Cribriform foramina

Where are the cribriform foramina located?

The foramina are localized in the cribriform plate (Lamina cribrosa). This is the horizontal part of the unpaired pneumatic ethmoid bone (Os ethmoidale).

The ethmoid bone itself consists of four parts:

• Cribriform plate (Lamina cribrosa) — contains the Foramina cribrosa. It also bears the crista galli (Crista galli) and its wing (Ala crista galli).
• Perpendicular plate (Lamina perpendicularis) — the vertical part participating in the formation of the bony nasal septum.
• Ethmoidal labyrinths (Labyrinthus ethmoidalis) — paired structures containing ethmoidal cells (Cellulae ethmoidales) and the nasal conchae: superior and middle.

Topography and contribution to skull wall formation

The cribriform plate with its foramina is an important element of two major cranial structures:

• Roof of the bony nasal cavity (Cavitas nasalis ossea). This wall is formed by the cribriform plate of the ethmoid bone together with the nasal bone, the nasal part of the frontal bone, and the body of the sphenoid bone. The nasal cavity itself is trapezoidal in shape, bounded anteriorly by the piriform aperture (Apertura piriformis), which is limited by the nasal bone, the nasal notch, and the anterior nasal spine of the maxilla. The posterior boundary is formed by the posterior nasal apertures — the choanae (Choanae). In the midline, the cavity is divided by the bony nasal septum (Septum nasi osseum), formed by the perpendicular plate of the ethmoid bone, the vomer (Vomer), the nasal spine of the frontal bone, and the sphenoidal crest.
• Anterior cranial fossa (Fossa cranii anterior). The fossa is conventionally bounded anteriorly by the frontal squama, and posteriorly by the lesser wings of the sphenoid bone and the prechiasmatic sulcus. Through the cribriform foramina, the anterior cranial fossa communicates with the nasal cavity. In addition to the Foramina cribrosa, the anterior cranial fossa communicates with the nasal cavity via the cecal foramen (Foramen caecum), through which an emissary vein passes.

What passes through the cribriform foramina?

The foramina serve as channels for the passage of the following structures:

• Olfactory filaments.
• Meningeal branches.

Do not confuse: anterior and posterior ethmoidal foramina

The skull anatomy also distinguishes the anterior and posterior ethmoidal foramina (Foramina ethmoidalia anterior et posterior). Unlike the Foramina cribrosa, they are located on the medial wall of the orbit, transmit the neurovascular bundles of the same name, and connect the orbit with the ethmoidal cells, the nasal cavity, and the anterior cranial fossa. The medial wall of the orbit, where they are situated, is formed by the frontal process of the maxilla, the lacrimal bone, the orbital plate of the ethmoid bone, and the lateral surface of the body of the sphenoid bone. The orbit itself is pyramid-shaped, with its apex corresponding to the optic canal (Canalis opticus).

Class and exam questions

What else to study on this topic

• Ethmoid bone (Os ethmoidale)
• Anterior cranial fossa (Fossa cranii anterior)
• Bony nasal cavity (Cavitas nasalis ossea)
• Orbit (Orbita) and its medial wall

Other topics in the "Anatomical Structures" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.