Dural Venus Sinuses |
Skull cap
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The location of the superior sagittal sinus is faintly visible. Why is the sinus not seen? Can see small veins coming through the periosteum.
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Brain covered with dura
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Numerous veins are seen entering the SSS which is faintly seen. All dural venous sinuses are situated between two layers of the dura.
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Dura
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If you touched the dura with your finger, what space would your finger be in?
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Dura covering left cerebral hemisphere reflected
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Cerebral veins are seen entering the SSS.
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Superior sagittal sinus
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A part of dura is cut to expose the unpaired SSS. It begins at crista gali and ends by becoming transverse sinus of one side (generally right).
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Part of occipital bone
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Note the internal occipital protuberance and faint lines indicating location of transverse sinuses.
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Dura - posterior view
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Two transverse sinuses are well seen. Right appears larger than the left. The right transverse sinus here is larger as SSS drains into it. What drains into the left transverse?
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Brain posterior view
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The straight sinus becomes the left transverse here. Also note the beginning of the left sigmoid sinus.
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Transverse sinuses
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As part of the dura is cut, sinuses are revealed.
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Direction of blood flow
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What is the direction of blood flow in the transverse sinus?
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Lateral view of brain, emissary veins
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In this view sigmoid sinus is better seen. Note the proximity of the sinus to the auditory canal. The vein entering the sigmoid sinus is perhaps the mastoid emissary vein. Emissary veins are small valve less veins that connect the dural sinuses with external regions. Thus these veins allow spread of infection from external to intracranial regions.
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Base of brain
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The brain removed from the cranial cavity. Note the dura covering the cerebellum and the left sigmoid sinus.
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Falx cerebri
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The dura covering the left cerebrum is reflected and part of the cerebrum removed. The falx cerebri is clearly visible. Note the superior and inferior sagittal sinuses running along its upper and lower borders.
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Straight sinus
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As more of the brain is removed, inferior sagittal sinus is seen forming the straight sinus by joining the great cerebral vein. Where is the straight sinus located?
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Straight sinus
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It is located where the falx joins the tentorium cerebelli.
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Confluens of sinuses
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The confluence of sinuses connects the superior sagittal, transverse and occipital sinuses. Since there are no valves in dural sinuses, blood can flow in any direction. Generally it flows towards the sigmoid sinus.
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Lateral view of brain covered with the dura.
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Left transverse sinus becoming the sigmoid.
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Tentorium cerebelli
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As dura is reflected, tentorium cerebelli is visible. Also note the cerebral veins entering the transverse sinus.
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Petrosal sinuses
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The right superior petrosal sinus is exposed as the tentorium is incised. It appears to be leading into the transverse sinus. On the left the big blue structure represents the end of the sigmoid sinus. (As sigmoid sinus passes through the jugular foramen it becomes the internal jugular vein.) The inferior petrosal sinus is not shown. Why are these called petrosal?
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Cranial cavity right side
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Because located on the petrous part of the temporal bone! Outline the right transverse becoming the sigmoid sinus.
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Sigmoid sinus
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Is this what you visualized?
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Cranial cavity crista gali to foramen magnum
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Where are the cavernous sinuses located?
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Cavernous sinuses
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Located on either side of the body of the sphenoid. The left is seen, while the right is covered by the dura.
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Right cavernous sinus
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Sinus is exposed by reflecting the dura. It is seen draining into the superior petrosal sinus. (Some blood leaves via the inferior petrosal and joins the internal jugular vein.)
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Structures passing through cavernous sinus
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The internal carotid artery and the abducens nerve go through the sinus (as seen on the left).
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Structures in wall of cavernous sinus
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The oculomotor, trochlear, ophthalmic and maxillary nerves are in its lateral wall as seen on the right.
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Cranial cavity front part
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Some periosteal and meningal vessels are piercing the dura. Also the big blue dot is the beginning of the SSS.
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