For citation purposes: Vallabhajosyula R, Babu CS. The bilateral additional origin of pectoralis major muscle: A case report. OA Anatomy 2014 Jul 18;2(2):18.

Case report

Gross Anatomy

The bilateral additional origin of pectoralis major muscle: A case report.

R Vallabhajosyula, CS Babu

Authors affiliations

(1) Newcastle University Medicine Malaysia, Nusajaya, Johor, Malaysia

(2) Sri Venkateswara Medical College, Tirupati, Andhra Pradesh, India

* Corresponding author Email:



In the routine dissection of pectoral region of upper limb anatomy, an additional slip of pectoralis major was observed. The origin of the extra slip was from 6th rib and the costal cartilage. The fibers of the slip were directed upwards and medially and joined with the deep fibers of pectoralis major and finally inserted to the lateral lip of intertubercular sulcus. The nerve supply was similar to that of pectoralis major. Earlier studies named the extra slip of pectoralis major as costohumeralis, where the origin was from the 6th rib and the costal cartilage. However, the insertion of the extra slip was found to be variating. According to the literature review, the slip runs either in conjunction with the pectoralis major or runs as a separate slip. Variations in the muscular fibers may not be symptomatic but are of academic interest. If symptomatic may be associated be altered kinetics of the joints which influences the movements of the joint or nerve entrapment.


In the present study, the extra origin of pectoralis major, was observed to asymptomatic and could not be associated with any clinical application, but is of academic interest.

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