Greater and lesser occipital nerve: the anatomy that decides the injection

There is more than one occipital nerve, they supply different territories, and which one is carrying your pain determines where the injection goes. Getting that wrong is one of the ordinary reasons a block does nothing.

Three nerves, three territories

• Greater occipital nerve. The main one, arising largely from the C2 nerve root. It emerges near the midline at the base of the skull and supplies the back of the head from there up and over toward the crown. Most of what is meant by an occipital nerve block targets this nerve.
• Lesser occipital nerve. Arising from C2 and C3, running further out to the side. It supplies the area behind and above the ear. Pain that sits behind the ear rather than at the midline points here.
• Third occipital nerve. From C3, supplying a small area low at the back of the head. It carries particular significance because it also innervates the C2-C3 facet joint, which makes it relevant when the neck joints are the source — see is my headache coming from my neck.

How the territory maps to what you feel

A useful exercise before your appointment is to trace the pain with a finger rather than describe it. Pain running from the base of the skull up over the back of the head, sometimes reaching the top or behind the eye, follows the greater occipital nerve. Pain sitting behind and above the ear follows the lesser. Both can be involved at once, which is why blocks are sometimes done at both sites — and how long that relief holds varies widely, see how long a block lasts.

This is also why one-sided pain in this distribution, with tenderness over the nerve and shooting or electric-shock quality, raises occipital neuralgia rather than migraine — see occipital neuralgia or migraine.

Why the head and the face share a pain system

The reason a neck nerve can produce pain behind the eye is convergence. Sensory fibers from the upper cervical roots and from the trigeminal nerve, which supplies the face, meet in the same region of the brainstem — the trigeminocervical complex. Input arriving from the back of the head is processed alongside input from the front of it, and can be felt there.

That anatomy is why blocking a nerve at the back of the head can help a headache felt at the front, which otherwise makes no sense at all.

The artery that changes the technique

The occipital artery runs alongside the greater occipital nerve. That single anatomical fact accounts for most of what is distinctive about doing this injection properly.

A landmark technique locates the nerve by measuring from bony points — typically along the line between the occipital protuberance and the mastoid process. It is a reasonable estimate of where the nerve usually is, and both the nerve and the artery vary in position between people. Ultrasound shows both, in real time, with Doppler to distinguish vessel from nerve, and shows the needle advancing. See ultrasound and fluoroscopic guidance.

So imaging is doing two jobs: keeping the injectate out of the artery — the main safety consideration, covered in side effects and risks — and making a negative result meaningful. Both matter — see why image guidance matters.

Why this matters for your appointment

If a previous block was placed at the standard greater occipital site and did nothing, the useful question is not only whether it was guided, but whether it was aimed at the right nerve. Pain behind the ear treated with a midline greater occipital block is a plausible reason for a genuine non-response. That is a fixable problem rather than evidence the approach does not work for you.

Common questions

Which occipital nerve is mine?

It is worked out from where you trace the pain and where the tenderness is, then confirmed by the response to blocking it. Bring a clear description, or trace it on yourself at the visit — contact us to arrange one.

Can both sides be blocked at once?

Yes, bilateral blocks are routine where the pain is on both sides. See occipital nerve block.

Why does blocking a nerve in my neck help pain behind my eye?

Because upper cervical and trigeminal sensory fibers converge in the trigeminocervical complex, so pain from the back of the head can be felt at the front. It is the same convergence that makes neck involvement so common in migraine — see is my headache coming from my neck.

Is the third occipital nerve blocked the same way?

It is a different and more precise target, and it is usually relevant when the C2-C3 facet joint is the suspected source — which is a cervicogenic picture. See cervicogenic headache treatment.

Sources

1. Zhang H, Yang X, Lin Y, Chen L, Ye H. The efficacy of greater occipital nerve block for the treatment of migraine: a systematic review and meta-analysis. Clin Neurol Neurosurg. 2018;165:129-133. doi:10.1016/j.clineuro.2017.12.026
2. Inan LE, Inan N, Karadaş Ö, et al. Greater occipital nerve blockade for the treatment of chronic migraine: a randomized, multicenter, double-blind, and placebo-controlled study. Acta Neurol Scand. 2015;132(4):270-277. doi:10.1111/ane.12393