Veins of the brain, Arachnoid and Pia Matter and Spinal Meninges Flashcards
(34 cards)
Describe the course of veins of the brain?
- Delicate venous drainage from the cerebral hemispheres emerges from the brain to form small venous structures in the pia mater
- These larger venous channels then form cerebral veins, which bridge the subarachnoid space and enter into endothelial-lined sinuses within the dura mater
Describe general characteristics of veins of the brain?
- Possess no valves
- Have extremely thin walls
- Pierce the arachnoid membrane and the inner or meningeal layer of the dura mater, and open into the cranial venous sinuses
What are the 2 types of veins of the brain?
- cerebral
- cerebellar
Cerebral veins are divided into which 2 groups?
- Superficial (External group) (Superior, middle and inferior cerebral veins)
- Deep (Internal) group
Describe the drainage of the superior cerebral veins?
Drain into the superior sagittal sinus
Describe the drainage of the middle cerebral vein?
Drains in the cavernous sinus
The middle cerebral vein is connected with?
- the superior sagittal sinus by the great anastomotic vein of Trolard > which opens into one of the superior cerebral veins
- the transverse sinus by the posterior anastomotic vein of Labbé > which courses over the temporal lobe.
Describe the drainage of the inferior cerebral vein?
Drain in the superior sagittal sinus, cavernous, sphenoparietal, and superior petrosal sinuses
Function of superior anastomatic vein?
connect superficial middle cerebral vein with the superior sagittal
Function of inferior anastomotic vein?
connects the superficial middle cerebral vein with the transverse sinus
Name the deep cerebral veins and what they drain?
- thalamostriate
- choroidal
> drain internal structures of the forebrain
- basal ganglia
- thalamus
- internal capsule
- choroid plexus
- hippocampus
Describe the course of the deep cerebral veins?
thalamostriate + choroidal veins = 2 internal cerebral veins
2 internal cerebral veins unite = great cerebral vein
> unite in midline
> lies beneath the splenium of the corpus callosum and drains the deep structures of the forebrain
Note: great cerebral vein is continuous with the straight sinus which lies in the midline of the tentorium cerebelli
Describe the drainage of the cerebral veins the dural venous sinuses?
- superior cerebral veins > superior sagittal sinus
- great cerebral vein > inferior sagittal sinus + joins with it to form straight sinus
> dural venous sinuses are connected to extracranial veins via emissary veins
Describe the consequences of cerebral damage caused by venous infarction?
manifests as epleptic attacks and focal paralysis of the limbs
Describe the arterial supply to the dura mater?
- Middle meningeal arteries – branch of maxillary artery
> supply the lateral surface - Ophthalmic artery
> branches supply the anterior surface - Occipital and vertebral arteries
> branches supply the posterior surface
Describe the nerve supply to the dura mater?
- Trigeminal nerve – except the posterior fossa.
- Posterior fossa is supplied by Vagus nerve and 2nd and 3rd cervical nerves
> Dura mater is pain sensitive as well as proximal portions of blood vessels at the base of the brain.
> Dural nerves follow arteries and terminate near arteries or venous sinuses
Describe the innervation of the anterior cranial fossa?
- meningeal branch of the ophthalmic nerve [V1]
- turns and runs posteriorly
- supplying the tentorium cerebelli and the posterior part of the falx cerebri. - meningeal branches from the ethmoidal nerves
- which are branches of the ophthalmic nerve [V 1 ]
- supply the floor and the anterior part of the falx cerebri.
Describe the innervation of the middle cranial fossa?
- supplied medially by meningeal branches from the maxillary nerve [V2]
- Supplied laterally, along the distribution of the middle meningeal artery, by meningeal branches from the mandibular nerve [V3]
Describe the innervation of the posterior cranial fossa?
- supplied by meningeal branches from the first, second, and, sometimes, third cervical nerves, which enter the fossa through the foramen magnum, the hypoglossal canal, and the jugular foramen
- Meningeal branches of the vagus nerve [X] have also been described.
Note: Possible contributions from the glossopharyngeal [IX] and hypoglossal [XII] nerves have also been reported.)
What is the arachnoid mater?
Is a thin avascular membrane composed of few layers of cells
> Bundles of collagen interspace the membrane.
> Outermost layer adheres to the inner surface of the dural mater and contains no collagen
Describe the components of the arachnoid mater?
- Arachnoid trabecularae > extend to pia mater and help to suspend the brain.
> Arachnoid does not dip into the sulci –hence creates a subarachnoid space between arachnoid and pia mater. - Subarachnoid space > filled with Cerebrospinal fluid (CSF)
What are subarachnoid cisterns?
spaces formed by openings in the subarachnoid space
> filled with CSF
Name the major subarachnoid cisterns?
- Cerebelomedullary cistern (Cistern magna )- between the inferior surface of the cerebellum and posterior to medulla
- Pontine cistern - anterior surface of the pons and medulla
- Interpeduncular cistern – between cerebral peduncles
- Superior cistern (Quadrigeminal cistern)
- Cistern of the great cerebral vein
What are arachnoid villi and describe their function?
- Major sites for reabsorption of CSF into the venous system.
- CSF enters the venous circulation through arachnoid villi
- Arachnoid villi penetrate the dural layer at certain dural venous sinuses
> more common in the superior sagittal venous sinuses - Large number of villi form arachnoid granulations
