With respect to the second part of the axillary artery, the medial cord lies medial, the posterior cord lies behind, and the lateral cord lies lateral. With respect to the third part of the axillary artery, the medial branches of the lateral and medial cords unite to form the median nerve which is lateral to the artery. The rest of the branches maintain the same relationship to the artery. Long thoracic nerve. Dorsal scapular nerve.
Pierces scalenus medius and supplies levator scapula and rhomboids.
C5 and 6. Found in the lower part of the posterior triangle. Passes backwards beneath the trapezius to supply supraspinatus and infraspinatus. Nerve to subclavius. C5 and 6.