Sistema músculo esquelético parte 2 — Transcript

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1. 0:09Okay, for methodological convenience we
2. 0:11had to skip that step. We had to skip
3. 0:17the surgical technique, so let's begin.
4. 0:23Okay, let's identify the five
5. 0:24fundamental elements of the
6. 0:26musculoskeletal system of our chicken
7. 0:27leg. We start with bone. It has a femur
8. 0:32, tibia, fibula. The fibula is
9. 0:35practically vestigial, one tarsal bone,
10. 0:37and four phalanges. We have five
11. 0:42phalanges and seven tarsal bones, so
12. 0:45our lower limb has 30 bones and
13. 0:47chickens have 18 little bones. This is
14. 0:54its tibia, a long bone. See how it
15. 0:57resists the force I apply to it. It's
16. 1:03rigid and strong. As expected, since
17. 1:06it's made of calcium and collagen. We
18. 1:11continue with cartilage. Let's see how
19. 1:15the cartilage is located at the ends,
20. 1:17both proximal and distal of the long
21. 1:19bone. This would be the tibia. Let's
22. 1:24also see how the cartilage adopts the
23. 1:27shape of the bone surface, the shape of
24. 1:30its reciprocal fit with the other bone
25. 1:33it will articulate with, which also has
26. 1:36its own cartilage that will allow these
27. 1:40two surfaces to slide with practically
28. 1:43zero friction. Ligaments. We already
29. 1:48know that a joint is formed by the
30. 1:50union of bone to bone, but what
31. 1:51stabilizes this union? Ligaments. Here
32. 1:54we can see the collateral ligament of
33. 1:56the chick's knee. Let's observe how it
34. 1:59goes from bone to bone. From bone to
35. 2:03bone. They are bands of fibrous tissue,
36. 2:06colorless, practically imperceptible.
37. 2:09Here we have the anterior and posterior
38. 2:10cruciate ligaments. Along with the
39. 2:12collateral ones. They give great
40. 2:14stability to this joint. Let's move on
41. 2:18to muscle, which is what we like to eat
42. 2:20, the tastiest part of the chicken is
43. 2:22what we eat, pure protein. We see how
44. 2:25the muscle is also distributed into
45. 2:28compartments. We can also see the
46. 2:32distribution of its muscle fibers there
47. 2:35. We also see the formation of an
48. 2:39aponeurotic fascia. All the tendons are
49. 2:42inside, we can't see them, but they
50. 2:45cross the joint. We can see a few there
51. 2:48and they go towards the toes. And
52. 2:52finishing with tendon, once we dry all
53. 2:55the muscles or muscle groups found in
54. 2:59the back of the leg, we can observe
55. 3:05that great biological wonder. We
56. 3:09observe the muscles and how they end in
57. 3:14cord-like tissues, better known as
58. 3:19tendons. Let's see how, without
59. 3:22exception, all the muscles, absolutely
60. 3:25all the muscles in this part of the
61. 3:28chick's body end in a tendon. Okay.
62. 3:37Let's look at this little muscle that
63. 3:39comes from a more proximal part of the
64. 3:41bone. It ends, they all end in tendons.
65. 3:50Let's see how the muscle thins out
66. 3:53until it forms a cord, a very resistant
67. 3:56tendinous cord. See how they all cross
68. 4:02the joint. And look at this, look at
69. 4:05this, this wonder of mechanics, of
70. 4:08biomechanics, uh that muscle would most
71. 4:12likely be called the common flexor of
72. 4:15the digits, and this one, the flexor of
73. 4:17the first phalanx. Interesting. Okay,
74. 4:25to finish up, let's analyze the basic
75. 4:27principles of the musculoskeletal
76. 4:29system in our little chicken. Let's
77. 4:33start with the first principle, which
78. 4:37tells us that a joint is the union of
79. 4:39two or more bones. Here we can see the
80. 4:41two bones. Each bone is in contact with
81. 4:44its own hyaline cartilage. These are
82. 4:49synovial joints because they have their
83. 4:52synovial membrane within this entire
84. 4:55ligament complex, and the synovial
85. 4:58membrane produces synovial fluid. And
86. 5:02just like this joint, all these
87. 5:04synovial joints have their ligaments,
88. 5:07which also stabilize the joints. We
89. 5:10don't see joint number one, the hip;
90. 5:12it's not here in this image. Two is the
91. 5:16knee, three is the ankle, four would be
92. 5:19the metatarsophalangeal, and five, the
93. 5:23joints of the phalanges, the
94. 5:26interphalangeal joints. Wow. Okay,
95. 5:30let's go with the second principle.
96. 5:32Muscles always originate in one bone
97. 5:34and insert into another bone, either
98. 5:36adjacent or far from the origin. In
99. 5:38this case, we can see a muscle that is
100. 5:41attached to or originates from the bone
101. 5:44. We see it; it is strongly attached
102. 5:48and runs underneath the ankle joint.
103. 5:53And let's observe, here is the origin.
104. 5:56The tendon follows, crossing under the
105. 5:59joint, it trifurcates, giving off three
106. 6:01tendinous bundles, and those tendinous
107. 6:04bundles cross the interphalangeal
108. 6:06joints and end almost at the claws. And
109. 6:11see what the contraction causes. Well,
110. 6:15in this case, I am pulling it, but it
111. 6:17mimics the contraction of that muscle.
112. 6:21Perfect. Let's go with the third
113. 6:23principle. Ligaments always originate
114. 6:26from one bone and insert into another
115. 6:28adjacent bone. Obviously, since
116. 6:32ligaments are so short, they must go
117. 6:34from bone to bone. We see it again, and
118. 6:38we are back at the knee. These are the
119. 6:41collaterals. Let's observe. What
120. 6:46happens if the ligaments are cut, if
121. 6:48the collaterals that give us lateral
122. 6:51stability are cut? See what happens to
123. 6:55the movement of that joint. A little
124. 6:59stiff. Let's observe what happens. The
125. 7:05movement increases, lateral stability
126. 7:10decreases, as does the anteroposterior
127. 7:13stability provided by the cruciate
128. 7:15ligaments. See what happens when we
129. 7:19section it. What would happen in an
130. 7:23anterior cruciate injury in athletes?
131. 7:27And the posterior ones too. Do you see
132. 7:30what happens if they are intentionally
133. 7:33severed? Look at what happens to the
134. 7:36anterior and posterior stability; they
135. 7:38practically get damaged, and that is
136. 7:41what ligaments are for. Their absence
137. 7:44allows for pathological movement that
138. 7:46can injure the cartilage, which is why
139. 7:48they only allow natural movements.
140. 7:51Fourth principle: tendons originate
141. 7:53from muscles and insert into bone.
142. 7:56Tendons always cross joints,
143. 7:58influencing their movement, as we can
144. 8:01appreciate in this shot. Or, as we see
145. 8:05in this shot, we can appreciate the
146. 8:08origin of the muscle, how the muscle
147. 8:11turns into a tendon, passes through the
148. 8:15ankle joint, runs distally until it
149. 8:18ends at the tips of the last phalanges,
150. 8:21and passes through one, two, three,
151. 8:24four, five joints. It is evident that
152. 8:27this tendon influences the movement of
153. 8:29these five joints. And look at what
154. 8:30happens. There is ankle flexion and
155. 8:32phalangeal extension. Observe it. This
156. 8:36is what this principle refers to. If a
157. 8:38muscle's tendon crosses several joints,
158. 8:40the contraction of that muscle will
159. 8:42influence the movement of the joints
160. 8:44its tendon crossed. And lastly, the
161. 8:52fifth basic principle. The proper
162. 8:56function of a synovial joint can never
163. 8:57dispense with any of the five
164. 8:59fundamental elements of the
165. 9:00musculoskeletal system. In this case,
166. 9:04we can observe that there are missing
167. 9:06muscles and missing tendons. If we stop
168. 9:10applying force with our little hands,
169. 9:12this is what happens. Just like in this
170. 9:17example, we cannot forget any of the
171. 9:19five fundamental elements of this
172. 9:21system. We must understand it as a
173. 9:23whole. Student YouTubers, I hope this
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