Bone Characteristics

Long Bone Anatomy

  • Diaphysis (Shaft): Long middle part. Made of strong compact bone. Houses the cavity where blood cells are produced. Covered by the periosteum (membrane containing cells that build and break down bone for remodeling).

  • Epiphysis (Ends): Rounded ends of the bone. Made of spongy bone (makes it lighter). Covered in smooth hyaline cartilage to protect joints from wear and tear.

4 Bone Categories

Type

Characteristics

Examples

Long Bones

Longer than wide; slightly curved for strength; work as levers.

Femur (thigh), Humerus (arm), Tibia, Radius

Short Bones

Cube-shaped; equal length and width; spongy bone inside.

Carpals (wrist), Tarsals (ankle)

Flat Bones

Thin and flat; protect organs and provide muscle attachment points.

Ribs, Scapula (shoulder blade)

Irregular Bones

Complex shapes with channels and projections for nerve pathways.

Vertebrae (spine)

Bonus Note: Sesamoid bones are small bones formed inside tendons crossing joints (e.g., the patella / knee cap).

Axial vs. Appendicular Skeleton

  • Axial Skeleton (80 bones): Torso/core support. Includes skull, spine, sternum, and ribs.

  • Appendicular Skeleton (126 bones): Limbs and girdles (arms, legs, pelvis, shoulders). Its main job is movement.

Extra Context: Bone Marrow & Transplants

  • Role of Bone Marrow: Spongy tissue inside bones that produces red and white blood cells.

  • Transplants: A lifesaving procedure for patients with blood cancers or disorders (like MDS).

  • Key Components for Patients:

    • Donors: Can be matched family members or unrelated volunteers registered through donor banks (like Be the Match).

    • Caregivers: Essential for 24/7 care during long recovery periods involving immune isolation.