Skeletal System Vocab and Identification

5 Functions of Skeletal System

-Support

-Protection

-Movement/Leverage

-Mineral Storage

-hemopoeisis

Osseous Tissue

Another name for bone tissue; a specialized connective tissue.

Long Bones

Bones that are longer than they are wide, with a shaft and two expanded ends (examples: femur, humerus).

Short Bones

Cube-shaped Bones

Flat Bones

Thin bones with large surface areas for muscle attachment and organ protection (examples: skull bones, ribs).

Irregular Bones

Bones with complex shapes that don't fit other categories (example: vertebrae).

Diaphysis

The hollow, tubular shaft of a long bone located between the proximal and distal ends.

Diaphysis

Epiphysis

The expanded end regions of a long bone, filled with spongy bone (plural: epiphyses).

Distal Epiphysis

Metaphysis

The region where the diaphysis meets the epiphysis; contains the growth plate in children.

Metaphysis

Medullary Cavity

The hollow space within the diaphysis, filled with yellow bone marrow in adults.

Medullary Cavity

Articular Cartilage

Smooth hyaline cartilage covering the ends of bones at joint surfaces.

Articular Cartilage

Periosteum

The tough, fibrous outer membrane covering bones, containing blood vessels and nerves.

Periosteum

Periosteum

Endosteum

The delicate membrane lining the inner surface of the medullary cavity.

Endosteum

Compact Bone

Dense bone tissue organized into osteons (Haversian systems); forms the outer layer of bones.

Compact Bone

Spongy Bone

Lightweight bone tissue organized into trabeculae; also called cancellous bone.

Spongy Bone

Trabeculae

The interconnected plates and bars that form the meshwork of spongy bone.

Trabeculae

Osteoid

The organic component of bone matrix consisting of collagen fibers and ground substance.

Collagen

Protein fibers in bone matrix that provide tensile strength and flexibility.

Hydroxyapatite

The crystalline form of calcium phosphate [Ca₁₀(PO₄)₆(OH)₂] that provides bone hardness.

Inorganic Material of Bones

Hydroxyapatite

Ground Substance

The non-fibrous component of bone matrix containing glycosaminoglycans and proteins.

Osteoblasts

Bone-building cells that secrete osteoid and facilitate mineralization.

Osteocytes

Mature bone cells trapped in lacunae that maintain the bone matrix and detect mechanical stress.

Osteoclasts

Large, multinucleated cells that break down and resorb bone tissue.

Osteoprogenitor Cells

Stem cells that differentiate into osteoblasts; also called osteogenic cells.

Osteon

The functional unit of compact bone; also called Haversian system.

Osteon

Haversian System

Another name for osteon; the circular structural unit of compact bone.

Haversian Canal

Central Canal

The channel in the center of an osteon containing blood vessels and nerves; also called Haversian canal.

Volkmann Canal

Lacunae

Small spaces in bone matrix that house osteocytes (singular: lacuna).

Red Bone Marrow

Hemopoietic tissue that produces blood cells; found in spongy bone of axial skeleton and proximal long bones.

Red Bone Marrow

Yellow Bone Marrow

Adipose tissue that stores fat; found in the medullary cavity of adult long bones.

Yellow Bone Marrow

Epiphyseal Plate

The cartilaginous growth plate in children and adolescents that allows longitudinal bone growth.

Epiphyseal Plate

Growth Plate

Another name for epiphyseal plate.

Epiphyseal Line

The remnant of the epiphyseal plate in adults after growth has ceased.

Epiphyseal Line

Endochondral Ossification

The process of bone formation from a cartilage template.

Epiphyseal Closure

The process when the growth plate stops functioning and becomes the epiphyseal line.

Bone Remodeling

The continuous process of bone breakdown and formation throughout life.

Osteolysis

The breakdown of bone tissue by osteoclasts.

Without Collagen

Growth Hormone

Hormone that stimulates bone growth and epiphyseal plate activity.

Without Minerals

Parathyroid Hormone (PTH)

Hormone that increases blood calcium by stimulating osteoclast activity.

Calcitonin

Hormone that decreases blood calcium by inhibiting osteoclast activity.

Estrogen

Female hormone that helps maintain bone density; deficiency leads to bone loss.

Testosterone

Male hormone that helps maintain bone density.

Vitamin D

Essential vitamin for calcium absorption in the intestines; deficiency leads to weak bones.

Vitamin C

Required for collagen synthesis; deficiency impairs bone formation.

Vitamin A

Stimulates osteoblast activity; both deficiency and excess can harm bones.

Achondroplasia

Genetic disorder affecting the FGFR3 gene, causing impaired epiphyseal plate growth and short stature.

Osteoporosis

"Porous bone" disease characterized by decreased bone density and increased fracture risk.

Osteopenia

Mild bone loss that may progress to osteoporosis.

Bone Mineral Density

A measure of the amount of mineral content in bone tissue.

DEXA Scan

Dual-energy X-ray absorptiometry; a type of bone density scan.

Fetal Skeleton

The developing skeleton in utero, primarily composed of cartilage.

Cartilage Template

The cartilaginous model that serves as the framework for bone development.

Bone Age

A measure of skeletal maturity based on epiphyseal plate development.

Axial Skeleton

The bones of the skull, vertebral column, and rib cage.

Appendicular Skeleton

The bones of the arms, legs, and their attachments to the axial skeleton.