Relative frequency of a subclavian vs. a transverse cervical origin for the dorsal scapular artery in humans.

BACKGROUND: The origin of the dorsal scapular artery to the rhomboid muscles in humans has been the subject of uncertainty. The present study sought to clarify which of its two most common sources (the transverse cervical artery or the subclavian artery) is the major source of the dorsal scapular artery.
METHODS: Gross anatomical dissection was used to visualize the origin and course of the dorsal scapular artery in human cadavers.
RESULTS: We found that the dorsal scapular artery typically arises from either of two main sources: the subclavian artery (about 75% of all sides) or the transverse cervical artery (about 25% of all sides). Subclavian origins were approximately equally divided between its second and third part. Other origins for the dorsal scapular artery were negligible in frequency. Those dorsal scapular arteries that arose from the subclavian artery passed between the upper and middle or middle and lower trunks of the brachial plexus to course to the rhomboid muscles. In the case of transverse cervical artery origin, the dorsal scapular artery arose as a branch that passed deep to the levator scapulae muscle before coursing to the rhomboid muscles. No noteworthy differences were observed between males and females.
CONCLUSIONS: These results strongly support the simple view, which does not appear widely accepted, that the subclavian artery is the most common source of the dorsal scapular artery to the rhomboid muscles and the transverse cervical artery a major but secondary source.