13 Facts About the Spinal Cord

Like a slender, fragile vine made of highly sensitive tissue and a billion neurons, your spinal cord is like a living extension of your brain running through the body. It’s also one of the most important parts of anatomy. It serves no less of a function than connecting your brain to your body and sending out all the vital nerve signals that allow you to do everything from picking up a pen to walking across a room. Here are 15 facts about this amazing body part.

1. The spinal cord is part of the central nervous system.
2. It’s like the internet, but for nerve signals.
3. The spinal cord functions independently of the brain.
4. It controls voluntary and involuntary movement of the muscles.
5. It’s less than an inch in diameter.
6. The spinal cord has gray and white matter, just like the brain.
7. It stops growing when you turn 5.
8. Your spinal cord can remember pain.
9. The spinal cord passes through 33 vertebrae.
10. It’s divided into 31 segments.
11. Damage to the spinal cord can cause paralysis.
12. A spinal tap might give you a headache.
13. Stem cells can repair spinal cord injuries.

The spinal cord is part of the central nervous system.

The brain and the spinal cord make up the central nervous system. The brain is in charge of thoughts, interpretations of the external environment through our senses, and our physical movements. The spinal cord is the main source of communication between the body and the brain. This is why spinal cord injuries disrupt the flow of information between the brain and other body parts.

It’s like the internet, but for nerve signals.

The spinal cord is a bundle of nerves sending and receiving a vast amount of signals from all over the body. It starts at the base of your brain, runs down the backbone, and terminates between your first and second lumbar vertebrae, in the lower back.

Not only does the spinal cord act as a hub for all nerve signals traveling between the brain and the body, but many receptors for pain and other stimuli communicate with the spinal cord through peripheral nerves. These small fibrous nerves are all over the body and send constant communication to the brain.

The spinal cord functions independently of the brain.

The spinal cord does not merely do the brain’s bidding. It can also generate and send signals directly to the muscles when necessary.

It controls voluntary and involuntary movement of the muscles.

The spinal cord is responsible for passing along the nerve signals that control not only voluntary movements like picking up a spoon or opening a door, but the involuntary movements of the diaphragm, bowels, and bladder.

It’s less than an inch in diameter.

You might assume that the spinal cord is very thick, since it serves such an important function in the human body. However, it gets its job done while being only 0.4 to 0.6 inches in diameter.

The spinal cord has gray and white matter, just like the brain.

The brain and the spinal cord contain the same essential materials, but organize them differently. In the brain, the gray matter comprises the outer portion of the brain’s physical material. In the spinal cord, the gray matter hangs out in the inner part of the cord. Gray matter is an accumulation of neurons that deal with either motor or sensory function. White matter contains the wiring for communication between the brain and other structures.

It stops growing when you turn 5.

The spinal cord undergoes a lot of growth in your first four to five years and reaches lengths of 16 to 20 inches, but from then on, it’s done. Your body keeps growing around the spinal column, which stays exactly as long as it was when you reached the age of 5.

Your spinal cord can remember pain.

When you experience an instance of major pain—like you stub your toe incredibly hard, or even break it—the neurons in your spinal cord will carry signals more easily to the nerves in your injured toe for several days, making the toe feel more sensitive. This is the result of a molecule thought to be the precursor to memory, known as PKMzeta. Your spinal cord is especially sensitive to this molecule and “records” instances of pain as a result.

The spinal cord passes through 33 vertebrae.

Between all those bony vertebrae stacked one on top of the other along your back are tiny spaces just big enough for your slender spinal cord to pass through.

It’s divided into 31 segments.

Each segment has many sets of nerves that exit the spinal cord: eight cervical sets, 12 thoracic, five lumbar, five sacral, and one coccygeal nerve.

Damage to the spinal cord can cause paralysis.

When the spinal cord is severed at any point due to injury, a number of resulting forms of paralysis can occur. Complete paralysis is when almost all sensory feeling and ability to control movement are lost below the injury. Incomplete paralysis refers to situations in which some motor or sensory function is preserved.

Other terms are quadriplegia or tetraplegia, which means the arms, hands, trunk, legs, and pelvic organs are all affected by the injury; and paraplegia, which means paralysis extends to all or part of the trunk, legs and pelvic organs. About 58 percent of spinal cord injuries result in paraplegia and about 42 percent in quadriplegia.

A spinal tap might give you a headache.

A spinal tap is a procedure in which a large needle is inserted into the spinal cord to remove fluid for medical tests. A very common side effect of spinal taps is a wretched headache that scientists can’t fully explain. One theory is that cerebrospinal fluid continues to leak out of the tiny hole left by the puncture, and the fluid volume loss somehow triggers the headache.

Stem cells can repair spinal cord injuries.

Studies have shown stem cell treatments have reparative effects on injured spinal cords, and in certain cases, may reverse paralysis. Stem cells can replace the nerve cells that have died, generate new supporting cells to reform myelin and stimulate regrowth of damaged axons, protect cells at the injury site from further damage, and prevent spread of injury by suppressing harmful inflammation.

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A version of this story was published in 2016; it has been updated for 2024.