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THE GLUTEAL REGION

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• It lies posterior to the pelvis between the level of the iliac crest and inferior border of gluteus maximus muscle.

• This region is made up of the gluteal muscles, ligaments, vessels (arteries & veins) and gluteal nerves.

• The two buttocks formed mostly by the three most prominent gluteal muscles are separated from each other by the intergluteal cleft.

• The inferior border is demarcated from the superior border of the thigh by the gluteal sulcus

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The buttock

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Gluteal ligaments• Two main ligaments make up the ligament

components of the gluteal region and they include;

• Sacrotuberous and sacrospinous ligaments.• These two ligaments converts the sciatic notch

of the hip bone into a greater and lesser sciatic foramina.

• The greater sciatic foramen forms a passageway through which structures entering and leaving the pelvis passes e.g. sciatic nerve.

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• The lesser foramen serves as a passageway for structures entering and leaving the perineum. E.g. pudendal nerve.

• It is therefore worthy of note that the greater sciatic foramen can be likened to a ‘door’ through which all arteries and nerves leave the pelvis to enter the gluteal region, including the piriformis muscle which almost fill the foramen.

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Gluteal muscles

• Muscles of the gluteal region are mainly in two groups:

• a deep group of small muscles, which are mainly lateral rotators of the femur at the hip joint and include;

• piriformis, obturator internus, gemellus superior, gemellus inferior, and quadratus femoris.

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• A more superficial group of larger muscles, which mainly abduct and extend the hip and include;

• The gluteus minimus, gluteus medius, and gluteus maximus-an additional muscle in this group, the tensor fasciae latae.

• The tensor fasciae latae stabilizes the knee in extension by acting on a specialized longitudinal band of deep fascia (the iliotibial tract) that passes down the lateral side of the thigh to attach to the proximal end of the tibia in the leg.

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Superficial group

• Gluteus maximus;• Is the largest muscle in the gluteal region and

overlies most of the other gluteal muscles except for the posterior 3rd of the gluteus medius and also forms a pad over the ischial tuberosity.

• origin/proximal attachment- ilium,posterior to the posterior gluteal line, posterior surface of the sacrum, coccyx and sacrotuberous ligament.

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• Insertion/distal attachment- iliotibial tract and gluteal tuberosity.

• Innervation- innervation is by the inferior gluteal nerve with root values L5, S1-2.

• Action- main action is extension and lateral rotation of the thigh.

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• Gluteus medius and minimus ;• These are fan-shaped small gluteal muscles

and their fibres passes the same direction.• Origin- medius originates from the external

surface of the ilium between the anterior and posterior gluteal line, while the minimus originates from the external surface of the ilium between the anterior and inferior gluteal line.

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• Insertion- medius inserts on the lateral surface of greater trochanter while minimus inserts on anterior surface of greater trochanter of femur.

• innervation- both by the superior gluteal nerve with root values L5 & S1.

• Action- both medially rotates and abducts the lower limb at the hip joint.

• Also keeps the pelvis at level when opposite leg is raised.

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Actions of the G. medius & minimus

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• Tensor fasciae latae;• The tensor fasciae latae muscle is the most

anterior of the superficial group of muscles in the gluteal region and overlies the gluteus minimus and the anterior part of the gluteus medius.

• Origin- Tensor fasciae latae originates from the outer margin of the iliac crest from the anterior superior iliac spine to approximately the tubercle of the crest.

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• Insertion- anterior aspect of the iliotibial tract of deep fascia, which runs down the lateral side of the thigh.

• Action- Stabilizes the knee in extension.• Working with the gluteus maximus muscle on

the iliotibial tract lateral to the greater trochanter, Stabilizes the hip joint by holding the head of the femur in the acetabulum.

• Innervation- superior gluteal nerve with root value L5 & S1.

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Deep group of gluteal muscles

• Piriformis;• A narrow pear-shaped muscle is the most

superior of the deep group of gluteal muscles. • It is a muscle of the pelvic wall and of the

gluteal region.• Origin- from the superior surface of the

sacrum and the sacrotuberous ligaments.

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• Insertion- superior surface of the greater trochanter of femur.

• Innervation- innervation is by the nerve to piriformis which are branches from ventra rami of S1 & S2.

• Action- acts as a stabilizer of the head of the femur in the acetabulum and also extends rotated thigh laterally and abducts flexed thigh.

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Piriformis (A)

A

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• Obturator internus, gamelli superior & inferior;

• These three fan-shaped muscles form a tricipital (3 heads).

• Often called triceps coxae.• They occupy the space between the piriformis

and the quadratus femoris muscle.

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• Obturator internus; • Origin- pelvic surface of obturator

membrane and surrounding bone.• Insertion- medial border of greater

trochanter of femur.• Innervation- nerve to obturator internus

with root value L5-S2.• Action- same as piriformis muscle.

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Obturator internus (B)

B

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• Gemellus superior and inferior;• (gemelli is Latin for twins) are a pair of

triangular muscles associated with the upper and lower margins of the obturator internus tendon.

• Origin- superior is from ischial spine, Infererior is from ischial tuberosity.

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• Insertion- its tendons blends with that of the obturator internus and inserts on the medial side of the greater trochanter of femur.

• Innervation- superior gamelli is by nerve to obturator while inferior gamelliis by nerve to quadratus femoris.

• Action- same as obturator internus and piriformis

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Superior & inferior Gamelli (C)

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• Quadratus femoris; • The most inferior of the deep group of muscles in the

gluteal region. • It is a flat rectangular muscle below the obturator

internus muscle and its associated gemellus muscles.• Origin- lateral border of ischial tuberosity• Insertion- the quadrate tubercle on the

intertrochanteric crest of the proximal femur.• Innervation- nerve to quadratus femoris.• Action- laterally rotates the femur at the hip joint and

also assist in steadying the head of the femur in the acetabulum.

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Quadratus femoris (D)

D

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GLUTEAL NERVES

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• Several important nerves arise from the sacral plexus and either supply the gluteal region or pass through it to supply the perineum and thigh.

• Many of the nerves in the gluteal region are in the plane between the superficial and deep groups of muscles.

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Superficial Gluteal Nerves

• The skin of the gluteal region is richly innervated by the clunial nerves (superior,middle and inferior).

• These nerves supply the skin over the iliac crest, between the posterior superior iliac spines, and over the iliac tubercles.

• Consequently, these nerves are vulnerable to injury when bone is taken from the ilium for grafting.

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• The superior clunial nerves are lateral cutaneous branches of the dorsal rami of L1- L3 nerves.

• They supply the skin of the gluteal region as far as the greater trochanter.

• The middle clunial nerves also lateral branches of the dorsal rami of S1 -S3 nerves,

• Supplies the skin and subcutaneous tissue over the sacrum and adjacent area of the buttock.

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• The inferior clunial nerves are gluteal branches of the posterior cutaneous nerve of the thigh, a derivative of the sacral plexus (ventral rami S1-S3).

• These nerves curl around the inferior border of the gluteus maximus.

• Supplies the inferior half of the buttock.

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• The perforating cutaneous nerve (S2 and S3) passes through the sacrotuberous ligament and the inferior part of the gluteus maximus.

• Supplies the skin over the inferior half of the buttock and the medial part of the gluteal fold.

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Deep Gluteal Nerves

• Seven deep gluteal nerves enter the gluteal region from the pelvis through the greater sciatic foramen:

• The superior gluteal nerve, sciatic nerve, nerve to the quadratus femoris, nerve to the obturator internus, posterior cutaneous nerve of the thigh, pudendal nerve, and inferior gluteal nerve.

• An additional nerve, the perforating cutaneous nerve, enters the gluteal region by passing directly through the sacrotuberous ligament

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• Superior gluteal nerve ;• The only gluteal nerve that passes superior to

the piriformis muscle.• It loops up over the inferior margin of gluteus

minimus and travels anteriorly and laterally in the plane between the gluteus minimus and medius muscles.

• Innervates G. minimus, medius and tensor fascia latae.

DIAGRAM OF GLUTEAL NERVE

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• Sciatic nerve;• The sciatic nerve enters the gluteal region through

the greater sciatic foramen inferior to the piriformis muscle.

• It descends in the plane between the superficial and deep group of gluteal region muscles.

• It lies just deep to the gluteus maximus at the midpoint between the ischial tuberosity and the greater trochanter.

• At the lower margin of the quadratus femoris muscle, the sciatic nerve enters the posterior thigh.

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• The sciatic nerve is the largest nerve in the body and innervates all muscles in the posterior compartment of the thigh.

• All muscles that flex the knee.• All muscles that work the ankle and foot. • It also innervates a large area of skin in the

lower limb.

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• Nerve to quadratus femoris;• Enters the gluteal region through the greater

sciatic foramen inferior to the piriformis muscle and deep to sciatic nerve.

• It descends along the ischium deep to the tendon of obturator internus and gamellus muscle.

• Supplies quadratus femoris and a small branch to gamellus inferior.

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• Nerve to obturator internus; • This nerve enters the gluteal region through

the greater sciatic foramen inferior to the piriformis muscle and between the posterior cutaneous nerve of the thigh and the pudendal nerve.

• It supplies a small branch to the gemellus superior and then passes over the ischial spine and through the lesser sciatic foramen to innervate the obturator internus muscle.

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• Pudendal nerve Body;• Lies medial to the sciatic nerve. • It passes over the sacrospinous ligament and

immediately passes through the lesser sciatic foramen to enter the perineum.

• The nerve is often hidden by the overlying upper margin of the sacrotuberous ligament.

• The pudendal nerve is the major somatic nerve of the perineum and has no branches in the gluteal region.

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• Inferior gluteal nerve; • Passes along the posterior surface of the

sciatic nerve. • It penetrates and supplies the gluteus

maximus muscle.

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• Posterior cutaneous nerve of the thigh; • It descends through the gluteal region just deep to

the gluteus maximus and enters the posterior thigh. • It has a number of gluteal branches, which loop

around the lower margin of the gluteus maximus muscle to innervate skin over the gluteal fold.

• A small perineal branch passes medially to contribute to the innervation of skin of the scrotum or labia majora in the perineum.

• The main trunk of the posterior cutaneous nerve of the thigh passes inferiorly, giving rise to branches that innervate skin on the posterior thigh and leg.

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Intramuscular injections• From time to time it is necessary to administer

drugs intramuscularly: that is, by direct injection into muscles.

• This procedure must be carried out without injuring neurovascular structures.

• A typical site for an intramuscular injection is the gluteal region.

• The sciatic nerve passes through this region and needs to be avoided.

• The safest place to inject is the upper outer quadrant of either gluteal region.

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• It is important to remember that the gluteal region extends as far forward as the anterior superior iliac spine.

• The sciatic nerve curves through the upper lateral corner of the lower medial quadrant and descends along the medial margin of the lower lateral quadrant.

• Occasionally, the sciatic nerve bifurcates into its tibial and common fibular branches in the pelvis, in which case the common fibular nerve passes into the gluteal region through, or even above, the piriformis muscle.

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• The superior gluteal nerve and vessels normally enter the gluteal region above the piriformis and pass superiorly and forward.

• The anterior corner of the upper lateral quadrant is normally used for injections to avoid injuring any part of the sciatic nerve or other nerves and vessels in the gluteal region.

• A needle placed in this region enters the gluteus medius anterosuperior to the margin of the gluteus maximus.

QUADRANT FOR INTERMUSCULAR INJECTION

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GLUTEAL ARTERIES

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• Two arteries enter the gluteal region from the pelvic cavity through the greater sciatic foramen, the inferior gluteal artery and the superior gluteal artery.

• They supply structures in the gluteal region and posterior thigh and have important collateral anastomoses with branches of the femoral artery.

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• Superior gluteal artery; • Originates from the posterior trunk of the internal iliac artery in

the pelvic cavity. • It leaves the pelvic cavity with the superior gluteal nerve through

the greater sciatic foramen above the piriformis muscle.• In the gluteal region, it divides into a superficial branch and a

deep branch: the superficial branch passes onto the deep surface of the gluteus maximus muscle;

• the deep branch passes between the gluteus medius and minimus muscles.

• In addition to adjacent muscles, the superior gluteal artery contributes to the supply of the hip joint.

• Branches of the artery also anastomose with the lateral and medial femoral circumflex arteries from the deep femoral artery in the thigh, and with the inferior gluteal artery.

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• Inferior gluteal artery; • Oiginates from the anterior trunk of the internal

iliac artery in the pelvic cavity. It leaves the pelvic cavity with the inferior gluteal nerve through the greater sciatic foramen inferior to the piriformis muscle.

• The inferior gluteal artery supplies adjacent muscles and descends through the gluteal region and into the posterior thigh where it supplies adjacent structures and anastomoses with perforating branches of the femoral artery.

• It also supplies a branch to the sciatic nerve.

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HAPPY BIRTHDAY

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GOODMORNING