In my past as a Kinesiologist I was constantly bombarded by the term “core”. I never bought in to the general idea that seems to pop out of that which SEEMS to be core=abdominals (or, to some people, abdominals and lumbar musculature). At the time I was of the idea that anything that connected to the vertebral column at any level had to be considered part of the “core”…this, to me, meant that any exercise was a “core” exercise and the only question was which portion of the movement was the focus. Now that I have taken up my Osteopathic studies I find, through anatomy, that I was pretty much on the ball. For the purpose of this piece I am going to focus on the connections from the arm to the abdominals, however, it should be noted that the body is legitimately ONE connected unit and that there are no breaks in the connection.So where do we start? I have to break this down somehow so I will start at the lateral lip of the intertubercular sulcus of the humerus (or the bicipital groove – the name may differ depending on your resource)…aka where pectoralis major attaches to your arm. We can follow pectoralis major across the thorax to the sternum, down to the xiphoid process, and in to the linea alba (where all of the abdominal muscles create a common aponeuoroses). We can also follow the other attachment points of the pectoralis major to the aponeurosis of the external oblique. That is about all that it really takes to show you how your arm is directly attached to your abdominal muscles…not too crazy there.
Obviously I won’t stop yet! There has to be some interesting take home ideas here. Let’s start at the pelvis (because principles dictate we should). The abdominal muscles attach to the pelvis – all of them. If there is distortion in the abdominal musculature there will be distortion in any structures related to them. If the pelvis is in lesion then we have distortion through the linea alba and back up to pectoralis major which can very easily be the beginnings of a shoulder problem. The reverse is true – a heavily lesioned pectoralis major (or another muscle in the shoulder girdle leading to distortion of the pectoralis major) has every opportunity to travel down the chain to distort the pelvis. Ever seen a pelvic lesion that will not correct by treating the pelvis? Make sure you check EVERYTHING else – including the shoulder girdle.
Now, hopefully, I have drawn a picture that might suggest there is at least the possibility that an issue such as adhesive capsulitis (frozen shoulder) can be linked to a pelvic lesion. Especially considering the alteration in blood flow that will accompany altered compression and tension on the brachial artery as well as the cephalic and basilic veins (amongst others). Also consider the altered forces placed on the brachial plexus as it follows the brachial artery. Food for thought. I am drawing connections here, not providing absolute answers – every case is different. I only aim to provide insight in to possibilities. Keep digging!