The brain and most of the overlying meninges have no pain receptors and are therefore insensitive to pain.
Pain referred to the head arises from intracranial or extracranial arteries, large veins or venous sinuses, cranial and cervical muscles, the basal meninges, and extracranial structures, such as the teeth and sinuses.
Thus, traction on vascular structures within the head, dilation or inflammation of cranial vascular structures, displacement of intracranial contents by tumor, abscess, increased intracranial pressure (ICP), and direct pressure on cranial nerves may result in headache.
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