RESEARCH STARTER
Spinal cord
The spinal cord is a crucial part of the central nervous system, extending approximately 18 inches from the base of the brain down through the vertebrae of the spine. It functions as an information superhighway, transmitting signals between the brain and the body, as well as facilitating reflex actions. Structurally, the spinal cord is protected by the vertebral column, which consists of 33 stacked vertebrae that allow for flexibility and movement. The spinal cord is divided into several anatomical regions: cervical, thoracic, lumbar, sacral, and coccygeal, with each region containing a specific number of spinal nerves that carry sensory and motor information.
The spinal cord itself is composed of gray matter, which contains nerve cell bodies, and white matter, which consists of myelinated nerve fibers. The gray matter is organized into horns that perform different functions, while the white matter surrounds these horns in organized tracts. The health of the spinal cord is vital, as injuries can lead to serious outcomes such as paralysis, with the severity often depending on the injury's location on the spine. Due to the inability of the spinal cord to heal itself, injuries typically require significant medical intervention and rehabilitation.
Authored By: Kennedy, Adrienne, MA 1 of 3
Published In: 2024 2 of 3
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Full Article
The spinal cord is a delicate, tube-like collection of nerves that begins at the base of the brain and travels through the vertebrae to the middle of the back. It is about 18 inches (45 centimeters) long and about half an inch (1.27 centimeters) thick at its widest point. It consists of nerve fibers that send signals from the brain to the body and vice versa. These nerves are also responsible for reflexes such as a knee jerk.
The vertebrae in the spinal column protect the spinal cord in the same way that the skull protects the brain. The brain and the spinal cord make up the central nervous system (CNS).
Background
The spinal cord consists of a narrow bundle of nerve cells extending from the brain to the level of the first or second lumbar vertebra, which is between the rib cage and the pelvis. The spinal cord is like an information superhighway; it receives messages from the brain and sends them to the different parts of the body. For example, the brain may send a message via the spinal cord telling the arms and legs to move. The body also sends messages to the brain through the spinal cord. Suppose a person touches a pan on a stove that is very hot. Their skin will send a message to their brain through the spinal cord. (This particular type of message is a reflex.) The brain will quickly send a message to the hand, making it pull back. Messages sent to and from the brain travel extremely fast.
The spinal cord is protected by the spinal column, which is also called the vertebral column or backbone. The vertebrae in the spinal column are stacked one on top of the other. They have a hollow arch, called a spinal canal, through which the spinal cord runs.
Adults have thirty-three vertebrae in their spinal column. These vertebrae are separated by cartilage discs, which give the spinal column flexibility. Healthcare professionals refer to the vertebrae using a letter and a number. The letter refers to the anatomical region of the body. For example, the C2 vertebra is the second in the cervical region.
The vertebrae are grouped into these anatomical regions:
Cervical: The seven cervical vertebrae are in the neck and allow the head and neck to move. These vertebrae are smaller than those in the other regions.
Thoracic: The twelve thoracic vertebrae are in the chest region and attached to the ribs. The spinal canal is smaller in this region. This puts the spinal cord at a greater risk of injury if the vertebrae are damaged.
Lumbar: The lumbar vertebrae bear the weight of the body. These vertebrae are the largest and widest. Their size allows them to absorb the stress put on the lower back when heavy objects are lifted.
Sacrum: The five sacral vertebrae connect the spine to the hips. These vertebrae are fused together.
Coccyx: The four vertebrae in this section are also fused together. They form the tailbone.
Overview
Like the spinal column, the spinal cord is divided into anatomical regions. It also has a cervical region, a thoracic region, a lumbar region, a sacral region, and a coccygeal region.
Spinal nerves make up the spinal cord. Thirty-one pairs of spinal nerves are in the spinal column; the number of nerve pairs in each anatomical region varies:
Cervical–eight nerve pairs
Thoracic–twelve nerve pairs
Lumbar–five nerve pairs
Sacral–five nerve pairs
Coccygeal–one nerve pair
Each nerve in the spinal cord is named based on the lower vertebrae it runs between. For example, the C2 nerve runs between the C1 and C2 cervical vertebrae.
Spinal nerves can be either sensory or motor nerves. Sensory nerves transmit sensations such as touch, pain, and temperature. Sensory nerves also send information to the spinal cord about the body's position. Motor nerves pass information received by the brain to the muscles to direct movement.
The spinal cord consists of gray and white matter. The gray matter is shaped like a butterfly. In the center of the gray matter is a canal filled with cerebrospinal fluid.
The four parts of what looks like a butterfly's wings are projections called horns. The two dorsal horns are near the back of the spinal cord, and the two ventral horns are near the front.
The different horns have different functions. For example, the ventral horns transmit information from the brain to the muscles, while the dorsal horns transmit sensory information.
The white matter surrounds the gray matter. It consists of bundles of nerve fibers called axons organized into columns. Each column is called a tract and transmits a different type of information.
The spinal cord is covered in three layers of tissue called meninges. The spinal cord and the meninges are in the spinal canal. The innermost membrane, called the pia mater, is attached to the spinal cord. The middle membrane is called the arachnoid mater. The outermost membrane, the dura mater, is the strongest of the three.
At the end of the spinal cord is a bundle of nerves called the cauda equina, this is Latin for horse's tail, which it resembles. The cauda equina carries signals to and from the legs and the pelvic organs, which include the rectum, bladder, and internal genital organs.
Injuries
A spinal cord injury disrupts the signals sent to and from the brain. Spinal cord injuries are usually serious and involve paralysis. Unlike other parts of the body, the spinal cord has a very limited ability to heal and repair itself. Most spinal cord injuries do not cut through the spinal cord but instead, they damage vertebrae that cut into the spinal cord. Nearly half of the 17,000 spinal cord injuries that occur in the United States each year are from motor vehicle accidents. Scientists have also found that the nervous system can sometimes reorganize its connections after injury, which may allow some recovery of movement or sensation.
Spinal cord injuries can be either incomplete or complete. In an incomplete injury, the spinal cord is only partially severed, and the individual may have some function below the injury. In a complete injury, the spinal cord is completely severed, and the individual has no function below the injury.
Generally, the higher the spinal cord injury, the more serious it is. An injury to the vertebrae in the neck can cause quadriplegia, paralysis in both the arms and legs, while an injury to the lower back usually causes paralysis in only the legs.
Bibliography
"Anatomy of the Spine." Mayfield Brain & Spine, Sept. 2018, www.mayfieldclinic.com/PE-AnatSpine.htm. Accessed 14 Mar. 2026.
Cramer, Gregory D., and Susan A. Darby. Clinical Anatomy of the Spine, Spinal Cord, and ANS. Mosby, 2013.
Dafny, Nachum. "Chapter 3: Anatomy of the Spinal Cord." Neuroscience Online, 7 Oct. 2020, nba.uth.tmc.edu/neuroscience/s2/chapter03.html. Accessed 14 Mar. 2026.
Fix, James. Atlas of the Human Brain and Spinal Cord. Jones & Bartlett Learning, 2008.
Freedman, Mark. "Spinal Cord." Merck Manual, Apr. 2025, www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/biology-of-the-nervous-system/spinal-cord. Accessed 14 Mar. 2026.
“Reflexes.” Cleveland Clinic, 11 Nov. 2025, my.clevelandclinic.org/health/articles/reflexes. Accessed 14 Mar. 2026.
Scioscia, Thomas. "Spinal Cord and Spinal Nerve Roots." Spine-Health, 22 Feb. 2026, www.spine-health.com/conditions/spine-anatomy/spinal-cord-and-spinal-nerve-roots. Accessed 14 Mar. 2026.
"Spinal Cord & Column." Sci-Info-Pages, www.sci-info-pages.com/spinal-cord-and-column/. Accessed 14 Mar. 2026.
“Spinal Cord.” Cleveland Clinic, 22 Oct. 2024, my.clevelandclinic.org/health/body/21946-spinal-cord. Accessed 14 Mar. 2026.
“Traumatic Spinal Cord Injury Facts and Figures at a Glance.” National Spinal Cord Injury Statistical Center (NSCISC), 2024, sites.uab.edu/nscisc/files/2024/06/Facts_and_Figures_2024_Final.pdf. Accessed 14 Mar. 2026.
Full Article
The spinal cord is a delicate, tube-like collection of nerves that begins at the base of the brain and travels through the vertebrae to the middle of the back. It is about 18 inches (45 centimeters) long and about half an inch (1.27 centimeters) thick at its widest point. It consists of nerve fibers that send signals from the brain to the body and vice versa. These nerves are also responsible for reflexes such as a knee jerk.
The vertebrae in the spinal column protect the spinal cord in the same way that the skull protects the brain. The brain and the spinal cord make up the central nervous system (CNS).
Background
The spinal cord consists of a narrow bundle of nerve cells extending from the brain to the level of the first or second lumbar vertebra, which is between the rib cage and the pelvis. The spinal cord is like an information superhighway; it receives messages from the brain and sends them to the different parts of the body. For example, the brain may send a message via the spinal cord telling the arms and legs to move. The body also sends messages to the brain through the spinal cord. Suppose a person touches a pan on a stove that is very hot. Their skin will send a message to their brain through the spinal cord. (This particular type of message is a reflex.) The brain will quickly send a message to the hand, making it pull back. Messages sent to and from the brain travel extremely fast.
The spinal cord is protected by the spinal column, which is also called the vertebral column or backbone. The vertebrae in the spinal column are stacked one on top of the other. They have a hollow arch, called a spinal canal, through which the spinal cord runs.
Adults have thirty-three vertebrae in their spinal column. These vertebrae are separated by cartilage discs, which give the spinal column flexibility. Healthcare professionals refer to the vertebrae using a letter and a number. The letter refers to the anatomical region of the body. For example, the C2 vertebra is the second in the cervical region.
The vertebrae are grouped into these anatomical regions:
Cervical: The seven cervical vertebrae are in the neck and allow the head and neck to move. These vertebrae are smaller than those in the other regions.
Thoracic: The twelve thoracic vertebrae are in the chest region and attached to the ribs. The spinal canal is smaller in this region. This puts the spinal cord at a greater risk of injury if the vertebrae are damaged.
Lumbar: The lumbar vertebrae bear the weight of the body. These vertebrae are the largest and widest. Their size allows them to absorb the stress put on the lower back when heavy objects are lifted.
Sacrum: The five sacral vertebrae connect the spine to the hips. These vertebrae are fused together.
Coccyx: The four vertebrae in this section are also fused together. They form the tailbone.
Overview
Like the spinal column, the spinal cord is divided into anatomical regions. It also has a cervical region, a thoracic region, a lumbar region, a sacral region, and a coccygeal region.
Spinal nerves make up the spinal cord. Thirty-one pairs of spinal nerves are in the spinal column; the number of nerve pairs in each anatomical region varies:
Cervical–eight nerve pairs
Thoracic–twelve nerve pairs
Lumbar–five nerve pairs
Sacral–five nerve pairs
Coccygeal–one nerve pair
Each nerve in the spinal cord is named based on the lower vertebrae it runs between. For example, the C2 nerve runs between the C1 and C2 cervical vertebrae.
Spinal nerves can be either sensory or motor nerves. Sensory nerves transmit sensations such as touch, pain, and temperature. Sensory nerves also send information to the spinal cord about the body's position. Motor nerves pass information received by the brain to the muscles to direct movement.
The spinal cord consists of gray and white matter. The gray matter is shaped like a butterfly. In the center of the gray matter is a canal filled with cerebrospinal fluid.
The four parts of what looks like a butterfly's wings are projections called horns. The two dorsal horns are near the back of the spinal cord, and the two ventral horns are near the front.
The different horns have different functions. For example, the ventral horns transmit information from the brain to the muscles, while the dorsal horns transmit sensory information.
The white matter surrounds the gray matter. It consists of bundles of nerve fibers called axons organized into columns. Each column is called a tract and transmits a different type of information.
The spinal cord is covered in three layers of tissue called meninges. The spinal cord and the meninges are in the spinal canal. The innermost membrane, called the pia mater, is attached to the spinal cord. The middle membrane is called the arachnoid mater. The outermost membrane, the dura mater, is the strongest of the three.
At the end of the spinal cord is a bundle of nerves called the cauda equina, this is Latin for horse's tail, which it resembles. The cauda equina carries signals to and from the legs and the pelvic organs, which include the rectum, bladder, and internal genital organs.
Injuries
A spinal cord injury disrupts the signals sent to and from the brain. Spinal cord injuries are usually serious and involve paralysis. Unlike other parts of the body, the spinal cord has a very limited ability to heal and repair itself. Most spinal cord injuries do not cut through the spinal cord but instead, they damage vertebrae that cut into the spinal cord. Nearly half of the 17,000 spinal cord injuries that occur in the United States each year are from motor vehicle accidents. Scientists have also found that the nervous system can sometimes reorganize its connections after injury, which may allow some recovery of movement or sensation.
Spinal cord injuries can be either incomplete or complete. In an incomplete injury, the spinal cord is only partially severed, and the individual may have some function below the injury. In a complete injury, the spinal cord is completely severed, and the individual has no function below the injury.
Generally, the higher the spinal cord injury, the more serious it is. An injury to the vertebrae in the neck can cause quadriplegia, paralysis in both the arms and legs, while an injury to the lower back usually causes paralysis in only the legs.
Bibliography
"Anatomy of the Spine." Mayfield Brain & Spine, Sept. 2018, www.mayfieldclinic.com/PE-AnatSpine.htm. Accessed 14 Mar. 2026.
Cramer, Gregory D., and Susan A. Darby. Clinical Anatomy of the Spine, Spinal Cord, and ANS. Mosby, 2013.
Dafny, Nachum. "Chapter 3: Anatomy of the Spinal Cord." Neuroscience Online, 7 Oct. 2020, nba.uth.tmc.edu/neuroscience/s2/chapter03.html. Accessed 14 Mar. 2026.
Fix, James. Atlas of the Human Brain and Spinal Cord. Jones & Bartlett Learning, 2008.
Freedman, Mark. "Spinal Cord." Merck Manual, Apr. 2025, www.merckmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/biology-of-the-nervous-system/spinal-cord. Accessed 14 Mar. 2026.
“Reflexes.” Cleveland Clinic, 11 Nov. 2025, my.clevelandclinic.org/health/articles/reflexes. Accessed 14 Mar. 2026.
Scioscia, Thomas. "Spinal Cord and Spinal Nerve Roots." Spine-Health, 22 Feb. 2026, www.spine-health.com/conditions/spine-anatomy/spinal-cord-and-spinal-nerve-roots. Accessed 14 Mar. 2026.
"Spinal Cord & Column." Sci-Info-Pages, www.sci-info-pages.com/spinal-cord-and-column/. Accessed 14 Mar. 2026.
“Spinal Cord.” Cleveland Clinic, 22 Oct. 2024, my.clevelandclinic.org/health/body/21946-spinal-cord. Accessed 14 Mar. 2026.
“Traumatic Spinal Cord Injury Facts and Figures at a Glance.” National Spinal Cord Injury Statistical Center (NSCISC), 2024, sites.uab.edu/nscisc/files/2024/06/Facts_and_Figures_2024_Final.pdf. Accessed 14 Mar. 2026.