FIGURE 13.

The hypothetical branching pattern of the brachial spinal nerves projected onto a transverse plane around the level of the fifth thoracic vertebra. The primaxial, intramural, and extramural branches, as well as their target muscles, are color-coded: purple for primaxial, blue for intramural, and dark green for extramural components. The dotted lines are the cutaneous branches. The names of the muscles are numbered. Primaxial branches: direct branches to the scalenus muscles, the long thoracic nerve to the serratus anterior muscle, and the dorsal scapular nerve to the rhomboids. The posterior primaxial cutaneous branch is innominate. The extramural branches are the thoracodorsal nerve to the latissimus dorsi and teres major, subscapular nerve to the subscapularis, and pectoral nerves to the pectoralis. The LCB carries extramural motor innervations into the radial and median nerves in the upper limb. The cutaneous extensions of the extramural branches are innominate.