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Joints
Chapter 8
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
Classification of Joints: Structural
• Material binding bones together and whether or not a joint cavity is present
• The three structural classifications are:1. FibrousSutures, Syndesmoses, Gomphoses
2. Cartilaginous cartilage
3. Synovial has a joint cavity
Classification of Joints: Functional
• Amount of movement allowed by the joint• The three functional classes of joints are:
1. Synarthroses – immovable (sutures)
2. Amphiarthroses – slightly movable (sternum)
3. Diarthroses – freely movable
Fibrous Structural Joints: Sutures
Figure 8.1a
Fibrous Structural Joints: Syndesmoses
Figure 8.1b
Cartilaginous Joints: Synchondroses
Figure 8.2a, b
Cartilaginous Joints: Symphyses
Figure 8.2c
Synovial Joints
• Those joints in which the articulating bones are separated by a fluid-containing joint cavity
• All are freely movable Diarthroses• Examples – all limb joints
Synovial Joints: General StructureKNOW THIS PICTURE!!
Gliding Movements
• One flat bone glides over another
Gliding Movement
Figure 8.5a
Angular Movement
• Flexion — bending movement that decreases the angle of the joint
• Extension — reverse of flexion; joint angle is increased
• Dorsiflexion- flexing foot, up movement of the foot
• Plantar flexion — Pointing toe, down movement of foot
Angular Movement
Figure 8.5b
Angular Movement
Angular Movement
• Abduction — movement away from the midline
• Adduction — movement toward the midline
• Circumduction — movement describes a cone in space
Angular Movement
Rotation
• The turning of a bone around its own axis
Figure 8.5g
Special Movements
• Supination and pronation• Inversion and eversion• Protraction and retraction• Elevation and depression• Opposition
Special Movements
Figure 8.6a
Special Movements
Figure 8.6b
Special Movements
Figure 8.6c
Special Movements
Figure 8.6d
Special Movements
Figure 8.6e
Synovial Joints: Knee – Other Supporting Structures
• Anterior cruciate ligament (ACL)• Posterior cruciate ligament (PCL)• Medial meniscus• Lateral meniscus
Ligaments help reinforce the joints
Synovial Joints: Knee – Other Supporting Structures
Figure 8.8b
Problems with ligaments
• The ligaments can be stretched or torn• Partially torn ligaments slowly repair
themselves• Completely torn ligaments require prompt
surgical repair
Dislocations• Occur when bones are forced out of
alignment
Arthritis• Most widespread crippling disease in the
U.S.• Symptoms – pain, stiffness, and swelling
of a joint
Aging & Joints1. Decrease in synovial fluid
2. Thinning of articular cartilage
3. Decrease in flexibility of ligaments
