Anatomy & Physiology: Bones and Joints

Comprehensive practice flashcards matching key anatomical vocabulary, structural and functional classifications, and physiological concepts from Chapter 7 (Skeletal System) and Chapter 8 (Joints).

Synarthrotic Joint

A functional classification of a joint denoting that it is immovable.

Amphiarthrotic Joint

A functional classification of a joint denoting that it is slightly movable.

Diarthrotic Joint

A functional classification of a joint denoting that it is freely movable.

Fibrous Joint

A structural classification of a joint where articulating bones make close contact and are fastened tightly together by dense connective tissue containing many collagen fibers.

Syndesmosis

A fibrous joint bound together by either a sheet (interosseous membrane) or a bundle (interosseous ligament) of dense connective tissue; classified functionally as amphiarthrotic.

Suture

A synarthrotic fibrous joint found exclusively between flat bones of the skull, united by a thin layer of dense connective tissue known as the sutural ligament.

Gomphosis

A synarthrotic fibrous joint formed by the insertion of a cone-shaped bony process into a bony socket, such as a tooth secured in the jawbone by the periodontal ligament.

Cartilaginous Joint

A structural classification of a joint where articulating bones are connected by hyaline cartilage or fibrocartilage, lacking a joint cavity.

Synchondrosis

A cartilaginous joint in which bands of hyaline cartilage unite bones; examples include the temporary epiphyseal plate and the permanent joint between the manubrium and the first rib.

Symphysis

An amphiarthrotic cartilaginous joint where articular surfaces covered with hyaline cartilage are attached to a broad, flat pad of fibrocartilage (e.g., the pubic symphysis and intervertebral discs).

Synovial Joint

A structurally complex diarthrotic joint bounded by an articular capsule consisting of an outer fibrous layer and an inner synovial membrane enclosing a fluid-filled joint cavity.

Bursa

A fluid-filled sac lined with synovial membrane that cushions movements and reduces friction where tendons cross over bony surfaces.

Meniscus

A fibrocartilage disc situated between articulating bone surfaces that acts to cushion the joint and distribute body weight evenly.

Ball-and-Socket Joint (Spheroidal Joint)

A multiaxial synovial joint consisting of a bone with a globular head that articulates with a cup-shaped cavity of another bone, allowing the widest range of motion including rotation.

Condylar Joint (Ellipsoidal Joint)

A biaxial synovial joint in which an ovoid condyle of one bone fits into an elliptical cavity of another, permitting movement in two planes without rotation.

Plane Joint (Gliding Joint)

A nonaxial synovial joint consisting of nearly flat or slightly curved articulating surfaces that permit sliding, back-and-forth, and twisting movements.

Hinge Joint

A uniaxial synovial joint in which the convex surface of one bone fits into the concave surface of another, permitting motion in a single plane (flexion and extension).

Pivot Joint (Trochoid Joint)

A uniaxial synovial joint in which a cylindrical surface of one bone rotates within a ring formed of bone and a ligament, permitting rotation only.

Saddle Joint (Sellar Joint)

A biaxial synovial joint in which both articulating bones possess concave and convex surfaces that complement each other, permitting movement in two planes.

Insertion

The more movable end or attachment of a skeletal muscle that is pulled toward the origin during muscle contraction.

Origin

The less movable or relatively fixed end or attachment of a skeletal muscle.

Abduction

Movement of a body part away from the midline of the body in the coronal plane.

Adduction

Movement of a body part toward the midline of the body in the coronal plane.

Flexion

A movement that decreases the angle between articulating parts at a joint.

Extension

A movement that increases the angle between articulating parts at a joint, straightening them.

Lateral Flexion

Bending of the head, neck, or trunk laterally to the side.

Dorsiflexion

Movement at the ankle that flexes the foot upward, bringing the superior surface closer to the shin.

Plantar Flexion

Movement at the ankle that extends the foot downward, pointing the toes away from the shin.

Circumduction

Movement of a body part such that its distal end describes a circle while the proximal end remains stationary.

Medial Rotation

Movement turning a bone or limb on its longitudinal axis toward the midline of the body.

Lateral Rotation

Movement turning a bone or limb on its longitudinal axis away from the midline of the body.

Supination

Rotation of the forearm so that the palm is turned upward or anteriorly into anatomical position.

Pronation

Rotation of the forearm so that the palm is turned downward or posteriorly.

Inversion

Movement of the foot turning the plantar surface (sole) medially.

Eversion

Movement of the foot turning the plantar surface (sole) laterally.

Protraction

Forward movement of a body part in the horizontal plane (e.g., jutting the jaw forward).

Retraction

Posterior movement of a protracted body part in the horizontal plane.

Elevation

Lifting or raising a body part superiorly, such as shrugging the shoulders.

Depression

Lowering or moving a body part inferiorly.

Aggrecan

The largest and most predominant proteoglycan in articular cartilage, containing side chains of chondroitin sulfate and keratan sulfate attached to a core protein via a link protein.

Rotator Cuff

A stabilizing musculotendinous sheath surrounding the shoulder joint formed by tendons blending with the fibrous layer of the joint capsule.

Long Bones

A class of bones characterized by elongated, narrow shafts with expanded ends (e.g., femur and humerus).

Short Bones

A class of bones that are roughly cubelike, having lengths approximately equal to their widths (e.g., carpals and tarsals).

Sesamoid Bones (Round Bones)

A special type of short bone embedded within tendons adjacent to a joint (e.g., the patella).

Flat Bones

Platelike bones characterized by broad surfaces that provide protection and extensive muscle attachment areas (e.g., ribs, scapulae, and skull flat bones).

Irregular Bones

Bones with complex, varied shapes that usually connect to several other bones (e.g., vertebrae and facial bones).

Epiphysis

The expanded portion located at each end of a long bone that articulates with an adjacent bone.

Diaphysis

The hollow, cylindrical shaft of a long bone situated between the proximal and distal epiphyses.

Metaphysis

The widening region of a long bone located between the diaphysis and the epiphysis.

Articular Cartilage

A layer of hyaline cartilage covering the articulating surface of an epiphysis that cushions bones and minimizes friction.

Periosteum

A tough, vascular covering of dense connective tissue that encloses the exterior of a bone except where articular cartilage is present.

Compact Bone (Cortical Bone)

Dense, solid osseous tissue composed of tightly packed osteons that forms the weight-bearing walls of the diaphysis and resists compression.

Spongy Bone (Cancellous Bone)

Porous osseous tissue consisting of branching bony plates called trabeculae, which reduces skeletal weight and houses marrow in the epiphyses.

Trabeculae

Branching bony plates and lattice-like struts that comprise spongy bone and align along lines of mechanical stress to distribute loads.

Medullary Cavity

The hollow, longitudinal chamber within the diaphysis of a long bone that is lined by endosteum and filled with bone marrow.

Endosteum

A thin cellular membrane containing bone-forming cells that lines the medullary cavity and the internal spaces of spongy bone.

Hematopoiesis

The physiological process of blood cell formation that takes place in the red bone marrow.

Red Bone Marrow

Specialized connective tissue located within spongy bone spaces and medullary cavities that produces erythrocytes, leukocytes, and blood platelets.

Yellow Bone Marrow

Adipose-rich tissue occupying adult bone cavities that functions primarily in fat storage and is inactive in blood cell production.

Hydroxyapatite

The primary inorganic mineral salt consisting of calcium phosphate ($Ca_{10}(PO_4)_6(OH)_2$) that makes up roughly $70\%$ of bone extracellular matrix and provides rigidity and hardness.

Osteocytes

Mature bone cells that occupy lacunae and maintain bone tissue structure and mineral homeostasis.

Lacunae

Small chambers or microscopic cavities embedded within the bone matrix that house osteocytes.

Canaliculi

Microscopic tubular channels traversing the bone matrix that interconnect lacunae, allowing osteocytes to transport nutrients and metabolic wastes via cellular processes.

Osteon (Haversian System)

The cylinder-shaped structural unit of compact bone comprising concentric lamellae surrounding a central canal.

Lamellae

Concentric rings or layers of calcified extracellular matrix arranged around a central canal within an osteon.

Central Canal (Haversian Canal)

A longitudinal channel running through the center of an osteon containing blood vessels and nerves that nourish osteocytes.

Perforating Canals (Volkmann's Canals)

Transverse channels that connect adjacent central canals, facilitating the passage of blood vessels and nerves from the periosteum to deeper bone tissue.

Osteoblasts

Bone-forming cells that synthesize, secrete, and deposit the extracellular organic bone matrix (osteoid).

Osteoclasts

Large, multinucleated cells derived from hematopoietic stem cells that secrete enzymes and acids to break down and resorb bone matrix.

Osteoid

The uncalcified, organic extracellular matrix secreted by osteoblasts consisting predominantly of collagen fibers prior to mineral precipitation.

Intramembranous Ossification

The mode of bone formation where bones develop directly from sheets of primitive embryonic connective tissue (mesenchyme), forming flat skull bones, clavicles, and the sternum.

Endochondral Ossification

The developmental process by which masses of pre-existing hyaline cartilage models break down and are progressively replaced by bone tissue.

Epiphyseal Plate

A band of hyaline cartilage located between the diaphysis and epiphysis in growing long bones that facilitates longitudinal growth.

Zone of Resting Cartilage

The layer of the epiphyseal plate closest to the epiphysis composed of inactive, non-dividing chondrocytes that anchor the plate to the epiphysis.

Zone of Proliferating Cartilage

The region of the epiphyseal plate characterized by columns of young chondrocytes undergoing active mitosis.

Zone of Hypertrophic Cartilage

The region of the epiphyseal plate where older chondrocytes enlarge, causing the plate to thicken and lengthen the bone, while the surrounding matrix calcifies and cells die.

Zone of Calcified Cartilage

The thin epiphyseal plate layer adjacent to the diaphysis composed of dead chondrocytes and calcified matrix that is invaded by osteoclasts and osteoblasts to form bone.

Bone Resorption

The breakdown and removal of bone matrix and minerals mediated by the enzymatic action of osteoclasts.

Bone Deposition

The synthesis and mineralization of new bone extracellular matrix mediated by osteoblasts.

Bone Remodeling

A continuous lifelong cycle of bone renewal comprising resorption by osteoclasts and deposition by osteoblasts, replacing $10\% - 20\%$ of the skeleton annually.

Parathyroid Hormone (PTH)

A peptide hormone secreted by the parathyroid glands in response to low blood calcium that stimulates osteoclasts to resorb bone and release $Ca^{2+}$ into circulation.

Calcitonin

A thyroid hormone released in response to high blood calcium levels that stimulates osteoblasts to deposit calcium into bone matrix.

Fragility Fracture

A fracture resulting from mechanical forces no greater than a fall from standing height, indicating impaired bone density or microarchitecture.

Osteopenia

A clinical state characterized by lower than normal bone mineral density that is not yet severe enough to be classified as osteoporosis.

Osteoporosis

A skeletal disorder characterized by severe bone demineralization and structural degradation, leaving spaces and canals that weaken bones and heighten fracture risk.

Simple Fracture (Closed Fracture)

A bone fracture in which the broken bone does not penetrate or tear through the surrounding skin or mucous membrane.

Compound Fracture (Open Fracture)

A fracture where the broken bone pierces the skin or mucous membrane, exposing internal tissues to the external environment.

Greenstick Fracture

An incomplete break occurring on the convex surface of a bent bone, common in children whose bones are flexible.

Fissured Fracture

An incomplete longitudinal fracture extending along the long axis of a bone.

Comminuted Fracture

A complete bone fracture that splinters and shatters the bone into multiple bone fragments.

Transverse Fracture

A complete fracture where the line of the break occurs at a right angle to the longitudinal axis of the bone.

Oblique Fracture

A complete fracture where the break extends across the bone at an angle other than a right angle to its longitudinal axis.

Spiral Fracture

A bone fracture caused by excessive rotational or twisting force applied along the shaft of a bone.

Cartilaginous Callus (Soft Callus)

A fibrocartilaginous repair mass formed by fibroblasts and chondrocytes that temporarily bridges the gap between fractured bone ends.

Bony Callus (Hard Callus)

A rigid mass of spongy bone tissue produced by osteoblasts that replaces the soft cartilaginous callus during fracture healing.

Bony Projections

Raised features, ridges, or processes on bone surfaces (e.g., tubercles, trochanters, and spines) that serve as attachment points for muscles, tendons, or ligaments.

Bony Depressions

Indentations, hollows, or shallow grooves on bones (e.g., fossae, foveae, and sulci) that accommodate adjacent structures, tendons, or articulating bones.

Bony Openings

Perforations, canals, or holes within bones (e.g., foramina and canals) that allow for the transit of nerves and blood vessels.