Nerve
Thoracodorsal nerve
Posterior-cord route to latissimus dorsi
High-yield
Its usual C6-C8 fibers supply latissimus dorsi. The nerve lies in the field of axillary node surgery, where injury can weaken the muscle's contribution to pulling the arm down and back.
Overview
Also called the middle subscapular nerve, it descends through the posterior axilla and joins the vessels entering latissimus dorsi. This route links the brachial plexus to a large muscle on the back that acts on the arm.
Learning this group? Read How to learn the brachial plexus.
Reference facts
- Origin
- Usually a branch of the posterior cord of the brachial plexus
- Root value
- Usually C6-C8, with C7 often emphasized
- Course
- Descends on the posterior axillary wall, joins the thoracodorsal vessels and reaches the deep surface of latissimus dorsi
- Motor
- Latissimus dorsi: contributes to arm extension, adduction and internal rotation
- Sensory
- No defined cutaneous field over the back; overlying skin is supplied separately
Clinical correlation
Latissimus dorsi is used in some reconstructive flaps. Whether the thoracodorsal nerve is retained or divided depends on the reconstruction; preserving its vascular supply and preserving its motor nerve are separate decisions.
Frequently asked questions
What are the roots of the thoracodorsal nerve?
Usually C6-C8, with C7 often emphasized.
What muscles does the thoracodorsal nerve supply?
Latissimus dorsi: contributes to arm extension, adduction and internal rotation.
What is the sensory distribution of the thoracodorsal nerve?
No defined cutaneous field over the back; overlying skin is supplied separately.
What is the course of the thoracodorsal nerve?
Descends on the posterior axillary wall, joins the thoracodorsal vessels and reaches the deep surface of latissimus dorsi.