Processus clinoideus anterior

Last edited and medically reviewed by Alaric Steinmetz on 31.08.2023

Synonyms

ACP, Anterior clinoid process

The Processus clinoideus anterior is a bilateral bony projection on the medial posterior border of the ala minor ossis sphenoidalis of the Sphenoid bone.

Anatomy

The Processus clinoideus anterior serves as an attachment site for the Tentorium cerebelli.

Pneumatization

Pneumatization of the Processus clinoideus anterior is present in approximately 25.5 % of cases[^1].

Clinical relevance

Complete or partial surgical removal of the Processus clinoideus anterior is referred to as Clinoidectomy and may be performed via an extradural or intradural approach [^2]. Clinoidectomy may be necessary for the treatment of pathologies such as Aneurysms at the origin of the Ophthalmic artery from the Internal carotid artery (ICA), in the cavernous ICA segment, or in the upper portion of the Basilar artery, as well as for Tumor in the region of the Processus clinoideus anterior[^2].

Figure

Anterior clinoid process — Schematic drawing of the lateral view of the left anterior clinoid process (ACP), showing the relationship between the ACP and the cranial nerves from an inferolateral perspective. The figure shows three coronal planes intersecting the ACP at three different levels, with three small schematic drawings illustrating the relationships between the ACP and cranial nerves III, IV, and V. (A) First coronal plane at the level of the tip of the ACP. (B) Second coronal plane at the junction of the medial border of the ACP and the posterior border of the roof of the optic canal. (C) Another coronal plane at the level of the midpoint of the posterior bony border of the roof of the optic canal. ACP: anterior clinoid process; ICA: internal carotid artery; ON: optic nerve; III, oculomotor nerve; IV, trochlear nerve; and V, trigeminal nerve. Figure adapted from Phuong Huynh-Le MD et al., “Surgical anatomy of the anterior clinoid process,” Journal of Clinical Neuroscience, 2004.