Anatomy and Physiology: Joints and Articulations

Comprehensive vocabulary flashcards covering the functional and structural classification of joints, synovial joint anatomy, stabilizing features, synovial joint categories, joint pathologies, and body movement terminology.

Articulation (Joint)

A location where two or more bones meet, serving to enable body movement, provide stability, and allow long bones to lengthen during growth.

Synarthrosis

A functional joint classification describing an immovable articulation that does not allow any movement between articulating bones ($\text{SYN} = \text{together/with}$, $\text{ARTHO} = \text{joint}$).

Amphiarthrosis

A functional joint classification describing an articulation that allows only a small amount of movement between articulating bones ($\text{AMPHI} = \text{both}$).

Diarthrosis

A functional joint classification describing a freely moveable articulation that permits a wide variety of specific movements ($\text{DIA} = \text{completely/through}$).

Fibrous Joints

A structural joint classification where bones are joined by dense regular collagenous connective tissue without an intervening joint space; functionally classified as synarthroses or amphiarthroses.

Cartilaginous Joints

A structural joint classification where articulating bones are held together by cartilage without a joint space; functionally classified as synarthroses or amphiarthroses.

Synovial Joints

A structural joint classification characterized by a fluid-filled cavity (joint space) and articular hyaline cartilage covering bone ends; functionally classified as diarthroses.

Suture

An immovable fibrous joint found exclusively between the adjacent edges of cranial bones, providing exceptional structural stability to protect the brain.

Gomphosis

An immovable fibrous joint ($\text{gompho} = \text{bolt}$) that anchors each tooth firmly into its bony socket in the jaw via the periodontal ligament.

Syndesmosis

A fibrous joint in which articulating bones (such as the radius and ulna or tibia and fibula) are bound by an interosseous membrane or ligament, allowing slight movement ($\text{DESMO} = \text{connection}$).

Synchondrosis

A cartilaginous joint in which bones are linked by hyaline cartilage without movement (synarthrosis), exemplified by epiphyseal plates and the first sternocostal joint.

Epiphyseal Plate

A temporary synchondrosis composed of hyaline cartilage that connects the diaphysis and epiphyses of developing long bones and ossifies into bone upon skeletal maturity.

Symphysis

An amphiarthrotic cartilaginous joint where articulating bones are united by a tough fibrocartilaginous pad or plug, such as the intervertebral joints and the pubic symphysis.

Articular Capsule

A double-layered connective tissue sleeve enclosing a synovial joint, consisting of an outer fibrous layer continuous with the periosteum and an inner synovial membrane.

Synovial Membrane

The inner vascular layer of the articular capsule that secretes synovial fluid and lines all internal joint surfaces except where articular cartilage is present.

Synovial Fluid

A viscous liquid that lubricates articulating joint surfaces to reduce friction, absorbs mechanical shocks, and distributes nutrients and removes wastes for avascular articular cartilage.

Articular Cartilage

A thin, avascular layer of hyaline cartilage that coats all exposed articulating bone surfaces within a joint to minimize friction and wear.

Ligament

A cord or sheet of dense regular collagenous connective tissue that connects one bone to another, providing strength and structural reinforcement to a joint.

Tendon

A structural component of skeletal muscle made of dense regular collagenous connective tissue that anchors muscle to bone and stabilizes the joint it crosses.

Muscle Tone

A continuous, low-level state of skeletal muscle contraction that generates stabilizing force across associated joints.

Bursa

A synovial fluid-filled fibrous sac situated in high-stress regions that cushions moving joint structures and minimizes friction between bones, tendons, and muscles.

Tendon Sheath

An elongated, tubular bursa that wraps around tendons in high-stress joint areas to protect them from friction during movement.

Nonaxial Joint

A synovial joint configuration that allows articulating surfaces to slide across one another in one or more planes without rotating around a fixed axis.

Uniaxial Joint

A synovial joint configuration that permits movement in only one plane around a single axis of rotation.

Biaxial Joint

A synovial joint configuration that allows motion in two planes around two perpendicular axes.

Multiaxial (Triaxial) Joint

A synovial joint configuration that permits movement across all three spatial axes, offering the greatest mobility.

Plane Joint (Gliding Joint)

The simplest nonaxial synovial joint, formed between flat articular bone surfaces that glide against each other (e.g., intercarpal joints of the wrist).

Hinge Joint

A uniaxial synovial joint in which the convex surface of one bone fits into the concave trough of another, allowing flexion and extension (e.g., the elbow joint).

Pivot Joint

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

Condylar Joint (Ellipsoid Joint)

A biaxial synovial joint in which an oval, convex projection of one bone seats into a complementary shallow concave depression of another (e.g., the metacarpophalangeal knuckles).

Saddle Joint

A biaxial synovial joint where each articulating bone surface has both concave and convex regions that interlock, permitting a wide range of motion (e.g., the carpometacarpal joint of the thumb).

Ball-and-Socket Joint

A multiaxial synovial articulation in which a spherical bone head articulates with a cup-shaped socket, permitting movement in all three axes (e.g., the shoulder and hip joints).

Osteoarthritis

The most common form of arthritis, caused by mechanical wear and tear, previous joint injuries, or aging; characterized by progressive articular cartilage loss, bone spur development, pain, and stiffness.

Rheumatoid Arthritis

A chronic autoimmune form of arthritis in which the body's immune system attacks joint tissues, producing synovial membrane thickening, joint swelling, and cartilage destruction.

Gouty Arthritis (Gout)

An inflammatory joint disease caused by the deposition and crystallization of uric acid (tophi) within joint spaces, triggering intense pain and tissue inflammation.

Gliding Movement

A nonaxial sliding motion between flat or nearly flat articulating surfaces at synovial joints.

Angular Movement

A category of motion that increases or decreases the angle between two articulating bones (including flexion, extension, abduction, and adduction).

Flexion

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

Extension

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

Hyperextension

The extension of an articulating joint beyond its normal anatomical position.

Abduction

An angular motion that moves a body part or limb laterally away from the anatomical midline of the body.

Adduction

An angular motion that brings a body part or limb medially toward the anatomical midline of the body.

Circumduction

An unpaired angular movement in which the distal end of a bone moves in a circular, cone-shaped path while the proximal end remains stationary; a combination of flexion, extension, abduction, and adduction.

Rotation

A nonangular motion in which a bone pivots or twists around its own imaginary central longitudinal axis.

Opposition

A special movement occurring at the first carpometacarpal joint that brings the palmar surface of the thumb across the palm to meet other fingertips.

Reposition

A special movement that returns the thumb to its standard anatomical position following opposition.

Depression

A special nonangular movement that shifts a body part in an inferior direction (e.g., opening the mandible).

Elevation

A special nonangular movement that raises a body part in a superior direction (e.g., closing the mandible).

Protraction

A special movement that shifts a body part forward in an anterior direction along the horizontal plane (e.g., jutting the jaw forward).

Retraction

A special movement that draws a body part backward in a posterior direction along the horizontal plane (e.g., pulling the jaw backward).

Inversion

A special rotational movement of the foot that turns the sole (plantar surface) medially toward the midline of the body.

Eversion

A special rotational movement of the foot that turns the sole (plantar surface) laterally away from the midline of the body.

Dorsiflexion

A special movement at the ankle joint that lifts the foot upward, decreasing the angle between the foot and the anterior leg.

Plantarflexion

A special movement at the ankle joint that points the toes downward, increasing the angle between the foot and the anterior leg.

Supination

A rotational movement of the forearm that orients the palm upward or anteriorly so that the radius and ulna lie parallel.

Pronation

A rotational movement of the forearm that rotates the palm downward or posteriorly, causing the radius to cross over the ulna.

Range of Motion (ROM)

The total amount or degrees of movement that a specific articulation is normally capable of achieving under healthy conditions.