Your brain itself feels nothing. It has no pain receptors at all. What actually hurts during a headache are the tissues surrounding your brain: the protective membranes wrapped around it, the blood vessels running through those membranes, and the muscles and nerves of your scalp and neck. If you could peer inside your skull during a headache, you’d see swollen blood vessels, inflamed tissue, and overactive nerves firing distress signals, all happening in structures most people never think about.
Your Brain Can’t Feel Pain
This is the most counterintuitive fact about headaches: the organ that processes all your pain is completely numb to its own. Brain tissue lacks the nerve endings (called nociceptors) that detect painful stimuli. Surgeons can and do operate on the brain while patients are awake, touching and even cutting brain tissue without causing pain. So when your head throbs, the pain is coming from the structures around your brain, not from the brain itself.
The real source of headache pain is the meninges, a set of three protective membranes that wrap around your brain and spinal cord. The outermost layer, called the dura mater, is loaded with sensory nerve fibers, especially near its blood vessels. The meninges are, in fact, the only pain-sensitive structure inside the cranium. Everything that happens during a headache, whether it’s a mild tension headache or a severe migraine, ultimately involves irritating or inflaming these membranes and the nerves threaded through them.
What a Tension Headache Looks Like
A tension headache, the most common type, starts outside the skull. The muscles of your scalp, forehead, jaw, and neck tighten and develop hypersensitive knots called trigger points: small, taut nodules in the muscle fibers. Research shows that the tenderness of these pericranial muscles directly correlates with both the intensity and frequency of headaches. People with chronic tension headaches have measurably stiffer trapezius muscles even on days when they don’t have a headache, suggesting a baseline state of muscle tension that lowers the threshold for pain.
If you could see this from the inside, it would look like bands of contracted muscle squeezing around your skull, compressing the sensory nerves that run through and alongside them. That’s why a tension headache feels like a tight band or pressure rather than a pulsing throb. The pain signals travel along the same trigeminal nerve network involved in migraines, but the initial trigger is muscular rather than vascular.
What Happens Inside Your Head During a Migraine
A migraine is a far more complex event, and if you could watch it unfold in real time with imaging technology, you’d see a dramatic cascade moving across your brain in stages.
The Electrical Wave
In people who experience migraine with aura (visual disturbances, tingling, or speech changes), the event begins with something called cortical spreading depression. This is a slow wave of intense electrical activity that rolls across the surface of the brain at roughly 2 to 3 millimeters per minute, like a power surge followed by a blackout. Functional brain imaging captures this as a propagating wave of increased blood oxygenation (the surge), followed by a zone of suppressed activity (the blackout). On an MRI, you’d see this as a bright band sweeping across the brain’s surface, trailed by a darker zone of depressed activity. This wave is what produces the visual sparkles, zigzag lines, or numbness that migraine sufferers recognize as an aura.
Blood Vessels Swell and Nerves Fire
As that electrical wave reaches the meninges, it triggers the trigeminal nerve, the large nerve responsible for sensation in your face and head. The nerve endings embedded in the dura mater release a flood of chemical signals. The most powerful of these is a protein called CGRP, the strongest vessel-dilating substance known in the human body. Along with it come other signaling molecules that widen blood vessels and trigger inflammation.
If you could see this moment inside your skull, the blood vessels in the dura mater would visibly engorge and swell. The tissue around them would become inflamed as immune cells called mast cells activate and release pro-inflammatory chemicals, including TNF-alpha and various interleukins. Fluid leaks from blood vessel walls into the surrounding tissue, a process called plasma protein extravasation. The dura essentially becomes a site of localized inflammation, swollen, hot with increased blood flow, and bristling with sensitized nerve endings.
The Pain Signal Travels Inward
Those sensitized nerve fibers in the meninges send signals down into the brainstem through the trigeminal pathway. The signals arrive at a relay station in the upper spinal cord and lower brainstem, where they converge with nerve inputs from the skin and muscles of the face and neck. This convergence is why migraines can make your face, scalp, and neck feel tender even though the inflammation is happening inside your skull. Second-order neurons then carry the pain signal upward through the brainstem to the thalamus and ultimately to the cortex, where you consciously experience it as pain.
Meanwhile, serotonin levels drop. Serotonin normally helps constrict blood vessels and modulate pain signaling. When levels fall, the vessel-dilating effects of nitric oxide go unopposed, contributing to further vascular swelling and pain. This is why medications that boost serotonin activity in the brain have long been used to treat migraines.
Cluster Headaches Light Up a Different Region
Cluster headaches, sometimes called “suicide headaches” because of their extraordinary intensity, involve a different brain region. PET scan imaging during active cluster headache attacks has shown activation of the hypothalamus, a small structure deep in the brain that controls your body clock, hormone release, and autonomic functions like sweating and pupil size. This hypothalamic involvement explains why cluster headaches follow clock-like patterns, often striking at the same time each day, frequently during sleep, and cycling in seasonal bouts. The trigeminal nerve is still the pain highway, but the generator of the attack appears to sit in this deep brain structure rather than in the cortex.
What the Aftermath Looks Like
Even after a migraine’s pain phase ends, your brain hasn’t returned to normal. Imaging studies from the 1980s onward have shown that the blood flow changes outlast the headache itself. During the aura phase, blood flow drops abnormally low in affected brain regions. As the headache progresses, blood flow gradually shifts from abnormally low to abnormally high. This hyperperfusion, essentially an oversupply of blood, persists after the pain resolves. This is the postdrome phase, often called a “migraine hangover,” and it explains why people feel foggy, drained, or slightly off for hours or even a day after the headache itself is gone. The plumbing inside your head is still recalibrating.
The Same Alarm System, Different Triggers
What ties all headache types together is the trigeminal nerve system. Whether the initial trigger is tight muscles, swelling blood vessels, electrical waves across the cortex, or hypothalamic activation, the pain ultimately channels through the same network of nerve fibers in and around the meninges. The brain itself sits at the center of the event, completely unfeeling, while the membranes wrapped around it absorb the full impact. The pain you feel in your head is really the pain of those membranes and the nerves running through them, amplified and interpreted by the very organ they’re designed to protect.