Bilateral variation of the pectoralis minor muscle discovered during practical dissection.

We describe a case of an original insertion of the pectoralis minor on the coracohumeral ligament, supraspinatus tendon and the capsule of the glenohumeral joint. This variation has been described in anatomy textbooks since the nineteenth century. The peculiarity of this case is that the right shoulder presented type 2 and the left type 1 of the three varieties described by Le Double in 1897. Le Double (1843-1913) was a French anatomist who wrote a treaty on anatomical variations, in particular those of the muscle. Lately, only three publications have reported this variation in anatomic studies. Some authors have described the rotator cuff syndrome caused by this variation and an ultrasound study has demonstrated a frequency of 9.57% for the detection of this variation. It is possible to try and find this variation while investigating in order to diagnose impingement, through ultrasound, CT arthrography or MRI. We believe that this variation should be taken into consideration by surgeons during surgical procedures and arthroscopy.