Anatomy of the Skeletal System

Introduction

• Dr. Dalia El-wafaey is an associate professor of Anatomy & Embryology at Sinai University.
• The presentation covers the skeletal system and joints.

Skeletal System (Bones)

• The skeleton is composed of the axial skeleton and appendicular skeleton.

Axial Skeleton

• The axial skeleton includes:
  • The skull and mandible
  • Vertebral column (33 vertebrae):
    • 7 cervical
    • 12 thoracic
    • 5 lumbar
    • 5 sacral vertebrae (fused to form the sacrum)
    • 3-4 coccygeal vertebrae (fused to form the coccyx)
  • Thoracic cage:
    • Sternum
    • 12 pairs of ribs

Appendicular Skeleton

• The appendicular skeleton consists of bones in the upper and lower limbs:
  • Lower limb:
    • Pelvic girdle (hip bone)
    • Femur (thigh bone)
    • Tibia and fibula (leg bones)
    • Bones of the foot (tarsals, metatarsals, phalanges)
  • Upper limb:
    • Pectoral girdle (scapula and clavicle)
    • Humerus (arm bone)
    • Radius and ulna (forearm bones)
    • Bones of the hand (carpus, metacarpus, phalanges)

Classification of Bones

• Long bones: Longer than they are wide, found in limbs (e.g., femur, humerus).
  • Shaft is called "Diaphysis".
  • Ends are called "Epiphysis".
• Short bones: Roughly cube-shaped, found in the wrist and ankle (e.g., carpals, tarsals).
• Flat bones: Thin, flat, and curved, found in the skull, ribs, and sternum (e.g., parietal bone, scapula).
• Irregular bones: Have complex shapes, found in the vertebrae and facial bones (e.g., vertebra, hip bone)
• Pneumatic bones: Contain air-filled cavities in the skull (e.g., some facial bones).
• Sesamoid bones: Small, round bones embedded within tendons, helping to reduce friction (e.g., patella).

Functions of the Skeletal System

• Support: Provides a framework for the body.
• Protection: Encloses vital organs (e.g., brain, spinal cord).
• Attachment: Provides points of attachment for muscles and ligaments.
• Movement: Acts as levers for movement at joints.
• Storage: Stores minerals like calcium and phosphorus.
• Blood cell formation: Bone marrow produces blood cells.

Joints

• Joints are the sites where bones meet.
• Various types of joints:
  • Fibrous joints: Connected by fibrous tissue, allowing little movement (e.g., sutures in the skull).
  • Cartilaginous joints: Connected by cartilage, allowing limited movement (e.g., intervertebral discs, epiphyseal plates).
  • Synovial joints: Most movable type, containing synovial fluid within a joint capsule, allowing a wide range of movements (e.g., knee, elbow).
    • Synovial joint types:
      • Plane joints (e.g., intercarpal)
      • Angular joint (e.g. elbow, knee)
      • Circumduction joints (e.g. hip, shoulder)
      • Hinge joints (e.g., elbow)
      • Pivot joints (e.g., radio-ulnar joints)
      • Condyloid joints (e.g.,wrist joint)
      • Ball and socket joints (e.g., shoulder, hip joints)
      • Saddle joints (e.g., carpometacarpal joint of the thumb)

Bursa

• Bursa are closed fibrous sacs lined internally with synovial membrane.
• They contain synovial fluid to reduce friction between tendons, bones, or skin.

This quiz focuses on the components of the skeletal system, including the axial and appendicular skeletons. It covers the various bones and structures such as the skull, vertebrae, pelvis, and limbs. Test your knowledge on human anatomy with this informative quiz!