The posterior cord is a part of the brachial plexus. It consists of contributions from all of the roots of the brachial plexus.Drake, Richard, et al. Gray's Anatomy For Students, Elsevier, 2005. pg. 657
The posterior cord gives rise to the following nerves:
Name Roots Supplies upper subscapular nerve C5-C6 subscapularis muscle of the rotator cuff lower subscapular nerve C5-C6 subscapularis muscle, teres major muscle thoracodorsal nerve C6-C8 latissimus dorsi muscle axillary nerve C5-C6 sensation to the shoulder and motor to the deltoid muscle and the teres minor radial nerve C5-C8, T1 triceps brachii muscle, the brachioradialis muscle, the extensor muscles of the fingers and wrist (extensor carpi radialis muscle), supinator, and the extensor and abductor muscles of the thumb
Additional images
References
MBBS resources http://mbbsbasic.googlepages.com/
External links - "Axilla, dissection, anterior view"