Our body map

Fix my Spine with Iona Collins

Do you suffer with joint pains? Shoulder pain, for example?

If you do, you may have looked up why your shoulder may be sore and what you can do to try and help your-self. No doubt, you’re thinking about the exercises that you’ve been doing so far, which may or may not be helping your pain.

Did any of the information mention that spinal problems can often cause referred pain to another part of the body?

How can you tell whether the painful shoulder is due to the shoulder joint itself, instead of your neck causing referred pain, giving the impression that your shoulder is problematic?

If your neck is actually causing your shoulder pain, then maybe neck exercises rather than shoulder exercises will be more useful to you.

Let’s try another example.

How about tingling in your hands at night. You may have read up about carpal tunnel syndrome, a common cause of nocturnal hand tingling, since we tend to bend our wrists when we curl up and sleep, which can compress the median nerve at the wrist joint. But, many of us have more than one pillow when we sleep, which causes us to sleep with our necks bent or flexed forward. This is a poor position for the neck, which can result in a trapped nerve in the neck and…tingling in the hands at night. So, do you have carpal tunnel syndrome, or a trapped nerve in your neck, or both? How do you help yourself get better if you don’t know where the pain is coming from?

This month, we introduce you to your own body map. The map should help you to work out whether your aches and pains may be coming from the spine – you could even work out which part of the spine to focus on.

A quick overview

Our brain leaves our head at the base of the skull at the brainstem and then it becomes the spinal cord. The spinal cord gradually thins down as pairs of nerves predictably peel away from the cord at regular intervals. In the lumbar spine, the spinal cord ends at a point called the conus, beyond which, the remaining individual nerves which supply the legs, bladder and bowel are collectively called the cauda equina (horse’s tail in Latin).

C,T,L,S

The bony spinal column is divided into the Cervical spine, the Thoracic spine (the part of the spine which has ribs attached), the Lumbar spine and the Sacrum.

The spinal nerves which leave the spinal cord in the Cervical spine are called Cervical nerve roots. There are eight pairs of Cervical nerve roots and they are left C1, right C1, left C2, right C2, left C3…etc as far as left and right C8. The cervical nerve roots supply feeling and function to the arms and hands.

The spinal nerves which leave the spinal cord in the Thoracic spine are called Thoracic nerve roots. There are twelve pairs of Thoracic nerve roots and they are left T1, right T1, left T2, right T2, left T3…etc as far as left and right T12. The thoracic nerve roots supply feeling and function to the torso.

The spinal nerves which leave the spinal cord in the Lumbar spine are called Lumbar nerve roots. There are five pairs of Lumbar nerve roots and they are left L1, right L1, left L2, right L2, left L3…etc as far as left and right L5. The lumbar nerve roots supply feeling and function to the legs and feet.

The spinal nerves which leave the spinal cord in the Sacral spine are called Sacral nerve roots. There are five pairs of Sacral nerve roots and they are left S1, right S1, left S2, right S2, left S3…etc as far as left and right S5. The sacral nerve roots supply feeling and function to the bladder and bowel.

Dermatomes and Myotomes

A myotome and a dermatome are terms used to describe muscles and skin which particular nerve roots supply. For example, C6 nerve root supplies sensation to the thumb and the L5 nerve root supplies sensation to the great toe. Here is the body map (diagram top right) for how spinal nerves convey sensation from different parts (dermatomes).

The book “Aids to the examination of the peripheral nervous system”, along with the link www.federaljack.com/ebooks/My collection of medical books, 208 Books (part 1 of 3)/AIDS TO THE EXAMINATION OF THE PNS ED 4TH.pdf provides a guide on how individual nerves can be tested as well as describing the nerves which supply different muscles. The book explains ankle weakness, for example. Inability to lift the ankle toward you may be an issue with L4 nerve, inability to push the ankle away from you may be an issues with the S1 nerve, for example.

So, the next time you have an aching knee, instead of blaming an arthritic knee for the pain, it may be worth considering whether your back is irritating the L3 nerve root, which can also cause referred pain to the knee. If your biceps ache when you raise a shoulder outward (abduction), then the issue may be a rotator cuff problem in your shoulder, or else it could be irritation of the C5 nerve root in your neck.

I hope this article has given you some food for thought.

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