Intervertebral foramen

The spine is made up of individual bones stacked on top of one another. Viewed from the side, each of two adjacent vertebrae has a ring-shaped structure attached behind its front portion, or body. The columns extending backward from there (the vertebral pedicles) have notches along their upper and lower edges. Where the lower notch of the upper vertebra meets the upper notch of the lower vertebra, a pair of openings forms, one on each side. These are the intervertebral foramina.

The front boundary of each opening is formed by the vertebral body and the intervertebral disc between the vertebral bodies, while the back boundary is formed by the facet joint. Unlike the spinal canal, which runs vertically through the center of the spine, the intervertebral foramina open out to the left and right.

Nerve roots branching off from the spinal cord pass through these passages, along with small blood vessels and fatty tissue beside them. These nerves extend to the arms and hands from the neck, and to the buttocks and legs from the lower back. In the lumbar spine, for example, a nerve root usually exits through the opening below the vertebra with the same number. The fourth lumbar nerve root exits through the opening between the fourth and fifth lumbar vertebrae.

The intervertebral foramina in the cervical spine open diagonally forward and outward.

The size of the intervertebral foramina is not fixed; it changes with movement.

• Bending forward — The space between the vertebrae above and below increases, widening the passage.
• Bending backward — The passage narrows.
• Bending or turning to one side — The passage on the side you bend or turn toward narrows.

A loss of intervertebral disc height or a change in the shape of a facet joint can also change the size of the passage. These changes commonly occur naturally with age. Imaging reveals degenerative changes around the intervertebral foramina in many people who have no symptoms as well.

Normally, you do not notice your intervertebral foramina. However, if bending your neck or lower back backward or to one side brings on tingling extending from your neck into your shoulder and arm, or a pulling sensation spreading from your lower back into your buttock and leg, structures around the passage may be affecting a nerve in that position. These sensations can also present as radicular pain spreading into the limbs. Changing position often brings relief.

• Avoid staying in one position for too long. If you have spent a long time at a desk with your head tilted backward or to one side, get up frequently and gently move your neck and lower back.
• Try moving in comfortable directions. When your neck or lower back feels stiff, try moving slowly forward, backward, and from side to side within a pain-free range. Avoid forcing yourself to bend backward in a painful direction.
• Strengthen your deep muscles. Exercises that firmly engage the abdominal, back, and buttock muscles help support the spine so it does not lean to one side.
• Check your pillow and chair. A pillow that is too high or too low can bend your neck to one side. A chair that supports your lower back is more comfortable.
• Do not be too alarmed by imaging findings. Even if you are told that the opening looks narrow on a scan, this is a change commonly seen in people without symptoms, too. It is important to consider both your current level of discomfort and the movements you can perform in daily life.

Seek a medical evaluation if tingling or weakness in an arm or leg lasts more than a few days or gradually worsens, if you frequently drop things from one hand, or if pain persists enough to wake you at night. Altered bladder or bowel sensation, or sudden weakness in both legs, are signs that require immediate medical attention.