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The spinal nerves are the body’s major nerves within theperipheral nervous system(PNS). These nerves are integral to the PNS because they control motor, sensory, and autonomic functions between the spinal cord and the body.
There are 31 pairs of spinal nerves located at the cervical, thoracic, lumbar, sacral, and coccygeal levels:
8 pairs of cervical nerves (C1-C8).
12 pairs of thoracic nerves (T1-T12).
5 pairs of lumbar nerves (L1-L5).
5 pairs of sacral nerves (S1-S5).
1 pair of coccygeal nerves (CO1).
Spinal nerves are peripheral nerves that emerge from the spinal cord and carry motor, sensory, and autonomic signals between the spinal cord and the rest of the body. There are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal, named according to their corresponding vertebral levels.
Each of these nerves branches out from the spinal cord, dividing and subdividing to form a network connecting the spinal cord to every part of the body.
Spinal nerves are structures that receive sensory information from receptors of the periphery body, and then transmit this information to the CNS.
Similarly, the spinal nerves transmit motor commands from the CNS to the muscles and glands of the periphery, so the brain’s instructions can be carried out quickly.
Anatomy of Spinal Nerves
Spinal nerves are large nerves that are distributed evenly along the spinal cord and the spine. The spine is a column of vertebrae bones that protects the spinal cord.
The spinal nerves are formed within a few centimeters of the spine on each side. Some groups of nerves merge to form a large plexus of nerves, whereas some divide into smaller branches without forming a plexus.
Spinal nerves emerge from the spinal column through an opening between adjacent vertebrae (known as intervertebral foramen).
This is the case for all spinal nerves except the first pair, which emerge between the occipital bone and the uppermost vertebrae.
Types and Spinal Nerves Function
As spinal nerves contain both sensory and motor fibers, they, therefore, have both sensory and motor functions. For sensory functions, the spinal nerves receive sensory messages from the skin, internal organs, and bones.
These spinal nerves will then send this sensory information to the sensory roots before reaching the sensory fibers at the back of the spinal cord.
For motor functions, the motor roots at the front of the spinal cord receive nerve messages and then transmit these messages to the spinal nerves.
Eventually, this information will be sent to small nerve branches, which will activate the muscles of the limbs and other body parts.
Cervical Nerves
There are 8 cervical nerves on each side of the spine (C1 to C8), located at the top of the spine, at the cervical vertebrae.
The cervical nerves C1 to C5 can form a cervical plexus through the merging of these nerves. These can divide into smaller nerves which can carry sensory messages and provide motor control to the muscles of the neck and shoulders.
This plexus can branch into nerves that carry sensory messages to provide motor control to the muscles of the arms and upper back.
Thoracic Nerves
Next, below the cervical nerves, are 12 pairs of thoracic nerves on each side of the spine (T1 to T12), located at the thoracic vertebrae of the spine.
Lumbar Nerves
Below the thoracic nerves are 5 pairs of lumbar nerves on each side of the spine (L1 to L5), located at the lumbar vertebrae of the spine.
The lumbar nerves L1 to L4 can combine to form the lumbar plexus, dividing into nerves that carry sensory messages and provide motor control to the muscles of the abdomen and legs.
Sacral Nerves
Further down the spine are 5 pairs of sacral nerves on each side of the spine (S1 to S5), located at the sacrum.
The spinal nerves from lumbar L4 to sacral nerves S4 can form the sacral plexus through the merging of these nerves. This plexus can divide into nerves that carry sensory messages and provide motor control to the muscles of the legs.
Coccygeal Nerves
Finally, at the base of the spine is 1 pair of coccygeal nerves on each side of the spine (CO1), located at the coccyx.
Spinal Nerve Damage
Below are some of the symptoms that can be experienced if damage were to occur to the spinal nerves:
Conditions that can affect the spinal nerves include the following:
Compressive neuropathy
This condition can occur when the spinal nerves are compressed. This can happen when the nerves that exit the spinal cord become trapped or swollen, and it can be extremely painful.
This condition typically affects older people, and the effects can be temporary or long-lasting, permanently destroying the spinal nerves.
Herniated disc
Also known as a slipped disc, this can occur when the vertebrae of the spine, including the cartilage, ligaments, and muscles, are disrupted. This disruption can cause the vertebrae to slip out of place.
A Herniated disc can cause permanent damage to the spinal cord.
Trauma
Spinal nerves can become damaged either mildly or severely after traumatic accidents. Trauma to the neck can come as a result of falling or blunt force to the neck, for instance.
This trauma can result in swelling, stretching, or tears of the cervical spinal nerves or the cervical plexus.
Lifting heavy objects or blunt force to the lower back can result in the lumbar spinal nerves or lumbar plexus being damaged and lead to lower back pains.
Spinal infections
Types of spinal infections can include disc infections and spinal bone infections and typically cause inflammation and pain which may travel into other parts of the body.
A spinal infection may begin near spinal nerve roots and thus will take effect on the spinal nerves which branch from it.
Guillan Barre Syndrome (GBS)
This is a condition that attacks the myelin sheath (protective insulating layer) of the neurons.
As this is a demyelinating condition, it can weaken the spinal nerves over time and cause weakness and tingling sensations all over the body. Eventually, it may even impair the muscles which control breathing.
Treatments of spinal nerve damage depend on the issue at hand. If there is an infection or inflammatory problem, anti-inflammatory medication can usually manage the milder symptoms.
Similarly, mild nerve pain may be managed with over-the-counter pain medication.
References
Eidelson, S. G. (2019, June 3). Spinal Nerve Disorders. https://www.spineuniverse.com/conditions/sciatica/spinal-nerve-disorders
Moawad, H. (2020, January 18). The Anatomy of Spinal Nerves. Very Well Health. https://www.verywellhealth.com/spinal-nerves-anatomy-4682599#associated-conditions
Gorman, N. (2021, May 31). Spinal Nerves. Kenhub. https://www.kenhub.com/en/library/anatomy/spinal-nerves
Lumen. (n.d.). Spinal Nerves. Retrieved 2021, August 9 from: https://courses.lumenlearning.com/boundless-ap/chapter/spinal-nerves/
Karina Ascunce GonzálezNeuroscience B.A. (Hons), Harvard UniversityPhD Neuroscience Student, Yale University
Karina Ascunce González
Neuroscience B.A. (Hons), Harvard University
PhD Neuroscience Student, Yale University
PhD Student at the Yale Biological & Biomedical Sciences' Interdepartmental Neuroscience Program interested in neurodegeneration, stem cell culture, and bioethics. AB in Neuroscience with a Secondary in Global Health & Health Policy from Harvard University. Karina has been published in peer reviewed journals.
Saul McLeod, PhD
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
Olivia Guy-Evans, MSc
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
