The Ethmoid Bone: Anatomy and Features

What does the Greek word 'Ethmos' mean, which is related to the Ethmoid bone?

Which part of the Ethmoid bone forms the roof of the nasal cavity?

What is located below the Ethmoid bone?

Which of these structures is not a part of the Ethmoid bone?

What part of the Ethmoid bone contributes to the medial wall of the orbit?

What are the large masses located on either side of the perpendicular plate in the ethmoid bone called?

What may occur if the cribriform plate is fractured?

What is a potential consequence of an ethmoid labyrinth fracture?

What symptom can result from inflammation of the ethmoid sinuses?

What might cause damage to the ethmoid bone?

The Ethmoid Bone

Originates from the Greek word "Ethmos," meaning sieve.
This reflects its lightweight and spongy structure.
It's a small, unpaired bone, forming part of the orbital complex.
Located within the paranasal sinuses.
Contributes to the medial wall of the orbit and forms part of the anterior cranial fossa.
Separates the nasal cavity from the cranial cavity, inferiorly and superiorly, respectively.
Innervation involves anterior and posterior ethmoidal branches.

Features of the Ethmoid Bone

Composed of four parts:
- Cribriform plate
- Perpendicular plate
- Ethmoid labyrinths

Cribriform Plate

Forms the roof of the nasal cavity.
Perforated by olfactory fibres.
The crista galli projects superiorly from the plate.

Perpendicular Plate

Forms the superior two-thirds of the nasal septum.
Descends from the cribriform plate.

Ethmoid Labyrinths

Large masses situated on either side of the perpendicular plate.
Contain ethmoid air cells, which are the ethmoid sinuses.

Clinical Relevance

Fracture of the cribriform plate can cause anosmia.
Ethmoid labyrinth fracture can allow communication between the nasal cavity and orbit, potentially leading to orbital emphysema.
Inflammation can cause rhinorrhoea (discharge of clear watery fluid) from one side of the nose and/or rhino sinusitis
Damage to the ethmoid bone can result from infection, inflammation, or facial trauma.

This quiz covers the anatomy and functions of the ethmoid bone, focusing on its structure, including the cribriform plate, perpendicular plate, and ethmoid labyrinths. Test your knowledge on how this bone contributes to the orbit and nasal cavity.