INI-CET 2009 — Anatomy

Question 1: Orbital blow-out fracture involves:

• A. Lateral wall and roof of orbit
• B. Medial wall and floor of orbit (Correct Answer)
• C. Medial wall and roof of orbit
• D. Lateral wall and floor of orbit

Explanation: Medial wall and floor of orbit - An orbital blow-out fracture typically involves the **medial wall** (lamina papyracea of the ethmoid bone) and the **floor** (maxillary bone) of the orbit because these are the weakest bony structures. - The force of impact on the globe is transmitted to the orbital walls, causing them to fracture outwards into the adjacent sinuses. *Lateral wall and roof of orbit* - The **lateral wall** (zygomatic bone) and **roof** (frontal bone) of the orbit are structurally strong and less commonly involved in isolated blow-out fractures. - Fractures in these areas typically result from high-impact trauma and are often associated with other facial bone injuries. *Medial wall and roof of orbit* - While the **medial wall** is frequently involved, the **roof** of the orbit is a thick, sturdy bone and is less susceptible to blow-out forces. - Fractures of the orbital roof usually occur due to direct impact or high-energy trauma to the forehead. *Lateral wall and floor of orbit* - Although the **floor** is commonly fractured, the **lateral wall** is a robust structure and is not typically involved in isolated blow-out fractures. - Combined fractures of the lateral wall and floor would indicate a more extensive orbital impact, often with other mid-facial trauma.