DBS is continuous, high-frequency electrical stimulation administered to targets inclusive of the ventral intermediate nucleus (VIM) of the thalamus, the globus pallidus internus
(GPI) and the subthalamic nucleus (STN).
The long head of biceps femoris may influence load transmission through the sacrotuberous ligament, but so too may the action of gluteus maximus, piriformis, obturator internus
, and perhaps the other hamstring muscles.
The essentially vertical lateral wall of an ischiorectal fossa is formed by the ischium with its attached obturator internus
and associated fascia (Figure 4).
We also want to use a certain amount of finesse, taking care not to traumatize the sacrospinous ligament, arcus tendineus, or most importantly, the iliococcygeal, coccygeal, and obturator internus
Later, other targets such as the globus pallidus internus
(GPi) and subthalamic nucleus (STN) have been used for advanced PD.
When you feel the junction of the inferior pubic ramus with the body of the pubic bone--one of the two most important landmarks--you then can slide your finger along the obturator internus
fascia right down to the ischial spine.
To protect these structures, the surgeon must dissect the adjacent paraurethral and paravaginal areas to place a finger to meet the instrument as it passes through the obturator internus
It passes through the following structures in the following order: gracilis, adductor brevis muscle, obturator externus muscle, obturator membrane, and beneath or through the obturator internus
muscle and periurethral endopelvic connective tissue; it finally exits through the opened vagina.