quadratus lumborum muscle
Anatomical term for a deep abdominal muscle that connects the pelvis to the lower spine and ribs.
The quadratus lumborum muscle is a deep muscle on both sides of the lumbar spine.
Compound of 腰 (こし, 'hip, lower back'), 方形 (ほうけい, 'square shape'), and 筋 (きん, 'muscle'), describing the muscle's location and shape.