Above & Underneath the Cranium

I shared a Neuroscience News and Research post on my facebook page the other day, and I got a question about it, so we’re here to get some answers!

The Question:

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I shared this photo with a couple of people and their reactions were definitely interesting. One person said “ewwww! that’s gross”, and another said “what’s that? it looks like food”. My two favorite responses were “that’s interesting! why so many layers?”, and “no I don’t [know], can I get some knowledge?” and that’s why we’re here!

The Answer:

First off, what’s the cranium? It’s the skull – the bony vault that encloses the brain. So, let’s explore what’s above and underneath the cranium [skull]. 

If we started at the surface of the head and dug down, there are 5 layers of soft tissue covering the cranium, and that is the scalp! What are these layers and why are they there?

Using the nemonic ‘SCALP‘ is a very easy and convenient way to remember what these layers are.

  • S – Skin: Consists of hair follicles, sweat glands, and sebaceous glands (that produces oil – called sebum – that coats the hair and skin) 
  • C – Connective tissue (dense): Consists of blood vessels and nerves 
  • A – Aponeurosis: Consists of muscles that help in the movement of the scalp (e.g. raising your eyebrows), and anchors the scalp to the head
  • L – Loose areolar connective tissue: Consists of connective blood vessels connecting those outside the cranium to those inside the cranium 
  • P – Pericranium: Consists of loose connective tissue that covers the skull

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And then we hit the skull! What’s underneath the skull? The meninges! 

The meninges are membranes of fibrous tissue that cover the brain and spinal cord. Their main functions are to protect, provide blood supply and provide a space for the flow of cerebrospinal fluid (a clear, colorless fluid that functions as lubricant, shock absorber, transportation medium between the brain and blood stream, and maintains pressure) for the brain and spinal cord. There are 3 layers of meninges:

  • Dura matter: thick and strong membrane 
  • Arachnoid matter: thin, transparent membrane consisting of web of collagen 
  • Pia matter: thin membrane, continuous with the folds of the brain 

There we go … there are layers to this! When you touch your scalp, just think of all the layers to it!

References

 

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