An estimated 12,500 spinal cord injuries occur in the U.S. every year, leaving the injured people, their friends, and their family, to cope with the aftermath of the catastrophe. For many, navigating the challenges of the health care system can feel a bit like going to medical school. Suddenly you’re learning a veritable cornucopia of new terms, and may be spending endless hours Googling spinal cord anatomy to fill in the gaps in your knowledge.
An educated patient is better equipped to advocate for his or her needs and interests. An education in spinal cord anatomy helps you understand what your doctor is saying, ask intelligent questions, and detect medical errors before they endanger your health.
Spinal Cord Anatomy: The Basics
Though you might think of your spinal cord as one single piece, it’s actually a column of nerves protected by a sheath of myelin and then further secured by 31 butterfly-shaped vertebrae (singular: vertebra).
Medical providers divide the spinal cord into four distinct regions. Knowing the region in which the injury is located is often the key to understanding diagnosis and treatment. The four spinal cord regions are:
- The cervical spinal cord: This is the topmost portion of the spinal cord, where the brain connects to the spinal cord, and the neck connects to the back. This region consists of eight vertebrae, commonly referred to as C1-C8. All spinal cord numbers are descending, so C1 is the highest vertebra, while C8 is the lowest in this region.
- The thoracic spinal cord: This section forms the middle of the spinal cord, containing twelve vertebrae numbered T1-T12.
- The lumbar spinal cord: This is a lower region of the spinal cord, where your spinal cord begins to bend. If you put your hand in your lower back, where your back bends inward, you’re feeling your lumbar region. There are five lumbar vertebrae, numbered L1-L5.
- The sacral spine: This is the lower, triangle-shaped region of the spine, also with five vertebrae. While the lumbar cord bends inward, the vertebrae of the sacral region bend slightly outward. There is no actual spinal cord in this section, it is made up of nerve roots which exit the spine at their respective vertebral levels.
- The coccygeal region, sometimes known as the coccyx or tail bone, consists of a single vertebra at the very base of the spinal cord.
Types of Spinal Cord Injuries
All spinal cord injuries are divided into two broad categories: incomplete and complete.
- Incomplete spinal cord injuries: With incomplete injuries, the cord is only partially severed, allowing the injured person to retain some function. In these cases, the degree of function depends on the extent of the injuries.
- Complete spinal cord injuries: By contrast, complete injuries occur when the spinal cord is fully severed, eliminating function. Though, with treatment and physical therapy, it may be possible to regain some function.
Incomplete spinal cord injuries are increasingly common, thanks in part to better treatment and increased knowledge about how to respond—and how not to respond—to a suspected spinal cord injury. These injuries now account for more than 60% of spinal cord injuries, which means we’re making real progress toward better treatment and better outcomes.
Some of the most common types of incomplete or partial spinal cord injuries include:
- Anterior cord syndrome: This type of injury, to the front of the spinal cord, damages the motor and sensory pathways in the spinal cord. You may retain some sensation, but struggle with movement.
- Central cord syndrome: This injury is an injury to the center of the cord, and damages nerves that carry signals from the brain to the spinal cord. Loss of fine motor skills, paralysis of the arms, and partial impairment—usually less pronounced—in the legs are common. Some survivors also suffer a loss of bowel or bladder control, or lose the ability to sexually function.
- Brown-Sequard syndrome: This variety of injury is the product of damage to one side of the spinal cord. The injury may be more pronounced on one side of the body; for instance, movement may be impossible on the right side, but may be fully retained on the left. The degree to which Brown-Sequard patients are injured greatly varies from patient to patient.
Knowing the location of your injury and whether or not the injury is complete can help you begin researching your prognosis and asking your doctor intelligent questions. Doctors assign different labels to spinal cord injuries depending upon the nature of those injuries. The most common types of spinal cord injuries include:
- Tetraplegia: These injuries, which are the result of damage to the cervical spinal cord, are typically the most severe, producing varying degrees of paralysis of all limbs. Sometimes known as quadriplegia, tetraplegia eliminates your ability to move below the site of the injury, and may produce difficulties with bladder and bowel control, respiration, and other routine functions. The higher up on the cervical spinal cord the injury is, the more severe symptoms will likely be.
- Paraplegia: This occurs when sensation and movement are removed from the lower half of the body, including the legs. These injuries are the product of damage to the thoracic spinal cord. As with cervical spinal cord injuries, injuries are typically more severe when they are closer to the top vertebra.
- Triplegia: Triplegia causes loss of sensation and movement in one arm and both legs, and is typically the product of an incomplete spinal cord injury.
Injuries below the lumbar spinal cord do not typically produce symptoms of paralysis or loss of sensation. They can, however, produce nerve pain, reduce function in some areas of the body, and necessitate several surgeries to regain function. Injuries to the sacral spinal cord, for instance, can interfere with bowel and bladder function, cause sexual problems, and produce weakness in the hips or legs. In vary rare cases, sacral spinal cord injury survivors suffer temporary or partial paralysis.