Bones and Bone Tissue Notes

Skull Cavities

• Orbit:

  • Houses the eyeball, blood vessels, muscles, nerves, and lacrimal gland (produces tears).

  • Formed by 7 bones: Frontal, Maxilla, Zygomatic, Sphenoid, Ethmoid, Lacrimal, and Palatine bones.

    • The frontal bone contributes to the superior part of the orbit.

    • The maxilla forms the inferior part of the orbit and contains the infraorbital foramen for the passage of nerves and blood vessels.

    • The zygomatic bone contributes to the lateral wall and floor of the orbit.

    • The sphenoid bone forms the posterior wall of the orbit and contains the optic canal for the optic nerve.

    • The ethmoid bone contributes to the medial wall of the orbit.

    • The lacrimal bone is a small bone in the medial orbit wall that contains the lacrimal fossa for the lacrimal sac.

    • The palatine bone contributes a small part to the posterior orbit floor.

• Nasal Cavity:

  • The first part of the respiratory tract, responsible for warming, humidifying, and filtering air.

  • Walls:

    • Roof: Cribriform plate of the ethmoid bone

    • Contains olfactory foramina for the olfactory nerves.

    • Floor: Hard palate (palatine processes of the maxillae and palatine bones)

    • Separates the nasal cavity from the oral cavity.

    • Posterior Wall: Sphenoid and ethmoid bones

    • Contains the opening to the nasopharynx.

    • Lateral Wall: Ethmoid, perpendicular plate of the palatine bone, inferior nasal concha, and maxilla

    • Features the superior, middle, and inferior nasal conchae to increase surface area.

  • Nasal Septum: Formed by hyaline cartilage, the ethmoid bone (perpendicular plate), and vomer.

    • Divides the nasal cavity into right and left halves.

• Paranasal Sinuses: Located within the Frontal, Sphenoid, Ethmoid, and Maxillary bones; lighten the skull and enhance voice resonance.

  • Frontal Sinuses: Located in the frontal bone above the orbits.

  • Sphenoid Sinuses: Located in the sphenoid bone, posterior to the ethmoid sinuses.

  • Ethmoid Sinuses: Located in the ethmoid bone between the nasal cavity and the orbits; consist of ethmoid air cells.

  • Maxillary Sinuses: Located in the maxillary bones lateral to the nasal cavity; the largest of the paranasal sinuses.

• **Oral Cav