Meninges

As meninges, fachsprachlich meninges ( abridged plural of meninx encephali, Greek μῆνιγξ, meninx - skin ', ancient Greek ἐγκέφαλος, enképhalos - brain ', belonging to the brain '), refers to the layers of connective tissue that within the skull ( intracranial) the surrounding brain. They were first described by Herophilus of Chalcedon about 300 BC.

There are three meninges. Most outside the dura mater is encephali ( dura mater ), which is also called pachymeninx. It is based on the arachnoid encephali ( arachnoid membrane ) more or less immediately. The innermost layer is the pia mater encephali ( soft meninges ). Is the subarachnoid space (space subarachnoideum ) between the arachnoid and the pia mater. These two inner meninges are summarized as encephali leptomeningeal ( pia mater ).

Outside of the skull ( extracranial ) make up the meninges as so-called spinal meninges continues surrounding the lying there part of the central nervous system ( CNS). According to their anatomical belonging to the spinal cord, they are now the spinal dura mater, arachnoid and pia mater spinalis called (Latin spinalis: , the spine / spinal cord belonging ').

Dura mater

The dura mater (often just called " Dura " ) is the outermost meninges. It consists of two sheets, at least in the region of the cranial bone, the outer sheet is the same as the periosteum. The two leaves separate at circumscribed spots of each other to form so-called " sine " a special form of venous sinuses. The inner layer of the dura mater pulls in the big gap between the two cerebral hemispheres and in the gap between the two cerebellar halves and forms by apposition with the inner Duralblatt of the respective adjacent part of the brain, the falx cerebri, the falx cerebelli and the tentorium cerebelli. The falx cerebri separates the two cerebral hemispheres in the sagittal plane and passes into the falx cerebelli, which separates the two halves of the cerebellum from each other. Accordingly, the tentorium cerebelli forms (tent roof of the cerebellum ), which separates the upper and cerebellum from each other. It is a rather lying horizontally in the skull structure having by their attachment points on various parts of the skull is a complex three-dimensional shape. Analog forms the diaphragm sellae. The pituitary gland is lower and thus extradural (outside the dura ) positions.

In the area of the spinal cord, the dura mater is not connected to the spinal canal. There are few bony points of attachment of the spinal dura mater: For one, the beginning at the edge of the foramen magnum of the occipital bone, on the other hand, the end of the Duraschlauchs in the amount of 1 / 2 Sacral vertebra. This a continuation of the medullary cone ( conus medullaris ) beginning filum terminale continues from here as filum terminale externum or dural and ends on the second coccygeal vertebrae, where it is also fixed by bone and is in continuity with the ligaments sacrococcygea anteriora.

The spinal canal is located between the dura and spinal canal a gap, the epidural or epidural space filled with adipose tissue. About an injection in this space ( epidural ) the exiting nerve roots can be anesthetized.

The dura is very sensitive to pain. In the cranial region, the sensory innervation is carried out by the ramus of the ophthalmic nerve and the tentorial meningeal rami of the anterior ethmoidal nerve, the maxillary nerve, the mandibular nerve and the vagus nerve.

The dura mater is mostly tight, kollagenfaseriges connective tissue and has mainly the function of an organ capsule.

Arachnoid

The arachnoid (or called " arachnoid " ) is the middle meningeal. It lies on the dura mater and the inside of it is through a normally closed, partly capillary area, the Subduralspalt (space subdural ) separately, which only widened by fluid or air collection and as a subdural space becomes apparent. The arachnoid over jumps, as well as the dura mater, the furrows of the brain and receives its name from the strong whitish drawing with fine collagenous fibers connective tissue that gives her a spinnwebartiges appearance. From the arachnoid is button-shaped outgrowths put on before in the dura mater ( sinus of the dura mater ) into the venous sinuses. These protuberances are called arachnoid villi ( Pacchioni granulations, arachnoid granulations ) and are a place of Liquorresorption.

Under the arachnoid is the subarachnoid space (space subarachnoideum ), which is filled with cerebrospinal fluid and thus represents the outer CSF space.

Pia mater

The pia mater is the innermost layer. It is the brain and spinal cord directly, covers this completely and extends into in all furrows. It consists of soft, delicate connective tissue.

Diseases

A dreaded disease is meningitis ( meningitis), which can be triggered among other things by viruses or bacteria (eg meningococcal ) ( infectious disease ). This disease can lead to mental retardation or even death. An inflammation of the brain involving the meninges is known as meningoencephalitis. Irritation of the meninges can be neurologically at meningism, recognize Brudzinski, Kernig, and Lasègue characters. More signs of meningeal irritation syndrome are headaches, light and sound sensitivity, nausea and vomiting. The symptoms may also in other diseases of the meninges occur, especially in migraine or subarachnoid hemorrhage.

Tumors of the meninges are called meningioma. Accident or any other reasons can cause bleeding into the spaces between the meninges, which are known as subdural or subarachnoid hemorrhage.