An Anthropometric Study of Relationships between Sella Turcica and Clivus in Human Skulls

Objective: The purpose of this study was to assess the morphological dimensions of the sella turcica (ST) and clivus, and determine whether correlations exist between these vital structures. The cranial fossa is rich in vital, delicate neural, and vascular structures. This makes skull base surgeries challenging, and the study of anatomical and morphometric relationships essential to perform safe surgery. While several studies have been published on morphological relationships between structures in the cranial base, a morphometric study of relationships between the ST and clivus is lacking.

Methods: This study utilized 35 dry human skulls; measurements of ST and clivus variables were ascertained using a digital caliper and ruler. The results were statistically analyzed and compared. For each dry skull, the following measurements were taken for the ST in the midsagittal plane: length (straight line between the tuberculum sellae and upper limit of the dorsum sellae), anterior height (distance between the tuberculum sellae and sella floor) and perimeter (contour of the sella turcica from the tuberculum sellae and upper limit of the dorsum sellae). Two measurements of the clivus were obtained in the midsagittal plane: length (distance from the upper limit of the dorsum sellae to the foramen magnum) and clival angle (angle formed between a line projected along the clivus and another line projected along the anterior cranial base). Statistical analysis was performed including correlation between the sellar and clival measurements.

Results: ST measurements (mean [SD]) for length, anterior height, and perimeter were 11.01 mm (1.67 mm), 7.07 mm (1.27 mm), and 16.94 mm (2.25 mm), respectively. Mean clival measurements (SD) for length and angle were 39.93 mm (3.45 mm) and 133.85 mm (6.11 mm), respectively. Pearson's correlation tests showed a moderate positive correlation between ST perimeter and clivus length (p < 0.01), and a moderate negative correlation between ST length and clivus length (p < 0.01). No significant correlation could be found between ST perimeter and length (p > 0.05). For other variables, no significant relationships were found (p > 0.05).

Conclusions: Morphological analyses of the various dimensions of skulls’ ST and clivus were consistent with published normative reference standards. Accordingly, two significant relationships were found between the ST and clivus based on the variables which were analyzed. A larger distance between the tuberculum sellae to the upper limit of the dorsum sellae is associated with a longer clivus; however, larger perimeter of the ST is associated with a smaller clivus. This new anatomical knowledge may contribute to preoperative surgical planning and to orient surgeons in space during drill out of the clivus in endoscopic posterior fossa approaches.

Publication History

Article published online:
15 February 2022