Part 4: Nasal Fossae, Orbit, Paranasal sinuses

What forms the nasal septum?

1. Anterior: Cartilage

2. Superior: perpendicular plate of ethmoid

3. Inferior: Vomer

Conchae (3 scroll-like bones) aka

Turbinates

List and location: Conchae (3 scroll-like bones)

1. Superior: extensions of ethmoid bones

2. Middle: extensions of ethmoid bones

3. Inferior: Separate facial bones

   (medially on coronal images)

Number of bones that from the orbit:

7

List the bones that from the orbit and what part of the orbit

• Roof: Frontal

• Floor: maxillary and zygomatic

• Medial Wall: lacrimal, ethmoid

• Lateral wall: Zygomatic, Sphenoid

• Extra: Palatine bone

Shape of orbit

conical

Orbital bones: Which section is the base, which section is the apex

Base: anterior, gets smaller as you cut posteriorly. Weakest portion→ blowout fracture

Apex: posterior

Blow-out fracture: fracture of inferior portion of the orbit (weakest portion)

List the paranasal sinuses:

Which paranasal sinus is present at birth?

maxillary

Which paranasal sinus is the largest?

maxillary

Which paranasal sinus is the last to develop? at what age?

sphenoid (or fontal) age 6-7

Which paranasal sinuses are rarely symmetrical?

frontal