Spinal Cord Injury Levels Explained: C1 to S5

How the Location of a Spinal Injury Affects Function: C1–S5 Levels Explained

Where a spinal cord injury happens mostly decides what a person can and can’t do afterward. As a rule, the higher the injury sits on the spine, the more of the body it affects. This guide explains spinal cord injury levels in plain words. It runs from the neck (C1) down to the tailbone area (S5). It also shows how doctors put a number and a grade on what happened.

Was your loved one just hurt in a serious accident? You may be holding a report full of letters and numbers. No one has explained them to you. We wrote this page to help you read it. This is educational information. It is not medical or legal advice. Your treating doctors are the right source for your family’s situation.

Why the location of a spinal cord injury matters

The spinal cord is the cable that carries signals between your brain and your body. When that cable is damaged, messages can’t reliably pass below the point of injury (Mayo Clinic). More nerves branch off higher up the cord. So an injury near the neck affects more of the body than one near the lower back.

These injuries often come from trauma, such as falls and road crashes. They can also come from other causes like tumors or infection (World Health Organization). In the catastrophic cases our attorneys handle, many spinal cord injuries follow truck crashes and other high-force collisions. In those cases, the sudden force of the impact damages the cord.

The four regions of the spinal cord and what a “level” means

The spinal cord has four regions. Doctors use them to describe where an injury happened:

• Cervical (C1–C8): the neck
• Thoracic (T1–T12): the upper and mid back
• Lumbar (L1–L5): the lower back
• Sacral (S1–S5): the base of the spine

Your “injury level” is what doctors call the neurological level of injury. This is the lowest segment where both feeling and movement still test normal on both sides of the body. Below that point, function may be reduced or lost.

Vertebrae vs. spinal cord segments — the detail that confuses everyone

Here is a point that trips up almost every family reading an MRI report. The vertebrae are the bones of the spine. The spinal cord segments are the nerve sections that run inside those bones. They do not line up one-for-one. The cord is shorter than the bony spine. So a segment often sits above the bone with the same number.

A report may name a broken bone at one spot and a nerve-injury level at another. Both matter. But they answer different questions. When you read a report, ask your care team which number is the neurological level. That number — not the fracture location — best predicts function.

Cervical (neck) injuries: C1–C8

Cervical injuries are the most severe. They can affect the arms, hands, trunk, legs, and even breathing. Neck-level injuries often cause tetraplegia (also called quadriplegia). This means reduced or lost function in all four limbs, the trunk, and the pelvic organs (Mayo Clinic). The higher the injury sits in the neck, the more function is usually affected.

Why C3–C5 injuries can be life-threatening

Injuries at C3 through C5 can be life-threatening. These nerves feed the phrenic nerve. That nerve drives the diaphragm — the main muscle for breathing. When these levels are damaged, a person may need a ventilator (a machine that helps them breathe). That is why high neck injuries are treated as emergencies.

Injuries at C1–C4 often affect breathing. They may cause paralysis below the neck. Lower neck injuries around C5–C8 may leave some shoulder, arm, or hand movement. Even then, the care needs last a lifetime. Many people with high neck injuries need round-the-clock personal care, special equipment, and permanent home changes.

Thoracic (upper and mid back) injuries: T1–T12

Thoracic injuries usually cause paraplegia. This means loss of feeling and movement in all or part of the trunk, legs, and pelvic organs. Arm and hand function usually stays normal (Mayo Clinic).

Higher thoracic injuries (around T1–T6) tend to affect trunk balance and core control more. Lower thoracic injuries (around T7–T12) often leave more trunk control. Many people with thoracic injuries use a manual wheelchair. They live active, independent lives. But in a complete injury, the loss of leg function is permanent.

Lumbar (lower back) injuries: L1–L5

Lumbar injuries mainly affect the hips and legs. They often affect bladder, bowel, and sexual function too. People often ask what happens with an L3, L4, or L5 injury. These can weaken the legs. They can also change how the hips and knees move.

Some people with lower lumbar injuries walk with braces or assistive devices. It depends on the level. It also depends on whether the injury is complete or incomplete. Others use a wheelchair for most of their movement. Outcomes vary widely. Two people with an L4 injury can lead very different daily lives. That is why your care team’s assessment matters more than any general chart.

Sacral injuries: S1–S5

Sacral injuries affect the hips, some leg movement, and bladder, bowel, and sexual function. These are the lowest injuries on the cord. They often keep more function, and many people walk.

That does not make them minor. Bladder, bowel, and sexual changes can deeply affect daily life and dignity. We never treat a “lower” injury as a small one.

Complete vs. incomplete spinal cord injuries

Whether an injury is complete or incomplete matters just as much as its level.

• A complete injury means all feeling and all movement control are lost below the point of damage (Mayo Clinic).
• An incomplete injury means some movement or feeling stays below the affected area.

This is why two people with the same “level” can have very different outcomes. A T6 complete injury and a T6 incomplete injury may work in entirely different ways. Incomplete injuries cover a wide range.

How doctors classify severity: the ASIA/ISNCSCI standard

There is no guesswork in how severity gets graded. Doctors use the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). This is a standard bedside exam of key muscles and sensory points. It is published by the American Spinal Injury Association (ASIA) (ASIA). The exam gives the neurological level and a severity grade on the ASIA Impairment Scale (AIS):

• A — Complete: no feeling or movement in the lowest sacral segments (S4–S5).
• B — Sensory incomplete: some feeling stays below the level, but no movement.
• C — Motor incomplete: some movement stays, but most key muscles are weak (less than half can move against gravity).
• D — Motor incomplete: more movement stays; at least half the key muscles can move against gravity.
• E — Normal: feeling and movement test normal.

People often search for the “3 levels of injury severity.” But the ASIA scale is the medical standard. It describes a range from complete (A) to near-normal (E) in five defined grades. Knowing the exact grade — not a rough description — is what guides the outlook and the rehab plan.

An AIS grade can also change over time. As swelling goes down and recovery continues, a doctor may re-examine and update the grade. This is why the timing and care of the ISNCSCI exam matter. It is also why we ask families to keep every version of it.

How the injury level shapes long-term needs

A higher, more complete injury generally means greater lifelong care needs. Common long-term supports include:

• Medical care and rehabilitation over months and often years
• Personal care attendants, sometimes around the clock
• Home changes — ramps, wider doors, roll-in showers
• Vehicle changes for wheelchair access
• Assistive technology and durable medical equipment

For the national picture, look to the National Spinal Cord Injury Statistical Center (NSCISC) at the University of Alabama at Birmingham. This is the federally supported registry that tracks U.S. spinal cord injury data. It covers how often injuries happen, their causes, and lifetime cost estimates (NSCISC). NSCISC data show that vehicle crashes and falls are among the leading causes of traumatic SCI. The Christopher & Dana Reeve Foundation publishes population estimates for Americans living with paralysis (Reeve Foundation). We cite these authorities rather than round numbers. A life-care plan built on a real registry carries more weight — with insurers and in court — than a generic figure.

When a spinal cord injury was caused by someone else

Many catastrophic spinal cord injuries come from serious accidents another party caused. In the worst cases, a loved one dies. These accidents include truck crashes and other high-force collisions. They can also include a delayed or missed diagnosis of a spinal injury. That kind of mistake can turn a survivable injury into permanent paralysis. When a family loses someone, that is the most catastrophic outcome there is. Florida law lets the family bring a wrongful-death claim (a case brought by the family after a death) (Fla. Stat. §768.19).

When someone else is responsible, a legal claim may help cover medical care, lost income, and future needs. We can’t promise any specific result. What we can do is explain your options clearly and honestly.

In the cases our attorneys handle, the neurological level and the AIS grade become central to showing future needs. They anchor the life-care plan. They also anchor the expert testimony that shows the true scope of harm. That is why understanding these details early, and keeping every exam report, can help your family.

A few Florida rules matter here. The deadline to file most personal-injury cases is generally two years for claims that arose on or after March 24, 2023 (Fla. Stat. §95.11). Florida also follows a modified comparative-fault rule. A person found more than 50% at fault generally recovers nothing (Fla. Stat. §768.81).

CHG Personal Injury Lawyers is a Florida-based firm. Our attorneys are admitted to The Florida Bar. We handle catastrophic cases nationwide. To learn about hiring an attorney, The Florida Bar offers free consumer resources (The Florida Bar). If you’d like to talk through your situation, you can request a free case evaluation at no cost.

You can also read our related guides:

• Spinal cord injuries overview
• Who pays medical bills during a spinal injury claim
• Paralysis and delayed-diagnosis claims
• Spinal cord injury and lost earning capacity

Frequently asked questions about spinal cord injury levels

This article is general information about spinal cord injury levels. It is not medical or legal advice, and no outcome is promised. For guidance about your family’s situation, speak with your treating doctors and a licensed attorney.