The meninges describe the membranous coverings of the mind and spinal cord. There are three layers of meninges, recognized as the dura mater, arachnoid mater and pia mater.
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These coverings have two significant functions:Provide a supportive framework for the cerebral and also cranial vasculature.Acting v cerebrospinal liquid to protect the CNS from mechanical damage.
The meninges space often associated cerebral pathology, together a typical site of infection (meningitis), and intracranial bleeds.
In this article, us shall look in ~ the anatomy of the three layers, and their clinical correlations.
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Fig 1 – outline of the meninges, and also their connection to the skull and brain.
The dura mater is the outermost great of the meninges and also is located straight underneath the skeleton of the skull and also vertebral column. The is thick, tough, and also inextensible.
The dura mater consists of 2 layered sheets of connective tissue:Periosteal layer – present the inner surface ar of the skeleton of the cranium.Meningeal layer – located deep to the periosteal layer. It is constant with the dura mater that the spinal cord.
The dural venous sinuses are located between the 2 layers of dura mater. They room responsible because that the venous drainage the the cranium and also empty right into the internal jugular veins.
The dura mater receive its own vascular supply – generally from the middle meningeal artery and vein. It is innervated by the trigeminal nerve (V1, V2 and also V3).
The meningeal class of dura mater crease inwards upon chin to type four dural reflections.
These reflections project right into the cranial cavity, dividing it into several compartments – each of which dwellings a subdivision the the brain.
The 4 dural reflect are:Falx cerebri – projects downwards to different the right and left cerebral hemispheres.Tentorium cerebelli – separates the occipital lobes from the cerebellum. It consists of a an are anteromedially because that passage of the midbrain – the tentorial notch.Falx cerebelli – off the right and also left cerebellar hemispheres.Diaphagma sellae – consist of the hypophysial fossa of the sphenoid bone. It has a small opening for passage of the stalk of the pituitary gland.
Clinical Relevance: Extradural and also Subdural Haematomas
A haematoma is a repertoire of blood. As the cranial cavity is efficiently a close up door box, a haematoma can cause a rapid rise in intra-cranial pressure. Fatality will an outcome if untreated.
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There space two types of haematomas involving the dura mater:Extradural – arterial blood collects between the skull and also periosteal layer of the dura. The causative courage is typically the middle meningeal artery, tearing as a repercussion of mind trauma.