Dura mater

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Dura mater

The dura mater (from the Latin "hard mother"), or pachymeninx, is the tough and inflexible outermost of the three layers of the meninges

Meninges

The meninges is the system of Mesotheliums which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater....
surrounding the brain

Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
and spinal cord

Spinal cord

The spinal cord is a long, thin, tubular bundle of neuron and glia that extends from the brain. The brain and spinal cord together make up the central nervous system....
. (The other two meningeal layers are the pia mater

Pia mater

The pia mater is the delicate innermost layer of the meninges?the membranes surrounding the brain and spinal cord.The thin, mesh-like pia mater closely envelops the entire surface of the brain, running down into the fissures of the cortex....
and the arachnoid mater

Arachnoid mater

The arachnoid mater is one of the three meninges, the membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial dura mater and the deeper pia mater, and is separated from the pia mater by the subarachnoid space....
.) The dura mater is not as tightly fitting around the spinal cord, extending past the spinal cord (at the second lumbar vertebra

Vertebra

A vertebra is an individual bone in the flexible column that defines vertebrate animals. The vertebral column encases and protects the spinal cord, which runs from the base of the cranium down the dorsal side of the animal until reaching the pelvis....
) to about the second sacral vertebra.

dura mater has two layers:

The dura separates into two layers at dural reflections, places where the inner dural layer is reflected as sheet-like protrusions into the cranial cavity.

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Encyclopedia

The dura mater (from the Latin "hard mother"), or pachymeninx, is the tough and inflexible outermost of the three layers of the meninges

Meninges

Brain

Spinal cord

Pia mater

Arachnoid mater

Vertebra

Layers and reflections

The dura mater has two layers:

a superficial layer, which is actually the skull's inner periosteum
Periosteum

Periosteum is a membrane that lines the outer surface of all bone, except at the joints of long bones. Endosteum lines the inner surface of all bones....
, called the endocranium.

a deep layer, the actual dura mater.

The dura separates into two layers at dural reflections, 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
Tentorium cerebelli

The tentorium cerebelli or cerebellar tentorium is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes....
exists between and separates the cerebellum
Cerebellum

The cerebellum is a region of the brain that plays an important role in the integration of perception, coordination and motoneuron control. In order to coordinate motor control, there are many neural pathways linking the cerebellum with the cerebrum motor cortex and the spinocerebellar tract ....
and brainstem from the occipital lobe
Occipital lobe

The occipital lobe is the Visual perception of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area, commonly called V1 ....
s of the cerebrum
Telencephalon

The cerebrum or telencephalon, together with the diencephalon, constitute the forebrain. It is the most anterior or, especially in humans, most superior region of the vertebrate central nervous system....
.

The falx cerebri
Falx cerebri

The falx cerebri, also known as the cerebral falx, so named from its sickle-like form, is a strong, arched fold of dura mater which descends vertically in the longitudinal fissure between the cerebral hemispheres....
, which separates the two hemispheres of the brain, is located in the longitudinal cerebral fissure between the hemispheres.

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

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space and the ventricular system around and inside the brain....
from the brain and empty into the internal jugular vein

Internal jugular vein

The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck....
.

They drain via the arachnoid villi, which are outgrowths of the arachnoid mater

Arachnoid mater

The arachnoid mater is one of the three meninges, the membranes that cover the brain and spinal cord. It is interposed between the two other meninges, the more superficial dura mater and the deeper pia mater, and is separated from the pia mater by the subarachnoid space....
(the middle meningeal layer) that extend into the venous sinuses. These villi act as one-way valves.

Meningeal veins, which course through the dura mater, and bridging veins, which drain the underlying neural tissue and puncture the dura mater, empty into these dural sinuses.

Clinical significance

A subdural hematoma

Subdural hematoma

A subdural hematoma is a form of traumatic brain injury in which blood gathers within the inner meningeal layer of the dura mater . Unlike in epidural hematomas, which are usually caused by tears in artery, subdural bleeding usually results from tears in veins that cross the subdural space....
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

Epidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull....
is a collection of blood between the dura and the inner surface of the skull, and is usually due to arterial

Artery

Arteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood....
bleeding.

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

Creutzfeldt–Jakob disease is a very rare and incurable degeneration neurology that is fatal. Among the types of transmissible spongiform encephalopathy found in humans, it is the most common....
.

Dural ectasia

Dural ectasia

Dural ectasia is a widening or ballooning of the dura_mater sac surrounding the spinal cord usually at the lumbosacral level. It is one of the major manifestations of Marfan syndrome....
is the enlargement of the dura and is common in connective tissue disorders, such as Marfan Syndrome

Marfan syndrome

Marfan syndrome is a genetic disorder of the connective tissue.It is sometimes inherited as a Autosomal dominant trait. It is carried by a gene called FBN1, which encodes a connective protein called fibrillin-1....
and Ehlers-Danlos Syndrome

Ehlers-Danlos syndrome

Ehlers-Danlos syndrome is a group of rare genetic disorders affecting humans caused by a defect in collagen synthesis. Depending on the individual mutation, the severity of the syndrome can vary from mild to life-threatening....
.

Additional images

ay769.png|Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. Image:Gray770.png|Diagrammatic transverse section of the medulla spinalis and its membranes. Image:Gray792.png|Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ. Image:Gray1196.png|Diagrammatic section of scalp. Image:Streptococcus pneumoniae meningitis, gross pathology 33 lores.jpg|Autopsy

Autopsy

An autopsy, also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction, is a medical procedure that consists of a thorough examination of a Dead body to determine the cause and manner of death and to evaluate any disease or injury that may be present....
photo from the CDC

Centers for Disease Control and Prevention

The Centers for Disease Control and Prevention is an agency of the United States United States Department of Health and Human Services based in Atlanta, Georgia, United States adjacent to the campus of Emory University and northeast of downtown Atlanta....
: The white "sheet" being held by the forceps

Forceps

Forceps are a handheld, hinged instrument used for grasping and holding objects. Forceps are used when fingers are too large to grasp small objects or when many objects need to be held at one time while the hands are used to perform a task....
is the dura mater. Image:Human brain dura mater description.JPG|Human brain dura mater

Dura mater

Layers and reflections

Drainage

Clinical significance

Additional images

External links