The largest branch of brachial plexus is ?
**Core Concept**
The brachial plexus is a complex network of nerves that originates from the spinal cord and supplies the upper limb. It is formed by the ventral rami of C5-T1 spinal nerves and is divided into roots, trunks, divisions, cords, and finally, individual nerves. The brachial plexus is a vital structure for motor and sensory function of the upper limb.
**Why the Correct Answer is Right**
The largest branch of the brachial plexus is the posterior cord, which arises from the posterior division of the lateral cord and the posterior division of the posterior cord. The posterior cord is the largest and most anterior branch of the brachial plexus and gives rise to several important nerves, including the axillary nerve, the radial nerve, and the thoracodorsal nerve. These nerves are responsible for motor and sensory innervation of the upper limb, particularly the muscles of the arm and forearm.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify which branch of the brachial plexus is being referred to. The brachial plexus has several branches, including the lateral cord, the medial cord, and the posterior cord, but none of these are the largest branch.
**Option B:** This option is incorrect because it is a distractor and does not correspond to any branch of the brachial plexus.
**Option D:** This option is incorrect because it is another distractor and does not correspond to any branch of the brachial plexus.
**Clinical Pearl / High-Yield Fact**
The brachial plexus is commonly injured in traumatic injuries to the shoulder or upper arm, such as fractures or dislocations. The posterior cord is particularly vulnerable to injury in these types of trauma. The axillary nerve, which arises from the posterior cord, is often affected in brachial plexus injuries, leading to weakness or paralysis of the deltoid muscle.
**Correct Answer: C. Posterior cord, the posterior cord is the largest branch of the brachial plexus.**