Anatom3DSternocostal part of left pectoralis major
Pars sternocostalis musculi pectoralis majoris sinistri · Sternokostální část levého velkého prsního svalu
Muscles
Looks like
The large lower part of the chest muscle, fanning from the breastbone and upper rib cartilages to the upper arm bone.
What it does
Pulls the arm down and across the chest and turns it inward, as in pushing or hugging.
Keeping it well
Can tear from the arm bone during heavy bench press; a pop, bruising and changed chest contour need early surgical assessment.