Week 11 Gluteal Region - Nerves.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 plex...

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 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 Nerves of the Gluteal Region  Sciatic Nerve o largest nerve in the body and is a branch of sacral plexus o emerges from pelvis through greater sciatic foramen, inferior to piriformis o runs inferiorly in gluteal region and anterior to sciatic nerve are obturator internus, superior and inferior gemelli and quadratus femoris and posterior to sciatic nerve is gluteus maximus o passes deep to long head of biceps femoris as it leaves gluteal region and enters posterior compartment of thigh o divisions: tibial nerve (anterior divisions of ventral rami of L4-S3 spinal nerves) and common fibular (peroneal) nerve (posterior divisions of ventral rami of L4-S2 spinal nerves) and is bound together by connective tissue o gives no branches in gluteal region  Posterior Cutaneous Nerve of Thigh  o branch of sacral plexus (anterior divisions of ventral rami of S2 and S3 spinal nerves and posterior divisions of ventral rami of S1 and S2 spinal nerves) and leaves pelvis through greater sciatic foramen, inferior to piriformis o descends deep to gluteus maximus, just medial to sciatic nerve  as it leaves gluteal region, passes superficial to long head of biceps femoris and continues on back of thigh superficial to hamstring muscles and deep to fascia lata o branches:  inferior clunial nerves: curve around inferior border of gluteus maximus and supply skin of inferior part of gluteal region  perineal branches: supply skin of superomedial thigh and adjacent perineum  cutaneous branches to back of thigh and upper leg  Superior Gluteal Nerve o branch of sacral plexus (posterior divisions of ventral rami of L4-S1 spinal nerves) and leaves pelvis through greater sciatic foramen, superior to piriformis, with superior gluteal vessels o runs forward between gluteus medius and gluteus minimus o branches:  muscular branches to gluteus medius, gluteus minimus and tensor fasciae latae  articular branch to hip joint  Inferior Gluteal Nerve o branch of sacral plexus (posterior divisions of ventral rami of L5-S2 spinal nerves) o leaves pelvis through greater sciatic foramen, inferior to piriformis, with inferior gluteal vessels o supplies gluteus maximus  Pudendal Nerve o branch of sacral plexus (anterior divisions of ventral rami of S2-S4 spinal nerves)  o leaves pelvis through greater sciatic foramen, inferior to piriformis, with internal pudendal vessels (most medial structure inferior to piriformis) and curves around posterior aspect of ischial spine and passes through lesser sciatic foramen to enter perineum  Nerve to Obturator Internus o branch of sacral plexus (anterior divisions of ventral rami of L5-S2 spinal nerves) o leaves pelvis through greater sciatic foramen, inferior to piriformis and just lateral to pudendal nerve and internal pudendal vessels and gives a branch to superior gemellus and passes through lesser sciatic foramen and supplies obturator internus  Nerve to Quadratus Femoris o branch of sacral plexus (anterior divisions of ventral rami of L4-S1 spinal nerves) o leaves pelvis through greater sciatic foramen, inferior to piriformis and descends deep (anterior) to obturator internus and gemelli and supplies quadratus femoris, inferior gemellus and hip joint 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