part of part of fourth ventricle anatomical cavity sulcus limitans of fourth ventricle http://upload.wikimedia.org/wikipedia/commons/7/77/Gray709.png sulcus limitans BAMS:slm neuronames:629 Wikipedia:Sulcus_limitans In the floor of the fourth ventricle, the sulcus limitans separates the cranial nerve motor nuclei (medial) from the sensory nuclei (lateral). In the superior part of the rhomboid fossa, it corresponds with the lateral limit of the fossa and presents a bluish-gray area, the locus ceruleus (which owes its color to an underlying patch of deeply pigmented nerve cells, termed the substantia ferruginea). [WP]. s. limitans fossae rhomboideae FMA:78496 UMLS:C0262332 UBERON:0009573 DHBA:12823 BAMS:slim NCIT:C33656