By Britt Van Hees
If you don’t know what or where your coccyx is, count yourself lucky. This little bone can make quite a ruckus when it’s not happy, often called coccydynia. The coccyx, or tailbone, is our little vestigial tail, after eons of evolution. It is often ignored and forgotten by most, but to me, it’s one of the most important bones in the body. Today we’ll go over why the coccyx matters and how it plays a role in pelvic pain, muscle tightness, nerve issues and even your neck movement!
#1) The coccyx: small but MIGHTY rudder
The coccyx is a tiny bone that joins with the pelvis at the sacrum to create the sacrococcygeal joint. Despite popular thought, the sacrococcygeal joint is mobile in many people. This joint varies from synovial (maximal mobility), to fibrocartilaginous (moderate mobility), to ossified (no mobility).1 Also, it is not unusual to have a small articular disc at the sacrococcygeal joint to help with this movement. Research has documented normal coccygeal movement is between 5-25° from standing to sitting.2 So, the coccyx can move. The location of the coccyx, at the base of the spine, and its ability to move can have far reaching implications on the rest of the body. For example: a change at the coccyx changes how the sacrum and pelvis moves. The pelvis is the body’s center of mass, so where the pelvis goes the body goes. Who would think such a little rudder could steer such a big ship?
#2) The coccyx: central attachment point of fascia, ligaments and muscles
The coccyx is also a central attachment point of fascia, muscles and ligaments on the inside and the outside of the pelvis. I mean, just look at all those beautiful muscles. And check out these ligaments!
So, if you imagine, a coccyx off-axis may create some problems. Let’s just take the pelvic floor muscles as an example. If, say, the coccyx is pulled over to the left, all the pelvic floor muscles attached to the left side of the coccyx will get short and weak, while the ones on the right will get stretched out and weak. This could lead to decreased “core” strength (pelvic floor is part of the “core”), incontinence (urinary or bowel) and/or pain (bowel, bladder, sex, exercise). The ligaments that attach to the coccyx also provide passive stability to the pelvis, primarily at the sacroiliac joint. A shift at the coccyx could create ligamentous tension, leading to the same problems. Some of these ligaments, like the anterior longitudinal and supraspinal ligament, even run all the way up to the head and neck! You can imagine how childbirth, a fall or throwing your back out could create a problem, not only locally at the tailbone, but further up or down the chain.
#3) The coccyx: base of the nervous system, MAGIC
This may be one of the more magical things. The spine houses the spinal cord. The spinal cord is the brain’s extension to the rest of the body. It starts in the skull, runs the whole spine and then attaches to your coccyx. The filum terminale (pictured above as Terminal filum), is the final thread of spinal cord that secures itself to the first coccygeal vertebra. Sometimes, if there is stiffness in the spine or at the coccyx itself, it can impact the mobility and health of the nervous system. When this happens the body may become protective in order to keep the nervous system safe. Often this protection can create symptoms of numbness and tingling, or a tightness that does not resolve after normal healing time. Examples of this would be a “hamstring tear” or “adductor strain” that has never fully healed. Often, the tight “muscle” is actually an unhappy nerve, and stretching it may feel good in the moment, but afterward worsens the symptoms. Treating the tailbone is one aspect, along with a multitude of other rehabilitation techniques, to improve the health and mobility of the nervous system.
#4) Oh Coccyx, My Coccyx
So, what to do with all this information? Well, hopefully be a little more thoughtful to your coccyx, it’s a cool little bone. Nice things you can do for your coccyx include: proper sitting posture, pelvic clocks, or even just going for a gentle walk to get some blood flow. And, if you’ve got pain down there, be sure to see your local pelvic floor PT or come visit us to get that tail wagging again!
1.Lee DG, Lee L-J, Vleeming A, Jones MA. The pelvic girdle: An integration of clinical expertise and research. 4th ed. Edinburgh: Elsevier/Churchill Livingstone; November 17, 2010:24-25.
2. Fogel G, Cunningham P, Esses S. Coccygodynia: evaluation and management. J Am Acad Orthop Surg.2004;12:49–54.