iniencephalus

iniencephalus

(ĭn′ē-ĕn-sĕf′ă-lŭs) [Gr. inion, back of the head, + enkephalos, brain]
A congenitally deformed fetus in which the brain substance protrudes through a fissure in the occiput, so that the brain and spinal cord occupy a single cavity.