Joints: Structure, Function, and Pathology

Comprehensive vocabulary flashcards covering structural and functional classifications, synovial joint types, angular/rotational/special movements, and clinical joint pathologies from BIOL 2457.

Joint (Articulation)

A junction or location where two or more bones meet, functioning to connect bones together and allow body movements.

Synarthrosis

A functional classification of joints that are immovable ("together-joint").

Amphiarthrosis

A functional classification of joints that permit slight movement ("both sides").

Diarthrosis

A functional classification of joints that are freely moveable ("through joint"); includes all synovial joints.

Fibrous Joint

A structural joint classification where bones are united directly by dense collagen fibers; functionally classified as synarthroses or amphiarthroses.

Suture

A fibrous synarthrosis joint composed of dense collagen fibers located specifically between cranial skull bones.

Gomphosis

A peg-in-socket fibrous synarthrosis joint found between the roots of teeth and the alveolar bone of the jaw.

Periodontal Ligament

The specific collagen fiber bundles that anchor the root of a tooth into the alveolar bone socket in a gomphosis joint.

Syndesmosis

A fibrous amphiarthrosis joint where bones are connected by an interosseous ligament or membrane, such as between the radius and ulna or tibia and fibula.

Cartilaginous Joint

A structural joint classification where articulating bones are united by cartilage; functionally classified as synarthroses or amphiarthroses.

Synchondrosis

A cartilaginous synarthrosis joint united by hyaline cartilage, such as the epiphyseal plate and the joint between rib #1 and the sternum; can convert to a synostosis when calcified.

Synostosis

A totally rigid, immovable bony joint formed by the complete fusion and calcification of two separate bones (e.g., coxa, calcaneus, and costal/sternal junctions).

Symphysis

A cartilaginous amphiarthrosis joint where bones are united by a fibrocartilage pad, such as intervertebral discs and the pubic symphysis.

Synovial Joint

A structurally complex diarthrotic joint characterized by an articular capsule enclosing a fluid-filled joint cavity between articulating bones.

Articular Cartilage

A layer of hyaline cartilage covering the opposing bony surfaces in a synovial joint, providing a smooth surface and absorbing shock.

Articular Capsule

A two-layered sleeve enclosing a synovial joint cavity, consisting of an outer fibrous capsule that holds bones together and an inner synovial membrane that secretes synovial fluid.

Synovial Fluid

A viscous fluid secreted by the synovial membrane into the joint cavity that provides shock absorption, lubrication, nourishment for chondrocytes, and protection for articular cartilage.

Bursa

A fluid-filled connective tissue sac lined with synovial membrane that reduces friction and pressure where ligaments, muscles, or tendons rub against bone.

Tendon Sheath

A specialized, elongated bursa that wraps completely around a tendon to reduce friction as the tendon slides across adjacent structures.

Plane Joint

A non-axial synovial joint with flat articulating surfaces that permits only back-and-forth and side-to-side gliding movements (e.g., intercarpal and intervertebral joints).

Hinge Joint

A uniaxial synovial joint in which a cylindrical projection fits into a complementary trough, permitting flexion and extension along a single axis (e.g., elbow, knee, ankle, and interphalangeal joints).

Pivot Joint

A uniaxial synovial joint where the rounded end of one bone rotates within a ring or sleeve formed by another bone and ligament (e.g., proximal radioulnar joint and atlantoaxial joint).

Condylar Joint

A biaxial synovial joint featuring an oval convex surface fitting into a complementary oval depression, allowing movement along two axes (e.g., metacarpophalangeal and radiocarpal joints).

Saddle Joint

A biaxial synovial joint where both articulating surfaces have concave and convex regions that fit together like a rider in a saddle (e.g., the carpometacarpal joint of the thumb).

Ball-and-Socket Joint

A multiaxial synovial joint where a spherical head articulates within a cuplike socket, permitting movement in all three planes (e.g., shoulder and hip joints).

Gliding Movement

A simple synovial joint motion where two relatively flat bone surfaces slide past each other without significant angular or rotational alteration.

Flexion

An angular movement that decreases the angle between articulating bones, bringing them closer together.

Extension

An angular movement that increases the angle between articulating bones, moving them farther apart.

Hyperextension

An extension movement that continues beyond the normal anatomical position.

Abduction

An angular movement that moves a limb or body part away from the midline of the body along the frontal plane.

Adduction

An angular movement that moves a limb or body part toward the midline of the body along the frontal plane.

Circumduction

A composite angular motion in which the distal end of a limb moves in a circle while the proximal attachment remains stationary, describing a cone shape.

Medial Rotation

A rotational movement around a bone's longitudinal axis where the anterior surface turns toward the midline of the body.

Lateral Rotation

A rotational movement around a bone's longitudinal axis where the anterior surface turns away from the midline of the body.

Pronation

A special movement of the forearm where the hand rotates medially so that the palm faces posteriorly or downward.

Supination

A special movement of the forearm where the hand rotates laterally into anatomical position so that the palm faces anteriorly or upward.

Dorsiflexion

A special movement at the ankle joint where the foot is lifted superiorly, pulling the toes upward toward the shin.

Plantarflexion

A special movement at the ankle joint where the foot is depressed, pressing the toes downward away from the shin (also known as plantar extension).

Inversion

A special movement of the foot that turns or tilts the sole medially toward the midline.

Eversion

A special movement of the foot that turns or tilts the sole laterally away from the midline.

Protraction

A special non-angular movement that moves a body part (such as the mandible or shoulder) anteriorly/forward in a transverse plane.

Retraction

A special non-angular movement that moves a protracted body part posteriorly/backward in a transverse plane.

Elevation

A special movement lifting a body part superiorly (upward), such as shrugging the shoulders or closing the mandible.

Depression

A special movement moving an elevated body part inferiorly (downward), such as lowering the shoulders or opening the jaw.

Opposition

A specialized saddle joint movement enabling the saddle joint of the thumb to touch the tips of other fingers on the same hand.

Joint Stability vs. Mobility

The inverse biomechanical relationship stating that the more mobile a joint is, the less stable it is, and conversely, the more stable a joint is, the less mobile it is.

Meniscus Tear

A tear in the fibrocartilage pads of the knee joint caused by trauma or age-related degeneration, often causing swelling and joint locking.

Bursitis

Inflammation and swelling of a bursa near a synovial joint, typically triggered by excessive friction or trauma.

Tendonitis

Inflammation and swelling of a tendon or its surrounding tendon sheath, typically caused by repetitive overuse or injury.

Sprain

A joint injury caused by stretching or tearing of reinforcing ligaments.

Dislocation

An injury where articulating bones are forcibly displaced out of their normal anatomical alignment, commonly resulting in sprains, inflammation, and immobility.

Osteoarthritis

The most common chronic degenerative joint disease, caused by years of mechanical wear and tear, leading to cartilage softening, bone spur formation, and joint crepitus.

Crepitus

A crunching or grating sound and tactile sensation produced when roughened, degenerated articular cartilage and bone spurs rub against each other.

Rheumatoid Arthritis

An autoimmune form of arthritis where white blood cells attack synovial joint tissues, breaking down cartilage and forming scar tissue that ossifies into joint deformities.

Pannus

An abnormal mass of inflammatory scar tissue formed in rheumatoid arthritis that erodes articular cartilage and eventually ossifies, causing joint ankylosis.

Gouty Arthritis

A painful metabolic inflammatory condition caused by the crystallization of excess uric acid into needle-like deposits within joints, triggering an acute immune response.