Dura mater

Last revised by James Williams on 11 Feb 2024

The dura mater, also known as the pachymeninx (plural: pachymeninges), is the tough outer layer of the meninges that surrounds the central nervous system and is pierced by the cranial nerves, the internal carotid arteries, and the vertebral arteries. The dura mater is superficial to and distinct from the leptomeninges, which comprise both the arachnoid mater and the pia mater.

Intracranially, the dura mater is formed by two layers:

  • outer endosteal layer, continuous via the skull sutures and foramina with the periosteum

  • inner meningeal layer, continuous inferiorly with the theca of the spinal cord

These two layers are adherent except where separated by the dural venous sinuses, including the cavernous sinus, which are therefore analogous to the epidural venous plexus of the spinal canal

As the outer layer is merely the periosteum, it surrounds the cranial bones and therefore extends into the sutures making the dura inseparable from these and thus limiting extradural hemorrhages to the sutures.

With age, the dura becomes thicker and more adherent to the overlying bones, accounting for the lower incidence of extradural hemorrhages in the elderly.

The inner layer requires little nourishment. Whereas the outer layer is markedly vascular and derives its blood supply from the adherent bone. Arterial supply is therefore dependent on the site of the dura:

All these vessels course between the two layers of the dura.

Until 2015 it was thought that the meninges lacked their own lymphatic drainage system, but since the groundbreaking work by Antoine Louveau et al, the details are gradually being teased out, although the precise anatomy of the meningeal lymphatic drainage system remains incomplete 6,7.

Like the arterial supply, innervation is dependent on the site of the dura:

"Dura mater" derives from the medieval Latin "durus" and "mater", i.e. "hard mother". This term was created by the Italian scholar, Stephen of Antioch (fl. 12th century) when he translated work by the Persian physician Haly Abbas in the 12th century 2,8. Islamic medicine at that time conjectured that the meninges gave rise to all the membranes of the body and expressed relationships between different tissue types in terms of familial relationships (mother, son, daughter, etc.).

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