Three nerves, one field
The greater occipital nerve arises from the dorsal ramus of C2 and pierces the semispinalis capitis before fanning across the posterior scalp. The lesser occipital nerve, from the cervical plexus, covers the lateral occipital surface, and the third occipital nerve serves the suboccipital midline.
Together they define a continuous posterior cranial field bounded below by the superior nuchal line.
Surface landmarks
The field is delimited in practice by the external occipital protuberance, the mastoid processes and the nuchal line — landmarks that are palpable and reproducible.