As nouns,
fissure of Sylvius is a hyponym of
sulcus; that is,
fissure of Sylvius is a
word with a more specific, narrower meaning than
sulcus:
- sulcus: (anatomy) any of the narrow grooves in an organ or tissue especially those that mark the convolutions on the surface of the brain
- fissure of Sylvius: the deepest and most prominent of the cortical fissures; separates the frontal lobes and temporal lobes in both hemispheres
Other hyponyms of sulcus include
central sulcus,
fissure of Rolando,
Rolando's fissure,
sulcus centralis,
lateral cerebral sulcus,
sulcus lateralis cerebri,
Sylvian fissure,
parieto-occipital fissure,
parieto-occipital sulcus,
calcarine fissure,
calcarine sulcus.