caudal vs spinal column

caudal

noun

  • A caudal vertebra. 

adj

  • Toward the tail end (hind end) of the body; in bipeds such as humans, this direction corresponds to inferior. 

  • Pertaining to the tail or posterior or hind part of a body. 

spinal column

noun

  • The vertebral column. 

How often have the words caudal and spinal column occurred in a corpus of books? (source: Google Ngram Viewer )