The serratus anterior muscle is a fan-shaped muscle lying in the lateral wall of the thorax. It is easily palpable between pectoralis major and latissimus dorsi muscles. Three parts of the muscle may be distinguished based on their origin and insertion - superior, middle, and inferior parts.

Origin: superior part - ribs 1 and 2, intercostal fascia; middle part - ribs 3 through 6; inferior part - ribs 7 and 8 (or 9, may extend to rib 10).

Insertion: superior part - superior angle of the scapula (anterior surface); middle part - medial border of the scapula (anterior surface); inferior part - medial border and inferior angle of the scapula (anterior surface).

Action: moves the scapula anterolaterally; suspends the scapula on the thoracic wall; draws the inferior angle of the scapula laterally (scapular rotation).

Innervation: long thoracic nerve (C5 - C7).

Blood supply: superior and lateral thoracic arteries, branches of the thoracodorsal artery.

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Serratus anterior muscle