Gluteal Region

Ilium (Part 1): Ala (wing)--

- broad area of thin bone for attachment of limb muscles 1.) gluteal muscles laterally 2.) iliacus muscle medially

Ischial Tuberosities

1. Bony prominences covered by the lower border of the gluteus maximus during extension of the hip (in standing), but is uncovered during flexion so that it bears the weight while in a sitting position. 2. To palpate, sit on your fingertips. 3. Serves as the origin (proximal attachment) of the hamstring muscles.

Posterior Superior Iliac Spine (PSIS)

1. Deep to the visible Venusian dimple above the medial aspect of the buttock. 2. A line joining the diples crosses the 2nd sacral spine, which marks the most inferior extent of the dural and subarachnoid sacs with the contained CSF. 3.This line also crosses the sacro-iliac articulation (SI joint).

The Hip Bone (os coxae)

1. Formed from the fusion of the ilium, ischium and pubis. a. 3 separate bones at birth joined by hyaline cartilage (GA 5.2) b. at puberty, still separated by triradiate cartilage centered in the acetabulum c. fusion begins at 15-17 years; complete by 20-25 years

Gluteal Fold and Sulcus

1. Gluteal fold - formed by the inferior margin of the gluteus maximus muscle. 2. Separates gluteal region from the posterior thigh.

Sciatic Nerve

1. L4-5, S1-S3 2. Passes midway between the ischial tuberosity and greater trochanter.

Greater Trochanter

1. Palpable bony process on the proximal, lateral femur, especially during passive abduction of the hip. The abductor muscles (hip) and iliotibial band cover the greater trochanter - therefore, it cannot be palpated while standing on one leg. 2. Constitutes the commonly described "width of the hips".

Tip of the Coccyx

1. Palpable bony prominence within the intergluteal (natal) cleft. 2. About 3-4 cm posterosuperior to the anus. 3. The 4th sacral spine and sacral cornu define the area of the sacrococcygeal ligament (sacral hiatus).

Posterior Compartment of the Thigh

1. Posterior cutaneous nerve of the thigh (posterior femoral cutaneous nerve) a. S1 and S2 from the anterior primary rami. b. S3 can also contribute via the perineal branch. c. This nerve runs deep to the fascia lata with branches penetrating the superficial fascia.

Iliac Crest

1. The highest level of the iliac crest is at the L4 vertebra. 2. The iliac crest serves as a guide to physicians performing spinal punctures. 3. The L4 vertebral level is also the bifurcation of the abdominal aorta into the common iliac arteries.

Intergluteal (natal) cleft

1. The sulcus between the buttocks. 2. "coin slot"

Gluteal Bursa

1.) deep to the gluteus maximus muscle a.) trochanteric bursa - between the muscle and greater trochanter b.) between the muscle and femur in the area of the lesser trochanter c.) between the muscle and the ischial tuberosity

Glut Max Comments

1.) one of the strongest muscles of the body, particularly well developed in man owing to his upright position 2.) When the IGN is severed and the muscle paralyzed, the patient experiences great difficulty in walking up an incline or standing upright from a sitting position. In addition, the stability of the knee joint and lower limb may be impaired. 3.) When the gluteus maximus is cut and reflected laterally, note the course of the sciatic nerve as it exits the infrapiriform foramen and passes midway between the ischial tuberosity and greater trochanter.

Nerve and Blood Supply to the Gluteal Region

A. Above the piriformis muscle (suprapiriform foramen) 1. superior gluteal artery & vein 2. superior gluteal nerve B. Below the piriformis muscle (infrapiriform foramen) 1. sciatic nerve (i.e., tibial and common fibular n) 2. posterior cutaneous nerve of the thigh 3. inferior gluteal artery & vein 4. inferior gluteal nerve 5. pudendal nerve 6. nerves to obturator internus and quadratus femoris C. The sciatic nerve or part of it may pass thru the piriformis muscle or above the muscle.

Superficial Lymphatic Drainage

A. Skin of buttocks - mainly to horizontal group of superficial inguinal nodes B. Skin over posterior compartment of the thigh - mainly to the vertical group of superficial inguinal nodes

Sacrum

a. 5 fused sacral vertebra b. wedged between 2 hip bones to form the pelvis c. transmits weight of body to these bones at the SI joint d. base articulates with L5 to form the lumbosacral joint (L5-S1)

Median cluneal nerves

a. A series of loops formed between adjacent lateral branches of the lower lumbar posterior rami together with those of the first four sacral nerves. b. Lies immediately posterior to the sacrum and coccyx. c. The medial branches of these posterior rami innervate the erector spinae and transversospinalis muscles. d. These nerves pierce the gluteus maximus muscle and supply the skin of the medial buttock near the intergluteal cleft.

Inferior Cluneal Nerves

a. Arise deep to the gluteus maximus from the posterior cutaneous nerve of the thigh (anterior primary rami, S1-S2). b. Supply the lower portion of the buttock.

Superior cluneal (cluneal = gluteal) nerves

a. Lateral branches of the upper lumbar posterior rami (L1-L3) b. Supply most of the skin of the buttock.

Medial Rotators of the Thigh at the Hip

a. Muscles - Gluteus medius, Gluteus minimus, TFL b. These muscles arise from the ilium anterior to the center of rotation of the hip joint. They pull the greater trochanter anteriorly, medially rotating the thigh when the limb is free (not planted). c. However, when the limb is planted (stance phase) and the opposite limb is free (swing phase) they not only keep the unsupported side of the pelvis level, but advance it, increasing the stride during swing phase.

Gluteus Minimus

a. Origin - anterior and deep to the medius on the ala of the ilium b. Insertion - greater trochanter (upper and anterior surface) in front of gluteus medius c. Innervation - Superior gluteal nerve (L5-S1) d. Action - thigh (hip) ABD and medial rotation

Tensor Fascia Lata

a. Origin - anterior iliac crest, ASIS b. Insertion - iliotibial tract (Gerdy's tubercle and lateral condyle of tibia) c. Innervation - Superior gluteal nerve (L4-5) d. Action - thigh (hip) flexion, hip ABD, medial rotation

Piriformis

a. Origin - anterior surface S2-S4, sacrotuberous ligament b. Insertion - superior border of the greater trochanter of the femur c. Innervation - S1 and S2 nerve roots, nerve to piriformis d. Action - lateral (external) rotation of the thigh (hip), ABD of flexed thigh, steady femoral head in the acetabulum Comments 1.) Originates inside the pelvis and leaves the pelvis through the greater sciatic foramen. 2.) The piriformis divides the greater sciatic foramen into a suprapiriform and infrapiriform foramen.

Gluteus Medius

a. Origin - external surface of ilium between anterior and inferior gluteal lines b. Insertion - lateral surface of greater trochanter of femur c. Innervation - Superior gluteal nerve (L5-S1) d. Action - thigh (hip) ABD and medial rotation; keeps pelvis level when opposite hip is raised

Gluteus Maximus

a. Origin - iliac crest and ilium posterior to posterior gluteal line, posterior sacrum & coccyx, and sacrotuberous ligament b. Insertion - deep fibers (1/4), gluteal tuberosity of the femur; superficial fibers (3/4), indirect attachment to femur (linea aspera) via iliotibial tract and lateral intermuscular septum; attachment of iliotibial tract at Gerdy's tubercle on the lateral condyle of the tibia c. Innervation - Inferior gluteal nerve (L5-S2) d. Action - to bring the thigh from a flexed position into line with the body, i.e., rising from a sitting position; extension of the femur (hip) as in climbing stairs; assist in external rotation

Quadratus Femoris

a. Origin - lateral border of ischial tuberosity b. Insertion - quadrate tubercle on intertrochanteric crest of femur c. Innervation - nerve to quadratus femoris (L5-S1) d. Action - lateral (external) rotation of the hip

Obturator Internus

a. Origin - medial surface of the obturator membrane and surrounding bones (pelvis) b. Insertion - medial surface of greater trochanter c. Innervation - nerve to obturator internus (L5-S1) d. Action - lateral (external) rotation of the hip Comments 1.) Originates inside the pelvis and leaves the pelvis through the lesser sciatic foramen. 2.) The two gemelli join the tendon of the obturator internus to insert via a common tendon on the medial aspect of the greater trochanter = triceps coxae

ABductors

a. The most important function of these muscles is keeping the pelvis level when the opposite (contralateral) foot is taken off the ground. b. These muscles are all innervated by the superior gluteal nerve. c. When a lesion of this nerve results in paralysis of these muscles, the pelvis will tilt downward (fall or sag) to the non-affected, opposite side when that limb is taken off the ground. If uncompensated, the patient will walk with a "dipping gait". This gait defect is a positive Trendelenburg test and may also be seen in other disorders such as congenital hip dislocation. (Fig 5.25) d. Dipping (sagging) of the hip makes the unsupported limb "too long", in effect; it won't clear the ground during swing-through. This is usually compensated for by leaning to the opposite side (opposite the unsupported limb) to "hike" the hip, or by increasing flexion at the hip and knee to "shorten" the free limb (steppage gait).

Femur

a. Upper end 1.) head - ball like, covered with articular cartilage 2.) fovea capitis - depression in the head, ligament of the head of the femur 3.) greater trochanter - upper margin of neck that joins with the shaft 4.) lesser trochanter - lower margin of neck that joins with the shaft 5.) intertrochanteric crest 6.) Intertrochanteric line 7.) gluteal tuberosity b. Shaft or body of the femur 1.) linea aspera - longitudinal ridge, posterior surface; medial lip; lateral lip

Ischium

a. body - helps form the acetabulum and the lateral wall of the pelvic cavity b. ramus - forms posteroinferior margin of obturator foramen c. ischial spine - junction of ramus and body d. ischial tuberosity - posteroinferior margin of ramus e. greater sciatic notch (foramen) f. lesser sciatic notch (foramen)

Pubis

a. forms the anterior or ventral component of the pelvic girdle b. body 1.) pubic crest 2.) pubic tubercle c. ramus 1.) superior - fuses with ilium and ischium to form the acetabulum 2.) inferior - fuses with ramus of ischium

Gamelli

a.Origin 1.) Superior - ischial spine 2.)Inferior - ischial tuberosity b. Insertion - tendon of obturator internus on the medial surface of the greater trochanter c. Innervation 1.) Superior - nerve to obturator internus (L5-S1) 2.) Inferior - nerve to quadratus femoris (L5-S1) d. Action - lateral (external) rotation of the hip

sciatic hernias

also exit via greater and lesser sciatic foramen

sacrospinous ligament

ischial spine to sacrum

sacrotuberous ligament

ischial tuberosity to sacrum

Other functions of the Gluteal Ligaments

ligaments convert notches into greater and lesser sciatic foramen these ligaments also support the SI joint

Ilium (Part 2): Iliac Crest

long curved superior border of ala, running from the anterior superior iliac spine (ASIS) to the posteior superior iliac spine (PSIS) 1.) internal, intermediate and external lips - for attachment of abdominal muscles 2.) ASIS - sartorius 3.) AIIS - rectus femoris 4.) auricular facet - articulates with sacrum 5.) forms a protective wall around the abdominal viscera 6.) provides attachment for thin, sheet or strap like muscles and for fascia 7.) tubercle of the iliac crest - upper attachment of the iliotibial tract (thickening of the fascia lata)

Ilium (Part 3): Body of the Ilium

thickest, most massive part 1.) receives weight of upper body via sacroiliac ligaments at iliac tuberosity 2.) transfers weight of upper body to the head of the femur 3.) body contributes to the acetabulum