Week 11 pt3.pdf

Gluteal Region Sacral Plexus  formed by lumbosacral trunk (ventral ramus of L5 spinal nerve + part of ventral ramus of L4 spinal nerve), ventral rami of S1, S2 and S3 spinal nerves and part of ventral ramus of S4 spinal nerve (remainder of ventral ramus of S4 joins coccygeal ple...

Gluteal Region Sacral Plexus  formed by lumbosacral trunk (ventral ramus of L5 spinal nerve + part of ventral ramus of L4 spinal nerve), ventral rami of S1, S2 and S3 spinal nerves and part of ventral ramus of S4 spinal nerve (remainder of ventral ramus of S4 joins coccygeal plexus)  sacral plexus lies against posterior pelvic wall, anterior to piriformis muscle  ventral rami branch into anterior and posterior divisions and then branches of sacral plexus contain fibers from anterior and/or posterior divisions of specific ventral rami  branches of sacral plexus supply muscles and part of skin of gluteal region, muscles and skin of posterior thigh, muscles and skin of entire leg and foot (except skin over medial aspect of leg and medial border of foot) and muscles and skin of perineum  main branches:  Sciatic nerve: largest nerve in body and is a composite nerve consisting of common fibular (peroneal) nerve (formed by fibers from posterior divisions of L4, L5, S1 and S2 ventral rami) and tibial nerve (formed by fibers from anterior divisions of L4, L5, S1, S2 and S3 ventral rami)  Superior gluteal nerve: formed by fibers from posterior divisions of L4, L5 and S1 ventral rami  Inferior gluteal nerve: formed by fibers from posterior divisions of L5, S1 and S2 ventral rami  nerve to piriformis: formed by fibers from posterior divisions of S1 and S2 ventral rami  nerve to quadratus femoris: formed by fibers from anterior divisions of L4, L5 and S1ventral rami  nerve to obturator internus: formed by fibers from anterior divisions of L5, S1 and S2 ventral rami  Posterior cutaneous nerve of the thigh (posterior femoral cutaneous nerve): formed by fibers from anterior divisions of S2 and S3 ventral rami and from posterior divisions of S1and S2 ventral rami  Pudendal nerve: formed by fibers from anterior divisions of S2, S3 and S4 ventral rami  pelvic splanchnic nerves: originate from ventral rami of S2, S3 and S4 spinal nerves and contain preganglionic parasympathetic fibers and join inferior hypogastric plexus Boundaries of the Gluteal Region  superior: iliac crest  inferior: gluteal fold (skin fold that separates gluteal region from posterior thigh)  medial: natal (intergluteal) cleft and cleft between right and left buttocks  lateral: line connecting ASIS to greater trochanter Cutaneous Innervation of the Gluteal Region  superior clunial nerves: dorsal rami of L1-L3 spinal nerves and supply skin of superior part of gluteal region  medial clunial nerves: dorsal rami of S1-S3 spinal nerves and supply skin of medial part of gluteal region  inferior clunial nerves: branches of posterior cutaneous nerve of thigh and curve around inferior border of gluteus maximus to supply skin of inferior part of gluteal region  lateral cutaneous branch of iliohypogastric nerve: supplies skin of superolateral part of gluteal region  lateral cutaneous nerve of thigh: supplies skin of inferolateral part of gluteal region Vessels of the Gluteal Region  superior and inferior gluteal arteries:  branches of internal iliac artery (originate within pelvis)  leave pelvic cavity and enter gluteal region via greater sciatic foramen with corresponding nerves  divide into branches distributed throughout gluteal region  internal pudendal artery:  branch of internal iliac artery (originates within pelvis)  accompanies pudendal nerve through gluteal region and into perineum  has no important branches in gluteal region  veins of gluteal region: superior and inferior gluteal and internal pudendal veins à accompany arteries of same name à drain into internal iliac vein Structures Passing Through the Greater Sciatic Foramen  piriformis muscle  sciatic nerve  posterior cutaneous nerve of thigh  superior and inferior gluteal nerves  nerve to obturator internus  nerve to quadratus femoris  pudendal nerve  superior and inferior gluteal vessels  internal pudendal vessels Structures Passing Through the Lesser Sciatic Foramen  obturator internus muscle  nerve to obturator internus  pudendal nerve  internal pudendal vessels