Anatomy 101

Study of the Human Body is the Study of God

Hiya, pre-med students! Due to the overwhelming demand from college students for more help with serious subjects and themes, docweasel.com brings you the latest in its scholarly series of anatomical studies. This week, we study the muscle group “gluteus maximus”. Click the pictures for detailed study.
-Sunny

Sacrotuberous ligament and coccyx
INSERTION: Deepest quarter into gluteal tuberosity of femur, remaining three quarters into iliotibial tract (anterior surface of lateral condyle of tibia)

Anatomy:
Origin: posterior gluteal line of the ilium, tendon of sacrospinalis, – dorsal surface of sacrum, coccyx and sacrotuberous ligament;
Insertion: gluteal tuberosity of femur and iliotibial tract of fascia lata – it inserts partly into the iliotibial band and partly into the gluteal tuberosity of the femur; – also inserting into the band, but further anteriorly is the tensor fascia lata.

ACTION: Extends and laterally rotates hip. Maintains knee extended via iliotibial tract

Function delay: the gluteus maximus, the fascia lata (which covers the gluteus medius, and the tensor fascia latae form a continuous fibromuscular sheath, the outer layer of the hip musculature; – action: – extends thigh at the hip, assists in laterally rotating the thigh.

Reversed origin insertion action: when leg is fixed as in standing the gluteus maximus is an extensor of the pelvis on the thigh;
Nerve supply: inferior gluteal.

NERVE: Inferior gluteal nerve (L5, S1,2)

Posterolateral Approach to the Hip: internal rotation of the hip may be facilitated by transversely sectioning several cm of the insertion of the gluteus maximus tendon on the femur; do this w/ hip maximally internally rotated, & place tip of hemostat under tendinious structure to lift it away from underlying vessels.

ORIGIN: Outer surface of ilium behind posterior gluteal line and posterior third of iliac crest lumbar fascia, lateral mass of sacrum<. Section: only the amount of the tendon necessary to allows sufficient internal rotation to dislocate the hip; - when performing this, the surgeon will often encounter bleeding from cruciate anastomosis vessels. Upper and middle third section of the muscle are abductors and the lower 1/3 is inactive as an abductor or adductor in the standing position.

CONCLUSION: Muscle mass enables frontal action movement and lateral gain and gait adjust. Lower tendons brake further restrain plus muscle reflex and ligiment restructure.

Gait: gluteus maximus contracts at heel-strike, slowing forward motion of trunk by arresting flexion of the hip and initiating extension; when gluteus maximus is weak, trunk lurches backward (maximus lurch) at heel-strike on weakened side to interrupt forward motion of trunk.

During normal walking, hip extension is primarily a function of hamstrings rather than gluteus maximus.

LOWER LINE: Outer surface of ilium behind posterior gluteal line and posterior third of iliac crest lumbar fascia, lateral mass of sacrum.

That’s the lesson for this week, please study the photos in detail. All this will be on the test.
-Sunny