Joints: Classification, Anatomy, Movements, and Pathology

Vocabulary practice flashcards covering structural and functional classifications of joints, synovial joint anatomy, axes and planes of motion, body movements, and joint pathologies.

Joint (Articulation)

A point in the body where two or more bones meet and connect.

Diarthrotic Joint

A freely movable joint, such as the shoulder, knee, or wrist.

Amphiarthrotic Joint

A slightly movable joint, such as an intervertebral disc.

Synarthrotic Joint

An immovable joint, such as a tooth in its socket.

Synostosis

A fusion of two bones into one by bone tissue, resulting in no mobility (e.g., fused skull bones after middle age or the adult coxal bone fused from three parts). It is not considered a joint.

Fibrous Joint

A joint where the bones are connected by dense regular connective tissue (usually called a ligament) with mobility ranging from synarthrotic to diarthrotic.

Suture

A synarthrotic fibrous joint found between most bones of the skull.

Syndesmosis

A fibrous joint where the length of connecting fibers varies and determines mobility; examples include the synarthrotic distal tibiofibular joint and the diarthrotic interosseous membrane of the forearm.

Gomphosis

A synarthrotic fibrous joint between a tooth and its alveolar socket, held by the periodontal ligament.

Cartilaginous Joint

A joint in which the articulating bones are united by cartilage, lacking a joint cavity.

Synchondrosis

An immovable (synarthrotic) cartilaginous joint where bones are united specifically by hyaline cartilage (e.g., epiphyseal plates and the first sternocostal joint).

Symphysis

A slightly movable (amphiarthrotic) cartilaginous joint where the main uniting tissue is fibrocartilage, though it may also contain hyaline cartilage (e.g., intervertebral discs and the pubic symphysis).

Synovial Joint

A joint where articulating bones are separated by a fluid-containing joint cavity; all joints are diarthrotic (freely movable).

Joint Cavity

A potential space within a synovial joint that contains lubricating synovial fluid derived by filtration from blood.

Articular Capsule

A two-layered capsule enclosing a synovial joint, consisting of an outer fibrous capsule and an inner synovial membrane that produces synovial fluid by filtration.

Articular Cartilage

Hyaline cartilage covering the opposing ends of bones in a synovial joint that absorbs compression forces to protect bone tissue.

Capsular Ligament

A reinforcing ligament of a synovial joint formed by a thickened region of the articular capsule.

Extracapsular Ligament

A reinforcing ligament located outside the joint capsule (e.g., the fibular and tibial collateral ligaments of the knee).

Intracapsular Ligament

A reinforcing ligament located inside the joint capsule (e.g., the anterior and posterior cruciate ligaments of the knee).

Articular Disc (Meniscus)

A fibrocartilage pad found in certain synovial joints (e.g., the knee and temporomandibular joint) that evens out compression forces, stabilizes the joint, and allows additional movements.

Bursa

A closed, flattened fibrous sac lined by synovial membrane and filled with synovial fluid that prevents friction between adjacent structures during joint movement.

Tendon Sheath

An elongated bursa that wraps completely around a tendon to reduce friction.

Bursitis

Inflammation of a bursa.

Anatomical Position

Standard reference position where the body is upright, face, palms, and feet point forward, limbs are vertical, and all digits of the hands are vertical.

Frontal (Coronal) Plane

A vertical plane that divides the body or an organ into anterior and posterior parts.

Sagittal Plane

A vertical plane dividing the body into left and right parts; includes midsagittal (exact midline) and parasagittal (unequal sides).

Transverse (Horizontal) Plane

A horizontal cross-section plane dividing the body into superior and inferior parts.

Translational (Linear) Movement

Movement occurring in a straight line without revolving around an axis, including elevation, depression, protraction, and retraction.

Protraction

A nonangular translational movement directed anteriorly.

Retraction

A nonangular translational movement directed posteriorly.

Elevation

Lifting a body part superiorly.

Depression

Moving an elevated body part inferiorly.

Angular Movement

A movement around an axis that changes the angle between two articulating bones (e.g., flexion, extension, abduction, adduction).

Flexion

An angular movement that decreases the joint angle between two articulating bones.

Extension

An angular movement that increases the joint angle between two articulating bones.

Abduction

Movement of a limb away from the midline of the body along the frontal plane.

Adduction

Movement of a limb toward the midline of the body along the frontal plane.

Circumduction

A movement that describes a cone in space by moving a limb in a circular fashion.

Inversion

A special movement of the foot that turns the sole medially.

Eversion

A special movement of the foot that turns the sole laterally.

Dorsiflexion

A special movement of the foot that lifts the foot upward toward the shin.

Plantar Flexion

A special movement of the foot that points the foot downward.

Rotation

Movement of a bone around its own longitudinal axis (e.g., medial/lateral rotation in appendicular limbs, left/right rotation in the axial skeleton).

Pronation

A rotational movement of the forearm that rotates the radius over the ulna to turn the palm posterior.

Supination

A rotational movement of the forearm that aligns the radius and ulna parallel, turning the palm anterior.

Plane Joint

A nonaxial synovial joint with flat articulating surfaces that permits only translational (gliding) movements (e.g., intercarpal and intertarsal joints).

Hinge Joint

A uniaxial synovial joint typically permitting flexion and extension along a single axis (e.g., elbow, knee, ankle, and interphalangeal joints).

Pivot Joint

A uniaxial synovial joint that permits rotation around a single longitudinal axis (e.g., proximal and distal radioulnar joints).

Condylar Joint

A biaxial synovial joint that allows movements around all axes except the axis of rotation (e.g., metacarpophalangeal knuckle joints).

Saddle Joint

A biaxial synovial joint where both articular surfaces have complementary concave and convex areas, allowing movements around all axes except rotation (e.g., 1st carpometacarpal joint and sternoclavicular joint).

Ball-and-Socket Joint

A multiaxial synovial joint featuring a spherical head fitting into a cuplike socket; permits movement in all axes including rotation (e.g., shoulder and hip joints).

Sprain

An injury where the ligaments reinforcing a joint are stretched or torn; heals slowly due to poor blood supply.

Dislocation

An injury where articulating bones are forced out of their normal alignment at a joint.

Joint Stability

A joint's resistance to dislocation, promoted by articular surfaces with fewer axes of movement, strong ligaments, and surrounding muscle tone.

Rotator Cuff

A stabilizing group of four tendons wrapped closely around the shoulder joint capsule.

Osteoarthritis

A noninflammatory degenerative joint disease caused by normal 'wear and tear' of aging, affecting most elderly individuals.

Rheumatoid Arthritis

A chronic autoimmune disease that begins with inflammation of the synovial membrane.

Gouty Arthritis (Gout)

An inflammatory joint disease caused by excess uric acid retention and deposition of uric acid crystals in synovial membranes.