Updated: Apr 19
The Anatomy of the Inner Core - Pelvic Physical Therapy Foundations
"The arm bone is connected to the shoulder bone..."
We all know of the song that goes “The arm bone’s connected to the shoulder bone” but did you know that there is a connection, not direct but with relationship to function, of the pelvic floor muscles and the respiratory diaphragm?
Anatomically the pelvic floor is a term which is utilized to describe the group of muscles which span along the base or opening of the pelvis and form the “floor” of the trunk. These muscles have multiple functions to include support of the pelvic organs, maintenance of urinary and fecal continence, sexual function and last (but not least) trunk stability. Anatomically the pelvic floor is one of four muscle groups which composes the ‘inner core’. The inner core is additionally composed of the Transverse abdominis, spinal multifidus AND the respiratory diaphragm. One of the functions of the inner core is intra-abdominal pressure management.
Pressure Management and Pelvic Floor Symptoms
Intra-Abdominal Pressure Management / Soda-Can Analogy
You may have either tried this before or seen someone else attempt to do it – The contents of a soda can are non-compressible if you attempt to do so when the can is full and sealed. This is secondary to the amount of pressure within the can, with the external pressure needing to be greater than the internal pressure to successfully crush the can.
This same analogy can be applied to the inner core musculature and the content of the
abdominal-pelvic region. As shown in the picture to the right (1), the inner core muscles make up a cylindrical structure similar to the aluminum structure of a soda can with the pelvic floor the ‘base’ of the can and the respiratory diaphragm the ‘top’ of the can. When you have good strength and support of these muscles the ‘cannister’ is strong and able to withstand force. This, from a functional standpoint, is important for it allows us to lift heavy objects, promote balance and trunk stability and even MAINTAIN URINARY CONTINENCE.
To better explain how this system works lets return back to the soda can analogy – If we were to take that soda can and crack the tab open thus breaking the seal, that once non-compressible can has now become compressible for less external pressure is needed to surpass the pressure requirement to compress the can. This analogy can now be related back to the musculature of the inner core. If one (or more) of these muscles are weak and/or lack coordination is present, this can lead to a “pressure leak” in the system thus making it more susceptible to dysfunction. Dysfunction in this system can lead to symptoms such as urinary/fecal incontinence, pelvic/perineal pressure, dysfunctional movement patterns and more which can secondarily lead to functional limitations and restrictions such as lifting restrictions, inability to perform high impact activities and reduced quality of life. Such dysfunction of the muscles of the inner core can occur secondary to a variety of reasons to include, but not limited to: chronic cough/chronic respiratory dysfunction, abdominal weakness due to diastasis recti and/or history of abdominal surgery, pelvic floor dysfunction, chronic constipation and more!
Contact us today to set up a pelvic health physical therapy evaluation so that we may be able to get down to the route cause of your problem and help you regain back control of your life!
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Park, Hankyu, and Dongwook Han. “The Effect of the Correlation between the Contraction of the Pelvic Floor Muscles and Diaphragmatic Motion during Breathing.” Journal of Physical Therapy Science, vol. 27, no. 7, 2015, pp. 2113–2115., https://doi.org/10.1589/jpts.27.2113.