The pectoralis muscle (pectoralis) is part of the thorax muscles of birds and is the largest muscle of the body.
It is divided into three parts:
This muscle moves the wing cranially and is the largest component of wing elevation.
Under this muscle sits the supracoracoid muscle. Both muscles form the mass of the chest.
The muscles of the chest can be affected by multiple toxic, infectious or genetic pathologies that cause changes of coloration, presence of hemorrhages or alterations of the muscular tonicity.
Anatomy of Domestic Animals, 5th Edition-Robert Getty