Brief Answer:
Anatomy and Function of the Erector Spinae

Detailed Answer:
Good afternoon sir. I've read your question as well as related questions and answers from colleagues to get a more complete understanding of the clinical context to your query. My understanding is that you suffer from idiopathic PD as well as from CAMPTOCORMIA. Your question in terms of asking as to which erector spinae muscle is "lazy, spastic, and attached to the 12th rib" to my interpretation is that you are looking for an answer as to which of the muscles or muscle groups in the back may be responsible for the abnormal posture of flexion which is characteristic of the CAMPTOCORMIA condition.

Let's clarify one question which is relatively easy to answer and that is the one you've posed as to which of the erector spinae attach to the 12th rib. That muscle is the erector spinaue LUMBORUM which attaches to the lowest of last 6 ribs of the thoracic cage. There are some anatomic variations that see this erector spinae muscle attaching to the last 9 ribs....but in any case the answer to your question as to which attaches to rib #12 is the LUMBORUM group of muscles. One of its major actions is to depress the lower ribs (to which it is attached) and is active at the end of inhalation and during forced or MAXIMAL exhalation. Look at this diagram as a link and see if you can appreciate what I've described in terms of the LUMBORUM muscles of the ILEOCOSTALIS group.

https://upload.wikimedia.org/wikipedia/commons/1/1a/Gray389_-_Erector_spinae.png

In terms of the other questions as to which of the erector spinae are "lazy" or "spastic" it is very difficult to determine just on the basis of the given information where the problem may be in this system of muscles that could be causing the BENT SPINE SYNDROME if in fact, there even is a primary problem at the level of the muscle or muscle group. In clinical practice no such identification is carried out since it is very difficult to isolate each of the muscle and test them both clinically as well as electrically. It would be extremely challenging technically and the invasiveness of such testing does not justify the outcomes which would not be expected to change even if a dysfunctional muscle could be identified.

We know that PARKINSON'S DISEASE is frequently found in association with the condition of CAMPTOCORMIA and therefore, the best strategy would be to optimize and focus treatments and therapeutic interventions on that entity. Having said that I would interject that there are other considerations along the lines of PARKINSON'S disease itself which are also recognized as being associated with bent spine syndrome such as MULTISYSTEM ATROPHY which is classified as a PARKINSON'S PLUS type of disease. Therefore, if your PD has never robustly responded to medication treatment of the regimen you are currently are then, I might suggest consideration of one of the other parkinsonian plus syndromes as a possible underlying cause. Multisystem atrophy may appear to be parkinson's like but it typically has a different set of predominant symptoms of an autonomic nature and does not respond very well to medication that generally is used to treat PD. But there is a clear and present between MSA and camptocormia.

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You can always reach me at the above address for this and other questions. I wish you the best with everything and hope this conversation has helped you give you a little more direction as to what you may wish to do as well as things you can discuss with your doctors in order to help feeling back to normal as soon as possible.

This query required 60 minutes of professional time to research, assimilate, and respond in complete form.

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