1. An anatomical structure composed of the tendons of four muscles that control rotation of the shoulder and of parts of the capsule of the shoulder joint.
2. The set of four muscles that control rotation of the shoulder.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.