middle rib vs veinlet

middle rib

noun
  • The main vein of a simple leaf or leaflet, running from the petiole to its apex, and from which the other veins usually spread. 

  • The continuation of the petiole of a pinnately compound leaf around which the leaflets attach. 

  • A cut of beef between the chuck rib and fore ribs. 

veinlet

noun
  • A small or secondary vein, especially on the wing of an insect or the leaf of a plant. 

How often have the words middle rib and veinlet occurred in a corpus of books? (source: Google Ngram Viewer )