VH Dissector: Lower Limb: Gluteal Region
VH Dissector: Lower Limb: Gluteal Region
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The gluteal region is largely formed by the gluteus maximus muscle. The region is bounded superiorly by the iliac crest and inferiorly by the inferior border of the gluteus maximus muscle.
The sacrotuberous and sacrospinous ligaments close the greater and lesser sciatic notches, respectively, forming foramina from which structures enter or leave the pelvis and perineum. These two ligaments resist backward rotation of the inferior end of the sacrum and provide an origin for the gluteus maximus muscle.
Greater Sciatic Foramen – doorway for structures entering or leaving the pelvis (e.g. sciatic nerve).
Lesser Sciatic Foramen – doorway for structures entering or leaving the perineum (e.g. pudendal nerve).
Rotate the pelvis for a posterior view. Follow the tendon of obturator internus as it attaches to the greater trochanter of the femur
Add the inferior gemellus muscle. Arise from the superior and inferior margins of the lesser sciatic notch on either side of the obturator internus tendon. The inferior gemellus muscle is the larger of the two gemelli
Add the quadratus femoris muscle which lies posterior to the hip joint and femoral neck, separated from them by the tendon of obturator externus and the transverse branch of the medial circumflex femoral artery. There is often a bursa between the anterior aspect of the muscle and the lesser trochanter
Add the piriformis muscle. This muscle is often called the key to the gluteal region because it delineates many important relationships. As we add more structures, pay close attention to their positions relative to piriformis.
Add the Sciatic Nerve. (L4, L5, S1-S3) – It is the largest nerve in the body; leaves the pelvis through greater sciatic foramen and enters the gluteal region inferior to the piriformis muscle. It runs inferolaterally deep to the gluteus maximus midway between the greater trochanter of the femur and the ischial tuberosity of the pelvis.
The sciatic nerve has two branches (tibial and common fibular) that are surrounded in a common epineurium until it reaches the popliteal fossa where it divides into their own components.
In 10%-12% of people the sciatic nerve divides before entering the gluteal region in which case the common fibular nerve pierces through the piriformis muscle.
In 0.5% of people the common fibular nerve passes superior to the piriformis and it is vulnerable to injury during intragluteal injections.
Change to the male pevis and add the superior gluteal nerve. (L4-S1), which exits the greater sciatic foramen superior to the piriformis muscle and goes on to innervate gluteus medius, gluteus minimus, and tensor fasciae latae
The nerve to quadratus femoris (L4, L5, S1) passes deep to the sciatic nerve and obturator internus muscle. It supplies the quadratus femoris muscle and inferior gemellus muscle. (not identified in this donor body)
Add the Inferior Gluteal Nerve. (L5, S1, S2), which exits the greater sciatic foramen inferior to the piriformis to innervate the gluteus maximus muscle.
The nerve to obturator internus (L5, S1, S2) exits greater sciatic foramen to supply the superior gemellus muscle; enters the lesser sciatic foramen to supply the obturator internus muscle. (not identified in this donor body)
The posterior femoral cutaneous nerve (S1, S2, S3) leaves the pelvis with the inferior gluteal and sciatic nerves. It passes deep to the gluteus maximus and supplies skin of the posterior thigh and popliteal fossa. It gives rise to the inferior clunial nerves. (not identified in this donor body)
Add the pudendal nerve . S2, S3, S4 – most medial structure to pass through greater sciatic foramen inferior to piriformis. It passes lateral to the sacrospinous ligament and passes through the lesser sciatic foramen to enter the perineum where it supplies the skeletal muscles of the perineum and sensory to the external genitalia.
Add the Superior Gluteal Artery which exits the pelvis through the greater sciatic foramen superior to the piriformis muscle. Supplies the gluteus maximus, medius, minimus, and tensor fascia lata. It anastomoses with the inferior gluteal and medial circumflex femoral arteries.
Anastomosis (from the Greek "anastomoun", meaning "provide with a mouth") refers to vessels from different origins coming together to supply the same area. Also known as collateral circulation.
Add the Inferior Gluteal Artery which exits the pelvis through the greater sciatic foramen inferior to piriformis and supplies the gluteus maximus, obturator internus, quadratus femoris, and superior parts of the hamstring muscles. It anastomoses with the superior gluteal artery and participates in the cruciate anastomosis.
Add the Internal Pudendal Artery which exits the pelvis through the greater sciatic foramen and follows the pudendal nerve into the perineum
Add the Gluteus Medius muscle which lies between gluteus maximus posteriorly and tensor fasciae lata anteriorly. Much of the muscle is covered by gluteus maximus.
Add the Gluteus Maximus muscle which is a large, coarsely fibered, quadrilateral mass of muscle, which forms the prominence of the buttock and covers the ischial tuberosity.
Credits:
Credits:
VH Dissector steps modified for Drexel Dissector by Haviva Goldman, PhD, Noel Goodstadt, DPT and Sophie Geagan (MD student) from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.
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