![]() After exiting the foramen, the nerve passes under the piriformis in 85% of people. The effect of shortening is to increase its diameter and, because of its location, this allows for direct pressure to be exerted on the sciatic nerve within the foramen, since they pass through it together. Note: Piriformis is a postural muscle, which will shorten if stressed ( Janda 1983). The tendon and nerve of obturator internus as well as the pudendal nerve and vessels pass through the foramen. ![]() The lesser sciatic foramen has as its boundaries the ischial body anteriorly, the ischial spine and the sacrospinous ligament superiorly and the sacrotuberous ligament posteriorly. Below the piriformis, a number of additional structures exit the pelvis via the greater foramen, including the sciatic nerve (usually), inferior pudendal nerve and vessels, inferior gluteal nerve and vessels, posterior femoral cutaneous nerves and the nerves to obturator internus and quadratus femoris ( Heinking et al 1997). ![]() The piriformis muscle passes through it as do the superior gluteal vessels and nerves, which leave the pelvis via this route. The greater sciatic foramen has as its anterosuperior margin the greater sciatic notch, with the sacrotuberous ligament forming its posterior boundary and the ischial spine and sacrospinous ligament providing its inferior borders. ![]() There are two sciatic foramina, the greater and the lesser on each side. Leon Chaitow ND DO, Judith DeLany LMT, in Clinical Application of Neuromuscular Techniques, Volume 2 (Second Edition), 2011 The sciatic foramina Treatments consist of using a doughnut-shaped pillow to reduce the pressure on the pudendal nerve, antiepileptic or TCA medications, image and nerve stimulator-guided pudendal nerve blocks positioned at the ischial spine or Alcock's canal (pudendal canal) with local anesthetic/steroid, and surgical decompression of the pudendal nerve. There may be associated urinary, anal, or sexual dysfunction. The distribution may be ipsilateral or even bilateral, and patients may demonstrate allodynia and hyperalgesia in the affected region. Patients report that sitting and other flexion activities of the hip (sitting, squatting, cycling, exercising) exacerbate the pain whereas standing or lying down relieves the discomfort. Sometimes, the pain may refer to the groin, medial thigh, buttock, and abdomen. Symptoms may include a stabbing, burning, or pinpricking sensation in the penis, scrotum, labia, perineum, or anorectal region. Pudendal nerve entrapment is sometimes referred to as cyclist' s syndrome. Pudendal neuralgia is often attributable to mechanical or inflammatory damage to the nerve caused by pressure or trauma. Finally, it divides into three branches: anal/rectal, perineal, and clitoral/penile. The nerve travels through the pelvis around the ischial spine, between the sacrospinous and the sacrotuberous ligaments. The pudendal nerve derives from the sacral plexus (S2–4) and enters the gluteal region via the greater sciatic foramen. Christo, Greg Hobelmann, in Current Therapy in Pain, 2009 Pudendal Nerve Entrapment (Pudendal Neuralgia)
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