Structure, Fx of Jts Part 1

PTA 1502: Functional Anatomy and Kinesiology:

Structure and Function of Joints Part I PTA 1502: Functional Anatomy and Kinesiology

Joints:

Joints Junction or pivot point between 2 or more bones Transfer and dissipate forces due to gravity, muscle Structure, Function affected by: Aging Long-term immobilization Trauma Disease

Classification of Joints:

Classification of Joints 3 Major Classifications Synarthrosis Amphiarthrosis Diarthrosis

Classification of Joints:

Classification of Joints Synarthrosis Dense, irregular connective tissue junction Relative rigid; little to no movement Examples Sutures of skull D istal tibiofibular joint Interosseous membranes (forearm, leg) Function B ind bones together, transmit force Disperse force across large area Reduces injury

Classification of Joints:

Classification of Joints Amphiarthrosis Junction formed primarily by fibrocartilage and/or hyaline cartilage Examples Inter-body joint of spine Disc absorbs/disperses forces between vertebrae Pubic symphysis Manubriosternal joint Restricted movement Transmit, disperse forces

Classification of Joints:

Classification of Joints Diarthrosis, “ Synovial Joints” Contains fluid-filled joint cavity between bones Synovial membrane Specialized for movement

Classification of Joints:

Classification of Joints 7 elements of Synovial Joints Synovial fluid (nutrition, lubrication) Articular cartilage (covers ends of bone) Articular capsule Capsular ligaments Blood vessels Sensory nerves

Articular Capsule:

Articular Capsule Composed of 2 layers Synovial membrane Inner layer Barrier to adjacent capillaries; permits only fluid/solutes of plasma into synovial fluid Manufactures, adds lubricant to joint fluid Fibrous, outer layer Dense irregular connective tissue Provides joint support, containment Thicker in some regions (resists/control movement); Capsular ligaments Anterior Glenohumeral ligaments, Medical collateral ligament, knee

Blood vessels and Sensory Nerves:

Blood vessels and Sensory Nerves Supply joint capsule Capillaries penetrate to depth of fibrous capsule, synovial membrane Sensory receptors primarily for pain, proprioception

Other Components of Synovial Joints:

Other Components of Synovial Joints Not present in all synovial joints, but common to some Intra-articular discs ( Menisci ) Pads of fibrocartilage Increases congruency F orce dispersion Tibiofemoral Joint (Knee) Distal radioulnar Joint Sternoclavicular Joint Acromioclavicular Joint Temperomandibular Joint

Other Components of Synovial Joints:

Other Components of Synovial Joints Labrum Shoulder, Hip Deepens concave surface Support, thicken attachment of joint capsule

Other Components of Synovial Joints:

Other Components of Synovial Joints Fat Pads Between capsule, synovial membrane Elbow, Knee Thickens joint capsule Causes inner surface of capsule to fill spaces within joint Reduces volume of synovial fluid

Other Components of Synovial Joints:

Other Components of Synovial Joints Synovial Plicae Slack, overlapped “ pleats” of tissue Composed of innermost layers of joint capsule knee, elbow Increases synovial surface area Allows full joint motion without tension If thickened, can produce pain, altered joint mechanics

Classification of Synovial Joints:

Classification of Synovial Joints

Synovial Joints:

Synovial Joints Hinge Joint Motion occurs primarily in plane located at right angles to axis of rotation ( door hinge ) Humeroulnar joint IP joints of digits Slight translation + rotation

Synovial Joints:

Synovial Joints Pivot Joint Mobile member oriented parallel to axis of rotation Primary motion of spin ( doorknob ) Proximal radioulnar joint Atlantoaxial joint

Synovial Joints:

Synovial Joints Ellipsoid Joint Convex, elongated surface and elongated concave surface Elliptical surfaces severely restrict spin but allow biplanar motions (flexion/extension; abduction/adduction) Radiocarpal joint

Ball and Socket Joint:

Ball and Socket Joint Spherical convex surface, cuplike socket Provides motion in 3 planes Symmetry of surfaces allows spin without dislocation Glenohumeral joint Hip joint

Plane Joint:

Plane Joint 2 flat or relatively flat surfaces Combination of sliding, some rotation Intercarpal joints ( wrist )

Saddle Joint:

Saddle Joint Each aspect of joint has 2 surfaces Concave surface Convex surface Surfaces oriented at right angles to each other Similar to saddle Front-back, concave Side-side, convex CMC, thumb

Condyloid Joint:

Condyloid Joint Similar to ball-and-socket Concave member very shallow Usually allows 2 degrees of freedom Typically occur in pairs Knee TMJ Atlanto-occipital joints MCP joint 1 st digit

Classifying Synovial Joints:

Classifying Synovial Joints Ovoid 1, imperfect, spherical (egg-shaped) surface Changing, articular surface 1 surface is Concave , the other Convex Sellar (saddle) Paired surfaces Opposite in direction Oriented 90 degrees to each other