|Insertion||Coracoid process of Scapula|
|Nerve supply||Medial Pectoral nerve|
|Actions||Draws the scapula down and forwards and elevates the ribs|
Pectoralis minor Origin and Insertions – Image modified from BodyParts3D, © The Database Center for Life Science licensed under CC Attribution-Share Alike 2.1 Japan
The Pectoralis Minor muscle lies underneath the Pectoralis major in the chest – frontal aspect. It originates from 3rd to 5th ribs and inserts on to the coracoid process of Clavicle as shown in the image.
Regarding actions, if the muscle contracts there 2 possibilities, if ribcage is kept stationary, it will draw scapula down and forward. Similarly, if Scapula is stabilized, rib cage will be pulled up to elevate (helps in deep inspiration).
Thoracic outlet syndrome
Compression and irritation of the neurovascular structures of upper limb. (brachial plexus and the blood vessels – subclavian and axillary arteries and veins) will lead to pain, swelling in the upper limb.
Possibility of compression at 3 regions: (numbered on the image below)
- between the anterior and middle scalene muscles, and the 1st rib; (more on this in Thorax module)
- between the clavicle and first rib
- in the subcoracoid space between the pectoralis minor tendon and it’s attachment on coracoid process.
Check previous lesson for Pectoralis Major and Next lesson for Trapezius muscle.