Chapter 9: Joints - Classification, Structure, and Movements

Comprehensive vocabulary flashcards covering functional and structural joint classifications, anatomy and accessory structures of synovial joints, body movements, and types of synovial joints.

Synarthrosis

A functional classification describing an immobile joint, such as the sutures found between the bones of the skull.

Amphiarthrosis

A functional classification describing a slightly moveable joint, such as the intervertebral disc between adjacent vertebrae.

Diarthrosis

A functional classification describing a freely moveable joint; categorized into uniaxial, biaxial, and multiaxial joints.

Uniaxial Joint

A diarthrosis joint that allows movement around a single axis or in a single plane, such as the knee joint or elbow joint.

Biaxial Joint

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

Multiaxial Joint

A diarthrosis joint that allows movement along three or more axes or planes, such as the shoulder and hip joints.

Fibrous Joint

A structural classification of joints where bones are joined together by fibrous connective tissue without a joint cavity; typically immovable (synarthrosis).

Suture

A type of fibrous joint united by dense fibrous connective tissue found specifically between the bones of the skull.

Syndesmosis

A type of fibrous joint where parallel bones are held together by a fibrous membrane or ligament, such as the antebrachial interosseous membrane connecting the radius and ulna.

Gomphosis

A specialized peg-and-socket fibrous joint that anchors the root of a tooth into its bony socket via the periodontal ligament.

Cartilaginous Joint

A structural classification of joints where bones are united by cartilage, allowing limited or slight movement (amphiarthrosis).

Synchondrosis

A cartilaginous joint united by hyaline cartilage, such as the temporary hyaline cartilage joint formed by the epiphyseal plate in growing long bones.

Symphysis

A cartilaginous joint where bones are united by a fibrocartilaginous pad or plate, such as the pubic symphysis or intervertebral discs.

Articular Capsule

A structure of connective tissue that completely encloses and strengthens a synovial joint, consisting of an outer fibrous membrane and an inner synovial membrane.

Articular Cartilage

A thin layer of hyaline cartilage that covers the articulating surfaces of bones within a synovial joint to reduce friction.

Joint Cavity

The fluid-filled space situated between the articulating surfaces of bones in a synovial joint.

Synovial Fluid

A viscous fluid secreted by cells of the synovial membrane that provides lubrication, supplies nutrients to articular cartilage, and removes cellular debris.

Extrinsic Ligaments

Reinforcing ligaments located outside of the articular capsule, such as the lateral collateral ligament (LCL) of the knee joint.

Intrinsic Ligaments

Reinforcing ligaments that are fused to the wall of the articular capsule and act as localized thickenings of the fibrous capsule, such as the iliofemoral ligament of the hip joint.

Intracapsular Ligaments

Reinforcing ligaments located inside the articular capsule, such as the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) of the knee joint.

Tendon

A dense regular connective tissue structure that attaches muscle to bone and provides added stability and support across a joint.

Bursa

A closed fluid-filled sac containing lubricating liquid that prevents friction between bones and overlying skin, muscles, or tendons.

Gliding Movement

A synovial joint movement where flat bone surfaces slide past one another in a back-and-forth or side-to-side motion.

Flexion

An angular movement occurring in the sagittal plane that decreases the angle between articulating bones.

Extension

An angular movement occurring in the sagittal plane that increases the angle between articulating bones, straightening the joint.

Hyperextension

Extension of a limb or body part beyond its normal anatomical position in the sagittal plane.

Abduction

An angular movement occurring in the coronal plane that moves a limb or body part away from the midline of the body.

Adduction

An angular movement occurring in the coronal plane that moves a limb or body part toward the midline of the body.

Circumduction

A circular movement pattern produced by the sequential combination of flexion, abduction, extension, and adduction.

Rotation

A movement of a bone turning around its own longitudinal axis toward (medial) or away from (lateral) the midline of the body.

Elevation

An upward motion in the vertical plane that raises a body part, such as closing the mouth by moving the mandible up or lifting the scapula.

Depression

A downward motion in the vertical plane that lowers an elevated body part, such as opening the mouth by moving the mandible down or lowering the scapula.

Protraction

An anterior motion in the horizontal plane that moves the mandible or scapula forward.

Retraction

A posterior motion in the horizontal plane that moves the mandible or scapula backward toward its anatomical position.

Inversion

A special movement of the foot at the intertarsal joints that turns the sole inward toward the midline of the body.

Eversion

A special movement of the foot at the intertarsal joints that turns the sole outward away from the midline of the body.

Dorsiflexion

A motion of the ankle joint that lifts the superior surface (top) of the foot toward the anterior lower leg.

Plantarflexion

A motion of the ankle joint that points the toes and lifts the heel, moving the foot downward.

Supination

A movement of the forearm that rotates the palm upward or anteriorly, placing the radius and ulna in a parallel orientation.

Pronation

A movement of the forearm that rotates the palm downward or posteriorly, causing the radius to cross over the ulna into an X-shape.

Opposition

A specialized movement of the first carpometacarpal joint that brings the tip of the thumb into contact with the tips of the fingers of the same hand.

Pivot Joint

A uniaxial synovial joint allowing rotational movement around a central axis; examples include the atlantoaxial joint ($\text{C1–C2}$ articulation) and proximal radioulnar joint.

Hinge Joint

A uniaxial synovial joint that allows flexion and extension movements; examples include the elbow, knee, ankle, and interphalangeal joints of the fingers and toes.

Condyloid Joint

A biaxial synovial joint that permits flexion/extension, abduction/adduction, and circumduction; examples include the radiocarpal joint of the wrist, metacarpophalangeal joints, and metatarsophalangeal joints.

Saddle Joint

A biaxial synovial joint characterized by opposing saddle-shaped surfaces that permits flexion/extension, abduction/adduction, and circumduction; examples include the first carpometacarpal joint of the thumb and sternoclavicular joint.

Plane Joint

A multiaxial synovial joint with flattened articulating surfaces that allows gliding movements, inversion/eversion of the foot, or flexion, extension, and lateral flexion of the vertebral column; examples include intertarsal joints and superior-inferior articular processes of vertebrae.

Ball-and-Socket Joint

A multiaxial synovial joint consisting of a rounded head fitting into a cuplike depression that permits flexion/extension, abduction/adduction, circumduction, and medial/lateral rotation; examples include the shoulder and hip joints.