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The middle region is a mostly fibrous portion. It consists of two layers: the endosteal layer, which lies closest to the skull, and the inner meningeal layer, which lies closer to the brain. [7] It contains larger blood vessels that split into the capillaries in the pia mater. It is composed of dense fibrous tissue, and its inner surface is ...
The dura mater covering the spinal cord is known as the dural sac or thecal sac, and only has one layer (the meningeal layer) unlike cranial dura mater. The potential space between these two layers is known as the epidural space, [5] which can accumulate blood in the case of traumatic laceration to the meningeal arteries.
In the brain a laminar organization is evident in the arrangement of the three meninges, the membranes that cover the brain and spinal cord. These membranes are the dura mater, arachnoid mater, and pia mater. The dura mater has two layers a periosteal layer near to the bone of the skull, and a meningeal layer next to the other meninges. [3]
These sinuses play a crucial role in cerebral venous drainage. A dural venous sinus, in human anatomy, is any of the channels of a branching complex sinus network that lies between layers of the dura mater, the outermost covering of the brain, and functions to collect oxygen-depleted blood. Unlike veins, these sinuses possess no muscular coat.
The pia firmly adheres to the surface of the brain and loosely connects to the arachnoid layer. [6] Because of this continuum, the layers are often referred to as the pia arachnoid or leptomeninges. A subarachnoid space exists between the arachnoid layer and the pia, into which the choroid plexus releases and maintains the cerebrospinal fluid ...
Vertebrate brains are surrounded by a system of connective tissue membranes called meninges, which separate the skull from the brain. Cerebral arteries pierce the outer two layers of the meninges, the dura and arachnoid mater , into the subarachnoid space and perfuse the brain parenchyma via arterioles perforating into the innermost layer of ...
The arachnoid mater is interposed between the two other meninges, the more superficial (closer to the surface) and much thicker dura mater and the deeper pia mater, from which it is separated by the subarachnoid space. The delicate arachnoid layer is not attached to the inside of the dura but against it, and surrounds the brain and spinal cord.
It is different from the internal granular layer of the cerebral cortex (commonly known as layer IV). Layer II is often grouped together with layer III and referred to as layer II/III. Layers I, II, and III are together referred to as the supragranular layers, because they are above layer IV. Brodmann has this to say about layer II: [1]