L5/ S1: Where The Lumbar Spine Meets The Sacrum

Are you wondering why there are cervical spine x-rays at the top of a post about L5/S1 which is the transition point between the spine and the pelvis—where the lumbar spine meets the sacrum of the pelvis? L represents the lumbar spine. 5 is the 5th or lowest vertebrae. S for the sacrum that is only one bone but is denoted by its vestigial joints so the 1 is for the top of the bone.

The X-Rays at the top are those of my children who went to the orthodontist this past week to get outfitted for braces. The idea that my kids have my small jaw and my wife’s larger teeth and that this fact will put me out of $10,000 simply boggles my mind. But I’ll save that for later posts.

My son’s neck is the x-ray on the left and my daughter’s is on the right. Notice the very painful difference in their cervical vertebrae. My daughter’s are lovely and spacious while my son’s are crunched and compressed.

There is no doubt in my mind that his neck is a mirror of my own. I have an excessively kyphotic back and before I started doing yoga was plagued with neckaches and muscle tension headaches. Before I learned about all the posture stuff and got physically fit I couldn’t stand for more than ten minutes before my neck would begin to ache just below head.

Back to L5/S1 where the lumbar spine meets the sacrum or pelvis. The aligment of this spot is a determinent of whether the pelvis is in a neutral position, tucked under or stuck out too far. And this alignment profoundly affects the neck.

The curves of the lumbar and cervical spine are meant to mirror each other which can only be achieved if the pelvis is well aligned.

lumbar spine meets the sacrumWhen the pelvis is in the correct or neutral position the transition where the lumbar spine meets the sacrum is smooth and clear. This allows for the lumbar spine to curve in succesfully which in turn allows the rest of the spine to proceed up and support the head.

When the pelvis is even fractionally off neutral the lumbar spine and cervical spine are thrown out of balance.

My son lives with his pelvis tucked under and his chin thrust forward and up. I have always known this and figured, like myself, he would deal with it when the time comes but seeing the x-ray was a serious wakeup call.

So now I am doing to my son exactly what my mother did to me that I still resent. I am telling him to sit up with his pelvis in the correct position. It is any better that I showed him x-rays and we looked at the skeleton to see exactly what happens to the neck when we tuck the pelvis? I rather doubt it. He is probably as annoyed as I was.

What is a parent to do?

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sp anatomy