Posterior Fossa
The compartment of the skull containing the cerebellum and brainstem, frequently assessed on fetal ultrasound.
Full Definition
The posterior fossa is the most posterior compartment of the intracranial space, bounded by the tentorium cerebelli superiorly and the occipital bone posteriorly. In fetal medicine, posterior fossa assessment is crucial for detecting neural tube defects and other central nervous system abnormalities. Key structures evaluated include the cerebellar hemispheres, vermis, fourth ventricle, and cisterna magna. Abnormalities such as Dandy-Walker malformation, cerebellar hypoplasia, or Blake's pouch cyst can be identified through careful sonographic examination of this region during the second-trimester anomaly scan.
Usage
Usage note: Always use as two words, never hyphenated.
In Context
- "Posterior fossa measurements were within normal limits with appropriate cerebellar development." — Fetal neurosonography report
- "An enlarged posterior fossa was noted, raising concern for Dandy-Walker spectrum disorder." — Prenatal ultrasound findings