In my opinion and of many others (Reference), the brightest spot in the progression of physiotherapy is our  evolving knowledge of pain science (ie why things hurt).

In this post I will try to explain the role of the homunculus. It is a recognizable term to most but beyond it being something to do with the brain I imagine things are little fuzzy:) It is important to physios because it broadens our understanding of pain.

The homunculus or, somatic sensory homunculus (SSH), is the portion of the sensory cortex which maps and represents our sensory nerves throughout our body (a map of our body in our brain). Large portions represent our hands, mouth, and tongue (refer to the blog photo). Smaller representation is given to our pinky toe and backside of our knee. Depending on your vocation or passion you may have areas that have larger representations when compared to others. For example, the SSH of the hand and fingers of a violinist would  be larger than of a soccer players (more area dedicated to the lower body).

Another example of how the SSH functions is in amputees. When someone loses a limb the SSH representation does not suddenly fall off. This is why people feel amputated areas, referred to as phantom limb pain or sensation, years into the future.

The SSH is in a constant state of flux. This is why we see change even during short episodes of pain. The changes are an attempt to protect us! If pain persists however, these adaptations can become harmful and previously  defined areas can become smudged (see video). Smudging refers to the blurring of once separate body parts and the increase in neuronal representation in the SSH.  This smudging can be the cause of radiating pain from back injuries (it’s actually rare for it to be a “pinched nerve“).

If you are in pain or the pain is begining to spread, there are things that can be done. To engage both the person and the nervous system the best treatment is a combination of the following three approaches.

1. A good interaction: pain neuroscience education (PNE) and empathetic listening.

2. Movement as medicine: A novel, non-threatening, and salient movement

3: Calming technique: A novel and comfortable hands on technique to calm the nervous system.

These approaches help re-define smudged borders by providing novel input, non threatening input and descending modulation from other centres in the brain.

Our thoughts and emotions can also have an effect on the SSH. Just thinking of moving a body part can light up the portion of the brain devoted to that body part. If we are able to think of movements in a positive way we can actually help to redefine the SSH borders and lessen pain:) This is why visualization is so effective at improving performance. It literally sharpens and improves the neurological processing in the brain.

So, what do you need to need to know?

  1. Pain from any injury is more complex than what’s happening at the tissue and hurt does not always equal harm.
  2. The bodies sensory map is represented in the Somatic Sensory Homunculus.
  3. By using evidence based treatments, novel movements, and improving our understanding of pain (PNE), we can help to redefine borders within the SSH and lessen pain.

I hope this post provided some food for thought! Keep on moving!


Great video my Khan Academy