joints (vertebral bodies and pubic bones) 3.  Diarthroses: freely movable joints (most appendicular joints)

4. Fibrous joints: 1.  Sutures: contain dense fibrous connective tissue until adulthood when they ossify (synostoses). skull bones (plates) 2. Syndesmoses: bones are connected by a filamentous sheet or cord (ligament or interosseous membrane); fibers are longer than in sutures but are only slightly more resilient, movement can range from slight to considerable. tibiofibular joint and the radioulnar joint. 3. Gomphoses: articulation of tooth with body alveolar surface. Peg in socket. Possesses a fibrous connection called the periodontal ligament. 

7. Cartilaginous joints: 1.   Synchondroses- hyaline cartilage unites bones at a synchondrosis. Cartilage is replaced by bone and becomes synarthrotic.  Epiphyseal plate and the costal cartilage of the first rib and the manubrium of the sternum. 2.   Symphyses- articular surface of bone covered by hyaline cartilage fused to an intervening pad or plate.  However, it is compressible, resilient and functionally amphiarthrotic. Pubic symphysis and the intervertebral discs.

9. Synovial: all synovial joints are diarthrotic (opposing bones move freely)  Five distinct features of the skeleton 1.  Articular cartilage: hyaline type forms a glassy smooth surface over the opposing ends of bones.                 2.  Joint cavity: small space 3.  Synovial fluid: largely derived from blood; has a viscous, egg-white consistency; leaks out of cartilage; weeping lubrication. 4.  Articular capsule        a.  Fibrous capsule (external)        b.  Synovial membrane (internal) 5.  Reinforcing ligaments: support and strengthen the joint

11. Synovial joints have supportive structures called bursae.  These structures are flattened sacs lined with a synovial membrane and contain a thin film of synovial fluid.  Bursae are located where ligaments, muscles, and tendons overlie and rub against bone.  Some synovial joints have pads of fibrocartilage between the ends of bones: menisci of the knee.

12. Joint motion Gliding: bones displaced in relation to one another (intercarpal and intervertebral joints) Angular: changing the angle between two bones      Flexion: decreasing the joint angle      Extension: increasing the joint angle      Abduction: moving away      Adduction: moving towards      Circumduction: draw around in a circle      Rotation: turning movement of a bone around its own axis (can be medial or lateral)

13. Special movements 1.   Supination: turning backwards (radius/ulna) 2.   Pronation: turning forwards (radius/ulna) 3.   Inversion: movement of the foot medially 4.   Eversion: movement of the foot laterally 5.   Protraction: movement of the mandible forward 6.   Retraction: movement of the protracted part back to its starting position 7.   Elevation: lifting a body part superiorly 8.   Depression: moving the elevated part inferiorly 9.   Opposition: touching your thumb to the tips of other fingers.

14. Types of synovial joints 1.  Plane joints: articular surface is flat and only allow for short gliding movements (intercarpal and intertarsal). 2.  Hinge joints: cylindrical projection of one bone fits into a trough-shaped surface on another bone (elbow). 3.  Pivot joints: rounded end of one bone protrudes into a sleeve or ring composed of bone or ligament (radius to ulna and axis to atlas). 4.  Condyloid joints: oval articular surface of one bone fits into a complementary depression in another (metacarpophalanges: knuckles).

15. 5.  Saddle joints: each articular surface has a concave and convex area (carpometacarpal joint of the thumb). 6.  Ball and socket: the spherical end of one bone articulates with a cuplike socket of another bone (shoulder or hip joints).