Pectoralis minor muscle

From Wikipedia, the free encyclopedia
  (Redirected from Pectoralis minor)
Jump to: navigation, search
Pectoralis minor
Pectoralis minor.png
Pectoralis minor (shown in red).
Pectoralis minor muscle and shoulder blade.png
Pectoralis minor muscle (shown in red). The bone shown in blue is shoulder blade.
Details
Latin Musculus pectoralis minor
Third to fifth ribs, near their costal cartilages
Medial border and superior surface of the coracoid process of the scapula
Pectoral branch of the thoracoacromial trunk
Medial pectoral nerve (C8, T1)
Actions Stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall, Rises ribs in inspiration
Identifiers
Gray's p.438
Dorlands
/Elsevier
m_22/12550138
TA A04.4.01.006
FMA FMA:13109
Anatomical terms of muscle

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

Origin and insertion[edit]

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.

Special notes[edit]

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. Pectoralis Minor divides the axillary artery into three parts.

Relations[edit]

The pectoralis minor muscle 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.[1]

Actions[edit]

The pectoralis minor depresses the point of the shoulder, drawing the scapula inferior, towards the thorax, and throwing its inferior angle posteriorly.

Variations[edit]

An individual with an axillary arch as well as sternalis muscle and an accessory abdominal portion of the pectoralis major.

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.[citation needed]

Additional images[edit]

References[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.

External links[edit]