Tipos de Músculos Esqueléticos — Transcript

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1. 0:02Welcome to Physiotopics! (English subs might contain mistakes, not my mother tongue, trying to do my best ;)
2. 0:04Today we will be talking about the kind of muscles in charge of moving our body.
3. 0:10As you might know, depending on the fiber that conforms the muscle,
4. 0:16we can differentiate 3 types:
5. 0:171. Those formed of striated muscle tissue, that is under our voluntary control,
6. 0:23such as the biceps brachii, enabling us to flex the arm when we wish it.
7. 0:282. Those formed of smooth muscle tissue, whose contraction we can´t control voluntarily,
8. 0:34present in blood vessels, airways and digestive system organs.
9. 0:393. And lastly, those muscles formed of striated cardiac muscle tissue, also out of our voluntary control,
10. 0:43that we can find only in the heart.
11. 0:49Did you know that in humans striated or skeletal muscle tissue constitutes of 40% of the body weight?
12. 0:57The muscle is mainly composed of water (75%),
13. 1:02protein (20%) and other substances such as inorganic salts, minerals, fat
14. 1:10and carbohydrates(5%) (1).
15. 1:14Today we are going to try to understand better this first group, through a macroscopic
16. 1:19analysis of its architecture. According to the number and orientation of the fibers
17. 1:24within the muscle.
18. 1:27The striated muscle is defined as the one that connects to bones,
19. 1:34going through one or more joints to move the skeletal system.
20. 1:40From the mechanical point of view, the main function of skeletal muscle is transforming
21. 1:44chemical energy into a mechanical one. The objective is to generate force or maintain a certain posture.
22. 1:50As in many other structures of the body,
23. 1:53the shape is determined by the function it is going to perform.
24. 1:57So, regarding the traditional classification, we can see two principal shapes:
25. 2:05FUSIFORM MUSCLES, formed mainly of type II or phasic fibers.
26. 2:10Its disposition is linear to the form of the muscle,
27. 2:16being able to produce fast and ample movements. For example triceps brachii.
28. 2:22This type of muscle is common in extremities, to do movements such as
29. 2:27throws and running.
30. 2:29PENNIFORM MUSCLES are arranged variably in relation
31. 2:34to the axis of the muscle and tendons, and not linearly.
32. 2:39The name comes from “penne”, meaning feather
33. 2:46representing the calamus (or quill) and
34. 2:51the feather tip the origin and insertion tendons,
35. 2:57and the barbs the muscle fiber disposition.
36. 3:01With this configuration, more muscle fibers can be “stored” in a smaller space
37. 3:06and the muscle can develop a higher force. They are predominantly formed of
38. 3:13type I or tonic fibers, slower than type II fibers but more resistant to fatigue.
39. 3:19That is why these are the muscles used for maintaining a posture
40. 3:25or stabilize the body.
41. 3:30Fusiform muscles, as well as penniform ones have different variants.
42. 3:37But in reality, muscles structure is a mix of both of them.
43. 3:47Thus, we can differentiate:
44. 3:50- Parallel muscles: with fibers parallel to the aponeurosis, such as the rectus abdominis.
45. 3:56- Quadratus muscles: such as the quadratus lumborum.
46. 4:01- Convergent muscles: such as the pectoralis major
47. 4:08originating in a wide space and inserting in a single point
48. 4:10- Circular muscles: such as the orbicularis oris
49. 4:15That´s all for today. Hope we helped you learn more
50. 4:23about the muscle, and how strongly associated its form and function are.
51. 4:29See you ;)