neuroanatomy Neuroanatomy is the study of the structure and organization of the nervous system. In contrast to animals with radial symmetry, whose nervous system consists of a distributed network of cells, animals with bilateral symmetry have segregated, defi ...

, dura mater is a thick

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. B ...

made of

dense irregular connective tissue Dense irregular connective tissue has fibers that are not arranged in parallel bundles as in dense regular connective tissue. Dense irregular connective tissue consists of mostly collagen fibers. It has less ground substance than loose connec ...

that surrounds the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

and

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

. It is the outermost of the three layers of membrane called the meninges that protect the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

. The other two meningeal layers are the arachnoid mater and the

pia mater Pia mater ( or ),Entry "pia mater"
in
cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...

. It is derived primarily from the

neural crest Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, per ...

cell population, with postnatal contributions of the paraxial

mesoderm The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical E ...

Structure

The dura mater has several functions and layers. The dura mater is a membrane that envelops the arachnoid mater. It surrounds and supports the

dural sinuses The dural venous sinuses (also called dural sinuses, cerebral sinuses, or cranial sinuses) are venous channels found between the endosteal and meningeal layers of dura mater in the brain. They receive blood from the cerebral veins, receive cerebr ...

(also called dural venous sinuses, cerebral sinuses, or cranial sinuses) and carries blood from the brain toward the heart. Cranial dura mater has two layers called ''

lamella Lamella (plural lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal ...

e'', a superficial layer (also called the periosteal layer), which serves as the skull's inner

periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structu ...

, called the endocranium and a deep layer called the meningeal layer. When it covers the spinal cord it is known as the ''dural sac'' or thecal sac. Unlike cranial dura mater, spinal dura mater only has one layer, known as the meningeal layer. The potential space between these two layers is known as the

epidural space In anatomy, the epidural space is the potential space between the dura mater and vertebrae (spine). The anatomy term "epidural space" has its origin in the Ancient Greek language; , "on, upon" + dura mater also known as "epidural cavity", "e ...

Folds and reflections

The dura separates into two layers at ''dural reflections'' (also known as ''dural folds''), places where the inner dural layer is reflected as sheet-like protrusions into the cranial cavity. There are two main dural reflections: * The

tentorium cerebelli The cerebellar tentorium or tentorium cerebelli (Latin for "tent of the cerebellum") is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes. Structure The cerebellar tentorium is an arch ...

exists between and separates the

cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...

and brainstem from the

occipital lobe The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head". The occipital lobe is the vi ...

s of the

cerebrum The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In ...

. * The

falx cerebri The falx cerebri (also known as the cerebral falx) is a large, crescent-shaped fold of dura mater that descends vertically into the longitudinal fissure between the cerebral hemispheres of the human brain,Saladin K. "Anatomy & Physiology: The Uni ...

, which separates the two hemispheres of the brain, is located in the

longitudinal cerebral fissure The longitudinal fissure (or cerebral fissure, great longitudinal fissure, median longitudinal fissure, interhemispheric fissure) is the deep groove that separates the two cerebral hemispheres of the vertebrate brain. Lying within it is a continu ...

between the hemispheres. Two other dural infoldings are the cerebellar falx and the sellar diaphragm: * The cerebellar falx (falx cerebelli) is a vertical dural infolding that lies inferior to the cerebellar tentorium in the posterior part of the

posterior cranial fossa The posterior cranial fossa is part of the cranial cavity, located between the foramen magnum and tentorium cerebelli. It contains the brainstem and cerebellum. This is the most inferior of the fossae. It houses the cerebellum, medulla and pons. ...

. It partially separates the cerebellar hemispheres. * The sellar diaphragm is the smallest dural infolding and is a circular sheet of dura that is suspended between the clinoid processes, forming a partial roof over the hypophysial fossa. The sellar diaphgram covers the pituitary gland in this fossa and has an aperture for passage of the infundibulum (pituitary stalk) and hypophysial veins.

Blood supply

This depends upon the area of the cranial cavity: in the anterior cranial fossa the anterior meningeal artery (branch from the ethmoidal artery) is responsible for blood supply, in the middle cranial fossa the middle meningeal artery and some accessory arteries are responsible for blood supply, the middle meningeal artery is a direct branch from the maxillary artery and enter the cranial cavity through the foramen spinosum and then divides into anterior (which runs usually in vertical direction across the pterion) and posterior (which runs posteriosuperiorly) branches, while the accessory meningeal arteries (which are branches from the maxillary artery) enter the skull through foramen ovale and supply area between the two foramina, and the in posterior cranial fossa the dura mater has numerous blood supply from different possible arteries: A. posterior meningeal artery (from the ascending pharyngeal artery through the jugular foramen)
B. meningeal arteries (from the ascending pharyngeal artery through hypoglossal canal)
C. meningeal arteries (from occipital artery through jugular or mastoid foramen)
D. meningeal arteries (from vertebral artery through foramen magnum)

Drainage

The two layers of dura mater run together throughout most of the skull. Where they separate, the gap between them is called a dural venous sinus. These sinuses drain blood and

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...

(CSF) from the brain and empty into the

internal jugular vein The internal jugular vein is a paired jugular vein that collects blood from the brain and the superficial parts of the face and neck. This vein runs in the carotid sheath with the common carotid artery and vagus nerve. It begins in the poste ...

Arachnoid villi Arachnoid granulations (also arachnoid villi, and pacchionian granulations or bodies) are small protrusions of the arachnoid mater (the thin second layer covering the brain) into the outer membrane of the dura mater (the thick outer layer). They ...

, which are outgrowths of the arachnoid mater (the middle meningeal layer), extend into the dural venous sinuses to drain CSF. These villi act as one-way valves. Meningeal veins, which course through the dura mater, and

bridging veins Bridging veins are veins in the subarachnoid space that puncture the dura mater and empty into the dural venous sinuses The dural venous sinuses (also called dural sinuses, cerebral sinuses, or cranial sinuses) are venous channels found between th ...

, which drain the underlying neural tissue and puncture the dura mater, empty into these dural sinuses. A rupture of a bridging vein causes a

subdural hematoma A subdural hematoma (SDH) is a type of bleeding in which a collection of blood—usually but not always associated with a traumatic brain injury—gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surround ...

Nerve supply

The supratentorial dura mater membrane is supplied by small meningeal branches of the

trigeminal nerve In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chew ...

(V1, V2 and V3). The innervation for the infratentorial dura mater are via upper cervical nerves and the meningeal branch of the vagus nerve.

Clinical significance

Many medical conditions involve the dura mater. A

occurs when there is an abnormal collection of blood between the dura and the arachnoid, usually as a result of torn bridging veins secondary to head trauma. An

epidural hematoma Epidural hematoma is when bleeding occurs between the tough outer membrane covering the brain (dura mater) and the skull. Often there is loss of consciousness following a head injury, a brief regaining of consciousness, and then loss of consciou ...

is a collection of blood between the dura and the inner surface of the skull, and is usually due to

arterial An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

bleeding. Intradural procedures, such as removal of a brain tumour or treatment of

trigeminal neuralgia Trigeminal neuralgia (TN or TGN), also called Fothergill disease, tic douloureux, or trifacial neuralgia is a long-term pain disorder that affects the trigeminal nerve, the nerve responsible for sensation in the face and motor functions such as ...

via a

microvascular decompression Microvascular decompression (MVD), also known as the Jannetta procedure, is a neurosurgical procedure used to treat trigeminal neuralgia (along with other cranial nerve neuralgias) a pain syndrome characterized by severe episodes of intense facial p ...

, require that an incision is made to the dura mater. To achieve a watertight repair and avoid potential post-operative complications, the dura is typically closed with sutures. If there is a dural deficiency, then a dural substitute may be used to replace this membrane. Small gaps in the dura can be covered with a

surgical sealant film A surgical sealant film is an implantable medical device used during surgery. It is a preformed flexible patch that is applied to supplement sutures and surgical staples to seal tissues and prevent leaks of fluid (including blood and cerebrospina ...

. In 2011, researchers discovered a connective tissue bridge from the

rectus capitis posterior major The rectus capitis posterior major (or rectus capitis posticus major, both being Latin for ''larger posterior straight muscle of the head'') arises by a pointed tendon from the spinous process of the axis, and, becoming broader as it ascends, is in ...

to the cervical dura mater. Various clinical manifestations may be linked to this anatomical relationship such as

headaches Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

and other symptoms that involved the cervical dura. The

rectus capitis posterior minor The rectus capitis posterior minor (or rectus capitis posticus minor, both being Latin for ''lesser posterior straight muscle of the head'') arises by a narrow pointed tendon from the tubercle on the posterior arch of the atlas, and, widening as i ...

has a similar attachment. The dura-muscular, dura-ligamentous connections in the upper cervical spine and occipital areas may provide anatomic and physiologic answers to the cause of the

cervicogenic headache Cervicogenic headache is a type of headache characterized by chronic hemicranial pain referred to the head from either the cervical spine or soft tissues within the neck. The main symptoms of cervicogenic headaches include pain originating in the ne ...

. This proposal would further explain manipulation's efficacy in the treatment of cervicogenic headache. The American Red Cross and some other agencies accepting blood donations consider dura mater transplants, along with receipt of pituitary-derived growth hormone, a risk factor due to concerns about

Creutzfeldt–Jakob disease Creutzfeldt–Jakob disease (CJD), also known as subacute spongiform encephalopathy or neurocognitive disorder due to prion disease, is an invariably fatal degenerative brain disorder. Early symptoms include memory problems, behavioral changes, ...

. Cerebellar tonsillar ectopia, or

Chiari Chiari may refer to: * Chiari (surname) *Chiari, Lombardy, a commune in Italy * The Chiari Institute, a medical institution in Great Neck, New York *Battle of Chiari (1701), part of the War of the Spanish Succession See also * Arnold–Chiari malf ...

, is a condition that was previously thought to be congenital but can be induced by trauma, particularly whiplash trauma. Dural strain may be pulling the cerebellum inferiorly, or skull distortions may be pushing the brain inferiorly.

Dural ectasia Dural ectasia is widening or ballooning of the dural sac surrounding the spinal cord. This usually occurs in the lumbosacral region, as this is where the cerebrospinal fluid pressure is greatest, but the spinal canal can be affected in any plane. ...

is the enlargement of the dura and is common in connective tissue disorders, such as Marfan syndrome and Ehlers–Danlos syndrome. These conditions are sometimes found in conjunction with

Arnold–Chiari malformation Chiari malformation (CM) is a structural defect in the cerebellum, characterized by a downward displacement of one or both cerebellar tonsils through the foramen magnum (the opening at the base of the skull). CMs can cause headaches, difficu ...

Spontaneous cerebrospinal fluid leak A cerebrospinal fluid leak (CSF leak or CSFL) is a medical condition where the cerebrospinal fluid (CSF) surrounding the brain or spinal cord leaks out of one or more holes or tears in the dura mater. A cerebrospinal fluid leak can be either crani ...

is the fluid and pressure loss of spinal fluid due to holes in the dura mater.

Etymology

The name ''

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

'' derives from the Latin for ''tough mother (or hard mother)'', a

loan translation In linguistics, a calque () or loan translation is a word or phrase borrowed from another language by literal word-for-word or root-for-root translation. When used as a verb, "to calque" means to borrow a word or phrase from another language whi ...

of Arabic (), literally 'thick mother of the brain', matrix of the brain, and is also referred to by the term "pachymeninx" (plural "pachymeninges").

Additional images

File:Blausen 0327 Dura.png, Dura mater (spinal section) File:Gray769.png, Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. File:Gray770-en.svg, Diagrammatic transverse section of the

medulla spinalis The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal ...

and its membranes. File:Slide1drdr.GIF, Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view. File:Slide3dsdd.GIF, Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view File:Streptococcus_pneumoniae_meningitis,_gross_pathology_33_lores.jpg, Autopsy. Dura mater is retracted by the forceps.

References

External links

*
youtube: exposure of falx cerebri, dura mater & arachnoid
{{Authority control Meninges