Bone Development, Joint Classifications, and Skeletal Pathology

Comprehensive vocabulary flashcards reviewing bone growth, remodeling, fracture repair, joint structures, biomechanical levers, and skeletal pathologies.

Intramembranous Ossification

The embryonic bone formation process that occurs within fibrous membranes to form the flat bones of the skull.

Endochondral Ossification

The bone formation process where an early hyaline cartilage model is replaced by bone, developing primary and secondary ossification centers and marrow cavities.

Epiphyseal Plate

A region of hyaline cartilage between the epiphysis and diaphysis of a developing long bone responsible for lengthwise bone growth.

Wolff's Law

The physiological principle stating that healthy bone adapts and remodels according to the mechanical stresses applied to it.

Osteoclasts

Bone cells that resorb and break down old bone matrix, liberating $\text{Ca}^{2+}$ into the bloodstream.

Osteoblasts

Bone-building cells that use $\text{Ca}^{2+}$ to synthesize and mineralize new bone matrix during growth and remodeling.

Bisphosphonates

A class of pharmaceutical drugs, including Fosamax and Boniva, that inhibit osteoclast activity to reduce bone resorption in conditions like osteoporosis.

Hematoma Formation

The initial step of bone fracture repair where bleeding occurs and a localized blood clot forms around the broken bone.

Granulation Tissue Formation

The second stage of fracture healing marked by angiogenesis and the migration of macrophages, osteoclasts, osteogenic cells, and fibroblasts to the fracture site.

Callus Formation

The third stage of fracture healing where fibroblasts deposit collagen and chondroblasts deposit fibrocartilage to create a temporary bridge and splint across the injury site.

Greenstick Fracture

An incomplete fracture in which one side of the bone breaks while the other side bends, characteristically occurring in children.

Comminuted Fracture

A bone fracture where the bone shatters or splinters into three or more pieces.

Oblique Fracture

A fracture in which the break line runs diagonally across the shaft of a long bone at an angle.

Spiral Fracture

A fracture resulting from severe torsional or twisting forces that produce a helical break pattern along the bone shaft.

Parathyroid Hormone (PTH)

A hormone secreted by the parathyroid glands in response to low blood $\text{Ca}^{2+}$ levels that stimulates osteoclasts to break down bone and release calcium into the blood.

Calcitonin

A hormone produced by C cells of the thyroid gland in response to high blood $\text{Ca}^{2+}$ levels that stimulates the deposition of calcium salts into bone.

Synarthrosis

A functional classification for an immovable joint.

Amphiarthrosis

A functional classification for a slightly movable joint.

Diarthrosis

A functional classification for a freely movable joint.

Suture

A fibrous synarthrotic joint found only between adjacent bones of the skull, holding them together with dense fibrous connective tissue.

Syndesmosis

A fibrous joint where bones are joined by ligaments or a broad sheet of fibrous tissue known as an interosseous membrane (e.g., tibiofibular joint).

Gomphosis

A peg-in-socket fibrous joint where the periodontal ligament anchors the root of a tooth into its alveolar socket.

Synchondrosis

A cartilaginous joint in which the connecting material between bones is hyaline cartilage, such as the epiphyseal plate or the joint between the first rib and the sternum.

Symphysis

A cartilaginous joint where the broad ends of articulating bones are joined by fibrocartilage, such as the intervertebral discs and the pubic symphysis.

Herniated Disc

A pathology where the gelatinous nucleus pulposus bulges or ruptures through the outer fibrous disc annulus, frequently causing nerve root compression.

Synovial Joint

A diarthrotic joint characterized by a synovial cavity enclosed by an articular capsule, lined by a synovial membrane, cushioned by articular cartilage, and lubricated by synovial fluid.

Bursa

A flattened, synovial fluid-filled fibrous sac that functions to decrease friction between bones, tendons, muscles, or skin during joint movements.

Tendon Sheath

A specialized tubular elongated bursa that encases a tendon to reduce friction as it moves through tight osteofibrous channels.

Class 1 Lever

A lever system where the pivot (fulcrum) sits between the effort force and the load, represented in the human body by posterior neck muscles balancing the head.

Class 2 Lever

A lever system where the load is positioned between the pivot (fulcrum) and the effort force, represented in the body by raising the body up onto the toes.

Class 3 Lever

A lever system where the effort force is applied between the pivot (fulcrum) and the load, represented in the body by the biceps brachii muscle flexing the elbow.

Planar Joint

A synovial joint with flat articulating surfaces that permits gliding, nonaxial movements back and forth and side to side (e.g., clavicle articulating with the manubrium).

Hinge Joint

A uniaxial synovial joint in which the cylindrical surface of one bone fits into the concave depression of another, permitting flexion and extension in a single plane (e.g., elbow joint).

Pivot Joint

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

Condyloid Joint

A biaxial synovial joint where an oval convex surface articulates with an oval concave depression, allowing flexion, extension, abduction, and adduction (e.g., radius articulating with the scaphoid).

Ball-and-Socket Joint

A multiaxial synovial joint where a spherical head articulates with a cuplike socket, permitting movements across all axes including circumduction and rotation (e.g., glenohumeral joint).

Saddle Joint

A biaxial synovial joint where both bones possess complementary concave and convex surfaces, characteristic of the joint between the trapezium and metacarpal of the thumb.

Achondroplastic Dwarfism

A skeletal condition where long bones stop growing during childhood due to a failure of cartilage growth in the metaphysis, resulting in shortened limbs with a normal-sized torso.

Pituitary Dwarfism

A condition resulting from a deficiency of growth hormone that leads to short stature while maintaining proportional body structures.

Rickets

A pediatric metabolic bone disorder caused by insufficient vitamin D or mineral deficiency, resulting in inadequately calcified, soft bones and bowed legs.

Osteomalacia

The adult equivalent of rickets caused by inadequate mineralization of bone matrix, leading to progressive softening and weakness of the skeleton.

Kyphosis

An exaggerated posterior thoracic curvature of the vertebral column, commonly presenting as a hunchback appearance.

Scoliosis

An abnormal lateral curvature and rotational deformity of the spine.

Lordosis

An abnormal exaggerated anterior curvature of the lumbar region of the spine, also referred to as swayback.

Osteoarthritis

A noninflammatory, degenerative joint disease occurring as part of aging where cartilage degradation outpaces replacement, often leading to bone spur formation.

Rheumatoid Arthritis

A chronic autoimmune inflammatory joint disorder affecting roughly $3\times$ more women than men, marked by symmetric inflammation and potential ankylosis of the joints.

Gouty Arthritis

An inflammatory condition triggered by the deposition of sodium urate salt crystals (derived from uric acid during purine metabolism) in articular cartilage and surrounding soft tissues.

Tibiofemoral Joint

The bicondylar hinge joint between the femur and tibia that forms the main articulation of the knee, stabilized by collateral ligaments, cruciate ligaments, and menisci.

Sprain

The overstretching or tearing of joint-associated ligaments and connective tissues, which heals slowly and is managed using the RICE protocol.

Strain

The overstretching or tearing of muscle fibers or tendons (a 'pulled muscle') that leads to inflammation (myositis) and is managed with the RICE protocol.

Auditory Ossicles

The three tiny bones in the middle ear—the malleus, incus, and stapes—that transmit mechanical sound vibrations from the tympanic membrane to the inner ear.