代償之王:胸小肌(Pectoralis Minor)

在「進行臀大肌訓練,臀大肌無感,反而腿後側肌群有感?」文章中談到了Synergistic Dominance(協同肌主配效應)之後,再來看Neurokinetic Therapy上的「The Pectoralis Minor, King of Compensation (代償之王:胸小肌)」文章,其中講到在訓練背闊肌之前,先進行胸小肌的放鬆,訓練的效果會更好

The pectoralis minor is a muscle that becomes easily shortened and tight due to many factors, including rounded shoulder posture, glenohumeral joint dysfunction,breathing dysfunction, and a variety of compensation patterns. It sits on top of the brachial plexus, and can therefore contribute to Thoracic Outlet Syndrome.

( 胸小肌很容易變的短縮與僵緊,原因有許多,包括圓肩姿勢、肩盂肱骨關節異常、呼吸異常及各種代償的模式。胸小肌位在臂神經叢的上方,因此造成胸廓出口症候群的發生。)

The pectoralis minor is located in an area of the shoulder with many other muscles, including the pectoralis major, biceps, deltoids, coracobrachialis, subscapularis, serratus anterior, and the latissimus dorsi.

( 胸小肌位在肩膀的區域中,這個區域也包含了其它的肌肉,包括胸大肌、肱二頭肌、三角肌、喙肱肌、肩胛下肌、前鋸肌及背闊肌。)

I find that clusters of muscles like this often can become dysfunctional due to poor biomechanics. This can lead to adhesions, facilitation/inhibition, and synergistic dominance. The pectoralis minor is often the overactive muscle in these compensation patterns.

( 由於欠佳的生物力學,這叢肌群時常發生異常的狀況,導致沾黏、誘發/抑制及協同肌主配效應。而在這些代償的模式中,胸小肌經常是過度活躍的情況。)

Rounded shoulder posture and forward head posture will cause the pectoralis minor to shorten. This action is called protraction and is opposed by the muscles of retraction. These include the middle trapezius and the rhomboids. Commonly the pectoralis minor becomes facilitated and the middle trapezius becomes inhibited. Release of the pectoralis minor followed by strengthening of the middle trapezius can be very effective in these cases.

( 圓肩姿勢及前位頭部錯姿將導致胸小肌短縮,這個動作稱為前突,會影響到中斜方肌與菱形肌。普遍來說,胸小肌處於誘發狀況下,中斜方肌會受到抑制。在這個情況下,進行中斜方肌的訓練之前,先進行胸小肌的放鬆,會得更非常好的效果。)

Because the pectoralis minor rounds the shoulder, it is opposed by the latissimus dorsi which moves the shoulder back and down. Again, release of the pectoralis minor followed by strengthening of the latissimus dorsi can be very effective.

( 胸小肌將肩膀往前拉動,而位在對側的背闊肌則是將肩膀往後往下進行移動。同樣的,在進行背闊肌的訓練之前,先進行胸小肌的放鬆,效果會更好。)

The pectoralis minor is a downward rotator of the scapula and oftentimes involved in glenohumeral dysfunction.  If it is facilitated, it can inhibit the serratus anterior, which contributes to upward rotation of the scapula. This can lead to impingement syndrome and sometimes winging of the scapula. The resultant scapular instability greatly contributes to shoulder joint dysfunction.

(胸小肌是一個肩胛骨的下轉肌群,經常涉及肩盂肱骨關節異常。若它處於誘發狀況,會抑制肩胛骨上轉肌"前鋸肌"的作用,導致夾擊症候群(Impingement Syndrome),而有時可能造成肩胛骨內緣外掀的情況,這種情況所產生不穩定肩胛骨會引起肩關節異常的狀況。)

The pectoralis minor is also an internal rotator of the humerus. When facilitated it can inhibit the external rotators of the humerus, including the long head of the biceps, the posterior deltoid, and the infraspinatus.

( 胸小肌也是肱骨的內轉肌。當它處於誘發的狀況下,會抑制肱骨的外轉肌群,包括肱二頭肌長頭、後三角肌及棘下肌。)

A common  shoulder injury that occurs from this is that the long head of the biceps comes out of its groove and moves medially towards the short head of the biceps. Release of the pectoralis minor followed by relocation of the long head of the biceps tendon is very effective in these cases.

( 一個普遍肩膀傷害的發生就是來自於胸小肌處於誘發的情況,肱二頭肌長頭(long head of the biceps)脫離其腱溝,而往肱二頭短頭(short head of the biceps)的內側進行移動。在這個例子中,先放鬆胸小肌之後,接著再進行肱二頭肌長頭的重新定位會非常有效率。)

The pectoralis minor also contributes to kinetic chain dysfunctions. For example, in the front line, the pectoralis minor often inhibits the psoas. In the diagonal line, it can inhibit the contralateral psoas. This is a factor in gait dysfunction.

( 胸小肌也會引起動力鍊異常的情況。舉例,在前側線,胸小肌經常抑制腰肌。在對側線,它會抑制對側的腰肌。這是步態異常其中一個因素。)

Also in gait it can inhibit the backward swing motion of the contralateral arm and the backward swing of the ipsilateral leg. Right thoracic rotation can be inhibited by the right pectoralis minor because of its contribution to internal rotation.

( 在步態中,胸小肌會抑制對側手臂後擺的動作及同側腳的往後擺動。右胸腔旋轉會被右側的胸小肌給抑制住,因為胸小肌步及內轉的動作。)

延伸閱讀《上肢伸展循環範例影片》。

圖片來源:American Family Physician

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