2 - Gluteal Region

Question 1

What vertebrae does the top of the iliac crest correspond with? What is this landmark for?

Answer 1

Between L4 and L5.

Landmark for lumbar puncture.

Question 2

What movements can be made by the muscles in the gluteal region?

Answer 2

Leg extension, abduction, and lateral rotation.

Question 3

What muscle is the prime hip extensor? What innervates this muscle?

Answer 3

Gluteus maximus.

Innervated by the inferior gluteal nerve (L5, S1, S2).

Question 4

How would you test that a patient’s gluteus maximus was working.

Answer 4

Have them lie prone (face down), flex at the knee to relax the hamstrings, and then raise their thigh from the table.

This is hip extension, and gluteus maximus is the main hip extensor.

Question 5

What are the hamstring muscles and what innervates each?

Answer 5

Biceps femoris laterally: innervated by the tibial portion of the sciatic nerve (S1)

Semitendinosis and semimembranosis medically: innervated by the tibial portion of the sciatic nerve (L5, S1)

Question 6

What makes something a hamstring?

What actions do the hamstrings do?

Answer 6

Origin on the ischium.

Leg extension.

Question 7

How would you test that a patient’s hamstrings are working?

Answer 7

Have them lie supine and flex the knee against resistance.

Question 8

What are the two gluteal muscles responsible for abduction? Which is the primary abductor? What is each muscle innervated by?

Answer 8

Gluteus medius: Primary abductor, responsible for pelvic tilt - innervated by superior gluteal nerve (L5).

Gluteus minimus: (deep to medius) also medially rotates the thigh - innervated by superior gluteal nerve.

Question 9

What can weakness of the gluteus medius cause?

Answer 9

Trendelenberg gait or gluteus medias lurch.

Question 10

What four muscles are responsible for lateral rotation?

Answer 10

1. Piriformis
2. Obturator internus
3. Gemelli
4. Quadratus femoris

Question 11

What is the specific action of the piriformis muscle? What innervates it?

Answer 11

Lateral rotation and abduction of flexed thigh.

Innervated by branches of rami from S1 and S2.

Question 12

What is a landmark for the piriformis muscle? What is another important piece of information regarding structures in this region?

Answer 12

Sciatic nerve passes between the piriformis and the superior gamellus.

Nerves and vessels near here are named according to their position superior or inferior to the piriformis.

Question 13

What is the specific action of the obturator internus muscle? What is it innervated by?

Answer 13

Laterally rotates extended thigh and abducts flexed thigh.

Innervated by the obturator internus (L5, S1, and S2).

Question 14

What is the specific action of the gemelli? What is each innervated by?

Answer 14

Laterally rotate the thigh when extended and abduct flexed thigh.

Innervation of superior gemellus: nerve to obturator internus

Innervation of inferior gemellus: nerve to quadratus femoris.

Question 15

What innervates the quadratus femoris?

Answer 15

The nerve to quadratus femoris (L5 and S1).

Question 16

What nerves supply cutaneous innervation to the gluteal region?

Answer 16

Superior cluneal nerves innervate superior 2/3 of buttock.

Middle cluneal nerves innervate area over sacrum surrounding buttock.

Inferior cluneal nerves innervate inferior 1/3 of buttock.

Question 17

Where do the deep gluteal nerves originate?

Answer 17

They are branches of the sacral plexus that leave the pelvis through the greater sciatic foramen.

All are inferior to the piriformis except the superior gluteal nerve.

Question 18

Describe the origin, location, and innervation of the superior gluteal nerve?

Answer 18

Arises from posterior division of ventral rami of L4, L5, and S1.

Superior to piriformis and travels with the superior gluteal artery.

Supplies gluteus medius and minimus and tensor fascia lata.

Question 19

Describe the origin, location, and innervation of the inferior gluteal nerve?

Answer 19

Arises from posterior division of ventral rami of L5, S1, and S2.

Inferior to piriformis, superficial to sciatic nerve. Travels with inferior gluteal artery.

Supplies gluteus maximus.

Question 20

Describe the origin, location, and innervation of the sciatic nerve?

Answer 20

Main branch of sacral plexus from ventral rami of L4, L5, S1-3 that come together at the inferior border of piriformis.

Does not supply any structures in the gluteal region.

Splits into Tibial nerve and Peroneal (common fibular) nerve.

Question 21

What is the origin of the tibial nerve? Where does it split from?

Answer 21

L4, L5, S1-3.

Splits from sciatic nerve in the thigh.

Question 22

What is the origin of the common fibular nerve? Where does it split from?

Answer 22

L4, L5, S1, S2.

Splits from sciatic nerve in the thigh.

Question 23

What is the origin, path, and innervation of the posterior femoral cutaneous nerve?

Answer 23

Supplies more skin than any other cutaneous nerve.

Ventral rami or S1 and S2 (posterior division) and anterior division of S2 and S3.

Leaves pelvis with inferior gluteal nerve and sciatic nerve at lower border of piriformis.

Question 24

What is the origin, path, and innervation of the nerve to quadratus femoris?

Answer 24

Ventral rami (anterior division) of L4, L5, S1.

Leaves pelvis deep to sciatic nerve and obturator internus muscle.

Innervates quadratus femoris and inferior gamellus muscles.

Question 25

What is the origin, path, and innervation of the nerve to obturator internus?

Answer 25

Anterior division of ventral rami L5, S1, and S2.

Medial to sciatic nerve.

Supplies superior gamellus muscle and passes posterior to the ischial spine to reenter the pelvis through the lesser sciatic foramen to supply the obturator internus.

Question 26

What is the origin, path, and innervation of the pudendal nerve?

Answer 26

Anterior division of ventral rami S2-4.

Most medial.

Passes lateral to sacrospinous ligament, reenters pelvis through the lesser sciatic foramen to supply structures in the perineum.

Question 27

What are the main arteries of the gluteal region? Where do they originate?

Answer 27

All branches of the internal iliac artery.

Superior gluteal artery (largest branch), inferior gluteal artery, and internal pudendal artery.

Question 28

What is the location of the superior gluteal artery and what do its branches supply? What does it anastomose with?

Answer 28

Superior to piriformis.

Superficial branch to gluteus maximus and skin, deep branches to gluteus medius, minimus, and tensor fascia lata.

Anastomoses with inferior gluteal artery and medial circumflex femoral artery.

Question 29

What is the location of the inferior gluteal artery? What does it supply and what does it anastomose with?

Answer 29

It’s inferior to the piriformis.

Supplies gluteus maximus, obturator internus, quadratus femoris, and superior hamstrings.

Anastomoses with superior gluteal artery, medial and lateral femoral circumflex arteries, and perforating arteries of profunda femoris.

Question 30

What is the location of the internal pudendal artery? What does it supply?

Answer 30

Lies anterior to the inferior gluteal artery, passes lateral to the pudendal nerve and reenters pelvis with it through the lesser sciatic foramen.

Supplies external genitalia and muscle in the pelvis region.

Question 31

What are the main veins in the gluteal region?

Answer 31

The gluteal veins: tributaries of the internal iliac veins and communicate with tributaries of the femoral vein

Internal pudendal veins: form a single vein which drains from the external genitalia and perineum.