(30) Gluteal Region & Posterior Thigh

Gluteal ligaments

sacrotuberous ligament and sacrospinous ligament

sacrotuberous ligament

ligament that runs from the PSIS/PIIS/Sacrum/coccyx to the ischial tuberosity

sacrospinous ligament

ligament that runs from the Sacrum/coccyx to the ischial spine

greater sciatic foramen

passageway for structures entering or leaving the lesser (true) pelvis, including the piriformis muscle (which subdivides it) & associated neurovasculature

lesser sciatic foramen

passageway for structures entering or leaving the perineum, including the obturator internus muscle, pudendal nerve, & internal pudendal vessels

Path of piriformis muscle

originates on the anterior surface of the sacrum -> passes through greater sciatic foramen, which it subdivides into superior & inferior portions

path of obturator internus

originates from inner margin of obturator foramen & obturater membrane -> passes through the lesser sciatic foramen

Structures passing through greater sciatic foramen above piriformis

- Superior gluteal artery

- Superior gluteal n

Structures passing through greater sciatic foramen below piriformis

- Inferior gluteal artery

- Internal pudendal artery

- Nerve to quadratus femoris

- Nerve to obturator internus

- Sciatic nerve

- Pudendal nerve

- Posterior femoral cutaneous nerve

Muscles of Gluteal Region

-gluteus maximus

-gluteus medius

-gluteus minimus

-tensor fasciae latae

-piriformis

-obturator internus

-superior gemellus

-inferior gemellus

-quadratus femoris

gluteus maximus

largest gluteal muscle that runs from the ilium behind posterior gluteal line/sacrotuberous ligament/ligaments on dorsum of sacrum to the iliotibial tract (mostly) & gluteal tuberosity of femur (about 1/4th of it)

-All fibers laterally rotate the thigh

- Upper fibers abduct the thigh (assist lesser gluteal muscles)

- Lower fibers extend the thigh powerfully (assist hamstring when demand for force is high)

-Innervated by the inferior gluteal nerve

iliotibial tract

Band of longitudinal fibers on lateral side of fascia lata that also attaches to the femur via the lateral muscular septum, which does not allow for much movement

gluteus medius

gluteal muscle that runs from the ilium between posterior and anterior gluteal lines to the lateral surface of greater trochanter that functions to abduct the thigh (most powerful muscle for this & (via anterior fibers) medially rotate the thigh

-Innervated by the superior gluteal nerve

gluteus minimus

gluteal muscle that runs from the ilium between the anterior and inferior gluteal lines to the anterior surface of greater trochanter that functions to abduct & (via anterior fibers) medially rotate the thigh

-Innervated by the superior gluteal nerve

most important FUNCTION of lesser gluteal muscles

keep the pelvis level & prevent hip adduction (via their action for hip abduction) during locomotion

tensor fasciae latae

gluteal region muscle that runs from the iliac crest between ASIS and iliac tubercle to the iliotibial tract

-All fibers abduct the thigh

-Anterior fibers flex the thigh

-Posterior fibers medially rotate the thigh

-Innervated by the superior gluteal nerve

Piriformis

gluteal region muscle that runs from the anterior surface of the sacrum to the greater trochanter that plays a minor role in lateral rotation, abduction, & extension of thigh, but mainly functions in proprioception

-Innervated by S1 & S2 direct branches from sacral plexus

Triceps Coxae

superior gemellus, obturator internus, inferior gemellus. all insert on the medial aspect of the greater trochanter.

superior gemellus

gluteal region triceps coxae muscle that runs from the lesser sciatic notch to the medial aspect of the greater trochanter that functions predominantly in proprioception

-Innervated by the nerve to obturator internus

obturator internus

gluteal region triceps coxae muscle that runs from the deep surface of the obturator membrane to the medial aspect of the greater trochanter that functions to laterally rotate the thigh

-Innervated by the nerve to obturator internus

inferior gemellus

gluteal region triceps coxae muscle that runs from the lesser sciatic notch to the medial aspect of the greater trochanter that functions predominantly in proprioception

-Innervated by the nerve to quadratus femoris

quadratus femoris

gluteal region muscle that runs from the lateral edge of the ischial tuberosity to the intertrochanteric crest that functions to laterally rotate & adduct the thigh

-Innervated by the nerve to quadratus femoris

Superior gluteal artery

branch of the posterior division of the internal iliac artery that passes superior to piriformis & supplies gluteus maximus, gluteus medius, gluteus minimis, tensor fasciae latae, & part of piriformis

inferior gluteal artery

Branch of the anterior division of the internal iliac artery that passes inferior to piriformis & supplies Gluteus maximus, part of Piriformis, Obturator internus, Quadratus femoris, Superior and inferior gemelli, & Upper hamstring muscles

internal pudendal artery

branch of the internal iliac artery that passes through the gluteal region on its way to supply the perineum

deep gluteal nerves

superior gluteal nerve

inferior gluteal nerve

nerve to quadratus femoris

nerve to obturator internus

sciatic nerve

pudendal nerve

posterior femoral cutaneous nerve

posterior femoral cutaneous nerve

nerve that runs medial to the sciatic nerve & provides somatic sensory innervation to inferior buttocks, posterior aspect of thigh, popliteal fossa, & lateral aspect of perineum (therefore responsible for some of the somatic pain of childbirth)

Piriformis Syndrome

form of sciatica characterized by pain in the buttocks (especially when sitting) resulting from compression of the sciatic nerve by the piriformis muscle, often following an injury of the buttocks

-more common in athletes who use the gluteal muscles, female, & the 12% of people where the common fibular division

of the sciatic nerve passes through the piriformis

Intramuscular Injections

should take place in the superolateral quadrant of the buttocks above the superior border of gluteus maximus, commonly into tensor fasciae latae

posterior compartment of thigh

contains biceps femoris (long & short heads), semitendinosus, semimembranosus, & the ischiocondylar part of adductor magnus, all of which are extensors of the thigh and/or flexors of the knee that originate from the ischial tuberosity

-All but the short head of biceps femoris are innervated by the tibial division of the sciatic nerve

-Supplied by the perforating branches of the deep artery of the thigh & the inferior gluteal artery

Hamstring Muscles

3 muscles (long head of biceps femoris, semitendinosus, semimembranosus) in the posterior compartment of the thigh that cross both the hip & knee joints.

-All originate on the ischial tuberosity

-Long Head of biceps femoris inserts on head of fibula

-Semitendinosus inserts on medial surface of proximal tibia

-Semimembranosus inserts on posterior part of medial condyle of tibia

-All function to extend the thigh & flex the leg

-Innervated by the tibial division of the sciatic nerve

pes anserinus

"goose's foot" structure composed of the tendons of sartorius, gracilis, & semitendinosus ("Silly Goose Step")

ischiocondylar part of adductor magnus

posterior thigh muscle that runs from the Ischial tuberosity to the adductor tubercle of femur that functions to extend, adduct, & (weakly) medially rotate the thigh

-Innervated by the tibial division of the sciatic nerve

short head of biceps femoris

posterior thigh muscle that runs from the lower linea aspera and lateral supracondylar line to the tendon of the long head of biceps femoris that functions to flex the leg

-innervated by the common fibular division of the sciatic nerve

deep artery of the thigh

branch of the femoral artery that passes superior & posterior to adductor longus that supplies all compartments of the thigh. Branches into perforating arteries.

perforating arteries

Branches of the deep femoral artery that pierce the pubofemoral part of adductor magnus to get to & supply the posterior compartment of the thigh

Sciatic nerve is deep to

gluteus maximus superiorly & long head of biceps femoris inferiorly; always protected by muscle

popliteal fossa

diamond-shaped space at the back of the knee that contains the tibial nerve (most superficial), popliteal vein, & popliteal artery with its genicular branches (most deep), all of which pass deep to gastricnemius

roof of popliteal fossa

deep fascia of the thigh & leg

floor of popliteal fossa

femur & capsule of knee joint

superomedial border of popliteal fossa

semimembranosus and semitendinosus

superolateral border of popliteal fossa

biceps femoris

inferomedial border of popliteal fossa

medial head of gastrocnemius

inferolateral border of popliteal fossa

lateral head of gastrocnemius and plantaris

Sural Nerve

Nerve of the lower leg formed from medial & lateral sural cutaneous nerves from the tibial & common fibular nerves. Runs parallel to the small saphenous vein

Genicular Anastomosis

Collateral circulation around the knee joint, which is necessary because certain joint positions kink certain arteries

-formed by superior medial genicular artery, superior lateral genicular artery, inferior medial genicular artery, & inferior lateral genicular artery

Popliteal aneurysm

aneurysm of the popliteal artery. often called the "silent killer" because genicular anastomosis enable adequate blood flow to continue to the lower leg until a certain point when it becomes an emergency situation