Fovea Ethmoidalis

Ethmoid Bone

From a practical standpoint, the ethmoid bone can be divided into four structures: two lateral masses, a sagittal midline lamina, and a horizontal plate (Fig. 2.1). The latter (cribriform plate) is the central part of the floor of the anterior cranial fossa. Several microscopic foramina perforate its thin structure, through which course the olfactory nerve filaments with their perineural investment.

Lamella Cribriform Plate

Fig. 2.1. The ethmoid plates and fovea ethmoidalis. A midline (perpendicular plate, PP) and two lateral vertical laminae: the medial one made by the vertical lamella of the middle turbi-nate (vlMT) on the top of which is the vertical lamella of the cribriform plate (vlCP), the lateral one is the lamina papyracea (LP). Horizontal lamella of the cribriform plate (hlCP), horizontal (hGL) and vertical (vGL) - ascending part - of ground lamella of the middle turbinate, crista galli (CG), fovea eth-madalis (FE)

Fig. 2.1. The ethmoid plates and fovea ethmoidalis. A midline (perpendicular plate, PP) and two lateral vertical laminae: the medial one made by the vertical lamella of the middle turbi-nate (vlMT) on the top of which is the vertical lamella of the cribriform plate (vlCP), the lateral one is the lamina papyracea (LP). Horizontal lamella of the cribriform plate (hlCP), horizontal (hGL) and vertical (vGL) - ascending part - of ground lamella of the middle turbinate, crista galli (CG), fovea eth-madalis (FE)

On the upper part of the sagittal midline lamina (crista galli) - located just above the cribriform plate - inserts the cerebral falx; the inferior part, below the cribriform plate, being referred to as the perpendicular lamina, a component of the nasal septum (Fig. 2.2-2.4).

The lateral masses (ethmoid labyrinth) are made of a variable number (3-18) of pneumatized cells separated by thin bony walls.

Each ethmoid labyrinth is closed by bony margins on its external and internal surfaces only. The external surface is made by the lamina papyracea that separates the cells from the orbit. Dehiscences may be present. As a result, the periosteum of the ethmoid cell comes in contact with the periosteum investing the orbital wall (periorbita). Medially, the labyrinth is bordered by two constant laminae hanging from the horizontal plate: the middle and superior turbinates. An uppermost small third ethmoid turbinate (supreme turbinate) can seldom be observed.

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  • jessika
    What is a basal lamella middle turbinate?
    2 years ago

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