Skeletal System and Bone Anatomy

Comprehensive vocabulary flashcards covering the skeletal system, bone anatomy, bone repair and remodeling, axial skeleton divisions, joint classifications, and skeletal pathology.

Epidermis

The outermost skin layer in which hair, nails, and glands originate.

Dermal blood vessels

Vessels that provide oxygen to the skin and function as a temperature regulation device by dilating and constricting.

Free nerve endings

Structures located in the dermis that provide sensation and warn the skin and body of danger.

Long bones

Bones that are characteristically longer than they are wide, such as the femur.

Short bones

Bones that are cube-shaped, having approximately equal length and width.

Flat bones

Plate-like bones that possess broad surfaces.

Irregular bones

Bones that exhibit complex, varied shapes.

Round bones

Bones that are circular in shape.

Periosteum

A tough, connective tissue covering enclosing the outer surface of a bone.

Epiphysis

The expanded portion situated at either end of a long bone.

Epiphyseal plate

A thin layer of hyaline cartilage located between the shaft (diaphysis) and the end (epiphysis) of a long bone where longitudinal growth occurs.

Diaphysis

The shaft portion of a long bone located between the two epiphyses.

Medullary cavity

The central hollow portion inside the diaphysis that contains yellow marrow.

Articular cartilage

A layer of hyaline cartilage capping the bone ends where they articulate with other bones.

Endosteum

The membrane lining the inner medullary cavity and the spaces within spongy bone.

Osteons

The structural and functional units of compact bone made of concentric matrix rings called lamellae.

Lacunae

Tiny chambers within the bone matrix that house osteocytes.

Trabeculae

Bony bars and plates found in spongy bone oriented along lines of stress to provide structural strength.

Osteoprogenitor cells

Unspecialized stem cells that are partially programmed to differentiate into bone cells.

Osteoblasts

Bone-forming cells that take up calcium from the blood to build and deposit new bone matrix.

Osteocytes

Mature bone cells situated within lacunae that maintain daily cellular activities of bone tissue.

Osteoclasts

Cells that resorb and break down bone matrix, releasing calcium into the blood.

Intramembranous ossification

The bone formation process where bone develops directly between two sheets of fibrous connective tissue, forming cranial bones.

Endochondral ossification

The process of bone development during which a hyaline cartilage model is gradually replaced by bone tissue.

Appositional growth

The mechanism by which bones increase in overall diameter and thickness.

Bone remodeling hormones

The three critical chemical messengers that regulate bone development and calcium balance: Parathyroid hormone, Calcitonin, and Growth hormone.

Stages of bone repair

The four sequential stages involved in healing a fracture: hematoma, fibrocartilaginous callus, bony callus, and remodeling.

Complete fracture

A fracture in which the bone is completely broken all the way through.

Incomplete (greenstick) fracture

A bone fracture where the break is partial and the bone remains continuous without separating into two parts.

Simple fracture

A closed fracture where the broken ends of the bone do not pierce through the skin.

Compound fracture

An open fracture where the broken fragments of bone pierce through the surrounding skin.

Impacted fracture

A fracture where the broken bone ends are forcefully driven and wedged directly into one another.

Spiral fracture

A ragged fracture resulting from severe rotational or twisting stresses applied across the bone.

Closed reduction

The process of re-aligning fractured bone fragments back into place manually without surgical intervention.

Open reduction

The surgical repair and fixation of broken bone fragments utilizing hardware like pins, screws, or plates.

Axial skeleton

The midline division of the skeletal system comprising the skull, hyoid bone, vertebral column, thoracic cage, and middle ear bones.

Paranasal sinuses

Mucous membrane-lined air chambers within the skull that reduce skull weight and amplify voice resonance; includes maxillary, frontal, sphenoidal, and ethmoidal sinuses.

Cranium

The 8-bone structure protecting the brain, consisting of the frontal, two parietal, occipital, two temporal, sphenoid, and ethmoid bones.

Coronal suture

The immovable fibrous joint uniting the frontal bone with the two parietal bones.

Lambdoidal suture

The immovable fibrous joint uniting the parietal bones with the occipital bone.

Squamosal suture

The immovable joint that joins each parietal bone to its adjacent temporal bone.

Sagittal suture

The midline immovable joint connecting the two parietal bones.

Vertebral column

The segmented skeletal column consisting of 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 3 to 5 coccygeal vertebrae.

Spinal adaptations for bipedalism

Evolutionary modifications facilitating upright posture including an S-shaped curvature, an enlarged vertebral size, and a centrally positioned foramen magnum.

Synarthrosis

A functional classification for an immovable joint, such as cranial sutures.

Amphiarthrosis

A functional classification for a slightly moveable joint, such as intervertebral discs.

Diarthrosis

A functional classification for a freely moveable joint, such as the knee or shoulder.

Synovial joint

A freely moveable joint enclosed by a joint capsule and synovial membrane containing synovial fluid and articulating cartilage surfaces.

Types of synovial joints

The six structural categories of diarthrotic joints: saddle, ball-and-socket, pivot, hinge, gliding, and condyloid.

Abduction

An angular movement that carries a limb away from the midline of the body.

Adduction

An angular movement that draws a limb back toward the midline of the body.

Synovial joint movements

The full spectrum of joint motions categorized as angular movements, circular movements, and special movements.

Osteoarthritis

A non-inflammatory degenerative joint disorder marked by the progressive breakdown and loss of articular cartilage.

Rheumatoid arthritis

A chronic joint disease characterized by systemic inflammation of the synovial membrane.

Gout

A metabolic form of acute arthritis precipitated by the accumulation and crystal deposition of excess uric acid.