Skeletal System

Major Bones of the Body

  • Skull: Protects the brain; includes the cranium and facial bones.

  • Cranium: The skullcap protecting the brain.

  • Mandible: The lower jawbone.

  • Vertebrae: Comprises the spine; categorized into cervical, thoracic, lumbar, sacral, and coccygeal regions.

  • Sacrum: The triangular bone at the base of the spine, formed from fused vertebrae.

  • Coccyx: The tailbone, located at the end of the vertebral column.

  • Ribs: Protects the thoracic cavity; includes true ribs, false ribs, and floating ribs.

  • Sternum: Located in the center of the chest, connects to the ribs.

  • Humerus: Upper arm bone; extends from shoulder to elbow.

  • Radius: Forearm bone located on the same side as the thumb.

  • Ulna: Forearm bone located on the side opposite the thumb.

  • Femur: Thigh bone; the longest bone in the body.

  • Patella: Knee cap; protects the knee joint.

  • Tibia: Shin bone; larger bone of the lower leg.

  • Fibula: Smaller bone of the lower leg, next to the tibia.

  • Pelvis: Supports the spinal column and protects organs in the lower abdomen.

  • Ilium: The largest bone of the pelvis.

  • Clavicle: The collarbone, connecting the arm to the body.

  • Carpals: The eight bones of the wrist.

Six Types of Joints

  1. Ball and Socket: (e.g., shoulder, hip) allows rotation and movement in multiple directions.

  2. Hinge: (e.g., elbow, knee) permits flexion and extension.

  3. Pivot: (e.g., neck) allows rotational movement.

  4. Saddle: (e.g., thumb) allows grasping and rotation.

  5. Plane: (e.g., intercarpal joints) allows sliding movements.

  6. Condyloid: (e.g., wrist) permits movement in two planes.

Types of Fractures

  • Greenstick: An incomplete fracture; bends like a green twig.

  • Transverse: A horizontal fracture across the bone.

  • Comminuted: The bone shatters into several pieces.

  • Spiral: A fracture that twists around the bone.

  • Stress Fracture: A hairline fracture from overuse or repetitive force.

  • Oblique Fracture: A diagonal fracture across the bone.

  • Avulsion Fracture: A fracture occurring when a fragment of bone is separated by the pull of a tendon or ligament.

Parts of a Long Bone

  • Diaphysis: The long shaft of the bone.

  • Epiphysis: The ends of the bone, often covered with articular cartilage.

  • Medullary (Marrow) Cavity: The central cavity where marrow is stored.

  • Periosteum: A fibrous membrane covering the bone surface.

  • Compact Bone: Dense and forms the outer layer of the bone.

  • Spongy Bone: Lighter, less dense bone found at the ends of long bones and in the interior of others.

  • Epiphyseal Line: The remnant of the growth plate in adults.

  • Articular Cartilage: Smooth tissue covering the ends of bones at joints.

Five Functions of the Skeletal System

  1. Support: Provides structure and shape to the body.

  2. Protection: Shields vital organs (e.g., brain, heart).

  3. Movement: Serves as levers for muscles to create movement.

  4. Mineral Storage: Stores minerals like calcium and phosphorus.

  5. Blood Cell Production: Produces blood cells in the bone marrow.

Five Shapes of Bone

  1. Long Bones: Longer than they are wide (e.g., femur).

  2. Short Bones: As wide as they are long (e.g., carpals).

  3. Flat Bones: Thin and flat (e.g., skull, ribs).

  4. Irregular Bones: Complicated shapes (e.g., vertebrae).

  5. Sesamoid Bones: Embedded in tendons (e.g., patella).

Landmarks of Bone

  • Trochanter: A large, blunt, irregularly shaped process (e.g., femur).

  • Crest: A narrow ridge of bone (e.g., iliac crest).

  • Foramen: An opening through a bone (e.g., optic foramen).

  • Fossa: A shallow basin-like depression in a bone (e.g., glenoid fossa).

  • Process: A projection or bump on a bone (e.g., spinous process of the vertebra).