chapter 9 Skeletal System: Articulations

Vocabulary practice flashcards covering structural and functional classifications of joints, joint anatomy, joint motions, specific synovial joints, and joint pathologies from Chapter 9 of Anatomy & Physiology.

Joint (Articulation)

A place of contact between bones, bones and cartilage, or bones and teeth.

Arthrology

The scientific study of joints.

Fibrous Joint

A joint where articulating bones are held together by dense regular connective tissue and lack a joint cavity.

Cartilaginous Joint

A joint where articulating bones are joined by hyaline cartilage or fibrocartilage, lacking a joint cavity.

Synovial Joint

A freely mobile joint where articulating bones are separated by a fluid-filled joint cavity and joined by ligaments.

Synarthrosis

An immobile joint; examples include sutures and gomphoses.

Amphiarthrosis

A slightly mobile joint; examples include syndesmoses, intervertebral joints, and the pubic symphysis.

Diarthrosis

A freely mobile joint; includes all synovial joints.

Gomphosis

A synarthrotic fibrous joint in which the roots of teeth articulate with the alveolar sockets of the mandible and maxillae via periodontal membranes.

Periodontal Membrane

Fibrous connective tissue that secures a tooth in the dental alveolus of the mandible or maxilla.

Suture

An immobile fibrous joint (synarthrosis) found only between certain skull bones, characterized by interlocking, irregular edges connected by very short fibers.

Synostosis

An immobile joint formed when the fibrous tissue of a suture becomes completely ossified in older adults.

Syndesmosis

An amphiarthrotic fibrous joint where parallel long bones (such as radius-ulna and tibia-fibula) are joined by an interosseous membrane.

Interosseous Membrane

A broad, dense regular connective tissue sheet that binds parallel bones together in a syndesmosis and provides a pivot for movement.

Synchondrosis

An immobile cartilaginous joint (synarthrosis) where bones are joined by hyaline cartilage, such as the epiphyseal plate and costochondral joints.

Symphysis

An amphiarthrotic cartilaginous joint featuring a pad of fibrocartilage between articulating bones that resists compression and acts as a shock absorber.

Articular Capsule

A double-layered capsule enclosing the joint cavity of a synovial joint, consisting of an outer fibrous layer and an inner synovial membrane.

Synovial Membrane

The inner layer of the articular capsule, composed primarily of areolar connective tissue, that lines internal joint surfaces and produces synovial fluid.

Articular Cartilage

An avascular layer of hyaline cartilage lacking a perichondrium that covers the articulating bone surfaces to reduce friction and cushion compression.

Joint Cavity

A fluid-filled physical space between articulating bones in a synovial joint that is lined by the synovial membrane.

Synovial Fluid

A viscous, oily fluid in the joint cavity that lubricates articular cartilage, acts as a shock absorber, distributes mechanical stress, and removes waste.

Extrinsic Ligaments

Synovial joint ligaments that are physically separate from the articular capsule.

Intrinsic Ligaments

Thickenings of the articular capsule itself that include ligaments located both outside and within the joint capsule.

Tendon

Dense regular connective tissue that attaches muscle to bone and helps stabilize joints; not part of the synovial joint itself.

Bursa

A fibrous, saclike structure containing synovial fluid and lined by a synovial membrane, located where bones, ligaments, muscles, skin, or tendons rub together to alleviate friction.

Tendon Sheath

An elongated bursa that wraps around a tendon where friction is excessive, common in the wrist and ankle.

Fat Pad

An accessory structure that acts as protective packing material in the joint periphery and fills spaces when joint shape changes.

Uniaxial Joint

A joint in which bone moves in only one plane or axis.

Biaxial Joint

A joint in which bone moves in two planes or axes.

Multiaxial Joint

A joint in which bone moves in multiple planes or axes.

Plane Joint

The simplest and least mobile uniaxial synovial joint, possessing flat articular surfaces that allow limited side-to-side gliding movements.

Hinge Joint

A uniaxial synovial joint where the convex surface of one bone fits into a concave depression of another, functioning like a door hinge.

Pivot Joint

A uniaxial synovial joint in which a bone with a rounded surface fits into a ring of bone and ligament, rotating on its longitudinal axis.

Condylar Joint

A biaxial synovial joint featuring an oval, convex surface articulating with an opposing concave surface.

Saddle Joint

A biaxial synovial joint where both articulating bone surfaces have convex and concave regions resembling a saddle.

Ball-and-Socket Joint

A multiaxial synovial joint where the spherical head of one bone fits into a cup-shaped depression of another, permitting the greatest range of motion.

Gliding Motion

A simple motion where two opposing surfaces slide back-and-forth or side-to-side along plane joints with limited movement in any direction.

Flexion

An angular movement in an anterior-posterior plane that decreases the angle between articulating bones.

Extension

An angular movement in an anterior-posterior plane that increases the angle between articulating bones.

Hyperextension

The extension of a joint beyond $180^\circ$ of its anatomical position.

Lateral Flexion

Movement of the trunk laterally in the coronal plane, occurring between vertebrae in the cervical and lumbar regions.

Abduction

Lateral movement of a body part away from the body midline.

Adduction

Medial movement of a body part toward the body midline.

Circumduction

A continuous movement where the proximal end of an appendage remains relatively stationary while the distal end traces a circle, forming an imaginary cone shape.

Pronation

Medial rotation of the forearm so that the palm of the hand is directed posteriorly.

Supination

Lateral rotation of the forearm that directs the palm of the hand anteriorly.

Depression

Inferior movement of a body part, such as lowering the mandible when opening the mouth.

Elevation

Superior movement of a body part, such as raising the mandible when closing the mouth.

Dorsiflexion

Movement limited to the ankle joint where the dorsal surface of the foot moves toward the anterior leg.

Plantar Flexion

Movement at the ankle joint where the foot and toes flex downward, such as standing on tiptoes.

Inversion

A movement of the foot that turns the plantar surface (sole) medially.

Eversion

A movement of the foot that turns the plantar surface (sole) laterally.

Protraction

Anterior movement of a body part from the anatomic position, such as jutting the jaw forward.

Retraction

Posterior movement of a body part toward the anatomic position, such as pulling the jaw backward.

Opposition

A special movement where the thumb crosses the palm to touch the fingertips, enabling grasping.

Temporomandibular Joint (TMJ)

The only mobile joint between skull bones, formed by the head of the mandible and the temporal bone, containing an articular disc.

Sternoclavicular Joint

A stable saddle joint formed by the manubrium of the sternum and the sternal end of the clavicle.

Acromioclavicular Joint

A plane joint formed by the acromion of the scapula and the lateral end of the clavicle; tearing its ligaments causes a shoulder separation.

Glenohumeral Joint

A ball-and-socket joint formed by the head of the humerus and the glenoid cavity of the scapula, characterized by high mobility and low stability.

Glenoid Labrum

A fibrocartilaginous ring that lines the margin of the glenoid cavity to deepen the socket for the humeral head.

Rotator Cuff Muscles (SITS)

A group of four muscles—supraspinatus, infraspinatus, teres minor, and subscapularis—whose tendons encircle and provide primary stability to the glenohumeral joint.

Humeroulnar Joint

A hinge articulation of the elbow joint formed between the trochlea of the humerus and the trochlear notch of the ulna.

Humeroradial Joint

An articulation of the elbow joint formed between the capitulum of the humerus and the head of the radius.

Anular Ligament

A ligament encircling the head of the radius to keep it in place against the radial notch of the ulna.

Acetabular Labrum

A fibrocartilaginous ring that lines the margin of the acetabulum to deepen the socket for the head of the femur.

Ligament of the Head of Femur (Ligamentum Teres)

A small ligament connecting the acetabulum to the fovea of the femur head; provides no mechanical strength but contains an artery supplying the femur head.

Retinacular Fibers

Ligamentous fibers of the hip articular capsule that wrap around the femoral neck and contain retinacular arteries supplying blood to the femoral head and neck.

Tibiofemoral Joint

An articulation of the knee joint located between the condyles of the femur and the condyles of the tibia.

Patellofemoral Joint

An articulation of the knee joint located between the patella and the patellar surface of the femur.

Fibular Collateral Ligament (LCL)

An extracapsular ligament reinforcing the lateral surface of the knee from the femur to the fibula, preventing hyperadduction of the leg.

Tibial Collateral Ligament (MCL)

An extracapsular ligament reinforcing the medial surface of the knee from the femur to the tibia, preventing hyperabduction of the leg.

Menisci

C-shaped fibrocartilage pads on top of the tibial condyles that cushion articular surfaces and stabilize the knee joint medially and laterally.

Anterior Cruciate Ligament (ACL)

An intracapsular knee ligament running from the posterior femur to the anterior tibia; prevents hyperextension and anterior displacement of the tibia.

Posterior Cruciate Ligament (PCL)

An intracapsular knee ligament running from the anteroinferior femur to the posterior tibia; prevents hyperflexion and posterior displacement of the tibia.

Talocrural Joint

A highly modified hinge joint (ankle joint) comprising two articulations within one capsule that permits dorsiflexion and plantar flexion.

Sprain

The stretching or tearing of ligaments without fracture or dislocation, often resulting from foot overinversion.

Strain

An injury where muscles and tendons are majorly affected rather than ligaments.

Osteoarthritis

A progressive degenerative joint disease caused by wear and tear of articular cartilage, commonly associated with aging.

Rheumatoid Arthritis

An autoimmune disease where the body's immune system attacks its own joint tissues, damaging the articular cartilage.

Gouty Arthritis

A form of arthritis typically seen in middle-aged or older males resulting from increased levels of uric acid that crystallize in joint tissues.