Pectoral Muscles: Area, Innervation & Function – Human Anatomy | Kenhub

Pectoral Muscles: Area, Innervation & Function – Human Anatomy | Kenhub


Hey, everyone. It’s Matt from Kenhub! And
in this tutorial, we will discuss the area, anatomy, and function of the pectoral muscles. The pectoral muscles consist of the pectoralis
major and the pectoralis minor, which are fan-shaped muscles of the shoulder. They shape
the anatomy of the breast. The pectoralis minor lies under the pectoralis
major and both form the anterior wall of the axilla where they can be palpated. The innervation is carried by the medial and
the lateral pectoral nerves (direct branches of the brachial plexus). The pectorals are
located close in relation to the brachial plexus, and both the subclavian artery and
vein, which all run between the muscle and the rib cage. The pectoralis major muscle is the most important
muscle for the adduction and anteversion of the shoulder joint, which is why it is also
known as the breaststroke muscle. It rotates the upper arm outwards and makes a powerful
stroke movement called retroversion when the arms are elevated or, for example, in wood
chopping. If the arms are fixed, the muscle lifts the
trunk, which can be helpful in climbing or during inspiration. The pectoralis minor has two main functions.
On one hand, it pulls the scapula anteriorly and inferiorly toward the ribs, known as abduction
and depression respectively. This leads to a dorsomedial movement of the inferior angle
of the scapula. This movement is both helpful when retracting the elevated arm as well as
moving the arm posteriorly behind the back. On the other hand, the pectoralis minor elevates
the third to fifth ribs, given a fixed scapula, and expands the ribcage. By those means, it
can also serve as an accessory muscle during inspiration. This video is more fun than reading a textbook,
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