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Articulations and Joints. Muse lecture #9 6/7/10. Joints Chapter 9. Joint Classifications Fibrous Joints Cartilaginous Joints Synovial Joints Types of Movements at Synovial Joints Types of Synovial Joints Factors Affecting Contact and Range of Motion at Synovial Joints
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Articulations and Joints Muse lecture #9 6/7/10
JointsChapter 9 • Joint Classifications • Fibrous Joints • Cartilaginous Joints • Synovial Joints • Types of Movements at Synovial Joints • Types of Synovial Joints • Factors Affecting Contact and Range of Motion at Synovial Joints • Selected Joints of the Body • Aging and Joints • Arthroplasty Muse Lecture #6
An Introduction to Articulations • Articulations • Body movement occurs at joints (articulations) where two bones connect • Joint Structure • Determines direction and distance of movement (range of motion) • Joint strength decreases as mobility increases
Classification of Joints • Two methods of classification • Functional classification is based on range of motion of the joint • Structural classification relies on the anatomical organization of the joint
Classification of Joints Party on Arth! • Functional Classifications • Synarthrosis (immovable joint) • No movement • Fibrous or cartilaginous connections • May fuse over time • Amphiarthrosis (slightly movable joint) • Little movement • Fibrous or cartilaginous connections • Diarthrosis (freely movable joint) • More movement • Also called synovial joints • Subdivided by type of motion
Classification of Joints • Structural Classifications • Bony • Fibrous • Cartilaginous • Synovial (capsulated)
Classification of Joints • Functional Classifications • Synarthroses (immovable joints) • Are very strong • Edges of bones may touch or interlock • Four types of synarthrotic joints: • suture • gomphosis • synchondrosis • synostosis
Classification of Joints • Synarthrotic Joints • Suture • Bones interlocked • Are bound by dense fibrous connective tissue • Are found only in skull • Gomphosis • Fibrous connection (periodontal ligament) • Binds teeth to sockets Yah can’t chomp without the gomph
Joints (Fibrous Joints) • Sutures • Occur only between bones of the skull • Syndesmoses • Permits slight movement • Interosseous membrane • Between the tibia and fibula in the leg • Gomphoses • Immovable joint • Joint in which a cone-shaped peg fits into a socket • Articulations of the teeth with the sockets of the maxillae and mandible
(b) Syndesmosis Joint held together by a ligament. Fibrous tissue can vary in length, but is longer than in sutures. Fibula Tibia Ligament Figure 8.1b
Joints (Fibrous Joints) • Lack a synovial cavity • The articulating bones are held very closely together by dense irregular connective tissue • Fibrous joints permit little or no movement • Three types of fibrous joints • Sutures • Syndesmoses • Gomphoses
Classification of Joints • Synarthrotic Joints • Synchondrosis • Is a rigid cartilaginous bridge between two bones: • epiphyseal cartilage of long bones • between vertebrosternal ribs and sternum • Synostosis • Fused bones, immovable: • metopic suture of skull • epiphyseal lines of long bones
Classification of Joints • Functional Classifications • Amphiarthroses • More movable than synarthrosis • Stronger than freely movable joint • Two types of amphiarthroses • syndesmosis: • bones connected by ligaments • symphysis: • bones separated by fibrous cartilage
Classification of Joints • Functional Classifications • Synovial joints (diarthroses) • Also called movable joints • At ends of long bones • Within articular capsules • Lined with synovial membrane
Synovial Joints • Components of Synovial Joints • Articular cartilages • Pad articulating surfaces within articular capsules: • prevent bones from touching • Smooth surfaces lubricated by synovial fluid: • reduce friction
Ligament Joint cavity (contains synovial fluid) Articular (hyaline) cartilage Fibrous capsule Articular capsule Synovial membrane Periosteum Figure 8.3
Synovial Joints • Components of Synovial Joints • Synovial fluid • Contains slippery proteoglycans secreted by fibroblasts • Functions of synovial fluid: • lubrication • nutrient distribution • shock absorption
Synovial Joints • Components of Synovial Joints • Accessory structures • Cartilages: • cushion the joint: • Fibrous cartilage pad called a meniscus (articular disc) • Fat pads: • superficial to the joint capsule • protect articular cartilages • Ligaments: • support, strengthen joints • sprain: ligaments with torn collagen fibers
Synovial Joints • Components of Synovial Joints • Accessory structures • Tendons: • attach to muscles around joint • help support joint • Bursae: • pockets of synovial fluid • cushion areas where tendons or ligaments rub
Coracoacromial ligament Subacromial bursa Humerus resting Cavity in bursa containing synovial fluid Bursa rolls and lessens friction. Humerus head rolls medially as arm abducts. Humerus moving (b) Enlargement of (a), showing how a bursaeliminates friction where a ligament (or otherstructure) would rub against a bone Figure 8.4b
Synovial Joints • Factors That Stabilize Synovial Joints • Prevent injury by limiting range of motion • Collagen fibers (joint capsule, ligaments) • Articulating surfaces and menisci • Other bones, muscles, or fat pads • Tendons of articulating bones
Synovial Joints [INSERT FIG. 9.1a] Figure 9–1a The Structure of a Synovial Joint.
Synovial Joints Figure 9–1b The Structure of a Synovial Joint.
Synovial Joints • Injuries • Dislocation (luxation) • Articulating surfaces forced out of position • Damages articular cartilage, ligaments, joint capsule • Subluxation • A partial dislocation
Movements • Types of Dynamic Motion • Linear motion (gliding) • Angular motion • Rotation • Planes (Axes) of Dynamic Motion • Monaxial (1 axis) • Biaxial (2 axes) • Triaxial (3 axes)
Movements Figure 9–2 A Simple Model of Articular Motion.
Movements Figure 9–2 A Simple Model of Articular Motion.
Movements • Types of Movements at Synovial Joints • Terms describe • Plane or direction of motion • Relationship between structures
Movements • Types of Movements at Synovial Joints • Linear motion • Also called gliding • Two surfaces slide past each other: • between carpal or tarsal bones
Movements • Angular Motion • Flexion • Angular motion • Anterior–posterior plane • Reduces angle between elements • Extension • Angular motion • Anterior–posterior plane • Increases angle between elements
Movements • Angular Motion • Hyperextension • Angular motion • Extension past anatomical position Angular Movements
Movements Figure 9–3a Angular Movements.
Movements • Angular Motion • Abduction • Angular motion • Frontal plane • Moves away from longitudinal axis • Adduction • Angular motion • Frontal plane • Moves toward longitudinal axis Think kidnapping Think adding
Movements Figure 9–3 Angular Movements.
Movements Figure 9–3 Angular Movements.
Movements • Angular Motion • Circumduction • Circular motion without rotation • Angular motion
Movements Figure 9–3 Angular Movements.
Movements • Types of Movement at Synovial Joints • Rotation • Direction of rotation from anatomical position • Relative to longitudinal axis of body • Left or right rotation • Medial rotation (inward rotation): • rotates toward axis • Lateral rotation (outward rotation): • rotates away from axis
Movements Figure 9–4a Rotational Movements.
Movements • Types of Movements at Synovial Joints • Rotation • Pronation: • rotates forearm, radius over ulna • Supination: • forearm in anatomical position
Movements Figure 9–4b Rotational Movements.
Movements • Types of Movements at Synovial Joints • Special movements • Inversion: • twists sole of foot medially • Eversion: • twists sole of foot laterally • Dorsiflexion: • flexion at ankle (lifting toes) • Plantar flexion: • extension at ankle (pointing toes) Plant your feet
Movements • Special Movements at Synovial Joints • Opposition • Thumb movement toward fingers or palm (grasping) • Protraction • Moves anteriorly • In the horizontal plane (pushing forward) • Retraction • Opposite of protraction • Moving anteriorly (pulling back)
Movements • Special Movements at Synovial Joints • Elevation • Moves in superior direction (up) • Depression • Moves in inferior direction (down) • Lateral flexion • Bends vertebral column from side to side
Movements Figure 9–5 Special Movements.
Movements Figure 9–5 Special Movements.
Movements • Classification of Synovial Joints by Shape • Gliding • Hinge • Pivot • Ellipsoid • Saddle • Ball-and-socket A Functional Classification of Synovial Joints