Human Anatomy: Ribcage and Skull

Ribcage

• Also known as the thoracic cage
• Protects organs in the chest cavity, including the heart, lungs, and major blood vessels
• Composed of:
  • 24 ribs (12 pairs)
  • Sternum (breastbone)
  • 12 thoracic vertebrae
• Ribs are divided into:
  • True ribs (1-7): attached directly to the sternum
  • False ribs (8-10): attached to the 7th rib
  • Floating ribs (11-12): not attached to the sternum or any other ribs

Skull

• Protects the brain and sensory organs (eyes, ears, nose, mouth)
• Composed of 22 bones that fuse together during childhood and adolescence
• Divided into:
  • Cranium: upper part of the skull that encloses the brain
  • Face bones: 14 bones that form the upper and lower jaws, nose, and orbit (eye socket)
• Features:
  • Foramen magnum: opening at the base of the skull where the spinal cord passes through
  • Nasal conchae: thin, curved bones that project into the nasal cavity
  • Zygomatic arch: cheekbone that forms the prominence of the cheek

Vertebrae

• 33 vertebrae in the human spine, divided into:
  • 7 cervical vertebrae (neck)
  • 12 thoracic vertebrae (chest)
  • 5 lumbar vertebrae (lower back)
  • 5 sacral vertebrae (fused to form the sacrum)
  • 4 coccygeal vertebrae (fused to form the coccyx)
• Each vertebra has:
  • Body: main portion of the vertebra
  • Vertebral arch: forms the posterior (rear) part of the vertebra
  • Spinous process: bony projection that extends from the vertebral arch
  • Transverse processes: bony projections that extend from the vertebral arch
• Intervertebral discs: soft, spongy tissue that separates adjacent vertebrae and acts as a shock absorber

Ribcage

• Thoracic cage protects heart, lungs, and major blood vessels in the chest cavity
• Composed of 24 ribs (12 pairs), sternum, and 12 thoracic vertebrae
• Ribs classified into true ribs (1-7), false ribs (8-10), and floating ribs (11-12) based on their attachment to the sternum

Skull

• Protects brain and sensory organs, including eyes, ears, nose, and mouth
• Composed of 22 bones that fuse during childhood and adolescence
• Divided into cranium (upper part) and face bones (14 bones)
• Features include foramen magnum, nasal conchae, and zygomatic arch

Vertebrae

• 33 vertebrae in the human spine, divided into cervical, thoracic, lumbar, sacral, and coccygeal regions
• Each vertebra has a body, vertebral arch, spinous process, and transverse processes
• Intervertebral discs act as shock absorbers, separating adjacent vertebrae