During routine dissection of upper limb, we came across a very interesting unilateral variation of subclavius muscle in an adult male cadaver. The origin of the muscle was normal i.e. from the first costochondral junction. Main muscle belly was inserting into the subclavian groove of clavicle. A small accessory belly from the main muscle mass was running inferolaterally with some of its fiber merging with coracoid process, some with axillary sheath and some with fascia covering subscapularis muscle. Apart from this accessory belly, another additional belly was passing posteriorly from the main muscle mass and was gaining attachment to the upper border of scapula lateral to the suprascapular notch. The main muscle mass along with all the additional bellies were supplied by nerve to subclavius. Presence of such accessory muscle can be a potential cause of thoracic outlet syndrome.
Subclavius posticus muscle, variation, thoracic outlet syndrome, suprascapular notch