4. Articulations/Joints Flashcards
What is a joint?
Place of contact between two or more bones (articulation)
Some joints are very mobile, others immobile
Mobility/stability relationship of joints
More planes or motion = reduced stability
How is joint stability increased?
Muscular support and ligamentous attachment
How are joints classified
By structure or function
Structural classifications of joints
Fibrous, cartilaginous, and synovial
Joint that connects bones connected and made of dense regular connective tissue
Fibrous joint
Joint that connects bones by plates of cartilage
Cartilaginous joint
Articular capsule with joint cavity
Synovial joint
Types of fibrous joints
Gomphosis, sutures, and syndesmosis
Characteristics and example of gomphosis
Immobile and consist of small amounts of dense connective tissue
Ex) teeth and sockets
Characteristics and example of sutures
Immobile and consist of small amount of dense connective tissue with irregular edges
Ex) skull bones
What does irregular edges do for sutures
Increases surface area, which increases stability
Characteristics and example of syndesmosis
Slightly mobile and consists of large amounts of dense regular connective tissues
Ex) interosseous membrane of tibia-fibula and radius-ulna
Types of cartilaginous joints
Synchondrosis and symphysis
Characteristics and example of synchondrosis
Immobile and connected by hyaline cartilage
Ex) 1st rib-manubrium, epiphyseal plates
Characteristics and example of symphysis
Slightly mobile and connected by fibrocartilage
Ex) intervertebral discs, pubic symphysis
Types of synovial joints
Planar, hinge, pivot, saddle, condylar, and ball-socket
Characteristics of synovial joints
Very mobile, consists of articular capsule with joint cavity, lined by articular/hyaline cartilage, and stable due to ligaments/muscles
Components of articular capsule of synovial joints
Fibrous capsule for support
Synovial membrane that lines joint cavity and secretes synovial fluid
Joint movement that decreases angle
Flexion
Joint movement that increases angle
Extension
Joint movement away from midline
Abduction
Joint movement toward midline
Adduction
Joint movement rotating outward
Lateral rotation
Joint movement rotating inward
Medial rotation
Joint movement superiorly
Elevation
Joint movement inferiorly
Depression
Joint movement forward
Protraction
Joint movement backward
Retraction
Joint movement where palm is rotated anteriorly
Supination
Joint movement where palm is rotated posteriorly
Pronation
Joint movement of sole of foot inward
Inversion
Joint movement of sole of foot outward
Eversion
Joint movement of elevating foot
Dorsiflexion
Joint movement of depressing foot
Plantar flexion
Types of movement at synovial joints
Nonaxial, uniaxial, biaxial, multiaxial
Movement in which bones slide across each other on plane (not around an axis)
Nonaxial movement
Movement around one axis
Uniaxial movement
Movement around 2 axes/planes
Ex) front to back and side to side
Biaxial movement
Movement around all three axes/planes
Ex) front to back, side to side, rotation/twisting
Multiaxial movement
Flat articular surface that undergoes nonaxial movement via gliding
Plane joint
Examples of plane joints
Intercarpal joints, intertarsal joints, and joints between vertebral articular surfaces
Joint consisting of a cylinder and trough that undergoes uniaxial movement via flexion and extension
Hinge joint
Examples of hinge joints
Elbow joints and interphalangeal joints
Joint consisting of a sleeve and axle that undergoes uniaxial movement via rotation
Pivot joint
Examples of pivot joints
Proximal radioulnar joints, atlantoaxial joint
Joint consisting of oval articular surfaces that undergoes biaxial movement via flexion/extension and adduction/abduction
Condylar joint
Examples of condylar joints
Metacarpophalangeal (knuckle) joints, wrist joints
Joint consisting of articular surfaces that are both concave and convex and undergoes biaxial movement via adduction/abduction and flexion/extension
Saddle joint
Examples of saddle joints
Carpometacarpal joints of the thumbs
Joint consisting of a cup (socket) and spherical head (ball) that undergoes multiaxial movement via flexion/extension, adduction/abduction, and rotation
Ball-and-socket joint
Examples of ball-and-socket joints
Shoulder joints and hip joints