“Pinched nerve” (or “trapped nerve”)

What

First of all, what is a “pinched nerve”? You might not believe me, but there are over 7 trillion (that’s a “7” with 12 “zeros”, 7.000.000.000.000) in the human body. They come in all sorts of lenghts, size, diameter, shape, function. Think about the nerves in your body as the electrical wiring system that connects your brain (the elaboration centre), the spinal cord and the rest of the body. Nerves innervate EVERYTHING in your body. Muscles, glands, organs, tissues, blood vessels, other nerves, literally everything is controlled by nerves. For obvious reasons, it would be impossible to classify all of them; however I can provide a list of the major nerves in the body.

Think about the brain and spinal cord as the main strcutres from which every single nerve develops. All the nerves in the body are either a continuation of the 31 pairs of SPINAL NERVES (that come out from the little holes on the side of each vertebra, which we also discuss HERE); or the come out directly from the skull (just above the neck, and these are called CRANIAL NERVES). 

Spinal nerves

Cervical Nerves (C1-C8):

• • They control the arms in terms of sensation and muscle action. 
  • Cervical plexus: muscle control of upper torso and neck + sensation in occiput (back of the head), shoulders and neck
  • Phrenic nerves: muscle control of the respiration process (diaphragm, pecs, traps, sternocleidmastoid, intercostals). 

Thoracic Nerves (T1-T12):

• • They innervate various organs in the body (lungs, heart, liver, stomach, small intestine)
  • Intercostal nerves: sensory information from the chest and abdomen + motor function of intercostal muscles and abdominal wall
  • Subcostal nerves: subcostal means (under the ribs) and this nerves supply various muscles in the abdomen

Lumbar Nerves (L1-L5):

• • They innervate everything below the belt line in terms of function, sensation and muscle action. 
  • Femoral nerve: motor and sensory information to various areas of the legs
  • Obturator nerve: motor + sensory info to and from the inner tigh
  • Sciatic nerve: motor and sensory (back of the leg). Largest nerve in the human body (and one of those who gets “trapped” quite easily). Duyring my years in practice, I can say between 50 to 70% of my clients had sciatic pain in their life.  

Sacral Nerves (S1-S5):

• • Sciatic Nerve: forms from branches originating from the lumbars and from the sacrum. It is composed of two major branches: Tibial Nerve and Common Peroneal Nerve
  • Pudendal Nerve: movement and sensation in the pubic region / genital area / genitals function

Coccygeal Nerve (Co1):

• • Coccygeal Plexus: supplies the sacrotuberal ligament as well as skin over the coccyx

These nerves are part of the peripheral nervous system and play a crucial role in transmitting signals between various parts of the body and the central nervous system (brain and spinal cord). They control sensations, motor functions, and autonomic functions of different regions. Keep in mind that there are many other smaller branches and variations of these nerves, but the ones listed above are some of the major ones derived from spinal nerves.

Cranial nerves

These are a special type of nerves because they are the only one to emerge directly from the brain, rather than from the spinal cord. During my 5 year course at the AECC in Bournemouth, studying these nerves became basically an obsession, especially because the functions they carry out are very complex and intricate (some of them control tiny muscles in the eye, some of them control salivary glands and face muscles, etc). Differently from the spine, where the exit points are all the same (the so called intervertebral foramen), the cranial nerves come out from different holes in the skull and identifying each of them is not easy. This is why we carried out so many dissection classes with real human specimens as well. I will never forget those lectures in the “wet lab”, and I feel very lucky for the chance the AECC gave us as students back in the days. 

There are 12 pairs of cranial nerves, and they are usually identified with roman numbers)

Olfactory Nerve (CN I):

• • Function: Sensory
  • Function: Olfaction (sense of smell)

Optic Nerve (CN II):

• • • Function: Sensory
    • Function: Vision

Oculomotor Nerve (CN III):

• • Function: Motor
  • Function: Controls most eye movements, including constriction of the pupil and adjusting the lens for focusing.

Trochlear Nerve (CN IV):

• • Function: Motor
  • Function: Controls movement of the superior oblique muscle of the eye.

Trigeminal Nerve (CN V):

• • Function: Mixed (Sensory and Motor)
  • Sensory Function: Provides sensation to the face and scalp; conducts sensory information from the skin, mucous membranes, and teeth.
  • Motor Function: Controls muscles of mastication (chewing).

Abducens Nerve (CN VI):

• • Function: Motor
  • Function: Controls movement of the lateral rectus muscle of the eye.

Facial Nerve (CN VII):

• • Function: Mixed (Sensory and Motor)
  • Sensory Function: Provides taste sensation to the anterior two-thirds of the tongue.
  • Motor Function: Controls facial expression muscles and stimulates salivary glands.

Vestibulocochlear Nerve (CN VIII):

• • Function: Sensory
  • Function: Responsible for hearing (cochlear portion) and balance and spatial orientation (vestibular portion).

Glossopharyngeal Nerve (CN IX):

• • Function: Mixed (Sensory and Motor)
  • Sensory Function: Provides taste sensation to the posterior one-third of the tongue and monitors blood pressure and oxygen levels in the blood.
  • Motor Function: Controls swallowing muscles and stimulates parotid salivary gland.

Vagus Nerve (CN X):

• Function: Mixed (Sensory and Motor)
• Sensory Function: Monitors and regulates visceral functions of the thoracic and abdominal organs.
• Motor Function: Controls muscles of the pharynx and larynx, and regulates heart and digestive functions.

Accessory Nerve (CN XI):

• Function: Motor
• Function: Controls muscles involved in head movement (sternocleidomastoid and trapezius muscles).

Hypoglossal Nerve (CN XII):

• Function: Motor
• Function: Controls muscles of the tongue for speech and swallowing.

As mentioned above, these cranial nerves play crucial roles in controlling various functions of the head and neck, including sensory perception, motor movements, and autonomic control.

Pinched nerve symptoms and causes

Nerves follow various “routes” in the body. Some of them pass in very narrow bone “gates” or passages; some of them pass through muscles, and so on. Let’s take an obvious case like the sciatic nerve to make things easier.

The sciatic nerve – as we have discussed earlier – originates from the lumbars and sacral segments. It leaves the pelvis through a passage called “greater sciatic foramen”, to go directly under a gluteal muscle called “piriformis”. In a small percentage of the population, it passes through the piriformis. The piriformis is a short and thick muscle which can become quite tight and “chunky”, especially in runners. If this muscles becomes thick enough, it can “pinch” or “trap” or compress the sciatic nerve. 

Another site of entrapment could be the spine, for example due to a build up of calcium in the intervertebral foramen. These bone spurs (or technically, osteophytes), can arise anywhere in the spine, commonly in the cervical and lumbar area. Like the example of the piriformis muscle mentioned above, they can “compress” and irritate the nerve, giving origin to a variety of unwanted symptoms.