Which nerves arise from the posterior cord of the brachial plexus?

The nerves that arise from the posterior cord of the brachial plexus include both the radial and axillary nerves. The posterior cord is formed by the merging of the posterior divisions of the upper, middle, and lower trunks of the brachial plexus and ultimately gives rise to the nerves that primarily innervate the muscles and skin of the posterior arm and upper limb.

The radial nerve is the largest branch of the brachial plexus, responsible for innervating the triceps brachii and muscles in the posterior compartment of the forearm, which are essential for extending the elbow and wrist. The axillary nerve, on the other hand, innervates the deltoid and teres minor muscles, playing a key role in shoulder abduction and stability.

Understanding the specific origins and functions of these nerves is crucial for clinical practice, particularly in interpreting injuries that may lead to weakness or paralysis in the affected areas.