Rare diseases · Sign or symptom
Abnormal skull base morphology
Abnormality of the skull base
HP:0002693
What it means
An abnormality of the base of the skull, which forms the floor of the cranial cavity and separates the brain from other facial structures. The skull base is made up of five bones: the ethmoid, sphenoid, occipital, paired frontal, and paired parietal bones, and is subdivided into 3 regions: the anterior, middle, and posterior cranial fossae. The petro-occipital fissure subdivides the middle cranial fossa into 1 central component and 2 lateral components.
Rare diseases that can present with this7
Very common80–99%
2The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Abnormality of cranial base
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.