3 Spinal Cord External Features Neuroanatomy 3 Dr Ahmed Kamal — Transcript

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1. 0:04External features of the spinal cord.
2. 0:08The external view of the spinal cord.
3. 0:12Here is the spinal cord. The spinal
4. 0:16cord is 45 cm long here. It is located
5. 0:21in the vertebral canal. Meaning, it is
6. 0:24inside the vertebrae. This is the
7. 0:26vertebral column on the outside. All of
8. 0:28this is the vertebral column. Which is
9. 0:30the spine. Inside it is a canal called
10. 0:33the vertebral canal. The spinal cord is
11. 0:35inside this vertebral canal. It is 45
12. 0:40cm long. Cylindrical in shape. Meaning
13. 0:44it is cylindrical in form. However,
14. 0:48this does not prevent it from having an
15. 0:50enlargement in the cervical region or
16. 0:53its upper part. There is a swelling
17. 0:55here. Which is called the cervical
18. 0:58enlargement. In the spinal cord, there
19. 1:01is another swelling called the lumbar
20. 1:03enlargement. So the one above is called
21. 1:06the cervical enlargement. And here is
22. 1:09the lumbar enlargement. At the bottom,
23. 1:12I can see the end of the spinal cord
24. 1:16forms a bulb. This bulb is called the
25. 1:19conus medullaris. So the spinal cord is
26. 1:23cylindrical in shape. Yes. In the upper
27. 1:29region, there is a cervical enlargement
28. 1:31. And in the lower region, there is a
29. 1:33lumbar enlargement. Then the last part
30. 1:36forms a bulb. It is called the conus
31. 1:39medullaris. Conus, like a cone here.
32. 1:42They call it the conus medullaris. The
33. 1:46beginning of the spinal cord is
34. 1:47important. And the end of the spinal
35. 1:49cord is important. The beginning of the
36. 1:52spinal cord is just below. The foramen
37. 1:56magnum. Meaning here, below the foramen
38. 1:59magnum. No one should say that the
39. 2:01foramen magnum contains the spinal cord
40. 2:04; no. This is always a question in the
41. 2:06exam. They ask you, what are the
42. 2:07contents of the foramen magnum? You
43. 2:08tell them, the lower part of the
44. 2:10medulla oblongata. Which is the first
45. 2:12part of the brain. And the cerebellar
46. 2:14tonsils. You should never say the
47. 2:17spinal cord. Why? Because the spinal
48. 2:19cord starts just below the foramen
49. 2:22magnum. That is number one. Number two.
50. 2:25The spinal cord in adults ends at the
51. 2:28lower border of L1. Or the upper border
52. 2:33of L2 vertebrae. Meaning here at the
53. 2:36lower border of the L1 vertebra. Or the
54. 2:39upper border of L2 vertebrae. This is
55. 2:42in adults. Of course, we must not
56. 2:44forget there is a cervical enlargement.
57. 2:47And this swelling means many cells. And
58. 2:50the lumbar enlargement means many cells
59. 2:53. What causes these many cells in the
60. 2:55cervical region? It gives rise to the
61. 2:57nerves that form the cervical plexus
62. 3:00and brachial plexus. And the lumbar
63. 3:04enlargement is what contains many cells
64. 3:06that give rise to the nerves forming
65. 3:09the lumbar plexus. Now let us look at
66. 3:13the spinal cord, here it is in the
67. 3:15vertebral canal. It ends at the lower
68. 3:19border of L1, or the upper border of L2
69. 3:23, and then I see here at the end of the
70. 3:26spinal cord a thin cord or thread
71. 3:29attached called the filum terminale.
72. 3:33This is the filum terminale, and we
73. 3:35will see later where it comes from. The
74. 3:37filum terminale, we see the spinal cord
75. 3:40is divided into segments. These
76. 3:43sections or parts into which the yellow
77. 3:46spinal cord is divided are segments in
78. 3:49the cervical region. 8 cervical
79. 3:52segments. 12 segments in the thoracic
80. 3:54region here. So 12. 5 lumbar segments
81. 4:00here, and...These are the black ones,
82. 4:05and one coccygeal. So the spinal cord
83. 4:09has 31 segments. 8 cervical, 12
84. 4:14thoracic, 5 lumbar, 5 sacral, and 1
85. 4:17coccygeal. From each segment, on both
86. 4:21the right and left sides, a pair of
87. 4:24spinal nerves emerges. Spinal nerves
88. 4:29are the 31 nerves we are talking about
89. 4:33right now. These nerves all emerge from
90. 4:36each segment, with a pair of nerves
91. 4:38coming out. The nerves that emerge at
92. 4:41the top are horizontal. The nerves that
93. 4:44emerge from the lower thoracic region
94. 4:46are oblique. The nerves that emerge
95. 4:48from the lumbar and sacral regions are
96. 4:51vertical. They form a nerve plexus that
97. 4:55resembles a horse's tail. The nerves
98. 4:58emerging from the spinal cord that
99. 5:01resemble a horse's tail and continue
100. 5:03into the vertebral canal are called the
101. 5:05cauda equina. So, the cauda equina
102. 5:08consists of the lower lumbar and sacral
103. 5:11nerves. Or the nerve roots that are
104. 5:14located inside the vertebral canal. So,
105. 5:17let's not forget that the spinal cord
106. 5:19is divided into 31 segments. These
107. 5:22segments are 8 cervical, 12 thoracic, 5
108. 5:26lumbar, 5 sacral, and 1 coccygeal.