By Drew Hall, D.C., Upper Cervical Chiropractor
Of every headache location, this is the one where the anatomy points most directly at the upper cervical spine. Pain at the base of the skull sits over the suboccipital region — the small space bounded by the occiput, the atlas, and the axis — and almost every structure in that space is capable of producing head pain.
What lives in that space
The suboccipital muscles. Rectus capitis posterior major and minor, obliquus capitis superior and inferior. Small, deep, and remarkable for their sensory density: Kulkarni and colleagues measured muscle spindle densities of 242 per gram in obliquus capitis inferior and 190 per gram in obliquus capitis superior (Neurology India 2001;49:355–359). Densities above 50 per gram characterize muscles built for positional sensing rather than force.
The greater occipital nerve. The medial branch of the C2 dorsal ramus, which emerges below obliquus capitis inferior, wraps around it, pierces semispinalis capitis, and passes through the trapezius aponeurosis to supply the scalp. Bovim’s anatomical work found the nerve invested by semispinalis in 90% of specimens and trapezius in 45%. It is a nerve that travels through muscle, which makes muscle tone part of its environment.
The atlanto-occipital and lateral atlanto-axial joints. Both are proven sources of head pain. Dreyfuss, Michaelsen, and Fletcher distended them in asymptomatic volunteers in 1994 and mapped the referral into the suboccipital region and over the head. Aprill, Axinn, and Bogduk demonstrated with controlled diagnostic blocks that the lateral atlanto-axial (C1–2) joint produces occipital headache (Cephalalgia 2002;22:15–22).
The myodural bridge. Rectus capitis posterior minor connects by dense fibrous tissue to the posterior atlanto-occipital membrane and onward to the cervical spinal dura — described by Hack and colleagues in 1995 and confirmed by a systematic review of 26 anatomical studies, which found strong evidence for dural connections from rectus capitis posterior minor, rectus capitis posterior major, and obliquus capitis inferior (Spine 2017;42:49–54). Zheng and colleagues established the bridge is composed of parallel type I collagen — fibers oriented for transmitting tension (The Spine Journal 2018).
Why pain here does not stay here
The reason suboccipital pain is felt over the head, behind the eye, or in the temple is convergence.
Upper cervical afferents from C1 through C3 terminate in the same brainstem region as descending trigeminal fibers — the trigeminal nucleus caudalis, extending to the C2 and C3 segments. Second-order neurons in this trigeminocervical complex receive both inputs and cannot distinguish them.
Bartsch and Goadsby demonstrated that this convergence is functionally active in both directions. Recording from 29 nociceptive neurons in the rat C2 dorsal horn receiving convergent trigeminal and cervical input, they showed noxious dural stimulation sensitized second-order neurons receiving cervical input (Brain 2003;126:1801–1813). Earlier, they showed that stimulating the greater occipital nerve increased central excitability to dural afferent input (Brain 2002;125:1496–1509). Their conclusion was that this mechanism may underlie the referral of pain between trigeminal and cervical structures, and contribute to cervical hypersensitivity in migraine.
This is the strongest published foundation for upper cervical involvement in headache, and it is worth being precise about what it shows: cervical and dural inputs share neurons and sensitize each other. It does not show that a positional misalignment causes headache.
Mechanisms with different levels of support
Since these come up constantly, here is where each actually stands.
The myodural bridge — established anatomy, confirmed across many independent studies. Its clinical significance in headache is plausible and still under investigation.
The dentate ligament-cord distortion hypothesis — proposed by Grostic in the Chiropractic Research Journal in 1988. The denticulate ligaments genuinely anchor the spinal cord to the dura. The hypothesis that upper cervical misalignment transmits meaningful tension through them to the cord is a single-author proposal in a non-indexed journal, never validated in controlled research.
Flanagan’s craniocervical choke point — a hypothesis regarding obstruction of cerebrospinal fluid and venous drainage at the skull base. Anatomically thoughtful, single-author, not independently validated.
I include all three because they are part of the conversation in my field. They are not equivalent, and presenting them as though they were would be misleading.
What suboccipital headache typically feels like
A deep ache or pressure at the base of the skull, often one-sided and staying on that side. It frequently spreads upward and forward over the head, sometimes to behind the eye. It is commonly worse after sustained postures — a long drive, a day at a screen — and often worse in the morning after a night on the wrong pillow. Neck movement, particularly rotation or looking up, may provoke it. The suboccipital area is often tender to firm pressure.
When it is not mechanical
Pain at the base of the skull sits close to structures where sudden problems are dangerous.
Thunderclap onset — maximal within a minute — is an emergency.
Occipital headache with fever, neck stiffness, and light sensitivity may be meningitis and is an emergency.
Sudden occipital or neck pain with dizziness, double vision, slurred speech, unsteadiness, or facial numbness may indicate vertebral artery dissection or posterior circulation stroke and requires emergency care. Dissection can follow trauma, heavy lifting, or forceful neck rotation — including rotational manipulation, which is one reason I do not use it.
Progressive worsening, or headache worse when lying flat or on waking with vomiting, warrants prompt imaging.
The upper cervical approach
Specific objective testing establishes whether a misalignment is present before anything is imaged. Cone beam CT then details the atlas and axis in three dimensions — important here, since C1-2 anatomy varies considerably and the correction is calculated from real structure.
No popping, twisting, or yanking. Retention is the measure: a held correction lets suboccipital tone settle and irritated joints regain motion. Healing takes time — tone patterns held for years soften over months.
The honest limit: upper cervical misalignment has not been proven to cause headache at the base of the skull. The referral patterns are experimentally demonstrated, the convergence physiology is published in Brain, and the myodural bridge is confirmed anatomy — the causal claim still exceeds the evidence.
This article is for educational purposes and is not medical advice. It does not establish a doctor-patient relationship. Thunderclap headache, occipital headache with fever or neck stiffness, or sudden neck pain with dizziness, double vision, slurred speech, or unsteadiness is a medical emergency.
