mollera caida Share definition Flag fallen fontanelle caida, Sp. fallen mollera, crown of head or calvarium sinking of soft spot on infant's head; seen with severe dehydration or weight loss famine and/or diarrhea. An ominous prognostic sign for infant mollera caida by Willard F. Zahn, M. D. April 22, 2003 Get the mollera caida mug.