**Core Concept**
The pinna, also known as the auricle, is the visible outer part of the ear. It has a complex innervation, with different nerves supplying various parts of the ear. Understanding the specific nerves involved in the innervation of the pinna is crucial for medical students to appreciate the sensory and motor functions of the ear.

**Why the Correct Answer is Right**
The great auricular nerve, a branch of the cervical plexus (C2 and C3 spinal nerves), provides sensory innervation to the majority of the skin of the pinna. This nerve originates from the cervical plexus and travels upward to reach the ear, where it divides into multiple branches to supply the skin of the pinna. The great auricular nerve is responsible for transmitting sensory information, such as touch and pressure, from the skin of the pinna to the central nervous system.

**Why Each Wrong Option is Incorrect**
**Option A:** The auriculotemporal nerve, a branch of the mandibular division of the trigeminal nerve (V3), primarily supplies the skin of the temporal region and the external auditory meatus, but not the majority of the skin of the pinna.

**Option B:** The auricular branch of the vagus nerve is responsible for parasympathetic innervation to the middle ear, particularly the tensor tympani and the stapedius muscles, but it does not supply the skin of the pinna.

**Option C:** The posterior auricular nerve, a branch of the facial nerve (cranial nerve VII), provides motor innervation to the posterior auricular muscle, which is responsible for moving the pinna, but it does not supply the skin of the pinna.

**Clinical Pearl / High-Yield Fact**
Remember that the great auricular nerve is a branch of the cervical plexus, which makes it a key landmark for identifying the location of the cervical plexus during surgical procedures.

**✓ Correct Answer: D. Great auricular nerve**