The ninth dorsal segment is next on the list for my Marion Clark exploration. A lesion of the ninth dorsal is most often an anterior displacement or a torsion according to Clark. Considering the rotational and flexion bias of the dorsal vertebrae this should be fairly clear. From a pathology point of view the anterior displacement is more likely problematic due to the decrease of size in the intervertebral foramina.
For most people, a lesion of the ninth dorsal segment is most likely to affect the greater splanchic nerve (due to some quirks of anatomy it may also affect the lesser splanchic nerve for some individuals). As a result of influence over the greater splanchic nerve effects will be seen in the: stomach, spleen, gall bladder, liver, kidney, small intestine, the ascending and transverse colon. It is also important to consider the connections to the celiac ganglia and adrenal medulla via the greater splanchic nerve. Also keep in mind that the greater splanchic nerve passes through the diaphragm on the way to the abdomen making it highly unlikely that any treatment aimed at the ninth dorsal segment or the greater splanchic nerve would be complete without addressing the diaphragm locally as well as neurologically (via the phrenic nerve). According to Clark the most affected viscus is the kidney when the ninth dorsal segment is in lesion.
As always, depending on the nature of the lesion in the ninth dorsal segment there will be excitation or inhibition to neurologically connected areas. If the intervertbral foramina is lessened bilaterally or unilaterally then the lesion will be inhibitory where the foramina is lessened.
Through my present investigation of Clark’s work I am currently very much in the mindset that basing much of my treatment on mechanical principles is the most effective way to provide physiological modulation. I am positive that my viewpoint will continue to evolve and I look forward to it. At the moment I am of the opinion that most results through Osteopathic treatment arise from the balancing of mechanical function – not only is there a display of localized alteration in physiological movement there is also alteration in structurally related physiology. This should be self evident through the principles of Osteopathy – my current point is that most treatment need not be localized to viscera or other specific structures. To provide an engineering reference (similar to what Dr. Still seemed fond of) there is no point fixing the steering wheel if you have a bent chassis – straighten the chassis and then see if the steering wheel needs to be fixed.
At the moment I am not going as deep in to the structural descriptions with Marion Clark’s work as I am more moved to provide related thoughts – for more in depth structural thoughts you can look at my post on the ninth rib. Due to the connections between the ninth rib and the ninth dorsal vertebra many of my thoughts have crossover.