A dermatome is an area of skin supplied by a single spinal nerve. There are 31 pairs of spinal nerves, forming nerve roots that branch from your spinal cord, but only 30 dermatomes.
Your spinal nerves help to relay sensory, motor, and autonomic information between the rest of your body and your central nervous system (CNS).
So why are
important? How many are there? And where can they be found? Continue reading as we answer these questions about dermatomes and more.
A single spinal nerve supplies sensation to certain areas of your skin, including each of your dermatomes.
Your spinal nerves
Spinal nerves are part of your peripheral
(PNS). Your PNS works to
the rest of your body with your CNS, which is made up of your brain and spinal cord.
You have
of spinal nerves. They form nerve roots that branch from your spinal cord. Spinal nerves are named and grouped by the region of the
that they’re associated with.
The five groups of spinal nerves are:
Cervical nerves: There are eight pairs of these cervical nerves, numbered C1 through C8. They originate from your neck.
Thoracic nerves: You have 12 pairs of thoracic nerves, numbered T1 through T12. They originate in the part of your spine that makes up your torso.
Lumbar nerves: There are five pairs of lumbar spinal nerves, designated L1 through L5. They come from the part of your spine that makes up your lower back.
Sacral nerves: Like the lumbar spinal nerves, you have five pairs of sacral spinal nerves. They’re associated with your sacrum, one of the bones in your pelvis.
Coccygeal nerves: You have only a single pair of coccygeal spinal nerves, which originate from the area of your coccyx, or tailbone.
Your dermatomes
Each of your
is associated with a single spinal nerve. These nerves transmit sensations, such as pain, from a specific area of your skin to your CNS.
Your body has
, one less than the number of spinal nerves. This is because the C1 spinal nerve typically doesn’t have a sensory root. As a result, dermatomes begin with spinal nerve C2.
Dermatomes have a
throughout your body. The exact dermatome pattern can actually vary from person to person. Some overlap between neighboring dermatomes may also occur.
Because spinal nerves exit the spine laterally, dermatomes associated with the torso and core are distributed horizontally. When viewed on a body map, they appear like stacked discs.
The dermatome pattern in the limbs is slightly different. This is due to the shape of the limbs as compared with the rest of the body. In general, dermatomes associated with your limbs run vertically along the long axis of the limbs, such as down your leg.
Your dermatomes are numbered based on which spinal nerve they correspond to. Below, we’ll outline each
and the area of the body that it’s associated with.
Remember that the exact area that a dermatome may cover can vary by individual. Some overlap is also possible. As such, consider the outline below to be a general guide.
Cervical spinal nerves
C2: lower jaw, back of the head
C3: upper neck, back of the head
C4: lower neck, upper shoulders
C5: area of the collarbones, upper shoulders, lateral forearm
C6: shoulders, outside of arm, thumb
C7: upper back, back of arm, pointer and middle finger
C8: upper back, inside of arm, ring and little finger
Thoracic spinal nerves
T1: upper chest and back, armpit, front of arm
T2: upper chest and back
T3: upper chest and back
T4: upper chest (area of
) and back
T5: mid-chest and back
T6: mid-chest and back
T7: mid-chest and back
T8: upper abdomen and mid-back
T9: upper abdomen and mid-back
T10: abdomen (area of belly button) and mid-back
T11: abdomen and mid-back
T12: lower abdomen and mid-back
Lumbar spinal nerves
L1: lower back, hips, groin
L2: lower back, front and inside of thigh
L3: lower back, front and inside of thigh
L4: lower back, front of thigh and calf, area of knee, inside of ankle
L5: lower back, front and outside of calf, top and bottom of foot, first four toes
Sacral spinal nerves
S1: lower back, back of thigh, back and inside of calf, last toe
S2: buttocks, genitals, back of thigh and calf
S3: buttocks, genitals
S4: buttocks
S5: buttocks
Coccygeal spinal nerves
buttocks, area of tailbone
Dermatomes are important because they can help to assess and diagnose a variety of conditions. For instance, symptoms that occur along a specific dermatome may indicate a problem with a specific nerve root in the spine.
Radiculopathies: refers to conditions in which a nerve root in the spine is compressed or pinched. Pain from
can follow one or more dermatomes. One form of
is
. Symptoms can include: pain
weakness
tingling sensations
Shingles:
is a reactivation of the
zoster (
) virus that lies dormant in the nerve roots of your body. Symptoms of shingles, such as pain and a rash, occur along dermatomes associated with the affected nerve root.
What does dermatome pain feel like?
Depending on the condition that’s affecting your dermatomes, the pain you feel may be different.
Commonly associated with dermatome conditions that may affect more than one dermatome are
like:
tingling sensations
itching
burning
weakness
What’s the difference between dermatomes and myotomes?
While dermatomes are areas of the skin a spinal nerve supplies sensation to,
are the groups of skeletal muscles a spinal nerve supplies sensation to.
Myotomes are also connected to more than one spinal nerve, so there is more overlap. This is unlike dermatomes, which are associated with a single spinal nerve.
Dermatomes are areas of skin connected to a single spinal nerve. There are 31 spinal nerves and 30 dermatomes. The exact area that each dermatome covers can be different from person to person.
Spinal nerves help relay information from other parts of the body to the central nervous system. As such, each dermatome transmits sensory details from a particular area of skin back to the brain.
Dermatomes can be helpful in evaluating and diagnosing conditions affecting the spine or nerve roots. Experiencing symptoms along a specific dermatome can help inform doctors about which area of the spine may be affected.