The policy said that PBRT may be medically necessary in the basisphenoid
region (a bone at the base of the skull) or cervical spine.
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
05) the incidence of fetuses with absent xiphoid process (TA group), incomplete ossification of sternebra (TB and TC groups), increased distance between hamulus and basisphenoid
, absent sternebrae and incomplete ossification of xiphoid process (TC group) (Table 2).
In our case, the key imaging feature was the osseous stalk arising from the basisphenoid
portion of the clivus, which is considered a morphologic hallmark of EP and is absent in other retroclival lesions, such as dermoids, epidermoids, arachnoid cysts, and neuroenteric cysts.
begins to ossify in the proximal region of basipterygoid processes and the crista sellaris (Table 2).
5 mm, and relatively large and deep basisphenoid
pits (Kumirai and Jones, 1990; Milner et al.
It started at the wing and pterygoid process of the basisphenoid
bone and connected to the joint capsule on the tip of the medial side of the mandibular condyle.
The aeration process begins at approximately 3 years of age in the anterior portion of the sphenoid bone in the area known as thepresphenoid, and it progresses posteriorly into the basisphenoid
area until it reaches the anterior wall of the clivus.
3); one pair of slender uroneurals; three epurals; a free parhypural; three thin supraneurals, generally straight; two supernumerary spines on first dorsal pterygiophore; no procumbent spines (spurs); thin Y-shaped basisphenoid
, free from parasphenoid and prootics; neurocranium with frontal tabs similar to Vincentia Castelnau, 1872 (Fraser 1972: pl 31); supramaxilla absent; posttemporal smooth or with 1-3 small serrae on posterior margin; preopercle with 2-3 small, widely spaced serrae near angle, ridge smooth; infraorbitals smooth; infraorbital shelf present on third bone; ring of scleral cartilage, no ossification present; 7 branchiostegals; ceratohyal notched, suture smooth with epihyal; urohyal with short anterior process.
Rostrally it articulates with the caudal edge of the basisphenoid
All animals used were adults, which was determined because the sutures between basisphenoid
and basioccipital and those of the occipital complex were not visible owing to a fusion of the bones (Morris, 1972).