The anatomy of the perineal branch of the sciatic nerve

Abstract

A "perineal" branch of the sciatic nerve has been visualized during surgery, but there is currently no description of this nerve branch in the literature. Our study investigates the presence and frequency of occurrence of perineal innervation by the sciatic nerve and characterizes its anatomy in the posterior thigh. Fifteen cadavers were obtained for dissection. Descriptive results were recorded and analyzed statistically. Twenty-one sciatic nerves were adequately anatomically preserved. Six sciatic nerves contained a perineal branch. Five sciatic nerves had a branch contributing to the perineal branch of the posterior femoral cutaneous (PFC) nerve. In specimens with adequate anatomical preservation, the perineal branch of the sciatic nerve passed posterior to the ischial tuberosity in three specimens and posterior to the conjoint tendon of the long head of biceps femoris and semitendinosus muscles (conjoint tendon) in one. In specimens in which the perineal branch of the PFC nerve received a contribution from the sciatic nerve, the branch passed posterior to the sacrotuberous ligament in one case and posterior to the conjoint tendon in three. Unilateral nerve anatomy was found to be a poor predictor of contralateral anatomy (Cohen's kappa = 0.06). Our study demonstrates for the first time the presence and frequency of occurrence of the perineal branch of the sciatic nerve and a sciatic contribution to the perineal branch of the PFC nerve. Clinicians should be cognizant of this nerve and its varying anatomy so their practice is better informed. Clin. Anat. 31:357-363, 2018. © 2018 Wiley Periodicals, Inc.

Previously Unreported Sciatic Nerve Variation: Case Report

“…The sciatic nerve has a large number of variations and understanding these is important in the diagnosis and treatment of pathologies involving this nerve [13][14][15]. To our knowledge, the variant described here has not been previously reported.…”

A perineal branch of the sciatic nerve: A case report

“…In one case, there were two of these variants arising independently from the SN. Coursing towards the perineum, this nerve passed posterior to the ischial tuberosity in three cases, posterior to the conjoint tendon (of biceps femoris and semitendinosus) in four cases, and posterior to the sacrotuberous ligament in one specimen (Gibbs et al, 2018).…”

“…al., 2014). Recently, the existence of a perineal branch of the SN was reported thus questioning the pre-existing fact that the SN only has distribution to the posterior thigh, knee, leg and foot (Gibbs et al 2018). The author further reported direct perineal branches from the SN as well as neural communications between the perineal branch and the PFCN.…”

A Variant of the Sciatic Nerve and its Clinical Implications

“…Normally, the sciatic nerve, after it leaves the pelvis through the greater sciatic foramen, is located between the greater trochanter (laterally) and the ischial tuberosity (medially) [ 5 , 6 ]. In the case presented herein, if this landmark location were assumed to contain the entire sciatic nerve with injections, electrode placement, acupuncture needle placement, or surgery and the area just lateral to the ischial tuberosity were engaged, then injury to the common fibular nerve might occur (Figure 1 ) [ 7 , 8 ].…”