Chapter 9, part 1 Articulations

Learning Objectives Contrast the major categories of joints, and explain the relationship between structure and function for each. Describe the structure of a synovial joint. Describe the dynamic movements of the skeleton. List the types of synovial joint, and discuss the relationship of structure to function in each.

Learning Objectives Describe the structure and function of the vertebrae, shoulder, elbow, hip and knee joints. Describe the relationship between joint strength and mobility. Describe the effects of aging on the joints.

SECTION 9-1 A Classification of Joints

Articulations Articulations Where two bones interconnect Immovable joints Synarthroses, or bony Slightly moveable joints Amphiarthroses, or fibrous / cartilagenous Freely moveable joints Diarthroses, or synovial

Synarthroses (immovable joints) Four major types Suture = skull bones bound together by dense connective tissue Gomphosis = teeth bound to bony sockets by periodontal ligaments Synchondrosis = two bones bound by rigid cartilaginous bridge Syntosis = two bones completely fused

Amphiarthroses (slightly movable joints) Two major types Syndesmosis = bones connected by a ligament Symphysis = bone separated by fibrocartilage

Diarthroses (freely movable joints) Bony surfaces enclosed within articular capsule Bony surfaces covered by articular cartilage Bony surfaces lubricated by synovial fluid Structures include Menisci Fat pads Accessory ligaments Bursae

Figure 9.1 The Structure of a Synovial Joint

SECTION 9-2 Articular Form and Function

Dynamic motion Dynamic motion Linear motion Angular motion Rotation Joints classified based on type of motion permitted Monaxial Biaxial Triaxial

Figure 9.2 A Simple Model of Articular Motion

Types of movement Gliding motion Two surfaces slide past one another Angular motion Flexion, extension, hyperextension Abduction, adduction Circumduction

Figure 9.3 Angular Movements PLAY Animation: Flexion, Extension, Hyperextension Figure 9.3

Rotational movement Left or right Medial (internal) or lateral (external) Pronation or supination in the bones of the forearm only

Figure 9.4 Rotational Movements Figure 9.4a,b

Figure 9.4 Rotational Movements Figure 9.4c

Special movement Movements of the foot Inversion and eversion Plantar flexion and dorsiflexion Movements of the thumb Opposition

Other movements Protraction moves a structure anteriorly Retraction moves a structure posteriorly Elevation moves a structure superiorly Depression moves a structure inferiorly Lateral flexion bends the vertebrae to one side

Figure 9.5 Special Movements

Structural classification of joints Gliding joints permit movement in a single plane Hinge joints are monaxial joints permitting angular motion in one plane Pivot joints are monaxial joints that permit rotation Ellipsoid joints are biaxial joints that pit one bone in an oval depression of another Saddle joints are biaxial joints with one concave and one convex bone face Ball-and-socket joints are triaxial joints that permit rotation and other movements

Figure 9.6 A Functional Classification of Synovial Joints

Figure 9.6 A Functional Classification of Synovial Joints PLAY Animation: Joint Motion Figure 9.6