Dural Venous Sinuses (Location + Visual Scheme) | Anatomy — Transcript

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1. 0:08Let's go ahead and talk about the  anatomy of the dural venous sinuses
2. 0:12and we're going to do that by first going  through the location of the dural sinuses
3. 0:17basically where they are in comparison to the  meninges and then we're going to visualize the
4. 0:22dural venous sinuses schematically so that  it's easier to remember the dural sinuses
5. 0:28and then in the next video we're going  to go through the cerebral veins and the
6. 0:32emissary veins and the diploic veins and  then the cerebral circulation in general.
7. 0:37All right, so the veins of the systemic  circulation consist of four kind of systems.
8. 0:44You have the veins of the heart, then you have the  veins of the inferior vena cava, and the veins of
9. 0:50the superior vena cava, and then you have the  portal system. So the superior venous sinuses
10. 0:57we're going to go through drain into the superior  vena cava so we can start by zooming in on this
11. 1:03figure and then take a small section of the skull  in order to see all the layers so these are all
12. 1:08the layers from the skin down to the brain tissue.  So first we have the skin all the dermal layers
13. 1:14then underneath that we have the skull and then  the meninges and then there's the cerebral tissue.
14. 1:20So the meninges are what we're essentially going  to focus on right now. So the meninges consists
15. 1:25of three layers. You have the pia mater  which is the thinnest most delicate layer
16. 1:32that lies just on top of the  surface of the brain tissue.
17. 1:36Then superficially to that you will find the  arachnoid mater, which is slightly thicker than
18. 1:42the pia mater, and underneath the arachnoid  mater you will find the subarachnoid space
19. 1:48which contains cerebrospinal fluid and you will  notice that there are these arachnoid granulations
20. 1:54that take the cerebrospinal fluid and then just  pumps them into the venous sinuses so that they
21. 1:59can get back into the circulation to complete  the circulation of the cerebrospinal fluid.
22. 2:05Then superficial to the arachnoid mater  you will find the thickest meninges
23. 2:10called the dura mater and notice that the  dura mater inside the cranium consists of
24. 2:15two layers there's first the periosteal  layer which lies very close to the skull
25. 2:21and then there's the meningeal layer which  lies very close to the arachnoid mater and
26. 2:26when you look at the spinal cord you'll notice  that dura mater only consists of one layer
27. 2:31which is the meningeal layer because the  periosteal layer stops at the foramen magnum.
28. 2:37Notice that the periosteal layer and  the meningeal layer are bound together
29. 2:42and only separate when they form the dural  venous sinuses and the dural septae. So if
30. 2:49I would ask you between which layers are the  dural venous sinuses located inside the head,
31. 2:57they are located between the periosteal  and the meningeal layer of the dura mater.
32. 3:02Awesome now finally let's go ahead and  go through the dural venous sinuses.
33. 3:07So what we're going to do is that we're going to  go through all the dural venous sinuses one by one
34. 3:13and we will use this table to help us do that.
35. 3:16All right, so first thing is that  I've divided the dural venous sinuses
36. 3:20into the ones that are located in the  midline, the ones that are located laterally,
37. 3:25the ones that are located  posteriorly and anteriorly,
38. 3:28and you will notice that when you're studying  the dural venous sinuses that there are different
39. 3:33ways to categorize the different dural  venous sinuses. You can also categorize
40. 3:37them as paired and unpaired for example,  but I like this one we'll stick with that.
41. 3:42All right, so first we have the superior and the  inferior sagittal sinus. Then there's a straight
42. 3:48sinus which connects these two or also called  a sinus rectus. Laterally you will find the
43. 3:55transverse sinus which continues as the sigmoid  sinus and then as the internal jugular vein.
44. 4:02Then we have the superior petrosal  sinus and the inferior petrosal sinus
45. 4:07which drain from the cavernous sinus and  then we have the sphenoparietal sinuses
46. 4:13which go along the sphenoid bone. Then we have the  anterior and the posterior inter-cavernous sinuses
47. 4:22which connect the two cavernous sinuses.
48. 4:25And then we have the basilar plexus and  you know plexus just means a network of
49. 4:31structures and the basilar plexus are  just a plexus of veins that connect
50. 4:37different adjacent structures together at the  basal region of the skull so it connects with
51. 4:44the cavernous sinuses, it connects with the  superior and the inferior petrosal sinuses,
52. 4:50and it also goes down and  connects with the vertebral veins.
53. 4:54Then we have the occipital sinus which is the  smallest sinus and then when the occipital sinus,
54. 5:01the superior sagittal sinus, and the straight  sinus meet, they form the confluence of sinuses.
55. 5:10So those are the main dural venous  sinuses that I want you to know
56. 5:14so let's go ahead and go through them in detail.
57. 5:17First, we have the superior sagittal sinus  which remember is the largest dural sinus.
58. 5:23It starts at the foramen cecum in the anterior  part of the cranial cavity and then goes along
59. 5:30the superior margin of the falx cerebri and then  goes back to drain into the confluence of sinuses.
60. 5:37Then we have the inferior sagittal sinus. The  inferior sagittal sinus goes along the inferior
61. 5:44edge of the falx cerebri and it receives  mainly tributaries from the falx itself
62. 5:50as well as some small veins from the  medial surface of the cerebral hemispheres.
63. 5:54The straight sinus drains the inferior  sagittal sinus into the confluence of sinuses.
64. 6:01More anteriorly we will find the anterior  and the posterior intercavernous sinuses
65. 6:07which just connects the right and  the left cavernous sinus together.
66. 6:11And notice that I've put in brackets variable  here because depending on your source
67. 6:15they can be anterior or posterior or  even inferior intercavernous sinuses
68. 6:21but the functions are the same, it just  connects the two cavernous sinuses together.
69. 6:25Then we have the basilar plexus which  remember just connects regional venous
70. 6:30structures. Then the transverse sinus drains the  confluence of sinuses into the sigmoid sinus.
71. 6:39The sigmoid sinus is a continuation of  the transverse sinus and it actually has
72. 6:44a pretty cool S-shaped form as it goes towards  the jugular bulb of the inferior jugular vein.
73. 6:51Then we have the superior and the inferior  petrosal sinuses which drain the cavernous
74. 6:57sinus into the sigmoid and the internal  jugular vein. Then we have the occipital sinus
75. 7:04and the occipital sinus is  the smallest sinus we have
76. 7:07and as you see it connects with the  confluence of sinuses and the sigmoid sinus.
77. 7:13Then we have the confluence of sinuses. The  confluence of sinuses is not really a structure
78. 7:20in itself, rather it's just a connecting point of  the superior sagittal sinus, the straight sinus,
79. 7:27and the occipital sinus. So when these three  sinuses meet they form the confluence of sinuses.
80. 7:34Then we have the cavernous sinus and the cavernous  sinus is actually divided by fibrous septae into
81. 7:42small caves and that's where the word cavernous  sinus comes from it comes from the word cave.
82. 7:49And if you look at this picture you will see  that there are different structures that pass
83. 7:54within the cavernous sinus because the cavernous  sinus is divided into these caves. There's this
84. 8:00mnemonic for all of all the structures that go  through the cavernous sinus which is O TOM CATS.
85. 8:06So O stands for the oculomotor nerve  which is the third cranial nerve,
86. 8:11T for the trochlear the fourth cranial nerve, then  O and M stand for the ophthalmic and the maxillary
87. 8:19branch of the trigeminal nerve, C stands for  internal carotid artery, A for the abducent nerve
88. 8:26the sixth cranial nerve and T is just a filler  in order to complete the mnemonic O TOM CATS.
89. 8:32So that was this one. The last one is  the sphenoparietal sinuses which receive
90. 8:38tributaries from the adjacent lobes and then drain  them into the cavernous sinus to then be drained
91. 8:45through the superior and the inferior petrosal  sinuses and then into the internal jugular vein.
92. 8:52So that was everything I had  about dural venous sinuses.
93. 8:56In the next video, we're going to go  through the branches of these dural sinuses.