Pectoralis minor muscle
|Origin||Third to fifth ribs, near the costochondral junction|
|Insertion||Medial border and superior surface of the coracoid process of the scapula|
|Artery||Pectoral branch of the thoracoacromial trunk|
|Nerve||Medial pectoral nerve (C8)|
|Actions||Stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall, raises ribs in inspiration|
|Latin||Musculus pectoralis minor|
|Anatomical terms of muscle|
Pectoralis minor muscle arises from the upper margins and outer surfaces of the third, fourth, and fifth ribs, 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 of the scapula.
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.[dead link]
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.
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.
- Dommerholt, Jan (2011). "Chapter 34 - Dry needling of trigger points". Neck and Arm Pain Syndromes. Churchill Livingstone. pp. 430–438. doi:10.1016/B978-0-7020-3528-9.00034-0. ISBN 978-0-7020-3528-9.
- Bentley, J. Nicole; Yang, Linda J. S. (2015). Nerves and Nerve Injuries. Academic Press. pp. 563–574. doi:10.1016/B978-0-12-410390-0.00012-3. ISBN 978-0-12-410390-0.
- Jacob, S. (2008-01-01). "Chapter 2 - Upper Limb". Human Anatomy. Churchill Livingstone. pp. 5–49. ISBN 978-0-443-10373-5.CS1 maint: date and year (link)
- http://www.teachmeanatomy.com/muscles-of-the-pectoral-region/[permanent dead link]
|Wikimedia Commons has media related to Pectoralis minor muscles.|
- Illustration: upper-body/pectoralis-minor from The Department of Radiology at the University of Washington
- Anatomy figure: 04:04-05 at Human Anatomy Online, SUNY Downstate Medical Center
- Anatomy figure: 05:02-08 at Human Anatomy Online, SUNY Downstate Medical Center
- Anatomy photo:05:ov-0200 at the SUNY Downstate Medical Center
- Anatomy photo:05:01-0102 at the SUNY Downstate Medical Center