Origin variations and brachial plexus relationship of the dorsal scapular artery

The dorsal scapular artery can either be a direct branch of the subclavian artery or a branch of the transverse cervical artery. Origin variation is related to its relationship with the brachial plexus. Anatomical dissection was performed on 79 sides of 41 formalin-embalmed cadavers in Taiwan. The origin of the dorsal scapular artery and the variations of its brachial plexus relationship were scrutinized and analyzed. Results showed that the dorsal scapular artery originated most frequently from the transverse cervical artery (48%), followed by the direct branch from the third part (25%) and the second part (22%) of the subclavian artery and from the axillary artery (5%). Only 3% of the dorsal scapular artery passed through the brachial plexus if its origin was the transverse cervical artery. However, 100% and 75% of the dorsal scapular artery passed through the brachial plexus when they were direct branches of the second and the third part of the subclavian artery, respectively. Suprascapular arteries were also found to pass through the brachial plexus when they were direct branches from the subclavian artery, but all passed over or under the brachial plexus if they originated from the thyrocervical trunk or transverse cervical artery. Variations in the origin and course of arteries around the brachial plexus are of immense value not only to the basic anatomical knowledge but also to clinical practices such as supraclavicular brachial plexus block and head and neck reconstruction with pedicled or free flaps.