Harrison's groove

[hărĭ-sənz]
n.
  1. A groove in the chest manifesting a deformity of the ribs caused by the pull of the diaphragm on ribs weakened by rickets or by other softening of the bone.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.