Cranial Nerves I–IV & VI: What They Control and How Upper Cervical Care May Help

When people hear “chiropractor,” they usually think of sore backs or stiff necks. But in the world of upper cervical care, especially with the Blair technique, we’re actually working much closer to the brain—and sometimes that makes a big difference in how your entire nervous system functions.

Let’s talk cranial nerves. There are 12 of them, and they’re responsible for everything from sight and smell to eye movement and facial function. Many of these nerves originate in the brainstem, which just so happens to live snugly where the skull meets the top of your neck—exactly where we adjust.

In this post, we’re focusing on Cranial Nerves I–IV and VI. Why not all 12? Because these particular nerves help you smell, see, and move your eyes—things you probably use every day without a second thought… until something starts feeling off.

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CN I – Olfactory Nerve

Job: Smell

Pathway: From the nose directly to the olfactory bulb (bypasses the brainstem)

Common Symptoms if Dysfunctional:

• Loss of smell (anosmia)

• Diminished taste

• Disconnection from certain emotional cues (smell is deeply tied to memory and mood)

Blair Upper Cervical Connection:

Even though CN I doesn’t pass through the brainstem, the integration of smell within the brain is still part of the broader nervous system function. Head injuries—often responsible for smell loss—can also shift the upper cervical spine. When that shift is corrected, patients often report clearer mental function and improved sensory awareness. It’s not a guarantee, but it’s not uncommon either.

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CN II – Optic Nerve

Job: Vision

Pathway: From the retina to the brain’s visual cortex

Common Symptoms if Dysfunctional:

• Blurry vision

• Tunnel vision or blind spots

• Light sensitivity

Blair Upper Cervical Connection:

The optic nerve also bypasses the brainstem, but here’s the catch: blood flow to the visual processing areas comes from the vertebral arteries, which travel through the upper cervical spine. A misaligned atlas can kink or compress those arteries. Many patients report improvements in visual clarity or pressure after upper cervical correction—not by directly “fixing” the eyes, but by restoring better blood and nerve flow to the areas that control them.

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CN III – Oculomotor Nerve

Job: Eye movement (up, down, inward), pupil constriction, eyelid elevation

Pathway: From the midbrain (brainstem) to several eye muscles

Common Symptoms if Dysfunctional:

• Drooping eyelid

• Difficulty focusing

• Eye drifting outwards

• Double vision or light sensitivity

Blair Upper Cervical Connection:

CN III emerges from the midbrain, which sits directly behind the top two vertebrae. If your atlas (C1) shifts out of alignment, it can put subtle pressure or irritation on the brainstem, disrupting the nerve’s ability to fire correctly. That’s why some people with weird eye symptoms, dizziness, or even migraines find relief after a Blair correction—it’s not magic; it’s neurology.

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CN IV – Trochlear Nerve

Job: Controls the superior oblique muscle, allowing downward and inward eye movement

Pathway: Also from the midbrain to the eye

Common Symptoms if Dysfunctional:

• Difficulty reading (especially up close)

• Trouble going down stairs

• Eye strain or head tilting to compensate

Blair Upper Cervical Connection:

The trochlear nerve is the smallest cranial nerve but can cause big issues when compromised. Because it also originates in the midbrain, even slight distortion of the brainstem due to upper cervical misalignment may affect how this nerve performs. We’re not saying every vision issue is a neck issue—but it’s worth considering if you’ve had head trauma, whiplash, or persistent visual strain.

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CN VI – Abducens Nerve

Job: Moves the eye outward (abduction) via the lateral rectus muscle

Pathway: Originates from the pons (part of the brainstem) and travels a long route to the eye

Common Symptoms if Dysfunctional:

• Eye drifting inward (cross-eyed appearance)

• Double vision when looking to the side

• Head turning to compensate

Blair Upper Cervical Connection:

CN VI is particularly sensitive because it travels a long and winding path, making it vulnerable to pressure and inflammation. Since it comes from the pons, a structure directly influenced by the alignment of the upper cervical spine, a misaligned atlas could be adding stress to its function. Blair adjustments help to reduce that interference—not by moving the nerve itself, but by relieving pressure at the source: the brainstem.

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Why This Matters

If you’ve ever experienced:

• Unexplained dizziness

• Eye fatigue

• Visual disturbances

• Weird head pressure

• Sensory changes in smell or focus

…it’s not unreasonable to look up—literally—to the top of your spine.

The upper cervical spine plays a crucial role in how your brain and body talk to each other. When the atlas or axis is misaligned (even slightly), it can disrupt blood flow, irritate the brainstem, and lead to issues that seem random or unrelated.

At our office, we don’t guess. We use precise 3D imaging and gentle corrections to restore balance to the nervous system, helping the cranial nerves function the way they’re supposed to.

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Ready to get your head on straight—literally?

Let’s schedule a consult and talk about what’s really going on at the top of your neck. The results might surprise you.

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