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Thoracodorsal Nerve

nervus thoracodorsalis

The thoracodorsal nerve is the motor supply to the latissimus dorsi, arising from the posterior cord of the brachial plexus and running along the posterior axillary wall to innervate the lat from its deep surface. It must be identified and preserved during axillary lymph node dissection for breast cancer, as its sacrifice produces latissimus dorsi weakness that impairs arm adduction and significantly affects breast reconstruction using latissimus flaps.

Region: Upper Back

Anatomical Data

Origin, Insertion & Supply

Origin	Posterior cord of the brachial plexus (C6, C7, C8)

Clinical Relevance

Clinical Notes

Thoracodorsal nerve preservation is a critical technical consideration in axillary clearance for breast cancer, because the latissimus dorsi flap used for breast reconstruction after mastectomy requires an intact thoracodorsal nerve for the muscle to survive as a functional flap. Deliberate division for therapeutic purposes is performed in patients undergoing latissimus dorsi denervation for axillary hyperhidrosis.

Pathology

Common Injuries & Conditions

Thoracodorsal Nerve Injury

Iatrogenic division during axillary lymph node dissection producing latissimus dorsi weakness and compromising latissimus flap viability for breast reconstruction, requiring careful nerve identification during axillary surgery.