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Meninges

Meninges

For medical students2 min readUpdated 2026-10-10

The brain and spinal cord are protected by three connective tissue layers known as the meninges. They are continuous with one another but exhibit important topographical and functional differences within the cranial cavity and the vertebral canal.

Three layersDura mater, arachnoid mater, and pia mater
Venous drainageOccurs via the dural venous sinuses
CSF circulationCirculates within the subarachnoid space

Dura Mater

The dura mater is the outermost, dense, fibrous layer that is richly vascularized and innervated, but contains few elastic fibers.

In the cranial cavity, the cranial dura mater (dura mater encephali) consists of two layers:

  1. Endosteal (external) layer (lamina externa) — adheres tightly to the cranial bones, serving as their internal periosteum. It contains a well-developed vascular network.
  2. Meningeal (internal) layer (lamina interna) — has a smooth, shiny surface lined by endothelium and faces the arachnoid mater.

Where these two layers separate, dural venous sinuses (sinus durae matris) are formed — rigid, valveless vascular channels that provide venous drainage from the brain, orbit, and cranial bones.

Additionally, the dura mater extends inward to form dense septa (dural folds) that partition various regions of the brain. These include:

Innervation of the cranial dura is supplied by meningeal branches of the trigeminal nerve, fibers of the vagus nerve, and the sympathetic nervous system. Blood supply is derived from branches of the carotid arteries (notably the a. meningea media).

The spinal dura mater (dura mater spinalis) has a different structure: it is an elongated cylindrical sac hanging loosely within the vertebral canal. It does not fuse with the periosteum, leaving space for the epidural space. Inferiorly, it continues as the filum terminale externum.

Arachnoid Mater

The arachnoid mater (arachnoidea) is a thin, avascular, transparent layer covered by endothelium. Its primary topographical feature is that it does not follow the contours of the brain surface; instead, it bridges across sulci, lying between the dura mater and the pia mater.

The arachnoid is closely connected to surrounding structures:

Pia Mater

The innermost layer, the pia mater (pia mater), adheres directly to the surface of the spinal cord and brain. It is a delicate layer with a dense vascular network.

Unlike the arachnoid mater, the pia mater closely follows all contours and irregularities of the brain surface, extending deep into every sulcus. Its blood vessels penetrate into the neural parenchyma, allowing the pia mater to perform a vital trophic function by nourishing the nervous tissue.

Meningeal Spaces

The spaces between the meningeal layers vary anatomically depending on the region of the central nervous system:

Mnemonic

The acronym DAP helps remember the layers from superficial to deep: Dura mater, Arachnoid mater, Pia mater.

Frequently asked questions

Which nerves innervate the cranial dura mater?

The cranial dura mater is innervated by branches of the trigeminal, vagus, hypoglossal, and upper cervical spinal nerves, along with sympathetic fibers.

  • Trigeminal nerve (n. trigeminus) — innervates the supratentorial dura via meningeal branches from the ophthalmic, maxillary, and mandibular nerves.
  • Vagus nerve (n. vagus) — supplies meningeal branches to the infratentorial dura in the posterior cranial fossa.
  • Hypoglossal nerve (n. hypoglossus) — also contributes meningeal branches in the posterior cranial fossa.
  • Spinal nerves — branches from the upper cervical segments innervate the dura inferior to the tentorium cerebelli.
What are the major subarachnoid cisterns of the brain?

Subarachnoid cisterns are enlargements of the subarachnoid space around the brain. The major cisterns include:

  • Cerebellomedullary cistern (cisterna cerebellomedullaris / cisterna magna) — located between the cerebellum and the medulla oblongata.
  • Chiasmatic cistern (cisterna chiasmatis) — located anterior to the optic chiasm.
  • Interpeduncular cistern (cisterna interpeduncularis) — located between the cerebral peduncles.
  • Cistern of the lateral recess (cisterna fossae lateralis cerebri) — located in the lateral sulcus.

Other cisterns include the interhemispheric, superior, ambient, pontine cisterns, and the cistern of the cerebellar vermis.

Which arteries supply the dura mater?

The blood supply to the dura mater is provided by branches of the external carotid, internal carotid, and vertebral arteries.

  • Middle meningeal artery (a. meningea media) — a large branch of the maxillary artery.
  • Anterior meningeal artery — a branch of the anterior ethmoidal artery from the internal carotid system.
  • Posterior meningeal artery — supplies the dura in the posterior cranial fossa.
  • Meningeal branches (rr. meningei) — arise from the vertebral artery and the cavernous segment of the internal carotid artery.
  • Ascending pharyngeal artery (a. pharyngea ascendens) — also contributes to dural blood supply.
What dural venous sinuses are formed within the dura mater?

The following venous sinuses are formed within the folds of the dura mater:

  • Superior and inferior sagittal sinuses (sinus sagittalis superior et inferior)
  • Straight sinus (sinus rectus)
  • Transverse sinus (sinus transversus)
  • Sigmoid sinus (sinus sigmoideus)
  • Occipital sinus (sinus occipitalis)
  • Cavernous sinus (sinus cavernosus)
  • Sphenoparietal sinus (sinus sphenoparietalis)
  • Superior and inferior petrosal sinuses (sinus petrosus superior et inferior)

The confluence of several sinuses is termed the confluence of sinuses (confluens sinuum).

What structures form the internal and external terminal filum of the spinal cord?

The terminal filum is formed by the fusion of spinal meninges inferior to the termination of the spinal cord.

  • Internal filum terminale (filum terminale internum) — formed by the fusion of the pia mater, arachnoid mater, and dura mater, containing no neural tissue.
  • External filum terminale (filum terminale externum) — is the caudal continuation and derivative exclusively of the spinal dura mater (dura mater spinalis).
How does the attachment of the dura mater differ between the brain and spinal cord?

In the cranial cavity, the outer layer of the dura mater tightly fuses with the cranial bones, acting as their internal periosteum. In the vertebral canal, the spinal dura does not fuse with the bones, forming a free dural sac and leaving room for the epidural space.

Where is cerebrospinal fluid located and how is it drained?

CSF circulates within the subarachnoid space (between the arachnoid and pia mater). Its resorption occurs via arachnoid granulations into the dural venous sinuses.

Which meningeal layer contains the most blood vessels?

The pia mater is the most vascularized meningeal layer. It extends into all sulci and accompanies blood vessels deep into the brain parenchyma, fulfilling a trophic function.

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