Scalp

Last revised by Daniel J Bell ◉ on 16 Jan 2022

The scalp (TA: calva) is the skin and subcutaneous tissue covering the neurocranium. It is composed of five layers and has a rich vascular supply which explains why it bleeds profusely and heals well.

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The scalp is composed of five layers which are easily remembered with this mnemonic. From external to internal the layers are:

  1. skin
    • usually covered in hair
    • thicker over the occiput
    • rich arterial supply and venolymphatic drainage
  2. connective tissue
    • ​a thick layer which has a rich vascular supply
    • contains numerous cutaneous nerves
  3. galeal aponeurosis (also known as the galea aponeurotica or epicranial aponeurosis)
    • strong aponeurosis that allows attachment for muscles of the scalp (occipitofrontalis, temporoparietalis and superior auricular muscles), all innervated by the facial nerve
  4. loose areolar tissue
    • a sponge-like layer of areolar tissue which allows the free movement of the first three layers over the underlying pericranium and skull
    • being so loose it is a potential space for collections and hematomas
  5. pericranium
    • a dense layer of fibrous connective tissue that is the external periosteum of the neurocranium (firmly attached)
    • extends into the cranial sutures

Numerous arteries supply the scalp, contributing to its rich vascular supply.
The arteries arise from both the internal and external carotid circulations:

Like the face, the scalp does not have lymph nodes. Lymph drains via small lymphatic channels to the submandibular, parotid, mastoid and occipital nodes. These form a collar of nodes at the junction of the head and neck.

Numerous cutaneous nerves supply sensation to the scalp depending on the location:

The muscles of the scalp (see above) are considered muscles of facial expression and therefore are all innervated by the facial nerve.

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