Introduction Joints, or articulations, are connections between bones that may or may not permit movement



Download 14.71 Kb.
Date conversion29.11.2016
Size14.71 Kb.

Introduction

  • Joints, or articulations, are connections between bones that may or may not permit movement.

  • Cartilage, fluid, or dense connective tissues are usually involved in holding joints together.

  • Joints are classified functionally by the amount of movement they allow.

  • Immovable or slightly movable joints tend to be in the axial skeleton.

  • Freely movable joints are more common in the appendicular skeleton.

Classification of Joints

  • Synarthroses (Immovable Joints)

  • Sutures are joints found only in the skull.

  • Bony edges interlock and short dense connective tissue fiber holds 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 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 6 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

  • Synovial fluid has three functions:

  • Nourishes the chondrocytes by entering and exiting the articular cartilages due to the forces acting on the joint

Articular Form and Function

  • Angular movements

  • Rotation

  • Special movements

  • Movements at the ankle include

  • Eversion/inversion

  • Dorsiflexion/plantar flexion

  • Lateral flexion

  • Movement of the pollex (thumb)

  • Opposition/reposition

  • Special movements that occur at many joints include:

  • Protraction is movement anteriorly in the horizontal plane.

  • Retraction is movement posteriorly in the horizontal plane.

  • Elevation is movement cranially in the vertical axis.

  • Depression is movement caudally in the vertical axis.

  • A Structural Classification of Joints

  • Plane joints  

  • Hinge joints

  • Flexion and extension

  • Pivot joints

  • Rotational movements

  • A Structural Classification of Joints (cont.)

  • Condylar joints

  • Flexion/extension and abduction/adduction

  • Saddle joints

  • Biaxial joints that also allow circumduction

  • Triaxial joints

  • Vertebral Movements

  • There are four possible movements of the vertebral column:

Representative Articulations

Aging and Articulations

Bones and Muscles

  • Skeletal and muscular systems are structurally and functionally interdependent.



The database is protected by copyright ©dentisty.org 2016
send message

    Main page