A chronically shortened pectoralis minor produces the distinctive protracted shoulder that does not lay down like the other shoulder when the client is on their back. It is easy to release with a little posterior static pressure on the greater tubercle while lifting displaced ribs off the upper thoracic vertebrae. Even in chronic cases, this is not so difficult to release in session.
The greater problem is in resolving the weakness of the muscles that oppose the pectoralis minor, especially lower trapezius. The pectoralis minor will returned to its shortened position and require ongoing self-care without resolving displaced joints and treating opposing muscles that lead to a chronically imbalanced shoulder girdle.
Pectoralis minor is can be confusing during an assessment. Its pain pattern is similar to the referral created by other muscles, like infraspinatus and pectoralis major, which produce anterior shoulder pain more frequently. A more detailed assessment is needed to separate out the true culprit.
Its structural implications are easy to spot when the trigger points hold it short and strong. It is often overlooked when its trigger points weaken the muscle and leave the scapula retracted or elevated.
Pectoralis minor is both a cause and a victim of thoracic outlet syndrome. When the cervical vertebrae and scalenes choke the brachial plexus, the pectoralis minor is weakened. When the trapezius (lower) is weak and pectoralis minor is short, the coracoid process can tilt and press on the brachial plexus. Pectoralis minor can also apply pressure to the costo-coracoid membrane, which houses the neurovascular bundle that supplies the upper extremity.
It can also be a problem to palpate when the client is modest or very sensitive in the axillary region. Many therapists get overly focused on the interscapular area where the pain is more prominent and easier to work. Often, the pectorals need to be treated to balance the shoulder girdle.
Pectoralis minor has an interesting fan-shaped structure with a statistically significant number of anomalies.
Here’s a section from Neuromuscular Assessment:NMA-pectoralis-minor
Pectoralis minor has a notable part in Thoracic Outlet syndrome. This post reviews those structures from front to back showing how the clavipectoral membrane bridges from the pectoralis minor to the subclavius over the neurovascular bundle.
There are a number of tests to evaluate Thoracic Outlet impairment by extending the arm out to the side or straight up and then having the patient breathe in or turn their head (Adson, Roos, Wright, Eden…). The radial pulse is check for changes in strength as the arm is extended and elevated. I find that a loss of pulse strength during the lifting and inhalation indicates a further investigation of the pectoralis minor but it is not always the problem. Physiotudors have a number of videos on these tests.
This protocol allows better access to the extrinsic chest muscles by placing the client in a recumbent position so that breast tissue falls out of the way where it is easily draped. This also opens the lateral wall of the rib cage for access under the shoulder blade.
Self-Care can be an important correcting posture that has tight, shortened pecs. Make sure to review the self-care section for the trigger point you are addressing.
This site is undergoing changes. Starting in early 2020, we began changing the format of the posts to include more extensive self-care, illustrations, therapist notes, anatomy, and protocols. We appreciate your input and feedback. You will see us adding posts and updating older posts as time permits.
Tony Preston has a practice in Atlanta, Georgia where he sees clients. He has written and taught about anatomy, trigger points, and cranial therapies since the mid-90s.
*This site is undergoing major changes. We are reformatting and expanding the posts to make it easier to read, more accessible, and
to include more patterns with better self-care. In the meanwhile, there will be inconsistency in formatting, content, and readability until we get the old posts updated. Please excuse our mess.