Anatomy & Physiology: Joints & Articulations

Flashcards based on lecture notes regarding the structural and functional classification of joints, specific synovial joint types, body movements, and regional anatomy of anatomy of articulations.

Joint

The location where two bones come together; also known as an articulation.

Stable Joints

Joints that allow little or no movement, often connected by fibrous connective tissue or cartilage to provide increased stability.

Freely Movable Joints

Joints containing a fluid-filled joint cavity and smooth articulating surfaces, providing a greater range of motion but less stability.

Structural Classification

A method of classifying joints based on the presence of fibrous connective tissue, cartilage, or a joint cavity.

Functional Classification

A method of classifying joints based on the amount of movement allowed: immobile, slightly movable, or freely movable.

Fibrous Joints

A structural classification where bones are united by fibrous connective tissue and do not contain a joint cavity.

Cartilaginous Joints

A structural classification where bones are connected by hyaline cartilage or fibrocartilage.

Synovial Joints

A structural classification where bones are separated by a fluid-filled joint cavity, allowing the greatest range of movement; the most common joint type in the body.

Synarthrosis

A functional classification describing an immovable or nearly immovable joint, providing strong connections and protection for internal organs.

Amphiarthrosis

A functional classification describing a slightly movable joint that provides both stability and limited flexibility.

Diarthrosis

A functional classification describing a freely movable joint; all synovial joints fall into this category.

Uniaxial Joint

A type of diarthrosis that allows movement in only one plane, such as the elbow joint.

Biaxial Joint

A type of diarthrosis that allows movement in two planes, such as the metacarpophalangeal (knuckle) joints.

Multiaxial Joint

A type of diarthrosis that allows movement in all three anatomical planes, such as the shoulder and hip joints.

Suture

A fibrous joint that connects the bones of the skull (except the mandible) and is functionally classified as a synarthrosis.

Synostosis

The process by which connective tissue or cartilage between bones ossifies and fuses completely into bone.

Fontanelle

Wider areas of connective tissue between skull bones in infants that allow for flexibility during birth and rapid brain growth.

Syndesmosis

A fibrous joint where parallel bones are joined by ligaments or an interosseous membrane, functionally classified as an amphiarthrosis.

Gomphosis

A specialized fibrous 'peg-and-socket' joint that anchors a tooth into its jaw socket via the periodontal ligament.

Synchondrosis

A cartilaginous joint where bones are connected by hyaline cartilage, such as the epiphyseal plate or the first sternocostal joint; functionally classified as a synarthrosis.

Symphysis

A cartilaginous joint where bones are connected by fibrocartilage, such as the pubic symphysis or intervertebral discs; functionally classified as an amphiarthrosis.

Articular Capsule

A structure made of fibrous connective tissue that surrounds the joint cavity of a synovial joint.

Articular Cartilage

A layer of cartilage covering the ends of bones in a synovial joint to reduce friction.

Synovial Membrane

The inner lining of the articular capsule that secretes synovial fluid.

Synovial Fluid

Fluid that lubricates the synovial joint, reduces friction, and nourishes the articular cartilage.

Bursae

Fluid-filled sacs (subcutaneous, submuscular, or subtendinous) that reduce friction between skin, muscles, or tendons and bone.

Tendon Sheath

A connective tissue sac that surrounds a tendon to help it move smoothly across a joint.

Pivot Joint

A type of synovial joint that allows rotation around a central axis, such as the atlantoaxial joint between $C1$ and $C2$ vertebrae.

Hinge Joint

A uniaxial synovial joint that allows flexion and extension, such as the elbow (humeroulnar) joint.

Condyloid Joint

A biaxial synovial joint that allows flexion/extension and abduction/adduction, such as the radiocarpal joint of the wrist.

Saddle Joint

A biaxial synovial joint where articulating surfaces are both concave and convex, allowing flexion/extension, abduction/adduction, and opposition; example: the first carpometacarpal joint of the thumb.

Plane Joint

A synovial joint that allows gliding movements (back and forth, side to side), such as the intercarpal joints of the wrist.

Ball-and-Socket Joint

A multiaxial synovial joint allowing flexion/extension, abduction/adduction, rotation, and circumduction; examples: shoulder and hip joints.

Flexion

A body movement in the sagittal plane that decreases the angle between body parts.

Extension

A body movement in the sagittal plane that increases the angle between body parts.

Abduction

Movement in the frontal plane that moves a body part away from the midline of the body.

Adduction

Movement in the frontal plane that moves a body part toward the midline of the body.

Circumduction

A circular movement that combines flexion, extension, abduction, and adduction.

Supination

Turning the forearm and hand so the palm faces up or anteriorly.

Pronation

Turning the forearm and hand so the palm faces down or posteriorly.

Dorsiflexion

Movement at the ankle joint that moves the foot upward toward the shin.

Plantarflexion

Movement at the ankle joint that moves the foot downward, such as pointing the toes.

Inversion

Turning the sole of the foot inward toward the midline of the body.

Eversion

Turning the sole of the foot outward away from the midline of the body.

Opposition

Movement of the thumb across the palm to touch the fingertips of other fingers.

Excursion

The range or extent of a movement from the starting position to the ending position.

Zygapophysial Joints

Plane synovial joints, also called facet joints, located between adjacent vertebrae that allow limited movement.

Temporomandibular Joint (TMJ)

The articulation between the mandible and temporal bone that combines hinge and gliding movements; contains an articular disc.

Glenoid Labrum

A fibrocartilage structure that deepens the glenoid cavity of the scapula to improve the stability of the shoulder joint.

Acetabular Labrum

A fibrocartilage structure that deepens the acetabulum to improve the stability of the hip joint.

Menisci

C-shaped fibrocartilage structures in the knee joint that provide cushioning, absorb shock, and improve joint stability.

Tibial Collateral Ligament (MCL)

A ligament that stabilizes the medial side of the knee and prevents excessive side-to-side movement.

Anterior Cruciate Ligament (ACL)

A ligament that prevents the tibia from sliding too far forward and resists hyperextension of the knee.

Talocrural Joint

The uniaxial hinge joint that forms the ankle, allowing dorsiflexion and plantarflexion.

Mesenchyme

The embryonic tissue from which bones, cartilage, and connective tissues of joints develop.