For example, clival chordomas account for 0.15-1 % of all intracranial tumors (Erdem et al., 2003; Jian et al., 2011), there location varying depending on whether they are at the upper clival (basisphenoid) or lower clival (basiocciput
) region (Stippler et al., 2009).
On CT, an expansile osteolytic lesion is seen involving clival occipital bone (basiocciput
) with multiple areas of end-osteal scalloping and marginal sclerosis, suggestive of chronicity.
Post-treatment MRI and CT showed new bony destruction near the basiocciput
area, as well as destruction of the narrow space and the cortex adjacent to the foramen magnum and associated new soft-tissue enhancement.
Results: The first finding was the presence of an unusual shallow incomplete median bony canal on the clivus in the basiocciput region.In addition, a bony spur (osteophyte) on medial side of right occipital condyle was found.
There are very few studies in literature about the presence of a bony canal on the clivus on basiocciput.
The inferior aspect of basiocciput was examined for the occurance of precondylar tubercle which consisted of bony elevations ranging from ridges near the anterior end of occipital condyles to larger median or paramedian projections along the anterior margin of foramen magnum.
Accessory vertebral elements along the anterior margin of foramen magnum interposed between the basiocciput and atlas may reduce the circumference of the foramen or cause asymmetry.
The supraocciput, exocciput, and basiocciput
can be accurately measured to determine the degree of overcrowding.
The posterior cranial fossa was defined as the osseous anatomical area with a floor formed by the occipital bone (basiocciput
portion of the clivus and supraocciput portion of the occipital bone up to the insertion of the tentorium cerebelli, which formed the superior boundary of this fossa) and the basisphenoid.
The adenoid diameter (line A) is measured by a perpendicular line from point A' to the intersection with the straight line of the basiocciput
(line B), which can be identified in a lateral nasopharynx x-ray.
The primary component of the sella turcica is the sphenoid bone with a component from the basiocciput
. Anteriorly, it is bounded by a bony ridge, the tuberculum sella, and posteriorly by the dorsum sella and the posterior clinoid processes.
The superior border is formed by the basisphenoid and basiocciput
. The posterior border is made up of the prevertebral fascia of the atlas and axis.