types of bone cells

Osteogenic Cells

Stem cells that differentiate into osteoblasts.

Osteoblasts

Bone-building cells that form new bone matrix through ossification and secrete lamellae.

Osteocytes

Mature bone cells that maintain the bone matrix and reside in lacunae.

Osteoclasts

Bone-destroying cells that break down bone matrix to remodel bone and release calcium into the blood.

Lamellae

Concentric rings of compact bone created by osteoblasts.

Central Canal

Surrounded by lamellae; contains blood vessels to nourish bone tissue.

Osteon (Haversian System)

The functional unit of compact bone, consisting of the central canal, lamellae, and osteocytes within lacunae.

Synarthroses

Immovable joints providing stability, such as skull sutures.

Amphiarthroses

Slightly movable joints that allow limited movement, like the pubic symphysis.

Diarthroses

Freely movable joints, primarily synovial joints, such as the knee and elbow.

Articular (Hyaline) Cartilage

Covers bone ends, reducing friction in synovial joints.

Synovial Membrane

Secretes synovial fluid for lubrication in the joint cavity.

Fibrous Articular Capsule

Encloses the joint.

Ligament

Connects bone to bone, stabilizing the joint.

Tendon

Connects muscle to bone, aiding movement.

Bursa

Fluid-filled sac that reduces friction.

Nonaxial Joints

Limited gliding movement, such as carpals in the wrist.

Uniaxial Joints

Movement in one plane; includes hinge joints (e.g., elbow and knee) and pivot joints.

Biaxial Joints

Movement in two planes; example includes the condyloid joint (wrist joint).

Multiaxial Joints

Movement in multiple planes; example includes ball and socket joints (shoulder and hip).

Calcitonin

Hormone released by the thyroid gland that lowers blood calcium levels by stimulating osteoblasts.

Parathyroid Hormone (PTH)

Hormone released by the parathyroid glands that raises blood calcium levels by activating osteoclasts.