sternocostal head of pectoralis major (muscle)

ster·no·cos·tal head of pec·to·ra·lis ma·jor (muscle)

[TA] portion of pectoralis major (muscle) originating from the sternum and ribs; acting alone the ternocostal part extends the arm at the shoulder joint; acting with the clavicular head it adducts the arm. See: pectoralis major (muscle). Synonym(s): pars sternocostalis musculi pectoralis majoris [TA], sternocostal part of pectoralis major muscle