The thoracodorsal artery (from the subscapular artery) divides into two main branches after giving the serratus anterior branch: the descending branch (running along the lateral border of the latissimus dorsi supplying its lateral edge) and the transverse branch (running horizontally near the muscle's inferior border). These branches are the basis of muscle-sparing latissimus dorsi flap design, allowing harvest of specific muscle segments rather than the entire muscle.
Thoracodorsal artery branch anatomy dictates muscle-sparing LD flap design: the descending branch supplies the lateral LD strip used in a partial LD flap preserving medial and superior muscle for scapular winging prevention; the transverse branch supplies the inferior muscle used in intercostal nerve-sparing extended LD flap variations. Pre-operative CT angiography maps the branch point and the dominant perforators arising from each branch. In thoracodorsal artery perforator (TAP) flap, perforators from the descending or transverse branches supply skin without sacrificing any muscle.
Preserving the transverse branch of the thoracodorsal artery while harvesting the descending branch territory allows a muscle-sparing LD flap that maintains the medial and superior LD for scapular stabilisation while providing adequate muscle volume for breast reconstruction; pre-operative CTA confirms the branch anatomy before surgery.
