Lecture on Sphenoid and Ethmoid Bones

Sphenoid Bone

• Location and Appearance

  • Located in the skull.
  • Resembles a butterfly.

• Bone Markings

  • Sphenoid Sinuses
    • Present within the sphenoid bone.
  • Sella Turcica
    • Contains the hypophyseal fossa.
    • Identification: A sticker pointing to this area would indicate the sella turcica.
  • Foramen
    • Optic Canal: Identified from various angles, crucial for recognizing optic nerves.
    • Foramen Rotundum: Present on both sides of the sphenoid.
    • Superior Orbital Fissure: Large fissure visible from multiple angles.
    • Foramen Ovale: Oval-shaped foramina.
    • Foramen Spinosum: Tiny foramen adjacent to foramen ovale.
  • Pterygoid Processes
    • Extensions from the sphenoid bone, important structural features.

• Orientation in the Skull

  • Recognize bone markings from different views (front and back of the skull).
  • Use sticks to identify the canals and foramen, e.g., foramen ovale and spinosum.

Ethmoid Bone

• Location and Orientation

  • Sits centrally in the skull, identifiable by its shark fin-like structure.

• Key Structures

  • Crista Galli
    • Shark fin-like structure on top of the bone.
  • Cribriform Plates
    • Located on either side of the crista galli.
    • Contain ethmoid air cells or sinuses.
  • Perpendicular Plate
    • Runs through the center, directly below the crista galli.
    • Visible in the nasal cavity, top portion known as the perpendicular plate.
  • Superior Nasal Concha
    • Hard to identify, typically not focused on.
  • Middle Nasal Concha
    • Ridges visible in the nasal cavity.
  • Inferior Nasal Concha
    • Located below the middle nasal concha.

• Nasal Cavity Identification

  • Identify the perpendicular plate and nasal conchae within the nasal cavity.
  • Differentiate between the middle nasal concha and inferior nasal concha.

• Additional Notes

  • The bone markings should be identified by their functional and anatomical significance.

This lecture provides a comprehensive review of the sphenoid and ethmoid bones, focusing on identification and anatomical significance of various bone markings and structures.