Muscles - Gluteal Region Flashcards
What are the superficial abductors and extenders?
Abduct and extend the femur.
Gluteus maximus, medius and minimus and tensor fascia lata.
What are the deep lateral rotators?
Laterally rotate the femur.
Quadratus femoris, piriformis, gemellus superior, gemllus inferior and obturator internus.
What is the arterial supply and venous drainage of these muscles?
Superior and inferior gluteal arteries, branches of the internal iliac artery.
Venous drainage follows the arteries.
Gluteus maximus
Largest of the gluteal muscles
Origin - gluteal surface of the ilium, sacrum and coccyx.
Insertion - gluteal tuberosity and iliotibial tract.
Innervation - Inferior gluteal nerve
Actions - main extensor of the thigh and assists with lateral rotation. Only used when force is required e.g. running and climbing.
Gluteus medius
Lies between the maximus and minimus. Fan shaped.
Origin - gluteal surface of ilium.
Insertion - lateral surface of the greater trochanter
Innervation - superior gluteal nerve
Action - abducts and medially rotates femur. Secures the pelvis during locomotion.
Gluteus minimus
Deepest and smallest of the gluteal muscles. Similar shape and function to gluteus medius.
Origin - ilium - converges to form a tendon
Insertion - anterior side of the greater trochanter.
Innervation - superior gluteal nerve
Action - abducts and medially rotates the femur. Stabilises the pelvis during locomotion.
Tensor fascia lata
Small superficial muscle lying towards the edge of the iliac crest. Functions to tighten the fascia lata.
Origin - anterior iliac crest, ASIS
Insertion - iliotibial tract, lateral condyle of the tibia.
Innervation - superior gluteal nerve
Action - assists the gluteus medius and minimus in abduction and medial rotation of the femur. Plays a supportive role in the gait cycle.
Clinical relevance - damage to the superior gluteal nerve
Innervates the superior gluteus and minimus.
Important role in stabilising the pelvis in locomotion.
In the standing position, the gluteus minimus and medius contract when the contralateral leg is raised, preventing the pelvis from drooping.
A charateristic finding in gluteal muscle weakness is Trendelenburg sign.
Trendelenburg sign
Produced when the patient is asked to stand unassisted on each leg in turn. In a postive sign, pelvic drop will occur of the unsupported leg. Pelvic drop can be observed by viewing the iliac crests.
For example, if the left gluteal muscles are weak the right side of the pelvis will drop when standing on the left leg.
Piriformis
Most superior of the deep muscles.
Origin - anterior surface of sacrum
Insertion - exits through the greater sciatic foramen and inserts onto the greater trochanter.
Innervation - nerve to piriformis
Action - lateral rotation and abduction of femur.
Obturator internus
Lateral walls of pelvic cavity. The obturator internus and gemmelli is sometimes known as the triceps coxae.
Origin - pubis and ischium at obturator foramen
Insertion - travels through the lesser sciatic foramen and inserts on the greater trochanter.
Innervation - nerve to obturator internus
Action - lateral rotation and abduction of the femur
The gemelli
Two narrow triangular muscles, separated by the obturator tendon.
Origin (superior) - ischial spine
Origin (inferior) - ischial tuberosity
Insertion - greater trochanter of the femur
Innervation (superior) - nerve to obuturator
Innervation (inferior) - nerve to quadratus femoris
Action - lateral rotation and abduction
Quadratus femoris
Flat, square shaped muscle - most inferior of the deep gluteal muscles. Located deep to the gemelli and obturator internus.
Origin - lateral side of ischial tuberosity
Insertion - quadrate tuberosity and the intertrochanteric crest
Innervation - nerve to quadratus femoris
Action - lateral rotation
