Mnings And Dural Folds Flashcards
What are the meninges
Three Membranous Layers (‘sacs’) that Surround and Protect the Brain and Spinal Cord
• Dura: tough fibrous membrane
(potential space)
• Arachnoid: soft translucent membrane
(space - csf, crebral vessels)
• Pia: microscopically thin, delicate adherent to surface of brain, follows every fold
Describe the dura
• Dura fuses with the periosteum lining inner table of skull bones
• Dura effectively then has two layers (while within the skull)
– Periosteal
– part against the inner table of bone
– Meningeal = part adjacent to arachnoid
• For most part two layers closely adhered (appearing as a single layer)
– but areas where they separate
• Separation of two layers forms
– Dural folds
– Dural venous sinuses (spaces which are filled with venous blood =venous channels)
What are faux cerebra and tentorium cerebellum
Dural folds
What are dural folds
Help to Stabilise the Brain and act as Rigid Dividers…
BUT… A rise in pressure inside the skull e.g. secondary to a bleed can lead to compression and displacement of parts of brain against rigid dural folds and/or through foramen magnum
Herniation
What are dural venous sinuses
Dural Venous Sinuses
Venous blood filled spaces created by separation of meningeal from periosteal layer of dura
• Found throughout the skull, surrounding the brain within the areas where dura has separated
• Dural venous sinuses connected to each other, and receive
blood from cerebral veins (draining brain)
• Eventually dural venous sinuses drain into internal jugular vein
Describe th location of dural venous sinuses
In the channel - superior Saginaw venous sinus - poiint of pidgin fall cerebra and hangs down
In free lower marginal falx, another sinus - inferior Saginaw sinus
Where space between both of these, another sinus runs between i the gap - the train hit situs
Inf sinus drains posteriorly into str8 sinus, which communicates with superior sinus.
Where str8 sinus meets superior sagutalainus, confluence of sinuses
Transverse sinuses move out laterally. Point @ which tentorium cerebelli just leaves the skull
Petrozavodsk connect cavernous to sigmoid andtransvers
What are cerebral veins, bridging veins and emissary veins
Cerebral Veins within Subarachnoid Space Drain into Dural Venous Sinuses Bridging veins traverse the Subdural “Space”
Scalp Veins Also Connect with Dural Venous Sinuses
Emissary veins traverse through the skull
Describe intracranial haemorrhage
Head trauma can lead to bleeding in ‘spaces’ between meningeal layers
• Blood vessels run along or traverse between the meningeal layers
• Injury and bleeding from these blood vessels will cause accumulation of blood in the ‘space’ between the meningeal layers
– Extradural – Subdural – Subarachnoid
• Bleeding can also occur within the brain tissue itself (e.g. contusions, tearing of white matter)
– Intracerebral haemorrhage
• Addition of ‘volume’ to an already fixed space (the skull) leads to rise in pressure and damage to brain tissue, brainstem and other important structures e.g. cranial nerves
Describe extradural haemorrhage
Middle meningitis artery - between inner table of bone and epriosteal layer
Margins f extra dural bleed will never go past bone
Extra dural haem orange
Arterial bleed
Describe subdural haemorrhage
Older ppl get cerebral atrophy, beb to head causis them to sheer - tear away from sinus- bleed on top of arachnoid but underrate dura
Venous blood usually from bridging veins
Descrbe subarachnoid haemorrhage
• Secondary to trauma or spontaneous rupture of blood
vessel e.g. aneurysm
– Usually a branch of ‘Circle of Willis’ (the arterial circuit
responsible for supplying brain structures)
• Blood leaks into subarachnoid space, mixing with CSF
– Sudden, often fatal
• CT imaging of head
– 93% picked up if within 24 hours; 100% if within 6 hours
– Lumbar puncture-if CT inconclusive: sample CSF to
identify presence of blood (haemoglobin degradation products)
