Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Joints (Articulations)  Weakest parts of the skeleton  Articulation – site where two or more bones meet  Functions of joints  Give the skeleton mobility  Hold the skeleton together

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Joints: Structural  Structural classification focuses on the material binding bones together and whether or not a joint cavity is present  The three structural classifications are:  Fibrous  Cartilaginous  Synovial

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Joints: Functional  Functional classification is based on the amount of movement allowed by the joint  The three functional classes of joints are:  Synarthroses – immovable  Amphiarthroses – slightly movable  Diarthroses – freely movable

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints  The bones are joined by dense, connective fibrous tissues  There is no joint cavity  Most are immovable  There are three types – sutures, syndesmoses, and gomphoses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Sutures  Occur between the bones of the skull  Comprised of interlocking junctions completely filled with connective tissue fibers  Bind bones tightly together, but allow for growth during youth  In middle age, skull bones fuse and are called synostoses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Sutures Figure 8.1a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Syndesmoses  Bones are connected by a fibrous tissue ligament  Movement varies from immovable to slightly variable  Examples include the connection between the tibia and fibula, and the radius and ulna

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Syndesmoses Figure 8.1b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous Structural Joints: Gomphoses  The peg-in-socket fibrous joint between a tooth and its alveolar socket  The fibrous connection is the periodontal ligament

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints  Articulating bones are united by hyaline cartilage or disks of fibrocartilage  Lack a joint cavity  Two types – synchondroses and symphyses

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Synchondroses  A bar or plate of hyaline cartilage unites the bones  Examples include:  Epiphyseal plates of children  Joint between the costal cartilage of the first rib and the sternum

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Synchondroses Figure 8.2a, b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Symphyses  Hyaline cartilage covers the articulating surface of the bone and is fused to an intervening pad of fibrocartilage  Amphiarthrotic joints designed for strength and flexibility  Examples include intervertebral joints and the pubic symphysis of the pelvis

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cartilaginous Joints: Symphyses Figure 8.2c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints  Those joints in which the articulating bones are separated by a fluid-containing joint cavity  Ends of the bones are covered in hyaline cartilage and the ends are encapsulated by synovial fluid  All are freely movable  Examples – all limb joints, and most joints of the body

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: General Structure  Synovial joints all have the following  Articular cartilage  Joint (synovial) cavity  Articular capsule  Synovial fluid  Reinforcing ligaments

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synovial Joints: General Structure Figure 8.3a, b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 8.2.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 8.2.2

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Table 8.2.3

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ball-and-Socket Joints  A spherical or hemispherical head of one bone articulates with a cuplike socket of another  Multiaxial joints permit the most freely moving synovial joints  Examples: shoulder and hip joints Types of Synovial Joints

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ball-and-Socket Joints Figure 8.7f

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Condyloid or Ellipsoidal Joints  Oval articular surface of one bone fits into a complementary depression in another  Both articular surfaces are oval  Biaxial joints permit all angular motions  Examples: radiocarpal (wrist) joints, and metacarpophalangeal (knuckle) joints

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Condyloid or Ellipsoidal Joints Figure 8.7d

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Gliding Movements  One flat bone surface glides or slips over another similar surface  Examples – intercarpal and intertarsal joints, and between the flat articular processes of the vertebrae

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Gliding Movement Figure 8.5a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  Hinge joints  Cylindrical projections of one bone fits into a trough-shaped surface on another  Motion is along a single plane  Uniaxial joints permit flexion and extension only  Examples: elbow and interphalangeal joints

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hinge Joints Figure 8.7b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pivot Joints  Rounded end of one bone protrudes into a “sleeve,” or ring, composed of bone (and possibly ligaments) of another  Only uniaxial movement allowed  Examples: joint between the axis and the dens, and the proximal radioulnar joint

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pivot Joints Figure 8.7c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Saddle Joints  Similar to condyloid joints but allow greater movement  Each articular surface has both a concave and a convex surface  Example: carpometacarpal joint of the thumb

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Saddle Joints Figure 8.7e