The vertebral arteries run up the back of your neck, threaded through small openings in the neck bones themselves. That bony path is what makes them vulnerable in a completely different way than the carotids — and why the symptoms can look nothing like what people expect from a “stroke.”
The four segments, and why they matter
V1
From where it branches off, up to where it enters the bony canal. Relatively mobile.
V2
Inside the bony canal through the neck vertebrae. Fixed in bone, so the artery is dragged along with whatever the neck bones do.
V3
The stretch between the top vertebra and the skull, where the artery loops and turns sharply. In the published martial-arts case reports, this is the segment where vertebral injuries cluster.
V4
Inside the skull, after piercing the covering of the brain. Dissections here carry different considerations than the neck segments.
Two different pictures are worth keeping apart here. Among vertebral dissections in the general population — most of which have nothing to do with sport — V2 and V3 are involved at roughly similar rates, with fewer at V1 and fewer still at V4. The clustering at V3 described above is a separate finding, drawn from the much smaller pile of martial-arts case reports. Neither figure corrects the other; they are counts of different groups of people.
Why the symptoms look different
The vertebral arteries feed the back of the brain — the brainstem and cerebellum, which handle balance, coordination, eye movement, and swallowing. So a vertebral dissection may announce itself as sudden vertigo, clumsiness on one side, double vision, trouble swallowing, or a severe pain at the back of the head and neck, rather than the classic face-droop-and-arm-weakness picture people associate with stroke.
This is exactly why these injuries get missed: a dizzy, nauseated grappler with a stiff neck reads as dehydration or a bad shot to the head, not as an arterial emergency.
How grappling loads these arteries
V2 is locked inside bone and V3 loops around the top of the spine, and in the published case reports from martial arts, vertebral injuries cluster at V3. Rotation is the theme that keeps recurring in survivor accounts. What no one has established is why — whether that anatomy explains it, or something else does. The positions below load those segments; that is a description of loading, not a claim about cause:
- Neck cranks and twisting escapes — rotation at end range under force.
- Stack passing — the neck folded and often twisted under a partner’s full weight.
- Inversions and ashi garami scrambles — the head bearing load in unusual orientations.
- Takedowns landing on the head or shoulder — sudden rotation and impact together.
As with the carotid, this is a description of loading patterns that appear in survivor accounts — not a risk ranking, and not a claim about how likely any position is to cause harm.