双语字幕
The Function and Origins of Serratus Anterior Muscle
前锯肌的功能与起点
And in this tutorial, we will discuss the serratus anterior muscle.
这节课，我们将讨论前锯肌。
The serratus anterior muscle is a fan-shaped muscle at the lateral wall of the thorax. Its main part lies deep under the scapula and the pectoral muscles. It is easy to palpate between the pectoralis major and latissimus dorsi muscles.
前锯肌是位于胸腔侧壁的一块扇形肌肉。大部分前锯肌位于肩胛骨下和胸肌深处。我们在胸大肌和背阔肌之间很容易触摸到前锯肌。
In athletic bodies, the muscle may even be visible to the naked eye along the ribs, underneath the axilla.
对于运动型身材，我们甚至可以沿肋骨，在腋下肉眼可见前锯肌。
The serratus anterior muscle originates at the first to ninth rib and inserts at the ventral surface of the medial border of the scapula. Because of its course, it has a saw-tooth or serrated appearance, hence the name “serratus anterior.”
前锯肌起自第 1-9 肋，止于肩胛骨内侧缘腹侧。由于其走向，前锯肌呈锯齿状外观，因此被称为“前锯肌”。
The muscle is further divided into three parts.
前锯肌进一步分为 3 个部分。
The superior part consists of the part from the first to second rib, extending to the superior angle of the scapula.
上部由第 1-2肋的部分组成，延伸到肩胛骨上角。
The intermediate part is from the second to third rib to the medial border of the scapula.
中部起自第 2-3 肋，终于肩胛骨内侧缘。
And the inferior part is the section from the fourth to ninth rib to the medial border and inferior angle of the scapula. This part is the most prominent and powerful one.
下部起自第 4-9 肋，终于肩胛骨内侧缘和下角。这一部分是最突出且最有力的部分。
The innervation is supplied by the long thoracic nerve, a branch of the brachial plexus. The contraction of the entire serratus anterior leads to a ventrolateral movement of the scapula along the ribs.
前锯肌受胸长神经，即臂丛的分支支配。整块前锯肌收缩导致肩胛骨沿肋骨做腹外侧运动。
Another function of the serratus anterior is the act of stabilization of the scapula within the shoulder.
前锯肌的另一种功能是稳定肩内的肩胛骨。
Finally, in a fixed scapula, the muscle lifts the ribs and acts as an accessory inspiratory muscle.
最后，在肩胛骨固定时，肌肉抬起肋骨，起到吸气辅助肌的功能。
Due to the pull of the inferior part at the lower scapula, the shoulder joint is shifted superiorly. This shifting, then, enables the arm to lift above ninety degrees.
肩胛骨下部的牵拉作用，导致肩关节上移。然后，这种上移使手臂向上抬起 90° 以上。
In contrast, the superior part depresses the scapula and thus acts antagonistically.
相反，上部压低肩胛骨，从而起到拮抗性作用。
相关单词学习
Latissimus Dorsi
①发音和释义
la•tis•sim•us dor•si/ləˌtɪs.ə.məs ˈdɔːr.saɪ/n. 背阔肌
A broad, flat muscle on each side of the midback, the action of which draws the arm backward and downward and rotates the front of the arm toward the body.
（图源：太帅图库）
相关知识点总结
| 前锯肌的起点 | 上部：第 1-2 肋，肋间筋膜 中部：第 3-6 肋 下部：第 7-8/9 肋可能延伸到第 10 肋（+外斜肌） |
| 止点 | 肩胛 （上部：上角前表面 中部：内侧缘前表面 下部：下角和内侧缘前表面） |
| 神经支配 | 胸长神经（C5-C7） 快速记忆口诀：SALT（serratus anterior - long thoracic【前锯肌--胸长】）& C5, 6, 7 【相关的神经根】raise your arms to heaven！ |
| 血供 | 胸上动脉和胸外侧动脉；胸背动脉分支 |
| 功能 | 肩胛-胸廓关节：拉动肩胛向前外侧移动；使肩胛骨悬吊在胸壁上；旋转肩胛骨。 |
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