tailpiece vs upper arm

tailpiece

noun
  • An appendage or appendix. 

  • An element, often triangular, to which the strings of a violin, guitar, etc. are attached at the lower end of an instrument. 

  • A short joist between a header and a wall. 

  • The part of a telescope containing the adjusting device for the eyepiece, etc. 

  • The part of a lock that transmits motion from the hub to the latch bolt. 

upper arm

noun
  • The section of an arm from the elbow to the shoulder. 

How often have the words tailpiece and upper arm occurred in a corpus of books? (source: Google Ngram Viewer )