Gluteal Region, Posterior Thigh, Popliteal Fossa

Skeletal and Surface Anatomy

Iliac Crest – extends from the anterior superior iliac spine to the posterior iliac spine

Gluteal Fold – coincides with the inferior portion of the Gluteus Maximus muscle

Gluteal Sulcus – skin crease formed by fat, inferior to the gluteal fold, seperates the buttock from the posterior thigh

Anterior and Posterior Iliac Spines – anterior prominence of ilium, posterior is located in a skin dimple ~4cm off midline

Ischial Tuberosity – covered by gluteus maximus when the thigh is extended, uncovered when the thigh is flexed (sitting)

Ischial Spine – projects medially and seperates the greater sciatic notch (superior) from the lesser sciatic notch (inferior)

Joints

Sacroiliac – the joint where the sacrum articulates (and eventually fuses) with the posterior ilium

Hip Joints – multi axial, ball and socket type of synovial joint made by the head of the femur articulating with the actabulum

The acetabulum is made up of the fused pubic, ischium, and ilium bones.

Movements

Extension of Thigh – lifting up ones leg, as in kicking a ball in front of you

Abduction of Thigh – raising ones leg to the side, as in the "X" phase of a jumping jack ( I X I X I X I X )

Muscles and Nerves

3 primary abductors of the hip are innervated by the Superior Gluteal Nerve. (G. medius, G. Minimus, and Tensor fascia lata)

Gluteus Minimus

Origin: outer surface of ilium between anterior and inferior gluteal lines, margin of greater sciatic notch

Insertion: Anterior border of the greater trochanter

Function: Abducts the thigh, rotates the thigh medially when the limb is extended

Nerve: Superior gluteal

Artery: Deep branch of the superior gluteal

Gluteus Medius

Origin: outer surface of ilium from the iliac crest and the posterior gluteal line above, to the anterior gluteal line below, gluteal aponeurosis.

Insertion: lateral surface of the greater trochanter

Function: abducts the thigh, rotates the thigh medially when the limb is extended

Nerve: Superior gluteal

Artery: Deep branch of the superior gluteal

1 Muscle innervated by the Inferior Gluteal nerve: Gluteus Maximus

Gluteus Maximus.

Origin: posterior gluteal line, tendon of sacrospinalis, dorsal surface of sacrum and coccyx, sacrotuberous ligament

Insertion: 1/3^rd into the Gluteal tuberosity of femur, 2/3^rds into the iliotibial tract

Function: extends thigh, assists in adducting and laterally rotating it; acting on insertion, muscle extends trunk

Nerve: Inferior Gluteal

Artery: superior gluteal, inferior gluteal, 1^st perforating branch of profunda femoris

Piriformis

Origin: the pelvic surface of sacrum between anterior sacral foramina, the margin of the greater sciatic foramen, sacrotuberus ligament

Insertion: the upper border of the greater trochanter of the femur

Function: rotates the thigh laterally, abducts the thigh when the limb is flexed

Nerve: ventral rami of S1 and S2

Artery: superior gluteal, inferior gluteal, internal pudundal

Superior Gemelli

Origin: outer surface of the ischial spine

Insertion: medial surface of the greater trochanter, blends with the obturator internus tendon

Function: rotates the thigh laterally

Nerve: Nerve to the obturator internus and gemellus superior (L5 and S1)

Artery: Inferior gluteal

Obturator Internus

Origin: Margins of the obturator foramen, obturator membrane, obturator fascia

Insertion: the medial surface of the greater trochanter

Function: rotates the thigh laterally, abducts the thigh when the limb is flexed

Nerve: Nerve to the obturator internus and gemellus superior (L5 and S1)

Artery: muscular branches of the internal pudundal, superior gluteal

Inferior Gemelli

Origin: upper part of the ischial tuberosity

Insertion: medial surface of the greater trochanter, blends with the obturator internus tendon

Function: rotates the thigh laterally

Nerve: nerve to the quadratus femoris and gamellus inferior (L5 and S1)

Artery: Inferior gluteal

Quadratus Femoris

Origin: lateral margin of the ischial tuberosity

Insertion: Quadrate tubercle of femur, linea quadrata

Function: adducts and laterally rotates the thigh

Nerve: nerve to the quadratus femoris and gamellus inferior (L5 and S1)

Artery: medial femoral circumflex

Muscles of the Posterior Thigh (Hamstrings) innervated by Tibial division of the Sciatic Nerve:

Semitendinosus

Origin: upper and medial impression of ischial tuberosity with tendon of the biceps

Insertion: upper part of the medial surface of tibia, deep fascia of the leg

Function: flexes the leg, extends the thigh, rotates the leg medially when the knee is semi-flexed

Nerve: Sciatic

Artery: perforating branches of profunda femoris, superior muscular branches of popliteal

Semimembranosus

Origin: upper and lateral facet of ischial tuberosity

Insertion: medial posterior surface of medial condyle of tibia

Function: flexes the leg, extends the thigh, rotates the leg medially when the knee is semi-flexed

Nerve: tibial division of the sciatic

Artery: perforating branches of profunda femoris, superior muscular branches of popliteal

Biceps Femoris

Origin: long head from ischial tuberosity and sacrotuberous ligament; short head from lateral lip of linea aspera, lateral supracondylar line of femur, lateral intermuscular suptum

Insertion: head of fibula, lateral condyle of tibia, deep fascia on the lateral side of leg

Function: flexes the leg, extends the thigh, rotates the leg laterally when the leg is semi-flexed

Nerve: Siatic (tibial portion to long head, peroneal portion to short head)

Artery: perforating branches of profunda femoris, superior muscular branches of popliteal

Sciatic nerve: splits into peroneal (fibular)- muscles in front and tibial – all the flexors in foot and calf. Both the peroneal and tibial give off branches that are the Sural nerves- provide cutaneous innervation to the posterior leg.

Vessels – arteries all branch from the internal iliac artery

Arteries

Superior Gluteal – largest branch off the internal iliac, passes thorough the greater sciatic foramen, divides into the superficial and deep branches. Superficial feeds the glutemus maximus, the deep feeds the gluteus medius and gluteus minimus as well as the tensor facia lata muscle

Inferior Gluteal – leaves the pelvis via the greater sciatic foramen. Feeds gluteus maximus, obturator internus, quadratus femoris, and the upper part of the hamstring muscles. Joins the superior in the cruciate anastomosis of the thigh

Internal Pudendal – leaves pelvis via the greater sciatic foramen, descends posterior to the ischial spine, reenters the pelvis via the lesser sciatic foramen. Supplies the external genitalia and muscles in the gluteal and pelvic regions

Veins

Gluteal – venae comitantes, can provide alternate route for returning blood if the femoral vein is occluded.

Internal Pudendal – drain the external genitalia

Genicular Anastomosis – important network of ten arterial vessels around the knee, supply joint capsule and adjacent bones

Other Structures

Sacrotuberous and Sacrospinous Ligaments – accessory ligaments of the sacroiliac joint, close the sciatic notches of the hip bone producing the greater and lesser sciatic foramen.

Greater Sciatic Foramen – "doorway to the pelvis", passageway for things leaving the pelvis (e.g. the sciatic nerve)

Lesser Sciatic Foramen – "doorway to the perineum", separated from the greater sciatic foramen by the ischial spine.

Trochanteric Bursa – separates the gluteus maximus from the lateral side of the greater trochanter

Gluteofemoral Bursa – separates the gluteus maximus from the superior part of the proximal attachment of the vastus lateralis

Ischial Bursa – separates the gluteus maximus from the ischial tuberosity, can become inflamed "weaver’s bottom"

Popliteal Fossa – diamond shaped region of the posterior knee between the Semitendinosus and the long head of the Biceps femoris. It contains the sciatic nerve (splitting into the Peroneal and Tibial, as well as their Surals), the popliteal vein, and artery. The inferior margin of the diamond is formed by the lateral and medial heads of the gratrocnemius.

Clinical Significance

Gluteus Medius Limp (Trendelenburg gait) – if the gluteus medius and minimus are paralyzed they can not support the pelvis.

When the foot is raised on the normal side the pelvis falls on that side
Also occurs with unilateral dislocation of the hip
The person walks with their center of gravity over the leg touching the ground

Foot-drop – the loss of eversion and dorsiflexion of the foot causes the foot to hang down; patient lifts the foot high to avoid it dragging on the floor

Due to injury to the common fibular nerve.

Gluteal Intramuscular Injections – a popular area to inject IM medications because of large absorptive area. Injections can be made safely only into the superolateral part of the buttock.

Fractures of Femoral Neck (broken hip) – an injury unique to humans, usually result from indirect violence (tripping over something), usually in older people, women > men

Lateral rotation and shortening of the limb are characteristic.
The more proximal the fracture the greater the risk of interrupting the vascular supply leading to arteriovenous shunt

The Fibular (peroneal) portion of the Sciatic nerve wraps around the head of the fibula and is prone to injury, especially in the case of proximal fractures of the fibula. Injury would result in "foot-drop"