The Collaborative International Dictionary of English v.0.48:

Myotome \My"o*tome\, n. [See Myotomy.] (Anat.)
   (a) A muscular segment; one of the zones into which the
       muscles of the trunk, especially in fishes, are divided;
       a myocomma.
   (b) One of the embryonic muscular segments arising from the
       protovertebrae; also, one of the protovertebrae
       themselves.
   (c) The muscular system of one metamere of an articulate.
       [1913 Webster]