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. 2015 Jun;28(3):254–258. doi: 10.1177/1971400915592549

Figure 2.

Figure 2.

Morphometric parameters of the posterior cranial fossa in a representative child with Costello syndrome. A) Midsagittal T1-weighted MRI; a = length of the basiocciput, between the spheno-occipital synchondrosis (S) and the basion (B); b = length of basisphenoid, between the top of the dorsum sellae (DS) and the spheno-occipital synchondrosis of the clivus (S); a + b = length of clivus; c = length of the supraocciput between the internal occipital protuberance (IOP) and the opisthion (OP); d = distance between the tip of the cerebellar tonsils (*) and McRae’s line (dashed line: B to OP); McRae’s line = antero-posterior diameter of the foramen magnum (AP); α = angle of the cerebellar tentorium (T) to Twining's line (TL: IOP to DS). B) Axial T2-weighted MRI; LL = maximum tranverse diameter of the foramen magnum. C) Coronal T1-weighted MRI; F = length of exocciput extends from the bottom of the occipital condyle (Co) to the top of the jugular tubercle (JT).