Lab 5—Gluteal and Posterior Thigh 1 1. Abduction of the Hip Joint Is

Lab 5—Gluteal and Posterior Thigh Muscles; Tendons — Questions 1 of 1

1. Abduction of the hip joint is performed with the aid of: 5. An elderly woman fell at home and fractured the great- A. The iliopsoas, rectus femoris, and sartorius, along with er trochanter of her femur. Which of the following muscles adductor muscles would continue to function normally? B. Gluteus maximus and the hamstring muscles A. Piriformis C. Gluteus medius and minimus, assisted by the sartori- B. Obturator internus us, tensor fasciae latae, and piriformis C. Gluteus medius D. Adductor longus and brevis and the adductor fibers of D. Gluteus maximus the adductor magnus; assisted by the pectineus and the E. Gluteus minimus gracilis E. Piriformis, obturator internus and externus, superior and inferior gemelli, and quadratus femoris, assisted by the gluteus maximus

2. The Piriformis muscle is primarily involved in 6. A 49-year-old Vietnamese man is diagnosed with tu- A. External rotation of the hip joint berculosis. On physical examination, large flocculent B. Abduction of the hip joint masses are noted over the lateral lumbar back, and a C. Hip adduction and knee flexion similar mass is located in the ipsilateral groin. This pattern D. Internal rotation of the hip joint of involvement strongly suggests an abscess tracking E. Thigh extension and knee flexion along which of the following muscles? A. Adductor longus B. Gluteus maximus C. Gluteus minimus D. Piriformis E. Psoas major

3. A 24-year-old woman complains of weakness when 7. An 8-year-old boy returns to your pediatric clinic be- she extends her thigh and rotates it laterally. Which of the cause he has a “pain in his butt” and walks with a limp. following muscles is paralyzed? He had just been at your office a couple of days ago for a A. Obturator externus normal summer check up and an update on his vaccina- B. Sartorius tions. When you ask him how this happened the boy said C. Tensor fasciae latae that the pain all started when your nurse gave him his D. Gluteus maximus booster shot in his left buttock. You have him demon- E. Semitendinosus strate his walk and you notice that he drops his right hip as he places all the weight on his left leg and swings his right leg forward. You place him prone on the examination table and test the strength of his ability to extend each thigh at the hip and flex his leg at the knee. Both legs flex normally with equal strength, and he can extend his thigh at the hip well, but you notice some falsity of his muscles just under the iliac crest on the left side only. You tell the boy and his mother that the booster shot he got a couple 4. A 67-year-old patient has been given a course of antibi- of days ago likely damaged which of the following? otics by gluteal intramuscular injections after a major ab- A. Lateral cutaneous nerve of the thigh giving him his pain dominal surgery. To avoid damaging the sciatic nerve B. Superior gluteal nerve partially paralyzing his gluteus during an injection, the needle should be inserted into medius muscle which of the following areas? C. Superior gluteal nerve partially paralyzing his gluteus A. Over the sacrospinous ligament maximus muscle B. Midway between the ischial tuberosity and the lesser D. Inferior gluteal nerve partially paralyzing his gluteus trochanter medius muscle C. Midpoint of the gemelli muscles E. Sciatic nerve partially paralyzing his hamstring muscles D. Upper lateral quadrant of the gluteal region E. Lower medial quadrant of the gluteal region

1 Lab 5—Gluteal and Posterior Thigh Muscles; Tendons — Answers

1. Answer C. (2) Abduction of the hip joint is per- 5. Answer D. (1) The gluteus maximus is inserted into formed with the aid of gluteus medius and minimus, as- the gluteal tuberosity of the femur and the liotibial tract. All sisted by the sartorius, tensor fasciae latae, and piriform- of the other muscles insert on the greater trochanter of is. Flexion is performed by the iliopsoas, rectus femoris, the femur, and their functions are impaired. and sartorius, along with adductor muscles, extension by gluteus maximus and the hamstring muscles, adduction by adductor longus and brevis and the adductor fibers of the adductor magnus; assisted by the pectineus and the gracilis, and lateral rotation by piriformis, obturator internus and externus, superior and inferior gemelli, and quadratus femoris, assisted by the gluteus maximus.

2. Answer A. (2) External rotation of the hip joint is 6. Answer E. (4) This is the classic presentation of a the primary action of the Piriformis muscle. The Piriformis psoas abscess. This clinical entity was formerly a fairly muscle is one of the deep muscles of the gluteal area of common complication of vertebral tuberculosis, but is now the lower limb. It is flat, pyramidal in shape, and lies al- rare in clinical practice in this country. The psoas muscle most parallel to the posterior margin of the gluteus medi- is covered by a fibrous sheath known as the psoas fascia. us. It is located partly within the pelvis (against the poste- This sheath is open superiorly, permitting an infection in- rior wall) and partly at the back of the hip joint. The origin volving the soft tissues around the spine to enter the of the muscle is by 3 fleshy digitations from the anterior sheath, then track down to the groin. The adductor longus surface of the sacrum (S2-S4). A few fibers arise from the (choice A) is a muscle of the medial thigh and is not relat- margin of the greater sciatic foramen and anterior part of ed to the lumbar portion of the back. The gluteus maxi- the sacrotuberous ligament. It exits the pelvis through the mus (choice B), gluteus minimus (choice C), and piriform- greater sciatic foramen and is inserted on the upper pos- is (choice D) are muscles of the buttock with no relation- terior border of the greater trochanter of the femur. Inner- ship to the groin. vation is by branches from the ventral rami of S1 and S2.

3. Answer D. (1) The gluteus maximus can extend and 7. Answer B. (7) The boy has lost partial function of rotate the thigh laterally. The obturator externus rotates the gluteus medius muscle causing hip drop on the oppo- the thigh laterally. The sartorius can flex both the hip and site side, which is called a “positive Trendelenburg sign.” knee joints. The tensor fasciae latae can flex and medially The gluteus medius (thus not answer c) is innervated by rotate the thigh. The semitendinosus can extend the thigh the superior gluteal nerve. The nurse who performed the and medially rotate the leg. injections likely injected too far medial within the buttock. Normally all injections should be performed in the upper lateral quadrant of the buttock, to stay away from the sciatic nerve and superior and inferior gluteal nerves that exit the pelvis through the greater sciatic notch. The lateral cutaneous nerve of the thigh (answer a) would pro- vide general sensation to the anterior region of the thigh. The superior clunial nerves supple the skin over the gluteus maximus and medius muscles. The inferior gluteal nerve (answer d) innervates the gluteus maximus muscle. The sciatic nerve (answer e) is not damaged because the 4. Answer D. (1) To avoid damaging the sciatic nerve pain does not extend down the back of the boy’s leg and during an intramuscular injection, the clinician should in- he has normal function of his hamstring muscles, which sert the needle in the upper lateral quadrant of the gluteal flex the leg at the knee. region. The inserted needle in the lower medial quadrant may damage the pudendal and sciatic nerves. The inserted needle midway between the ischial tuberosity and the lesser trochanter may damage the sciatic and posterior femoral cutaneous nerves on the quadratus femoris. The inserted needle over the sacrospinous ligament may damage the pudendal nerve and vessels.

2 Lab 5—Gluteal and Posterior Thigh Nerves—Questions 1 of 1

1. The gluteus maximus is innervated by the: 5. An active mountain climber develops pain in the but- A. Obturator nerve tock and tingling and numbness in the lower limb as a B. Femoral nerve result of hypertrophy of the piriformis muscle. Which re- C. Tibial branch of the sciatic nerve gion of the lower limb is most likely to be a site of the al- D. Inferior gluteal nerve tered sensation? E. Superior gluteal nerve A. Posterior thigh B. Lateral leg C. Medial thigh D. Sole of the foot E. Gluteal region

2. The gluteus medius and minimus are innervated by the 6. A 34-year-old woman is brought into the emergency A. Obturator nerve room following her car accident in which she hit a patch of B. Femoral nerve ice and slammed into the back of a trash truck. She can’t C. Tibial branch of the sciatic nerve walk because she has incredible pain in her left knee and D. Inferior gluteal nerve hip. She thinks her knee hit the left side of the dashboard E. Superior gluteal nerve as she twisted under the seat belt as she was thrown forward. She reports severe pain as you move her hip. You order a plain film of the leg up to the pelvis and it shows no broken bones but posterior displacement of the head of the femur out of the acetabulum. You tell her the good news is that she has not broken any bones, but that she has dislocated her hip. She is sedated in order to forceful- ly relocate her femoral head back into the acetabulum. Despite successful relocation you are concerned that she has damaged which of the following nerves, which may take several months to regain function? 3. During an interview, a 34-year-old psychiatric patient sud- denly becomes aggressive. The patient is quickly taken to A. Obturator a quiet, private room and given an intramuscular injection B. Pudendal of haloperidol in the upper outer quadrant of the buttock. C. Sciatic The injection is given at this specific location to prevent D. Femoral damage to which of the following nerves? E. Superior gluteal A. Common peroneal B. Lateral femoral cutaneous C. Obturator D. Sciatic E. Superior gluteal

4. A 31-year-old male female presents to you with difficul- ty in walking and climbing stairs for the last 3 weeks. Physical examination reveals a waddling gait, with her trunk swaying from side to side towards the weight bear- ing limb. When she stands on her right leg, the pelvis on the left side falls; but when she stands on the left leg, the pelvis on the right side rises. Which of the following nerves is injured?

A. Right superior gluteal nerve B. Left femoral nerve C. Right obturator nerve D. Right femoral nerve E. Right inferior gluteal nerve

3 Lab 5—Gluteal and Posterior Thigh Nerves—Answers

1. Answer D (2) The obturator innervates mostly the 5. Answer B. (6) Active athletes who use their gluteal adductor muscles. The inferior gluteal nerve innervates muscles extensively may present with hypertrophy of the the gluteus maximus while the superior branch innervates piriformis muscle. In some individuals, the common pero- the gluteus minimus and medius. The tibial branch of the neal component of the sciatic nerve courses through this sciatic innervates muscles of the lower leg. The femoral muscle rather than emerging inferior to it. The hypertro- nerve innervates the quadriceps femoris and sartorius phy compresses the nerve, leading to the altered sensa- muscles. tion in the area of distribution of the superficial peroneal nerve.

2. Answer E. (2) The obturator innervates mostly the 6. Answer C. (7) About 85% of hip dislocations occur adductor muscles. The inferior gluteal nerve innervates in a posterior direction as the head of the femur slips out the gluteus maximus while the superior branch innervates of the acetabulum. This stretches the ischiofemoral liga- the gluteus minimus and medius. The tibial branch of the ment, which makes up the posterior aspect of the joint sciatic innervates muscles of the lower leg. The femoral capsule. Posterior displacement is also the typical direc- nerve innervates the quadriceps femoris and sartorius tion of force resulting from the striking of one’s knee on muscles. the dashboard in a head-on car accident. Anterior hip displacement is unusual since the very strong iliofemoral ligament stabilizes the joint anteriorly and also limits hip extension. The sciatic nerve passes just posterior to the hip joint and may be damaged when the hip is displaced posteriorly, thus compromising innervation to the hamstring and posterior compartment of the leg. The superior gluteal nerve (answer e) exits the greater sciatic notch, but is generally cranial to a posteriorly displaced head of the femur and is mobile enough that it is unlikely to be 3. Answer D. (4) Injections are given in the upper, out- damaged. Therefore this is the second best answer. er quadrant of the buttocks to prevent damage to the sciatic nerve, which is present in the lower quadrant. The other nerves listed arc not particularly vulnerable to injections into the buttocks.

4. Answer A. (13) Patient is having paralysis of gluteal medius (and minimus) muscles, characterized by the waddling gait. They are supplied by superior gluteal nerve. The Trendelenburg’s test is positive when the patient stands on one leg and the pelvis on the opposite side falls due to the paralysis of hip abductors. Normally, the opposite side rises to maintain the center of gravity. In the clinical vignette, the patient’s pelvis falls on the “left” side, therefore the “right” superior gluteal nerve is injured. While pelvis on the right side rises, therefore left superior gluteal nerve is normal. Gluteus medius originates from the ilium bone between middle and posterior gluteal lines. It is inserted into the greater trochanter. Gluteus medius is a powerful abductor of thigh along with gluteus minimus and tensor fasciae latae; all three muscles are innervated by superior gluteal nerve. Learning Objective: The Trendelenburg’s test is positive when the patient stands on one leg and the pelvis on the opposite side falls due to the paralysis of hip abductors. Normally, the opposite side rises to maintain the center of gravity

4 Lab 5—Gluteal and Posterior Thigh Vessels—Questions 1 of 1

1. A 75-year-old woman slips on the kitchen floor and falls. She complains of pain in her left hip and cannot stand up. She is taken to the hospital, and it is recommended that she have a total hip replacement involving removal of the femoral head and replacing it with a prosthesis. The surgeon indi- cates that this procedure is necessary because of interrup- tion of the predominant blood supply to the head of the femur. Which blood vessel gives rise to a branch that is the major source of arterial blood supply to the head and neck of the femur? A. Superior gluteal artery B. Obturator artery C. Profunda femoral artery D. Inferior gluteal artery E. Femoral artery

5 Lab 5—Gluteal and Posterior Thigh Vessels—Answers

1. Answer C. (6) The medial circumflex artery pro- vides most of the blood supply to the head and neck of the femur and is typically a direct branch of the profunda femoral artery.