Skip to main content
Back

Anatomy & Physiology: Joints and Synovial Joint Function

Control buttons has been changed to "navigation" mode.
1/28
  • Structural classification of joints

    Based on the material binding bones and presence of a joint cavity: fibrous joints (fibrous tissue, no cavity), cartilaginous joints (cartilage, no cavity), and synovial joints (fluid-filled cavity).

  • Functional classification of joints

    Based on movement allowed: synarthroses (immovable), amphiarthroses (slightly movable), and diarthroses (freely movable).

  • Fibrous joints types

    Include sutures (skull bones tightly bound), syndesmoses (bones connected by ligaments), and gomphoses (peg-in-socket, e.g., tooth socket).

  • Sutures characteristics

    Seams between skull bones with interlocking edges and short connective fibers; immovable and protect the brain; ossify into synostoses in middle age.

  • Syndesmoses movement

    Movement depends on ligament length; short fibers allow little movement (e.g., tibia-fibula), long fibers allow more (e.g., radius-ulna interosseous membrane).

  • Cartilaginous joints types

    Synchondroses: bones united by hyaline cartilage, usually immovable (e.g., epiphyseal plates). Symphyses: bones united by fibrocartilage, slightly movable (e.g., intervertebral discs).

  • Synovial joint defining feature

    Articulating bones separated by a fluid-filled joint cavity, allowing substantial freedom of movement (diarthroses).

  • Synovial joint articular capsule layers

    Two layers: an external fibrous layer of dense irregular connective tissue and an inner synovial membrane producing synovial fluid.

  • Functions of synovial fluid

    Reduces friction, lubricates joint surfaces, nourishes cartilage, and contains phagocytic cells to remove debris.

  • Factors stabilizing synovial joints

    Shape of articular surfaces, number and location of ligaments, and muscle tone.

  • Common synovial joint movements

    Flexion, extension, abduction, adduction, and rotation.

  • Types of synovial joints

    Plane (gliding), hinge (flexion/extension), pivot (rotation), condylar (angular), saddle (greater freedom), and ball-and-socket (multiaxial).

  • Temporomandibular joint (TMJ) movements

    Allows hingelike opening/closing, anterior gliding to brace condyle, and lateral excursion for grinding food.

  • Shoulder joint stability

    Highly mobile ball-and-socket joint stabilized mainly by muscle tendons (rotator cuff) and ligaments; shallow glenoid cavity reduces stability.

  • Elbow joint type and stability

    Hinge joint allowing flexion and extension; stability from interlocking bones and strong collateral ligaments.

  • Hip joint stability features

    Ball-and-socket joint with deep acetabulum and strong ligaments; more stable than shoulder due to socket depth and ligament arrangement.

  • Knee joint complexity

    Largest joint with three articulations; stability from menisci, ligaments (collateral and cruciate), and muscle tendons; allows flexion, extension, and some rotation.

  • Common joint injuries

    Sprains (ligament tears), dislocations (bone displacement), and cartilage tears (menisci damage).

  • Osteoarthritis characteristics

    Degenerative joint disease from cartilage wear; causes stiffness, pain, and bone spurs; common in elderly and weight-bearing joints.

  • Rheumatoid arthritis pathophysiology

    Autoimmune inflammation of synovial membrane causing joint swelling, pannus formation, cartilage erosion, and possible ankylosis.

  • Gouty arthritis cause and symptoms

    Uric acid crystal deposition in joints causing sudden, severe pain, often in the big toe; more common in men.

  • Lyme disease impact on joints

    Bacterial infection from tick bites causing joint pain, arthritis, and systemic symptoms; treated with early antibiotics.

  • Muscle tone role in joint stability

    Low-level muscle contraction maintains tendon tension, reinforcing joint stability, especially in shoulder, knee, and foot arches.

  • Opposition movement

    Movement of the thumb touching fingertips, enabled by the saddle joint of the thumb, crucial for grasping and manipulation.

  • Bursae and tendon sheaths function

    Reduce friction between moving structures near joints; bursae are fluid-filled sacs, tendon sheaths are elongated bursae around tendons.

  • Articular discs (menisci) functions

    Improve fit between bones, increase joint stability, and reduce wear; found in knees and jaw.

  • Hyperextension definition

    Extension of a joint beyond its normal anatomical position.

  • Supination vs. pronation

    Supination rotates forearm so palm faces anteriorly with radius and ulna parallel; pronation rotates palm posteriorly with radius crossing ulna.