Chapter 8: Joints and Articulations

Comprehensive vocabulary flashcards covering structural and functional classifications of joints, features of synovial joints, movement types, and clinical joint pathologies from Chapter 8.

Joint (Articulation)

The junction where two or more bones meet in the skeleton, functioning to enable movement and hold the skeleton together.

Synarthrosis

An immovable joint, typically represented structurally by fibrous joints.

Amphiarthrosis

A slightly movable joint, typically represented structurally by cartilaginous joints.

Diarthrosis

A freely movable joint, structurally classified as a synovial joint.

Suture

An immovable fibrous joint found exclusively in the skull where interlocking bone edges are bound tightly together by very short connective tissue fibers.

Syndesmosis

A fibrous joint in which bones are united by ligaments or bands of fibrous tissue that vary in length but are longer than those found in sutures (e.g., between the tibia and fibula).

Gomphosis

A specialized 'peg-in-socket' fibrous joint in which the periodontal ligament secures the root of a tooth into the socket of the alveolar bone.

Synchondrosis

A cartilaginous joint where bones are united by hyaline cartilage, such as an epiphyseal plate or the joint between the first rib and the manubrium of the sternum.

Symphysis

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

Synovial Joint

A joint in which articulating bones are separated by a fluid-containing joint cavity, allowing free mobility.

Articular Cartilage

Smooth hyaline cartilage covering the opposing bone surfaces in a synovial joint that absorbs compression and prevents bone-on-bone friction.

Joint Cavity

A fluid-filled space within a synovial joint containing a small amount of synovial fluid, capable of expanding if fluid accumulates during inflammation.

Articular Capsule

A two-layered capsule enclosing the synovial joint cavity, providing structural strength to prevent the articulating bones from being pulled apart.

Synovial Fluid

A viscous fluid occupying free spaces within the articular capsule that reduces friction between cartilages, formed via filtration of blood through capillaries in the synovial membrane.

Reinforcing Ligaments

Capsular bands of dense connective tissue that reinforce and strengthen the articular capsule of a synovial joint.

Meniscus

A crescent-shaped wedge of fibrocartilage that partially divides the joint cavity at the knee, improving joint fit and reducing friction.

Bursa

A flattened, fluid-filled fibrous sac lined with synovial membrane that cushions and reduces friction where bones, ligaments, tendons, muscles, or skin rub together.

Plane Joint

A nonaxial synovial joint with flat articulating surfaces that permits short slipping or gliding movements, such as intercarpal and intertarsal joints.

Hinge Joint

A uniaxial synovial joint in which a cylindrical projection fits into a trough-shaped surface, permitting motion in a single plane like a door hinge (e.g., elbow, knee, and interphalangeal joints).

Pivot Joint

A uniaxial synovial joint in which a rounded end of one bone articulates with a ring of bone and ligament, permitting rotation around a longitudinal axis (e.g., proximal radioulnar joint and the atlantoaxial joint between C1 and C2).

Condyloid Joint (Ellipsoidal Joint)

A biaxial synovial joint where an oval convex surface fits into a complementary elliptical depression, permitting angular motion in two planes (e.g., radiocarpal joint and metacarpophalangeal knuckle joints).

Saddle Joint

A biaxial synovial joint where both articulating bones have reciprocal concave and convex surfaces, exemplified by the carpometacarpal joint between the trapezium and the first metacarpal bone of the thumb.

Ball-and-Socket Joint

A multiaxial synovial joint featuring a spherical head that articulates with a cup-like depression, providing the widest range of motion (shoulder and hip joints).

Origin

The point of attachment of a skeletal muscle to an immovable or less movable bone.

Insertion

The point of attachment of a skeletal muscle to the movable bone.

Gliding Movement

A simple joint movement where flat or nearly flat bone surfaces slide back-and-forth or side-to-side over one another without significant angular change.

Flexion

An angular movement along the sagittal plane that decreases the angle between articulating bones (e.g., bending the elbow or knee).

Extension

An angular movement along the sagittal plane that increases the angle between articulating bones, straightening a bent limb or body part.

Hyperextension

The extension of a joint beyond its anatomical position.

Abduction

An angular movement along the frontal plane that moves a limb away from the midline of the body, or spreads the fingers apart.

Adduction

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

Circumduction

A continuous sequence of flexion, abduction, extension, and adduction where the distal end of a limb describes a circle while tracing a cone in space.

Rotation

The turning of a bone around its own longitudinal axis, directed either medially toward the midline or laterally away from it.

Supination

The rotational movement of the forearm in which the radius and ulna are parallel and the palm faces anteriorly or superiorly.

Pronation

The rotational movement of the forearm in which the radius rotates across the ulna forming an X-shape, turning the palm posteriorly or inferiorly.

Elevation

A nonangular movement lifting a body part superiorly, such as shrugging the shoulders upward or closing the jaw.

Depression

A nonangular movement lowering an elevated body part inferiorly, such as returning the shoulders down or opening the jaw.

Inversion

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

Eversion

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

Dorsiflexion

Movement of the ankle that lifts the foot so that its superior surface approaches the shin, pointing the toes upward.

Plantar Flexion

Movement of the ankle that depresses the foot, pointing the toes downward away from the shin.

Protraction

A nonangular movement in the transverse plane that moves a body part anteriorly, such as jutting the mandible forward.

Retraction

A nonangular movement in the transverse plane that draws a protracted body part posteriorly back to its anatomical position.

Opposition

The saddle joint movement of the thumb enabling it to touch the tips of the other digits on the same hand.

Osteoarthritis

A chronic, degenerative 'wear-and-tear' joint disorder characterized by the gradual erosion of articular cartilage and formation of bone spurs.

Rheumatoid Arthritis

A chronic, autoimmune inflammatory joint disorder in which the body's immune system attacks its own synovial membranes.

Gout

An inflammatory joint disease caused by the deposition of uric acid crystals in the soft tissues and synovial cavities of joints.

Sprain

An injury in which the reinforcing ligaments of a joint are stretched or torn.

Dislocation

An injury in which the articulating bones of a joint are forced completely out of their normal alignments.

Bursitis

Inflammation of a bursa, typically caused by repetitive physical trauma, friction, or excessive pressure.

Tendonitis

Inflammation of a tendon or tendon sheath, most commonly induced by chronic overuse.

Lyme Disease

An inflammatory disease caused by bacteria transmitted by tick bites, leading to joint pain, arthritis, skin rash, and flu-like symptoms.

Unhappy Triad (Lateral Knee Injury)

A combination of knee injuries typically caused by a strong lateral blow (e.g., from a hockey puck), resulting in tearing of the tibial collateral ligament, medial meniscus, and anterior cruciate ligament (ACL).

Acetabular Labrum

A rim of fibrocartilage bordering the acetabulum that deepens the socket of the hip joint to enhance articular stability.

Ligamentum Teres (Ligament of the Head of the Femur)

An intracapsular flat band of connective tissue running from the acetabulum into the fovea capitis on the head of the femur.