Trapezius aplasia: Indications for a dual developmental origin of the trapezius muscle

Abstract

Aplasia of the trapezius muscle is a rarely encountered, mostly asymptomatic anomaly. We report a case of isolated unilateral complete trapezius aplasia that was noticed during a dissection course. Apart from isolated cases, trapezius aplasia may occur in different combinations with other muscle aplasias. We suggest that the patterns of concomitant muscle involvement are indicative of a combined occipital and cervical somitogenic origin.