| Pectoralis minor | |
|---|---|
 Pectoralis minor (shown in red). | |
 Pectoralis minor muscle (shown in red). The bone shown in blue is theshoulder blade. | |
| Details | |
| Origin | Third to fifthribs, near the costochondral junction |
| Insertion | Medial border and superior surface of thecoracoid process of thescapula |
| Artery | Pectoral branch of thethoracoacromial trunk |
| Nerve | Medial pectoral nerve (C8) |
| Actions | Stabilizes thescapula by drawing it inferiorly and anteriorly against thethoracic wall, raises ribs in inhalation |
| Identifiers | |
| Latin | musculus pectoralis minor |
| TA98 | A04.4.01.006 |
| TA2 | 2305 |
| FMA | 13109 |
| Anatomical terms of muscle | |
Pectoralis minor muscle (/ˌpɛktəˈrælɪsˈmaɪnər/) is a thin, triangular muscle, situated at the upper part of thechest, beneath thepectoralis major in the human body. It arises from ribs III-V; it inserts onto thecoracoid process of thescapula. It is innervated by themedial pectoral nerve. Its function is to stabilise thescapula by holding it fast in position against thechest wall.
From the muscle's origin, the muscle's fibers pass superiorly and laterally, converging to form a flat tendon.
Pectoralis minor muscle arises from the upper margins and outer surfaces of the 3rd, 4th, and 5thribs near theircostal cartilages, and from theaponeuroses covering theintercostalis.[1]
Its tendon inserts onto the medial border and upper surface of thecoracoid process of thescapula.[1][2]
The muscle receives motor innervation from themedial pectoral nerve.[3]
Pectoralis minor muscle forms part of the anterior wall of theaxilla.[4] It is covered anteriorly (superficially) by theclavipectoral fascia. Themedial 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.[5]
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[6] (in contrary sequence compared to the nodes) - first part medial, second part deep/posterior, third part lateral in relation to the pectoralis minor.
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 thePoland syndrome.[7]
Pectoralis minor muscledepresses the point of theshoulder, drawing thescapula superior, towards thethorax, and throwing itsinferior angle posteriorly.
This article incorporates text in thepublic domain frompage 438 of the 20th edition ofGray's Anatomy(1918)
