UMich Practice Questions- Lower Limbs - Sheet1

Question 1

A patient with a diabetic ulcer in the anterior midline of the ankle region experienced loss of cutaneous sensation on the dorsal surface of the foot. Which nerve was most likely damaged?

Answer 1

The superficial fibular nerve provides cutaneous innervation to the lower anterior third of the leg and the dorsum of the foot. It reaches the dorsum of the foot by crossing over the anterior midline of the ankle region.

Question 2

A saphenous cutdown is a surgical procedure that involves cutting through the skin to locate the greater saphenous vein in order to insert a catheter or cannula. You can find the vein as it passes ___________________ with the saphenous nerve.

Answer 2

Anterior to the medial malleolus

Question 3

A cashier develops painful and tortuous varicose veins in her lower limb. Her doctor explains that prolonged standing at her job led to failure of the valves in the:

Answer 3

Perforating veins. Perforating veins are anastamosing channels that shunt blood from the superficial veins to deep veins. These perforating veins have valves to ensure that blood only flows in the superficial to deep direction.

Question 4

Where does the lesser saphenous vein run?

Answer 4

The lesser or small saphenous vein is a superficial vein that begins as the dorsal venous arch and runs behind the lateral malleolus, up the middle of the back of the leg, and terminates as the popliteal vein in the popliteal fossa.

Question 5

The distal part of the lesser saphenous vein was mobilized for grafting. Following the operation, the patient complained of numbness (loss of cutaneous sensation) on the distal lateral side of the leg and the lateral side of the foot. What nerve was damaged during the operation?

Answer 5

The sural nerve runs with the lesser saphenous vein, posterior to the lateral malleolus and up the back of the leg. It provides cutaneous innervation to the skin of the posterior surface of the lower leg and the skin of the lateral side of the foot.

Question 6

What is the femoral triangle?

Answer 6

The femoral triangle is an area bounded superiorly by the inguinal ligament, laterally by the sartorius, and medially by the medial edge of adductor longus. There are two main things in the femoral triangle: the femoral nerve and the femoral sheath, which encloses the femoral artery, vein, and canal.

Question 7

What is the femoral canal?

Answer 7

In human anatomy of the leg, the femoral sheath has three compartments. The lateral compartment contains the femoral artery, the intermediate compartment contains the femoral vein, and the medial and smallest compartment is called the femoral canal. The femoral canal contains efferent lymphatic vessels and a lymph node embedded in a small amount of areolar tissue.

Question 8

An elderly woman was found to have a hernial sac in the right femoral triangle and a marked weakness in adduction at the right hip joint. Which nerve was likely compressed by this herniation?

Answer 8

Obturator n. The nerve which supplies the adductor compartment is the obturator nerve, so that must be the structure that was injured. Although the obturator nerve is not in the femoral triangle, it enters the thigh by passing through the obturator canal and under pectineus, part of the floor of the femoral triangle.

Question 9

When walking, the action of the iliopsoas muscle results in what motion at the hip joint?

Answer 9

Flexion. The iliopsoas is a combination of the iliacus muscle and the psoas major which inserts on the lesser trochanter of the femur. It is the most powerful hip flexor. Other hip flexors include sartorius, rectus femoris, and pectineus.

Question 10

If the femoral artery is occluded at the beginning of the adductor canal, which artery could help provide viability to the leg through collateral circulation?

Answer 10

The descending branch of the lateral circumflex femoral artery. It anastamoses with both the descending genicular branch of the femoral artery as well as the lateral superior genicular branch of the popliteal artery. These connections provide collateral circulation to the knee and leg.

Question 11

At which site could one expect to enter the femoral vein with a simple percutaneous (through the skin) introduction of an instrument?

Answer 11

Medial to the femoral arterial pulse. From lateral to medial, these are the structures in the femoral triangle: femoral nerve, artery, vein, and canal. The artery, vein, and canal are in the femoral sheath, but the nerve is not! So, the vein would be found medial to the arterial pulse.

Question 12

What anterior thigh muscle must be retracted to expose the adductor canal and its contents?

Answer 12

Sartorius!

Question 13

A serious complication of fractures of the femoral neck is avascular necrosis of the femoral head. This usually results from rupture of which artery?

Answer 13

Medial circumflex femoral a. Remember that the medial circumflex femoral a. supplies blood to the femoral neck. During fractures of the femoral neck, this artery may be ruptured, and the femoral neck will be deprived of blood.

Question 14

A ruptured aneurysm in the most proximal portion of the deep femoral artery would result in a hematoma located initially in the:

Answer 14

Femoral triangle. The deep femoral artery branches from the femoral artery in the femoral triangle. So, if the aneurysm ruptured in the most proximal portion of the deep femoral artery, the hematoma would be in the femoral triangle.

Question 15

Roots of the obturator n.?

Answer 15

L2, L3, L4

Question 16

Roots of the femoral n.?

Answer 16

L2, L3, L4

Question 17

Roots of the common fibular n.?

Answer 17

L4, L5, S1, S2

Question 18

Roots of the tibial n.?

Answer 18

L4, L5, S1, S2, S3

Question 19

Roots of the superior gluteal n.?

Answer 19

L4, L5, S1

Question 20

Roots of the inferior gluteal n.?

Answer 20

L5, S1, S2

Question 21

A patient with a tuberculous abscess (localized collection of pus) on the iliopsoas muscle in the femoral triangle presented impaired flexion of the thigh and extension of the leg. Which of the following nerves was likely involved?

Answer 21

Femoral nerve. The quadriceps muscles, innervated by the femoral nerve, are the most important leg extensors. Rectus femoris, a component of the quads, is also a hip flexor. So, the patient’s deficits, as well as the clinical history of an abscess in the femoral triangle, are consistent with an injury to the femoral nerve

Question 22

An obturator hernia that compresses the obturator nerve in the obturator canal may affect the function of all of the following muscles EXCEPT: adductor brevis, adductor longus, gracilis, obturator externus, pectineus

Answer 22

Pectineus.

Question 23

Childhood immunizations are sometimes given via intramuscular injections into the quadriceps muscles of the anterior thigh. At the mid-thigh level, a needle passing into the space deep to the sartorius muscle might pierce the femoral vessels as they lie in the:

Answer 23

Adductor canal. Sartorius is the roof of the adductor canal. The femoral artery, femoral vein, saphenous nerve, and nerve to vastus medialis are all found in the adductor canal, deep to sartorius.

Question 24

During a surgical procedure in which the lower abdominal wall has been opened, the retractor blades damaged a nerve lying between the iliacus and psoas major muscles. The patient has weakened hip flexion and an inability to extend the knee, as well as analgesia on the anterior thigh and medial leg. What nerve has been compressed?

Answer 24

Femoral n.

Question 25

In the middle third of the thigh, the superficial and deep femoral arteries are separated by

Answer 25

Adductor longus. Since adductor longus is the posterior border of the adductor canal, this explains why the femoral artery is considered part of the adductor canal, while the deep femoral artery is not in the adductor canal. The deep femoral artery runs deep to the adductor canal, but immediately superficial to adductor brevis and magnus.

Question 26

During recovery from a gunshot wound of the right pelvis, the patient notices a lurch in his gait. When he lifts his left foot off of the ground, his pelvis dips down on the left side. The nerve that appears to have been injured is the:

Answer 26

Superior gluteal n.

Question 27

The team doctor tells a football player that he has “a pulled hamstring” muscle. This results from a tearing of the origin of a hamstring muscle from the:

Answer 27

Ischial tuberosity

Question 28

If the head of the femur is dislocated postero-medially, compression of which nerve is likely to result?

Answer 28

Sciatic n.

Question 29

What muscle passes through the lesser sciatic foramen? Gluteus minimus, obturator internus, piriformis, quadratus femoris, superior gemellus

Answer 29

Obturator internus

Question 30

The short head of biceps femoris muscle is innervated by which nerve?

Answer 30

The short head of biceps femoris is innervated by the common fibular nerve; all the other muscles in the hamstring compartment are innervated by the tibial nerve. Both of these nerves are branches of the sciatic nerve.(The femoral nerve innervates muscles of the anterior thigh.)

Question 31

When the femur is fractured, the broken distal end often turns posteriorly to enter the popliteal fossa due to muscle traction. Because of its position deepest in the fossa, which structure is most vulnerable to laceration?

Answer 31

Popliteal a. The popliteal fossa contains the popliteal artery, popliteal vein, common fibular nerve, and tibial nerve. The popliteal artery is the deepest structure in the fossa–it lies on the posterior side of the knee joint. So, it is the structure that would be most likely to be lacerated by the broken distal end of the femur. The popliteal vein lies superficial to the artery, and the tibial nerve lies superficial to the popliteal vein. These three structures are right in the middle of the fossa. The common fibular nerve descends toward the fibular neck, on the lateral side of the popliteal fossa.

Question 32

The deep femoral artery is the principle blood source for the muscles in which compartment of the thigh?

Answer 32

The deep femoral artery supplies the posterior compartment of the thigh with three to four perforating arteries. These arteries pierce adductor magnus and supply blood to the hamstrings–biceps femoris, semitendinosus, and semimembranosus. The anterior compartment of the thigh (the quadriceps) receives blood from the femoral artery. The medial compartment of the thigh receives blood from the obturator artery and medial circumflex femoral artery, as well as the deep femoral. The gluteal region receives blood from the superior and inferior gluteal arteries.

Question 33

When, in approximately 12% of people, the common fibular nerve passes through the piriformis muscle, the nerve may be compressed. This would affect part of which muscle? Adductor magnus, biceps femoris, gluteus maximus, semimembranosus, semitendinosus.

Answer 33

Biceps femoris. Biceps femoris, semimembranosus, and semitendinosus are all part of the hamstrings compartment, which is innervated by the tibial nerve. But, the short head of biceps femoris is the one part of the hamstring compartment that is innervated by the common fibular nerve instead of the tibial nerve.

Question 34

Weakness in climbing stairs or jumping would indicate a lesion in which nerve?

Answer 34

Inferior gluteal n. Since the question specifies that there is a weakness when climbing steps or jumping, you should know that there is a problem with powerfully extending the hip. And that’s what gluteus maximus does. The nerve to gluteus maximus, the inferior gluteal nerve, must be the nerve that was injured.

Question 35

The medial thigh muscles rotate the femur medially, counterbalanced by muscles of the _____________ thigh, including the ___________ muscle, which rotates the femur laterally.

Answer 35

A good way to answer this question is to look for a muscle that is a lateral rotator of the thigh and then make sure that the compartment that it is listed with is correct. Piriformis laterally rotates the thigh; it is a member of the lateral compartment which includes other muscles that laterally rotate the thigh, like obturator internus and the superior and inferior gemellus muscles. So, this is the best answer. Tensor fasciae latae is in the lateral compartment, but it’s a medial rotator of the thigh, so this is not a correct answer. Rectus femoris is one of the quadriceps muscles, found in the anterior compartment of the thigh. This compartment extends the knee and flexes the hip, but these muscles do not rotate the thigh. Biceps femoris is a muscle in the posterior compartment–it’s a hamstring muscle that extends the hip and flexes the knee.

Question 36

Of the branches of the internal iliac artery, the one exiting from the greater sciatic foramen superior to the piriformis muscle is the:

Answer 36

Superior gluteal a.

Question 37

In a hunting accident, an arrow pierces the mid-calf of a hunter. A major artery is lacerated in the posterior leg, and you notice that the sole of his foot is cold and pale. The dorsum of the foot is warm and normally colored. The artery that seems to be injured is the:

Answer 37

The popliteal artery divides into two arteries: the posterior tibial artery and anterior tibial artery. The posterior tibial artery supplies the posterior compartment of the leg with blood. It also passes into the sole of the foot, where it branches to form the medial and lateral plantar arteries. So, the injury to the posterior surface of the leg and the lack of perfusion to the foot all point to an injury to the posterior tibial artery. The fibular artery is a branch of the posterior tibial artery that gets blood to the fibular compartment of the leg. You can tell that this was not the main artery damaged because this artery is not important for perfusing the foot.

Question 38

What is the action of the tibialis anterior tendon?

Answer 38

The tibialis anterior inverts and dorsiflexest the foot.

Question 39

A patient complains of localized pai ni na swollen lower calf and cannot strongly plantar flex his foot. What tendon may have ruptured?

Answer 39

Calcaneal t. Gastrocnemius and soleus insert on the calcaneus via the calcaneal tendon, a tendon of the lower calf which is the thickest and strongest tendon of the body. These muscles are important plantarflexors of the foot, so it is likely that the tendon connected to these muscles has been damaged.

Question 40

A tennis player feels a “pop” in her calf as she is playing. Her calf becomes tender and there is some slight amount of swelling. Upon examination, her physician informs her that she has ruptured the slender tendon of a small muscle that attaches to the calcaneus. She has apparently ruptured the:

Answer 40

Plantaris m. Plantaris is a very small muscle in the posterior compartment of the leg. It has a very long and thin tendon that attaches directly to the calcaneus–it does not insert on the calcaneal tendon along with gastrocnemius and soleus. Plantaris acts to flex the leg and plantarflex the foot, but is is not the major muscle responsible for either of these motions. Like the other muscles of the posterior compartment, it is innervated by the tibial nerve.

Question 41

While on vacation in Florida following her final exams, a scuba diving medical student is accidentally speared by her diving partner. The end of the spear passes medial to lateral, posterior to the medial malleolus. It severs an artery there, which is the:

Answer 41

The posterior tibial artery passes from the posterior compartment of the leg, behind the medial malleolus, before entering the foot. In the foot, it splits to form the medial and lateral plantar arteries. Remember–this is one of the structures that is lined up behind the flexor retinaculum in a very characteristic way. To review, the order here is, from anterior to posterior: tendon of Tibialis posterior, tendon of flexor Digitorum longus, posterior tibial Artery (and vein), tibial Nerve, and tendon of flexor Hallucis longus. So, T, D, A, N, H equals Tom, Dick, ANd Harry.

Question 42

A construction worker lacerates the dorsum of his foot just below his ankle. Profuse bleeding that occurs would result from cutting which vessel?

Answer 42

Dorsalis pedis artery. The dorsalis pedis is an extension of the anterior tibial artery that supplies the dorsal aspect of the foot. (The name change occurs at the level of the ankle, so that’s why this isn’t the anterior tibial artery.) Dorsalis pedis travels on the dorsum of the foot, slightly toward the medial side, and it would be the artery most likely damaged by this injury.

Question 43

Pain may result from friction of the tendon of which muscle that passes deep to the anterior fibers of the long plantar ligament.

Answer 43

Fibularis longus. Remember: fibularis longus runs from the lateral side of the foot across the entire sole of the foot, traveling deep to the long plantar ligament. The friction between these two closely related structures may lead to discomfort. The tendon of tibialis posterior crosses behind the medial malleolus and enters the plantar surface of the foot on the medial side, inserting on navicular, the medial cuneiform, and metatarsals 2-4.

Question 44

In an accident involving farm machinery, a farmer recieves a cut on the dorsum of his ankle. As you inspect the wound and test for functional and sensory deficits, you find that no tendons have been cut, but the dorsalis pedis artery and the accompanying nerve have been cut. You would expect to find: foot drop, inability to extend big toe, numbness between first and second toes, or weakness in foot inversion?

Answer 44

Numbness between the first and second toes. The nerve running with the dorsalis pedis artery is the deep fibular nerve. This nerve innervates the anterior compartment of the leg and the extensors on the dorsum of the foot. At the point where it was cut, the nerve had already given off all its branches to the anterior compartment of the leg. So, the farmer should still be able to dorsiflex his foot (preventing foot drop), and all of the muscles that invert his foot should be intact. Although extensor hallucis brevis (on the dorsum of the foot) has been denervated, extensor hallucis longus is in the anterior compartment of the leg, and that muscle should still be able to extend the great toe.

Question 45

A patient with a fracture to the left upper tibia was treated with a plaster cast. A few days later he started to develop progressive numbness over the dorsum of the foot and weakness in dorsiflexion. The cast was quickly changed and the signs were attributed to nerve compression. The compressed nerve was most likely the:

Answer 45

Common fibular n. The common fibular nerve must have been compressed in the cast. You can figure this out by thinking about the two branches of the common fibular nerve. The first branch is the deep fibular nerve which innervates the anterior compartment of the leg and is responsible for dorsiflexion of the foot. The second branch, the superficial fibular nerve, innervates the lateral (everter) compartment and provides cutaneous innervation to the dorsum of the foot.

Question 46

What action does popliteus m perform?

Answer 46

It flexes and rotates the leg medially so that the knee can unlock.

Question 47

A patient has been diagnosed with bone cancer in the fibula that necessitates its removal. Which of the following muscles would be least affected following removal of the fibula? Biceps femoris, extensor digitorum longus, flexor digitorum longus, flexor hallucis longus, peroneus tertius.

Answer 47

Flexor digitorum longus. Flexor digitorum longus is the most medial muscle in the deep posterior compartment of the leg. This means that it takes origin from the middle half of the posterior surface of the tibia and is not attached to the fibula in any way. Biceps femoris inserts on the head of the fibula and the lateral condyle of the tibia. Extensor digitorum longus is a muscle on the lateral side of the anterior compartment of the leg. This means that it takes origin from the fibula, and would be affected by its removal. Flexor hallucis longus is the most lateral muscle in the posterior compartment, so it originates from the fibula, too. Finally, fibularis (peroneus) longus and brevis, the two muscles of the lateral compartment, both take origin from the fibula.

Question 48

THE LATERAL OR EXTERNAL ROTATION OF THE THIGH AT THE HIP IN THIS PATIENT IS CAUSED BY ALL OF THE FOLLOWING MUSCLES EXCEPT: Pectineus, Gluteus maximus, Piriformis, Obturator internus, Quadratus femoris

Answer 48

Pectineus

Question 49

Which of the following muscles IS NOT important in making a fist for a power grip? Adductor pollicis, dorsal interossei, extensor digitorum, flexor digitorum profundus

Answer 49

Dorsal interossei