Lesser Occipital Nerve, Lateral View

Description

Arising from the cervical plexus, the lesser occipital nerve (typically C2, with variable C3 contribution) is traced in lateral profile as it ascends along the posterior border of the sternocleidomastoid muscle from the upper neck toward the mastoid process and lateral occipital scalp. Superiorly, its cutaneous branches spread over the area posterior to the auricle, running superficial to the investing fascia as they approach the superior nuchal line. Surrounding landmarks in this side view include the auricle and external acoustic region, the adjacent occipital and temporal portions of the skull, and layered facial and cervical musculature that frames the nerve’s course. Color coding separates nerves from regional veins and the red muscle planes. Clinically, this nerve matters because its superficial course at the posterior margin of sternocleidomastoid makes it a frequent culprit in cervicogenic headache patterns and a target for diagnostic and therapeutic blocks. A small injection placed just posterior to the sternocleidomastoid near the level of the mastoid can anesthetize the posterolateral scalp and retroauricular skin, but overlap with the greater occipital and great auricular nerves often confounds sensory maps. Surgical planning also benefits from a clear depiction of this anatomy, since posterior cervical incisions, lymph node biopsies, and flap elevation near the mastoid can produce painful neuroma or postoperative dysesthesia if the lesser occipital nerve is transected. Surface anatomy is the key. Neurology and pain medicine educators can pair this figure with headache algorithms and peripheral nerve block technique guides, while anatomy faculty will find it effective for teaching cervical plexus cutaneous branches in head and neck dissection or prosection labs. Medical publishers can also drop it into otologic, dermatologic, and plastic surgery texts when explaining retroauricular sensation and incision planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.