A patient presents with swelling under the left ear lobule and complains of pain. Which of the following structures is the likely cause of the pain?

Correct Answer: D. Greater auricular nerve

Swelling under the ear lobule with pain points to the greater auricular nerve (GAN), a branch of the cervical plexus (C2–C3). The GAN is the primary sensory nerve to the auricle and the skin over the parotid region and lower ear. When pathology (infection, inflammation, trauma, or lymphadenopathy) affects the area beneath the ear lobule, the GAN is compressed or irritated, producing sharp, localized pain. This is clinically relevant in India where parotitis (viral or bacterial), cervical lymphadenitis, and post-vaccination lymph node enlargement are common presentations. The GAN's superficial course along the posterior border of the sternocleidomastoid muscle makes it vulnerable to compression. Unlike the facial nerve (which innervates muscles of facial expression and carries taste from anterior 2/3 tongue), the GAN is purely sensory to the auricle and surrounding skin. The auriculotemporal nerve (a branch of V3) supplies the temporal region and anterior auricle, not the area directly under the ear lobule. The investing layer of deep cervical fascia is a structural layer, not a nerve, and does not cause localized pain on its own.

Why the other options are wrong

A. Investing layer of deep cervical fascia — This is a structural fascial layer, not a nerve. While it may be involved in swelling (as part of the fascial compartment), it does not directly cause pain. Pain arises from nerve irritation or compression, not from fascia itself. This is a distractor that confuses anatomy layers with neural structures. B. Facial nerve — The facial nerve (CN VII) innervates muscles of facial expression and carries parasympathetic fibers to salivary glands; it does not provide sensory innervation to the auricle or skin under the ear lobule. Facial nerve pathology (Bell's palsy) presents with facial weakness, not localized ear pain. This option traps students who confuse the facial nerve's broad head/neck involvement with auricular sensation. C. Auriculotemporal nerve — The auriculotemporal nerve (V3 branch) supplies the anterior and superior auricle and temporal skin, not the area directly beneath the ear lobule. It also carries postganglionic parasympathetic fibers to the parotid gland. Swelling under the ear lobule (posterior/inferior auricle) is outside its sensory distribution. This is a classic NBE trap pairing auricular pathology with the wrong auricular nerve.

High-Yield Facts

Mnemonics

GAG for Greater Auricular nerve Greater Auricular nerve = Great sensory nerve for Auricle and Generally causes pain when compressed. Arises from cervical plexus (C2–C3), not cranial nerves. Auricular Nerve Map (3-way split) GAN (C2–C3) = posterior/inferior auricle + ear lobe + parotid skin. Auriculotemporal (V3) = anterior/superior auricle + temporal. Vagus (CN X) = small part of auricle (Arnold's nerve). Use this to rule out V3 and CN VII.

NBE Trap

NBE pairs "swelling under ear" with auriculotemporal nerve (V3) to trap students who memorize "auricular nerve = V3" without learning the specific anatomical territories. The posterior/inferior location is the key discriminator—only GAN covers this zone.

Clinical Pearl

In Indian clinical practice, post-vaccination cervical lymphadenopathy (especially after COVID-19 or routine immunizations) commonly compresses the GAN, causing sharp ear pain that is often misattributed to otitis media. Palpating the posterior border of the sternocleidomastoid and eliciting tenderness confirms GAN involvement, guiding conservative management rather than unnecessary ENT referral.

_Reference: Bailey & Love Ch. 38 (Head and Neck Anatomy); Robbins Ch. 7 (Nervous System); Harrison Ch. 379 (Cranial Nerves and Cervical Plexus)_