Bilateral pectoralis major and pectoralis quartus variants: A conjoined tendon passing through the inter tubercular groove

The pectoralis major has been described to insert on to the lateral lip of the intertubercular groove of the humerus. The pectoralis quartus is a variant that runs parallel to the lateral border of the pectoralis major. It has been described with insertions in to the pectoralis major at the lateral lip of intertubercular groove, short head of the biceps, and coracobrachialis. This case report describes additional bilateral variants found in an elderly male cadaver.

The first variant included a conjoined tendon of the pectoralis major and quartus that passed superiorly through the intubercular groove to insert to the blended fascia of the superolateral glenohumeral joint capsule. The second variant included different insertions between the left and right pectoralis quartus in to pectoralis major fascia. These findings have not been previously reported in the literature. The bilateral presence of such variants also makes this case unique. Clinical and surgical considerations are included in the discussion of this case report.