Veins of the brain – Venae cerebri
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The veins of the brain are not equipped with valves and pass in the subarachnoid space, with some of them passing under ependyma. They are classified into two groups, the supratentorial (superficial and deep) and infratentorial group. The superficial cerebral veins collect blood from the cerebral cortex and drain into the venous sinuses. The deep cerebral veins drain blood from the diencephalon and deep parts of the hemispheres into the great cerebral vein. The infratentorial veins drain blood from the cerebellum and brainstem into the venous sinuses. Eventually, all the blood is drained into the superior bulb of the internal jugular vein. Blood from the venous sinuses can also flow out by emissary veins into the extracranial veins of the head. Deep veins of the brain (venae profundae cerebri)
• 1 Internal cerebral vein (v. interna cerebri)
– a paired vein located above the roof of the third ventricle, in the telondiencephalic fissure – collects blood from the basal ganglia, 1 internal capsule, septum, choroid plexus and 2 from parts of the white matter of the hemispheres – is formed by the confluence of three veins: 1.1 Anterior vein of septum pellucidum (v. anterior septi pellucidi) – drains blood from the septum pellucidum and head of the caudate nucleus 1.2 Superior choroid vein (v. choroidea superior) – drains blood from the choroid plexus of the lateral ventricle 1.3 Superior thalamostriate vein (v. thalamostriata superior) – drains blood from the thalamus, striatum, and internal capsule (lies under the stria terminalis of the thalamus) 2 Great cerebral vein of Galenos (v. magna cerebri) – a large, short, unpaired vein – is formed by a union of the right and left internal cerebral vein under the splenium of the corpus callosum – the basilar vein empties into the great cerebral vein – enters the quadrigeminal cistern (cistern of great cerebral vein) and drains into the straight sinus
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Superficial veins of the brain (venae superficiales cerebri)
• 1 Superior cerebral veins (vv. cerebri superiores) – collect blood from the superior part of the hemispheric convexity and empty into the superior sagittal sinus • 2 Superficial middle cerebral vein (v. cerebri media superficialis)
– a visible vein begins close to the supramarginal gyrus, runs along the lateral cerebral sulcus and drains into the sphenoparietal or cavernous sinus 2.1 Superior anastomotic vein of Trolard (v. anastomotica superior) – a connection between the superficial middle cerebral vein and superior cerebral veins (superior sagittal sinus) 2.2 Inferior anastomotic vein of Labbé (v. anastomotica inferior) – a connection between the superficial middle cerebral vein and inferior cerebral veins (transverse sinus) 3 Deep middle cerebral vein (v. cerebri media profunda) – accompanies the middle cerebral artery 1 at the base of the lateral cerebral fossa – drains the insular lobe and empties into the basal vein 2.1 4 Inferior cerebral veins (vv. cerebri inferiores) – drain the inferior part of the hemispheric convexity and inferior surface of the hemisphere 2 – empty into the transverse, superior petrosal, 4 and inferior petrosal sinus 5 Basal vein of Rosenthal (v. basalis) 2.2 – originates by the confluence of the deep middle cerebral vein, anterior cerebral vein, and small inferior thalamostriate veins at the level of the anterior perforated substance – collects blood from the inferior surface of the frontal lobe and adjacent parts of diencephalon 5 – encloses the cerebral crura, passes via the ambiens cistern and drains into the great cerebral vein
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Central nervous system Original venous plexuses are preserved around the spinal cord as the vertebral venous plexuses. In the cranial cavity the plexuses have not disappeared but have transformed into the sinuses of the dura mater. The infratentorial veins are the cerebellar veins accompanying homonymous arteries. They drain into the great cerebral vein in the midline and laterally into the nearest venous sinuses (superior petrosal, transverse, sigmoid sinus). The textbook pattern of the confluence of the sinuses arrangement occurs in only 10 % of cases. The Willis chords are transverse columns segregating the lumen of the sinuses, especially in the superior sagittal sinus. The central nervous system does not contain lymphatic vessels. The lymphatic system is substituted by the flow of interstitial fluid along the throbbing extracranial cerebral arteries and also via the cribriform plate of the ethmoid bone and by the circulation of cerebrospinal fluid. The bridging veins are the terminal segments of the superficial cerebral veins. The emissary veins connect the sinuses of the dura mater, diploic veins, and extracranial veins.
Clinical notes A spread of infection from the face and orbit can happen intracranially by venous anastomoses. Purulent processes of the upper lip can spread by the deep facial vein or pterygoid plexus, inflammatory processes from the orbit by the superior ophthalmic vein into the cavernous sinus. Dural venous sinuses thrombosis is one form of stroke. The thrombosis is often complicated by a haemorrhage resulting from blood stasis and oedema. The typical sudden symptoms are headache, weakness, visual impairment, motor and perceptual disorder. Selective catheterization of the inferior petrosal sinus: A catheter is introduced into the internal jugular vein. The inferior petrosal sinus represents the nearest catheterization point for blood sampling from the pituitary gland. The sampling is used for the diagnosis of ACTH-secreting and growth hormone-producing hypophysial adenomas (endocrinology, oncology).