Morphological Variation of Anterior Clinoid Process in Dry Human Skulls

Abstract

Introduction: The anatomical relationship of the Anterior Clinoid Process (ACP) with its neighboring structures in the base of the skull is complex with different variations. Thus, study of its morphology is essential in defining and directing surgery.
 Objective: This study aims to investigate the anatomy of the anterior clinoid process and prevalence of Caroticoclinoid foramen (CCF) to highlight its variations.
 Methodology: The measurements were performed in 31 dry human skulls to define the structure of ACP, the presence of CCF and other relevant landmarks using digital Vernier Calipers.
 Results: The mean length, basal width and thickness of the right ACP was 9.88+/- 1.36 mm, 8.72+/-1.50 mm, and 5.21+/-1.83 mm respectively and that of the left was 10.30+/-1.47, 8.73+/-1.71, and 5.33+/-1.60 mm respectively. Paired t-test was used to compare the mean of these sides. Type III was the most common form of ACP for both the sides. Out of 31 skulls, CCF was observed in 12 (38.7%) skulls with 7 (22.6%) in right and 5 (16.13%) in left side. Distances between neighboring ACP’s, between Posterior Clinoid process (PCP), between ACP to Crista Galli (CG) and ACP to PCP were 24.41+/-2.32, 20.01+/-3.23, 31.6+/-2.20, and 8.30+/-3.10 mm respectively.
 Conclusion: This article highlights the detailed morphology of ACP. There is variation in relation to its dimensions across other studies. This study also explores the prevalence of CCF and parasellar landmarks in relation to ACP giving an idea of the exposure achievable during surgical approach of the region.

Morphometric measurements of anterior clinoid process in relation to parasellar osseous structures and their clinical significance

“…Our study concurred with the study by Natsis K et al 21 but their values for the ACP-PCP distance are higher than our values and distance between ACP tips and distance between PCP tips are much lower than our values. Our study also concurred the studies by Lone M et al 7 and Dagtekin A et al 10 but their values for all the parameters in parasellar region are lower than our values (table 4) 3 Natsis K et al 5 Lone M et al 18 Dagtekin A et al A study by Neslihan B et al 22 found that distance between ACP tips was 25.8±2.7mm and the distance between ACP-PCP was 10.7±2mm in right and 10.4±2.1mm in left side and these values are higher than our values. Most of the previous studies are from outside India and few are from southern and eastern part of India but our study was conducted on the population of North India.…”

“…The anterior clinoid process are the bony projections presents on the medial end of lesser wing of sphenoid bone and connects the body of sphenoid to the lesser wing by two roots -anterior and posterior root (optic strut) [3][4][5] . Anterior root of the anterior clinoid process forms the roof and posterior root forms the floor of the intracranial part of optic canal, whereas the base of the anterior clinoid process forms a part of lateral wall of optic canal [6][7][8] . The anterior clinoid process (ACP), optic strut (OS) and the surrounding parasellar structures are very important as they are closely related to the nerves, vessels, glands, and part of base of brain like optic nerve, ophthalmic artery, internal carotid artery, cavernous sinus, pituitary gland, basilar artery and interpeduncular fossa 9,10 .…”