Important Abstract-Innervation of Obturator Internus Muscle

[nyt]

I recently had an MRI that showed moderate to severe atrophy of the right obturator internus muscle. Therefore, I went on a search because the only thing that will cause atrophy of a muscle (unless you have a neurological disease which I don't have) is the nerve to the muscle is damaged. I started to research the nerve innervation to the obturator internus muscle. For this group I have posted the abstract plus a direct quote from a small section of the paper that is significant for transgluteal pudendal decompression surgery.

"The nerve to the obturator internus (obturator internus nerve) ran on the posterior surface of the sacrospinous ligament, turned to enter the lesser sciatic foramen, and was distributed to the obturator internus from the pelvic surface."

I am now seeing Dr. Aradillos-Lopez at the Vincera Institute in Philadelphia, PA. He is a neurologist that specializes in Complex Regional Pain Syndrome. We discussed the possibility that my pudendal surgery is what may have caused the atrophy to the right obturator internus. I told him if it did then at some point I should have left sided obturator internus atrophy. Dr. Aradillos felt it would really depend on where the SSL was cut so he didn't think it necessarily would happen on the left side plus we don't know in my case if the type of bladder sling I had is the culprit.

I am not regretting I had my pudendal surgery and I CANNOT say that the pudendal surgery is what caused my right obturator internus atrophy because I have other complicating factors but just want others to be knowledgeable when they talk with their physicians about the course of the obturator internus nerve when the SSL is cut during the transgluteal pudendal decompression approach.

Anat Rec. 2001 May 1;263(1):41-52.
Anatomical study of the obturator internus, gemelli and quadratus femoris muscles with special reference to their innervation.
Aung HH1, Sakamoto H, Akita K, Sato T.

Abstract

The manner of innervation of the obturator internus, superior and inferior gemelli, and the quadratus femoris in humans (101 pelvic halves) and in rhesus monkeys (Macaca mulatta: 8 pelvic halves) were investigated. In most specimens, the inferior gemellus originated from the lateral surface of the ischial tuberosity and also from the medial surface (intrapelvic origin) just beneath the obturator internus and was covered by the falciform process of the sacrotuberous ligament. The superior gemellus was frequently innervated by the nerve to the obturator internus and the nerve to the quadratus femoris (60.4%), and the inferior gemellus was innervated by the obturator internus nerve in two specimens. The quadratus femoris nerve originated from more cranial segments than the obturator internus nerve, however these nerves had various communication patterns inside and outside the muscles. According to the intramuscular nerve distribution, in some specimens the branches to the superior gemellus from the quadratus femoris nerve extended to the inferior gemellus, and the branches to the inferior gemellus were distributed to the obturator internus. The present findings revealed that the positional relationships among the branches to the obturator internus and gemelli muscles are relatively constant, although the branching patterns and innervation patterns were varied. The various patterns and routes are considered to reflect the variability of the differentiation patterns of the anlage of the muscles. A possible schematic model of the positional relationships between the muscles and the nerves is proposed.