The Collaborative International Dictionary of English v.0.48:

Scala \Sca"la\, n.; pl. Scalae. [L., a ladder.]
   1. (Surg.) A machine formerly employed for reducing
      dislocations of the humerus.
      [1913 Webster]

   2. (Anat.) A term applied to any one of the three canals of
      the cochlea.
      [1913 Webster]