Pectoralis minor muscle () is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major in the human body.

Structure

Attachments

Pectoralis minor muscle arises from the upper margins and outer surfaces of the third, fourth, and fifth

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

s, near their costal cartilages and from the aponeuroses covering the intercostalis. The fibers pass superior and lateral and converge to form a flat tendon. This tendon inserts onto the medial border and upper surface of the

coracoid process The coracoid process (from Greek κόραξ, raven) is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula (hence: coracoid, or "like a raven's beak"). Pointing laterally forward, it, together with t ...

of the scapula.

Relations

Pectoralis minor muscle forms part of the anterior wall of the axilla. It is covered anteriorly (superficially) by the clavipectoral fascia. The medial pectoral nerve pierces the pectoralis minor and the clavipectoral fascia. In attaching to the coracoid process, the pectoralis minor forms a 'bridge' - structures passing into the upper limb from the thorax will pass directly underneath.http://www.teachmeanatomy.com/muscles-of-the-pectoral-region/ 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. The pectoralis minor divides the axillary artery into three parts (in contrary sequence compared to the nodes) - first part medial, second part deep/posterior, third part lateral in relation to the pectoralis minor.

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 but happens with certain uncommon diseases, such as the Poland syndrome.

Function

Pectoralis minor muscle depresses the point of the shoulder, drawing the scapula superior, towards the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the c ...

, and throwing its inferior angle posteriorly.

References

External links

* * * * *
Slide
{{Authority control Muscles of the upper limb cs:Prsní svaly