Pectoralis minor muscle
| Pectoralis minor | |
|---|---|
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| Latin | musculus pectoralis minor |
| Gray's | subject #122 438 |
| Origin | third to fifth ribs, near their costal cartilages |
| Insertion | medial border and superior surface of the coracoid process of the scapula |
| Artery | pectoral branch of the thoracoacromial trunk |
| Nerve | medial pectoral nerve (C8, T1) |
| Actions | stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall |
The pectoralis minor is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major.
Contents |
[edit] Origin and insertion
It arises from the upper margins and outer surfaces of the third, fourth, and fifth ribs, near their cartilages and from the aponeuroses covering the intercostalis.
The fibers pass superior and lateral and converge to form a flat tendon, which is inserted into the medial border and upper surface of the coracoid process of the scapula.
[edit] Innervation
The Pectoralis muscle is innervated by the medial pectoral nerve.
[edit] Special notes
Axillary nodes are classified according to their positions relative to the pectoralis minor muscle. Level 1 are lateral, Level 2 are deep, Level 3 are medial.
[edit] Relations
The pectoralis minor muscle is covered anteriorly (superficially) by the clavipectoral fascia. The medial pectoral nerve pierces the pectoralis minor and the clavipectoral fascia.
[edit] Actions
The pectoralis minor depresses the point of the shoulder, drawing the scapula inferior and medial, towards the thorax, and throwing its inferior angle posteriorly.
[edit] Variations
The origin is from the second, third and fourth or fifth ribs. The tendon of insertion may extend over the coracoid process to the greater tubercle. It may be split into several parts. Absence of this muscle is rare.
[edit] Additional images
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Pectoralis minor muscle
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Anterior surface of sternum and costal cartilages
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Left scapula, costal surface
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The axillary artery and its branches
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The veins of the right axilla, viewed from in front
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The right brachial plexus with its short branches, viewed from in front
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Nerves of the left upper extremity
[edit] External links
- LUC pcmn
- UWASH pectoralisminor
- 13631566 at GPnotebook
- SUNY Figs 04:04-05
- SUNY Figs 05:02-08
- SUNY Labs 05:ov-0200
- SUNY Labs 05:01-0102
- Slide
- Muscles/PectoralisMinor at exrx.net
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
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