"Measurement of Pectoralis Minor Muscle Length: validation and clinical application"
Throughout our early clinical rotations, a common impairment that we noticed was forward shoulder posture (look around your classroom and you will see it as well!). In our program, we were taught to measure muscle strength using Kendall's technique. In her book, Muscles: Testing and Function, in Posture and Pain, Kendall demonstrates measuring the length of the pec minor, along with several other muscles, in the supine position, from the posterolateral border of the acromion to the table top (>3-4 finger lengths being an adaptively shortened muscle). In this position, the biceps brachii, coracobrachialis, and pectoralis minor could all contribute to the protracted/anteriorly tilted shoulder, due to the common attachment to the coracoid process. We commonly found that the scapula lowered to normal position with shoulder flexion, which would indicate adaptively shortened coracobrachialis, even though the common assumption is the pec minor being the culprit.
This article demonstrates that the pectoralis minor is indeed found to be adaptively shortened in many individuals and provides a much more reliable technique to measure the length of the pectoralis minor, as long as proper palpation skills are used. The key is to use a tape measure or caliper to measure the distance between the coracoid process and the sternal edge of the 4th rib. While there may not be sufficient evidence to start using this in the clinic right away, this new technique is something to consider when examining patients.
Pectoralis Minor Muscle:
Origin: Anterior surface of the sternal ends of ribs 3-5
Insertion: Coracoid Process of the scapula
Action: Protracts and depresses the scapula. Helps elevate the ribs (if O and I are reversed)
Innervation: Medial Pectoral Nerve (C8-T1)
1/16/2013 01:40:01 am
how do i find and palpate the sternal edge or the costochondral junction of the 4th rib frm where the muscle originates,,,
"The investigator located the landmark by initially finding the inferior-medial aspect of the first rib at the sternum distal to the medial clavicle, and then counting down to the fourth rib."
5/27/2013 11:23:28 am
What role does the serratus anterior play in this mix? You mention biceps brachii, coracobrachialis, and pectoralis minor as culprits in anteriorly protracting the shoulder. Isn't that what the serratus anterior does? Are you ruling it out due to the anterior tilt?
5/29/2013 12:29:15 pm
10/27/2013 09:46:09 am
I thoroughly enjoyed this blog and created a Weebly account too.
10/28/2013 01:52:54 pm
Glad you are enjoying it! Let us know if there is any specific content or information you would like to learn more about!
6/19/2014 02:12:53 pm
May I ask about 3-4 finger length what does it mean in cm or mm
10/12/2017 01:23:59 pm
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