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Perpendicular Plate of the Ethmoid

lamina perpendicularis ossis ethmoidalis

The perpendicular plate is a thin vertical sheet of bone that hangs down from the cribriform plate of the ethmoid bone and forms the upper part of the bony nasal septum. It joins the vomer below and behind and the septal cartilage in front. Above, it is continuous with the crista galli inside the skull.

Anatomical Data

Structure & Landmarks

Articulations	Vomer Septal cartilage of the nose Nasal bones and nasal spine of the frontal bone Crest of the sphenoid bone
Landmarks	Upper bony nasal septum Continuous above with the cribriform plate and crista galli Joins the vomer posteroinferiorly Joins the septal cartilage anteriorly
Ossification	Ossifies from the ethmoid's median ossification centre during the first year of life and fuses with the rest of the ethmoid in early childhood; it joins the vomer later in childhood.

Clinical Relevance

Clinical Notes

The perpendicular plate is often deviated as part of a deviated nasal septum and may be partly removed in septoplasty. Because it is attached directly to the cribriform plate, forceful twisting of the bony septum during surgery can fracture the skull base and cause a cerebrospinal fluid leak, so surgeons cut rather than twist it. It can also fracture in nasal and naso-orbito-ethmoid injuries.

Pathology

Common Injuries & Conditions

Deviated Nasal Septum

A bend in the nasal septum involving the perpendicular plate and septal cartilage, causing nasal blockage on one or both sides; treated with septoplasty if troublesome.

Cerebrospinal Fluid Rhinorrhoea

A leak of clear brain fluid from the nose after fracture of the cribriform plate, which can follow nasal trauma or rough manipulation of the perpendicular plate.

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