The Skeletal System - Anatomy and Physiology

This unit explores the structure, function, and health of the skeletal system. It covers how bones provide support, movement, protection, blood cell production, and mineral storage while constantly remodeling to maintain homeostasis. You learn the major divisions of the skeleton (axial vs. appendicular), specific bones and their roles, types of joints and their movements, and common conditions such as fractures, scoliosis, arthritis, and osteoporosis. The unit also highlights medical advances like joint replacements and how lifestyle factors, stress, and nutrition influence bone health.

Bone Remodeling

Continuous balance of formation and resorption.

Ossification

Process of turning cartilage into bone.

Compact Bone

Dense outer bone layer providing strength.

Spongy Bone

Porous inner layer containing marrow spaces.

Periosteum

Membrane covering outer bone surface.

Endosteum

Inner lining of marrow cavity.

Diaphysis

Shaft of a long bone.

Epiphysis

Rounded end of a long bone.

Epiphyseal Plate

Growth region of cartilage in young bones.

Medullary Cavity

Central hollow space containing marrow.

Trabeculae

Lattice-like structures in spongy bone.

Canaliculi

Microscopic channels connecting bone cells.

Osteon

Structural unit of compact bone.

Haversian Canal

Central channel for blood vessels in osteons.

Volkmann’s Canal

Perpendicular passage linking Haversian canals.

Lacunae

Small cavities housing osteocytes.

Osteocyte

Mature bone cell maintaining tissue.

Chondrocyte

Cartilage cell.

Collagen

Protein giving bone tensile strength.

Hydroxyapatite

Mineral crystals providing bone hardness.

Flat Bone

Bone type protecting organs (e.g., skull).

Irregular Bone

Complex shape, e.g., vertebra.

Short Bone

Cube-like bone for stability, e.g., carpals.

Sesamoid Bone

Small bone embedded in tendon, e.g., patella.

Long Bone

Elongated bone aiding movement, e.g., femur.

Skull Foramina

Openings for nerves and vessels.

Mandible

Only movable skull bone.

Maxilla

Upper jaw bone.

Suture Lines

Junctions of immovable skull plates.

Cranial Bones

Bones enclosing the brain.

Facial Bones

Bones forming front of skull.

Cervical Vertebrae

Upper 7 bones of spine.

Thoracic Vertebrae

12 vertebrae supporting ribs.

Lumbar Vertebrae

5 large lower back bones.

Sacrum

Fused triangular bone of pelvis.

Coccyx

Vestigial tailbone at spine base.

True Ribs

First 7 pairs attached directly to sternum.

False Ribs

Next 3 pairs attached indirectly.

Floating Ribs

Last 2 pairs with no anterior attachment.

Manubrium

Upper portion of sternum.

Sternum

Breastbone protecting thoracic cavity.

Clavicle

Collarbone connecting sternum to scapula.

Scapula

Shoulder blade, triangular bone.

Humerus

Upper arm bone.

Radius

Lateral forearm bone (thumb side).

Ulna

Medial forearm bone (pinky side).

Carpals

Small wrist bones.

Metacarpals

Bones of the hand.

Phalanges

Finger and toe bones.

Pelvic Girdle

Structure connecting legs to spine.

Ilium

Large flared bone of pelvis.

Ischium

Lower posterior pelvic bone.

Pubis

Anterior pelvic bone joining at pubic symphysis.

Femur

Longest and strongest bone in body.

Patella

Knee cap, sesamoid bone.

Tibia

Medial, weight-bearing shin bone.

Fibula

Lateral, thinner lower leg bone.

Tarsals

Ankle bones.

Metatarsals

Bones of the foot.

Cartilage

Flexible connective tissue at joints.

Synovial Cavity

Space within synovial joint.

Meniscus

Cartilage pad cushioning knee joint.

Bursa

Fluid-filled sac reducing friction at joints.

Sprain

Ligament injury.

Strain

Muscle or tendon injury.

Dislocation

Bone forced out of joint.

Kyphosis

Excessive thoracic curve.

Lordosis

Exaggerated lumbar curve.

Osteoporosis

Condition of weakened, porous bones.

Bone Density

Measurement of mineral content per area.

Vitamin D

Nutrient essential for calcium absorption.

Parathyroid Hormone

Hormone that increases blood calcium by stimulating osteoclasts.

Calcitonin

Hormone lowering blood calcium by promoting storage in bone.

Hip Replacement

Prosthetic substitution for damaged femoral joint.

Ceramics in Implants

Materials resisting wear in modern prostheses.

Robotic Surgery

Technology improving precision in joint replacements.