Bones of the Skull

Bones of the Skull

• The skull is a complex structure composed of 22 individual bones, joined together by sutures.
• These bones are crucial for protecting the brain, supporting facial structures, and providing attachment points for muscles.
• The skull can be broadly divided into two main regions: the cranium (braincase) and the facial skeleton.

Cranium Bones

• The cranium encloses and protects the brain.
• It comprises eight bones:
  • Frontal bone: Forms the forehead and part of the eye sockets.
  • Parietal bones (two): Form the top and sides of the skull.
  • Temporal bones (two): Located beneath the parietal bones, they house the inner ear structures and parts of the middle ear.
  • Occipital bone: Forms the back and base of the skull, connecting with the spinal column.
  • Sphenoid bone: A complex, butterfly-shaped bone situated at the base of the skull, crucial for supporting other skull bones and housing parts of the eye and temporal bones.
  • Ethmoid bone: A light, irregularly-shaped bone that contributes to the orbital walls, nasal cavity, and cranial floor.

Facial Skeleton Bones

• The facial skeleton provides the framework for the face, containing important structures like the eyes, nose, and mouth.
• It consists of 14 individual bones, including:
  • Maxillae (two): Forms the upper jaw, including the upper teeth sockets.
  • Palatine bones (two): Forms part of the hard palate and the eye socket walls.
  • Zygomatic bones (two): Form the cheekbones.
  • Nasal bones (two): Form the bridge of the nose.
  • Lacrimal bones (two): Small bones in the medial wall of the eye socket, associated with the tear ducts.
  • Inferior nasal conchae (two): Thin, scroll-shaped bones within the nasal cavity, influencing airflow.
  • Vomer: A thin, roughly rectangular bone forming part of the nasal septum.
  • Mandible: The only movable bone of the skull, forming the lower jaw.

Sutures

• Sutures are the immobile fibrous joints connecting the cranial bones.
• They provide strength and stability to the skull.
• Key sutures include the coronal suture (joins frontal and parietal bones), sagittal suture (between the two parietal bones), lambdoid suture (between parietal and occipital bones), and squamous sutures (between parietal and temporal bones).

Function of Skull Structure

• Protection of the brain: The cranium's intricate structure forms a strong, protective enclosure for the fragile brain tissue, shielding it from physical trauma.
• Support for the face: Facial bones provide a structural framework for the eyes, nose, mouth, and other facial features, enabling their proper functionality.
• Attachment for muscles: The skull bones offer attachment points for numerous muscles involved in facial expressions, jaw movement, and head movements, enhancing movement control.
• Sense organ housing: Several skull bones contain openings and cavities that accommodate sense organs like the eyes, ears, and nasal cavity.
• Formation of the nasal cavity and oral cavity: Skull bones work together to form the cavities for the nose and mouth.
• Protection of sense organs: The skull bones protect vital sense organs such as the eyes, ears, and openings for the nasal cavity and mouth.

Skull Development

• Skull development is a complex process that begins prenatally and is completed in childhood.
• The bones of the skull initially form as intramembranous bones within membranes.
• The sutures play a crucial role in the process, allowing for skull growth and development.
• Early skull growth has implications for health and head shape.