The vertebral arteries are a pair of major blood vessels supplying blood to the brain. Located in the neck, one on each side of the body, they are part of the vertebrobasilar system. This system delivers oxygenated blood to specific regions of the brain and upper spinal cord.
Its Path Through the Neck
Each vertebral artery typically originates from the subclavian artery, located below the collarbone. From there, it ascends through the neck, passing between muscles like the longus colli and anterior scalene. It then usually enters the transverse foramen of the sixth cervical vertebra (C6), though it can occasionally enter at C7.
The artery continues upward, traveling through the transverse foramina of each cervical vertebra, usually from C6 to C2. These bony tunnels protect the artery as it ascends. After exiting the transverse foramen of the axis (C2), the artery takes a complex course. It curves laterally and superiorly, passing through the transverse foramen of the atlas (C1), then wraps around the posterior arch of C1 before entering the skull. This winding path provides flexibility for neck movements.
Reaching and Supplying the Brain
After its journey through the neck, each vertebral artery enters the skull through the foramen magnum, a large opening at the base. Inside the skull, the two vertebral arteries merge. This union typically occurs at the lower border of the pons, a part of the brainstem, forming the single, midline basilar artery. Together, the vertebral and basilar arteries constitute the vertebrobasilar system, supplying the posterior portion of the brain.
This system delivers blood to several brain regions. It provides oxygenated blood to the brainstem, which controls many involuntary life-sustaining functions like breathing and heart rate. The cerebellum, responsible for coordination, balance, and fine motor skills, also receives blood from this system. Parts of the posterior cerebrum, including regions of the occipital and temporal lobes involved in vision and cognitive functions, are supplied by branches of the vertebrobasilar arteries.
Why Its Location Is Important
The anatomical path of the vertebral artery, particularly its close association with the cervical spine, makes it susceptible to mechanical influences. As it travels through the bony tunnels of the cervical vertebrae and curves around the atlas (C1), it can be affected by extreme neck movements. Rapid or forceful rotation, extension, or flexion of the neck can place mechanical stress on the artery, including stretching, compression, or twisting.
Such mechanical stress, especially at the C1-C2 level where the artery makes a loop, may lead to issues like arterial dissection, a tear in the inner lining of the artery. Since the vertebrobasilar system supplies brain areas involved in balance, vision, coordination, and consciousness, any disruption to blood flow can have noticeable consequences.
Symptoms like dizziness, vertigo, visual disturbances, or trouble with coordination can indicate reduced blood flow. Understanding this anatomical vulnerability helps explain why certain neck movements or spinal conditions can impact the function of these blood vessels.