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Serratus anterior muscle: want to learn more about it?

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Serratus anterior muscle

Serratus anterior muscle (Musculus serratus anterior)

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. In athletic bodies the muscle may be even visible to the naked eye along the ribs underneath the axilla.

The serratus anterior muscle originates from the 1st to 10th rib and inserts at the anterior surface of the scapula. Due to its course it has a “serrated” or “saw-toothed” appearance.

This article will discuss the anatomy of the serratus anterior muscle.

Key facts about the serratus anterior muscle
Origin Superior part: Ribs 1-2, Intercostal fascia
Middle part: Ribs-3-6
Inferior part: Ribs 7-8/9/10 (+ external oblique muscle)
Insertion

Superior part: Anterior and posterior surface of superior angle of scapula

Middle part: Anterior surface of entire medial border of scapula

Inferior part: Anterior and posterior surface of inferior angle of scapula

Innervation

Long thoracic nerve (C5- C7)

Mnemonics: 'SALT' (stands for serratus anterior - long thoracic) & 'C5, 6, 7 raise your arms to heaven!'

Blood supply Superior and lateral thoracic arteries, thoracodorsal artery branches
Function Scapulothoracic joint: Draws scapula anterolaterally, Suspends scapula on thoracic wall, Rotates scapula (draws inferiorly angle laterally)

Origin and insertion

The serratus anterior muscle originates at the 1st to 9th rib and inserts at the ventral surface of the medial border of the scapula. The muscle is further divided into three parts:

  • Superior part: 1st to 2nd rib → superior angle of the scapula
  • Intermediate part: 2nd to 3rd rib → medial border of the scapula
  • Inferior part: 4th to 10th rib → medial border and inferior angle of the scapula.

The inferior part of the muscle is the most prominent and powerful one.

Wondering how you're going to revise the anatomy of the serratus anterior muscle? Our handy trunk wall muscle anatomy chart has your back. 

Serratus anterior muscle seen in a human cadaver. Notice how the muscle fibers follow the course of the ribs onto which they attach.

Innervation

The innervation is supplied by the long thoracic nerve (C5-7), a branch of the brachial plexus.

The innervation for the serratus anterior is very easy to remember if you just know the right mnemonics! 'SALT' stands for 'Serratus Anterior = Long Thoracic' and will help you remember the name of the nerve, while knowing 'C5, 6, 7 raise your arms to heaven!' means you'll never forget the nerve roots associated with it!

Learn everything about the muscles of the thoracic wall with our video tutorials, quizzes, labeled diagrams, and articles:

Blood supply

The vascular supply to the serratus anterior comes from the superior and lateral thoracic arteries (branches of the axillary artery) as well as branches from the thoracodorsal artery (branch of subscapular artery).

Function

The contraction of the entire serratus anterior leads to a anterolateral movement of the scapula along the ribs. Due to the pull of the inferior part at the lower scapula, the shoulder joint is shifted superiorly. This shifting now enables to lift the arm above 90° (elevation).

In contrast, the superior part depresses the scapula and thus acts antagonistically. Another function of the serratus anterior is the active stabilization of the scapula within the shoulder. Finally, in a fixed scapula the muscle lifts the ribs and acts as an accessory inspiratory muscle.

Solidify your knowledge about the thoracic muscles with our quiz:

Serratus anterior muscle: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

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“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

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