Introduction Joints, or articulations, are connections between bones that may or may not permit movement. –Cartilage, fluid, or dense connective tissues is usually involved in holding joints together. Joints maybe classified structurally or functionally by the amount of movement they allow. –Immoveable or slightly moveable joints tend to be in the axial skeleton. –Freely moveable joints are more common in the appendicular skeleton.
Classification of Articulations Structural Classifications - anatomical
Classification of Articulations Functional Functional Classification - physiological
Synarthroses (Immovable Joints) Sutures are joints found only in the skull. –Bony edges interlock and short dense connective tissue fiber hold the bones together. A gomphosis is the joint between a tooth and the alveolar fossa of the maxillae or mandible. –Periodontal ligaments hold the tooth to the bone in the gomphosis. A synchondrosis is a joint in which hyaline cartilage separates the ends of the bones involved in the joint. A synostosis occurs if bones fuse together to form one bone.
Amphiarthroses (Slightly Movable Joints) A syndesmosis occurs when to bones are connected by relatively long connective tissue ligaments. Connecting bones using a fibrocartilage pad forms a symphysis.
Diarthroses (Freely Movable Joints) Synovial joints are typically found at the ends of long bones in the upper and lower limbs. All synovial joints have six basic characteristics: –A joint capsule –Articular cartilages –A joint cavity filled with synovial fluid –A synovial membrane lining the joint capsule –Accessory structures –Sensory nerves and blood vessels
Figure 8.1 Structure of a Synovial Joint Synovial Joints
Synovial Fluid Synovial fluid has three functions: –Lubricates the surfaces of the articular cartilages on the ends of the bones. –Nourishes the chondrocytes by entering and exiting the articular cartilages due to the forces acting on the joint. –Acts as a shock absorber.
PLAY Movements Types of Movements Angular movements Rotation
Special Movements Movements at the ankle include: –Eversion/inversion –Dorsiflexion/plantar flexion Movement of the vertebral column includes: –Lateral flexion Movement of the pollex (thumb): –Opposition/reposition
Special Movements Movements that occur at many joints include: –Protraction: anterior movement in the horizontal plane –Retraction: posterior movement in the horizontal plane –Elevation: cranial movement in the vertical axis –Depression: caudal movement in the vertical axis
PLAY Joint Structure Structural Classification of Synovial Joints Plane joints: –Nonaxial or multiaxial Hinge joints: –flexion and extension Pivot joints: –rotational movements
Structural Classification of Synovial Joints Condylar joints: –flexion/extension and abduction/adduction Saddle joints: –biaxial joints that also allow circumduction Ball and socket joints: –triaxial joints
Figure 8.7a,b The Temporomandibular Joint (TMJ) The Temporomandibular Joint
Vertebral Movements There are four possible movements of the vertebral column: –Anterior flexion, or bending forward –Extension, or bending backward –Lateral flexion, or bending to the side –Rotation–twisting
Figure 8.10 The Sternoclavicular Joint The Sternoclavicular Joint
Figure 8.11a The Anterior ShoulderFigure 8.11b The Lateral Shoulder The Shoulder Joint
Figure 8.11c Sectional ShoulderFigure 8.11d Superior Shoulder The Shoulder Joint