Lower limb I

Question 1

Sciatic nerve transection

Answer 1

Hip abduction is normal-The saphenous branch of the femoral nerve – the longest cutaneous nerve in the body – is intact, so there is retention of normal sensation along the medial side of the anterior aspect of the leg down to the base of the hallux. Peripheral nerve injuries result in flaccid paralysis, with loss of stretch reflexes of the paralysed muscles. The foot is plantar flexed due to gravity, (foot drop). However, it is not everted (eversion is produced by the peroneus longus and brevis, which are paralysed), nor is it inverted, a function of the paralysed long flexors of the foot. The quadriceps is innervated by the intact femoral nerve, and hip abduction, effected by the gluteus medius and minimus, supplied by the intact superior gluteal nerve, is unaffected.

Question 2

Femoral artery anatomy

Answer 2

The common femoral artery lies on the lateral side of the vein and divides 3 cm distal to the inguinal ligament. The superficial femoral artery becomes the popliteal by passing through the hiatus in the adductor magnus. The posterior tibial pulse is sought behind the medial malleolus.

Question 3

l3-5 nerve roots

Answer 3

In the lumbar spine (in contrast to the cervical spine) nerve roots emerge below their respective vertebrae: thus an L4/5 disc lesion would be expected to affect the L4 root and an L5/S1 disc lesion to affect the L.5 nerve root. Knee extension is mediated by L2, 3 and 4; ankle dorsiflexion by L4 and 5; inversion of the foot by L4 alone; eversion of the foot by S1, and ankle plantar flexion by S1 and 2. Although L5 contributes to hip abduction and extension, knee flexion and ankle dorsiflexion, weakness is often minimal because of the contribution of other roots to these movements and tends to be maximal in extension of the toes, particularly the great toe.

Question 4

Femoral nerve damage

Answer 4

The femoral nerve may be damaged from fractures of the pelvis or femur, or dislocations of the hip, and hip or hernia surgery. It can also be involved in psoas abscesses, thigh wounds and frequently in large psoas haematomas in patients with haemophilia and diabetic amyotrophy. Partial lesions are common from thigh wounds with the nerve to the quadriceps most frequently involved and causing great problems in walking with the knee often giving way, especially when descending stairs. It leads to a loss of power in the knee extension. In addition there is quadriceps wasting, loss of knee jerk and impaired sensation over the front of the thigh.

Question 5

Lateral cutaneous nerve

Answer 5

The lateral cutaneous nerve of the thigh supplies the antero-lateral aspect of the thigh. It has no motor branches. Meralgia Paraesthetica is a condition which where there is irritation of the nerve causing sensory changes in the distribution of the lateral cutaneous nerve of the thigh without any motor changes.L2 and L3 supply part of the dermatome described but both have motor branches. The femoral nerve supplies the quadriceps muscle, and the saphenous nerve runs with the saphenous vein to supply an area of skin below the knee on the medial aspect of the leg.

Question 6

Common peroneal nerve

Answer 6

The common peroneal nerve (also known as the common fibular nerve) can be compressed by a below knee cast at the level of the fibula neck. It supplies the muscles of the anterior and lateral compartments of the leg, producing dorsiflexion of the foot, ankle and toes, as well as eversion of the foot. The superficial peroneal nerve gives sensory supply to most of the dorsum of the foot. The deep peroneal nerve supplies the first web space. The action of standing on tip-toes is produced by ankle plantar flexion ie. Gastrocnemius and soleus, supplied by the tibial nerve.The lower leg also receives sensory innervation from the saphenous and tibial nerves which would be unaffected, therefore sensory loss would be incomplete.

Question 7

varicose veins short saphenous

Answer 7

The short saphenous system passes posterior to the lateral malleolus and ascends the leg lateral to the Achilles tendon. It usually perforates the popliteal fossa and terminates in the popliteal vein. The incompetent valve is likely to be at this junction.The great saphenous passes above the medial malleolus, ascending obliquely across the inferior third of the patella and passes a hands breadth posterior to the patella on the medial side of the knee. It passes through the superficial fascia and the saphenous opening in the fascia lata, ending at the sapheno-femoral junction.

Question 8

Femoral triangle

Answer 8

From lateral to medial, the femoral triangle contains the femoral nerve and its branches, the femoral artery and its branches, including the profunda femoris and the femoral vein with its main tributary the long saphenous vein. The short saphenous vein enters the popliteal vein in the popliteal fossa.

Question 9

Anterior compartment of leg muscles

Answer 9

tibialis anterior
extensor hallucis longus
extensor digitorum longus
fibularis tertius (peroneus tertius)

The muscles of the compartment are dorsiflexors of foot

The anterior compartment of the leg is supplied by the deep fibular nerve (deep peroneal nerve). The nerve contains axons from the L4, L5, and S1 spinal nerves.

The compartment of the leg is supplied by anterior tibial artery.[1]
The structures of anterior compartment can be remembered using the mnemonic, “TEA DEPt” for Tibialis anterior, Extensor hallucis longus, Anterior tibial artery, Deep peroneal nerve, Extensor digitorum longus and Peroneus tertius

Question 10

Tibial spine

Answer 10

The tibial spine is the origin of the anterior cruciate ligament (ACL). This provides resistance to anterior translation of the tibia on the femur as well as resistance to hyperextension of the knee. Avulsion of the tibial spine is likely to defunction the ACL. The collateral ligaments of the knee attach to the medial proximal tibia and the head of the fibula and are unlikely to be affected, hence there will be normal resistance to varus and valgus stressing of the knee joint. The extensor mechanism of the knee is anterior to the tibial spine and is unlikely to be affected. Patella tracking and straight leg raising should not be impaired.

Question 11

excruciating pain on passive plantar flexion of the big toe, but not on passive dorsiflexion. Passive dorsiflexion and plantar flexion of the ankle do not cause as much pain.

Answer 11

In compartment syndrome, pain is worsened by passive stretching of the affected compartment. In this case the muscle being stretched is flexor hallucis longus. This muscle is in the deep posterior compartment of the leg, along with flexor digitorum longus and tibialis posterior.The anterior compartment contains tibialis anterior, extensor hallucis longus, extensor digitorum longus and peronius tertius.The superficial posterior compartment contains gastrocnemius. plantaris and soleus.The lateral compartment contains peroneus longus and brevis. There is no medial compartment of the leg.

Question 12

pain radiates down the leg to the ankle. On examination he has weakness of the quadriceps, reduced knee jerk reflex and reduced sensation over the patella

Answer 12

The history suggests a prolapsed intervertebral disc. The quadriceps are supplied by the femoral nerve whose root value is L2-L4. The skin over the patella is usually part of the L3 dermatome, and the root value of the knee jerk is L3/L4. The sciatic nerve innervates the muscles of the posterior compartment of the thigh and the muscles of the leg. It provides sensory innervation for the posterior thigh, the leg and the foot. The ilioinguinal nerve supplies a small area of skin on the medial aspect of the upper thigh as well as the scrotum and penis. Femoral nerve compression at the level of the inguinal ligament is unlikely given the history of injury and back pain

Question 13

numbness along the lateral side of the foot.

Answer 13

The sural nerve arises from the tibial nerve. It is purely sensory and supplies the lateral border of the leg and the lateral border of the foot. It lies approximately 1cm posterior to the distal fibula and may be damaged during operations on the distal fibula. The saphenous nerve supplies the medial aspect of the leg up to the medial malleolus. The deep peroneal nerve supplies the first web space whilst the superficial peroneal nerve usually supplies the rest of the dorsum of the foot. The tibial nerve supplies the heel and branches into the medial and lateral plantar nerves to innervate the sole of the foot.

Question 14

On examination he has marked wasting of the right buttock area, erectile dysfunction no leg pain

Answer 14

The internal iliac artery divides into two branches, the posterior division and the anterior division. The posterior division gives off the superior gluteal artery which supplies gluteus medius and minimis. The anterior division gives off the inferior gluteal artery which supplies gluteus maximus. All the muscles of the buttock are therefore supplied by the internal iliac artery, so compromise of this vessel would lead to visible buttock wasting.The blood supply of the penis is mainly derived from the pudendal artery (a branch of the internal iliac artery) and so this would also suggest the internal iliac artery was affected.As there is no leg pain the lesion is unlikely to be affecting either the common iliac artery or any branches of the external iliac artery. The superficial femoral artery is a continuation of the external iliac artery and this gives off the profunda femoris.

Question 15

Quadriceps femoris

Answer 15

The quadriceps femoris is the great extensor muscle of the leg, forming a large fleshy mass that covers the front and sides of the femur. It is subdivided into separate portions, which have received distinctive names. One, occupying the middle of the thigh and connected above with the ilium, is called from its straight course the rectus femoris. The other three lie in immediate connection with the body of the femur, which they cover from the trochanters to the condyles. The portion on the lateral side of the femur is the vastus lateralis; that covering the medial side, the vastus medialis; and that in front, the vastus intermedius

Question 16

lateral aspect of knee sup to deep structures

Answer 16

The correct order of superficial to deep structures on the lateral aspect of the knee joint is skin, fibular collateral ligament, popliteus muscle tendon and lateral meniscus.

Question 17

Profunda femoris

Answer 17

The profunda femoris artery (deep femoral artery) is a large vessel arising from the lateral and back part of the femoral artery, from 2 to 5 cm below the inguinal ligament. At first it lies lateral to the femoral artery; it then runs behind it and the femoral vein to the medial side of the femur and, passing downward behind the adductor longus, ends at the lower third of the thigh in a small branch which pierces the adductor magnus and is distributed on the back of the thigh to the hamstring muscles. The terminal part of the profunda is sometimes known as the fourth perforating artery.

Question 18

short head of biceps femoris innervation

Answer 18

The short head of biceps femoris arises from the lateral lip of the linea aspera, between the adductor magnus and vastus lateralis, extending up almost as high as the insertion of the gluteus maximus; from the lateral prolongation of the linea aspera to within 5 cm of the lateral condyle; and from the lateral intermuscular septum. The fibres of the short head merge into the aponeurosis formed by the long head; this aponeurosis becomes gradually contracted into a tendon, which is inserted into the lateral side of the head of the fibula and by a small slip into the lateral condyle of the tibia. At its insertion, the tendon of biceps femoris divides into two portions, which embrace the fibular collateral ligament of the knee joint. From the posterior border of the tendon, a thin expansion is given off to the fascia of the leg. The tendon of insertion of this biceps forms the lateral hamstring; the common peroneal nerve descends along its medial border. The nerve to the short head of the biceps femoris is derived from the common peroneal part of the sciatic nerve.

Question 19

biceps femoris

Answer 19

The short head of biceps femoris arises from the lateral lip of the linea aspera, between the adductor magnus and vastus lateralis, extending up almost as high as the insertion of the gluteus maximus; from the lateral prolongation of the linea aspera to within 5 cm of the lateral condyle; and from the lateral intermuscular septum. The fibres of the short head merge into the aponeurosis formed by the long head; this aponeurosis becomes gradually contracted into a tendon, which is inserted into the lateral side of the head of the fibula and by a small slip into the lateral condyle of the tibia. At its insertion, the tendon of biceps femoris divides into two portions, which embrace the fibular collateral ligament of the knee joint. From the posterior border of the tendon, a thin expansion is given off to the fascia of the leg. The tendon of insertion of this biceps forms the lateral hamstring; the common peroneal nerve descends along its medial border. The nerve to the short head of the biceps femoris is derived from the common peroneal part of the sciatic nerve.

Question 20

A patient complains of deficit in the cutaneous field halfway down the anterior surface of the thigh.

Answer 20

The pectineus is supplied by the second, third and fourth lumbar nerves through the femoral nerve and by the third lumbar through the accessory obturator when this exists. Occasionally it receives a branch from the obturator nerve. The anterior surface of the thigh receives its innervation from, the femoral nerve as well so that is the nerve most likely to be injured. In the thigh, the anterior division of the femoral nerve gives off anterior cutaneous branches. The anterior cutaneous branches comprise the intermediate and medial cutaneous nerves. The intermediate cutaneous nerve pierces the fascia lata (and generally the sartorius) about 7.5 cm below the inguinal ligament and divides into two branches that descend in immediate proximity along the forepart of the thigh to supply the skin as low as the front of the knee. Here they communicate with the medial cutaneous nerve and the infrapatellar branch of the saphenous, to form the patellar plexus. In the upper part of the thigh, the lateral branch of the intermediate cutaneous communicates with the lumboinguinal branch of the genitofemoral nerve

Question 21

Innervation to the peroneus brevis muscle

Answer 21

The peroneus brevis is supplied by the fourth and fifth lumbar and first sacral nerves through the superficial peroneal nerve. The superficial peroneal nerve is one of the two terminal branches of the common peroneal nerve. The common peroneal nerve winds around the neck of the fibula and can be injured in cases of fracture neck of fibula. Such an injury can result in paralysis or paresis of peroneus brevis due to indirect involvement of the superficial peroneal nerve

Question 22

Which one of the following muscles is attached to the tibial tuberosity

Answer 22

The tuberosity of the tibia gives attachment to the ligamentum patellae (which is the single strong tendon of the quadriceps femoris, including rectus femoris, vasti medialis, intermedius and lateralis). A bursa intervenes between the deep surface of the ligament and the part of the bone immediately above the tuberosity.

Question 23

stab injury a patient has his sciatic nerve cut as it exits the pelvis

Answer 23

The sciatic nerve is a large nerve that runs down the lower limb. It is the longest single nerve in the body. The sciatic nerve supplies nearly the whole of the skin of the leg, the muscles of the back of the thigh and those of the leg and foot. A transection of the sciatic nerve at its exit from the pelvis will affect all the above-mentioned functions except cutaneous sensation over the anteromedial surface of the thigh, which comes from the femoral nerve

Question 24

The lateral compartment of the leg containing the peroneus longus and brevis muscles is innervated by the

Answer 24

The superficial peroneal nerve supplies the peronei longus and brevis and the skin over the greater part of the dorsum of the foot. It passes forward between the peronei and the extensor digitorum longus, pierces the deep fascia at the lower third of the leg and divides into a medial and an intermediate dorsal cutaneous nerve. In its course between the muscles, the nerve gives off muscular branches to the peronei longus and brevis and cutaneous filaments to the skin of the lower part of the leg

Question 25

A footballer fell awkwardly because of a rash challenge. He sustained a blow to his left knee and was stretchered off the playing field. On examination of his injured knee the physiotherapist found excessive posterior movement of the tibia on the femur

Answer 25

The posterior cruciate ligament (PCL) is stronger, but shorter and less oblique in its direction, than the anterior. It is attached to the posterior intercondyloid fossa of the tibia and to the posterior extremity of the lateral meniscus and passes upward, forward and medialward, to be fixed into the lateral and front part of the medial condyle of the femur. This configuration allows the PCL to resist forces pushing the tibia posteriorly relative to the femur

Question 26

vein for venous cut down

Answer 26

The lower limb has both deep and superficial venous systems. The short and long saphenous veins constitute the superficial system. They have many perforating veins that drain to the deep system. The short saphenous is a continuation of the lateral end of the dorsal venous arch and passes behind the lateral malleolus before rising to enter the politeal vein in the popliteal fossa. The long saphenous vein is a continuation of the medial dorsal venous arch and passes in front of the medial malleolus and then up the medial aspect of the lower limb to enter the femoral vein. It has three tributaries in the groin (superficial epigastric, superficial external pudendal and superficial circumflex iliac).

Question 27

medial fascial compartment of leg

Answer 27

The medial fascial compartment of the thigh contains adductor longus, adductor brevis, adductor portion of adductor magnus, gracilis, pectineus and obturator externus. They are all supplied by the obturator nerve except the pectineus, which is supplied by the femoral nerve. Sartorius lies in the anterior fascial compartment and the hamstring portion of adductor magnus lies in the posterior fascial compartment of the thigh.

Question 28

Which muscle tendon is used to achieve an ACL reconstruction?

Answer 28

Rectus femoris, vastus medialis, vastus intermedius and vastus lateralis form the quadriceps tendon. This tendon inserts on the patellar. Biceps femoris, semitendinosus, semimembranosus and the hamstring portion of adductor magnus are all in the posterior fascial compartment of the thigh. Biceps femoris inserts on the head of the fibula. Semimembranosus inserts on the medial condyle of the tibia

Question 29

In flat foot deformity. Which ligament is likely to have been disrupted in his injury?

Answer 29

The ability of the medial longitudinal arch to prevent flatfoot deformity depends on the dynamic support of the posterior tibial tendon, the static support of ligaments and capsule (including the Spring ligament), and the manner in which the tarsal bones interlock. The ankle (tibiotalar) joint is a hinge joint. As with most hinge joints there is strong support at the sides but not in front and behind. The deltoid ligament is attached above to the medial malleolus and fans out to attach below, mainly on the talus, but also on the calcaneus. On the lateral side there are three smaller ligaments (anterior and posterior talofibular ligaments and calcaneofibular ligament). The ankle joint is most stable in dorsiflexion. The intermalleolar distance increases in dorsiflexion due to the increased width of the anterior part of the talus bone.

Question 30

swelling and pain anterior to his knee.Which knee bursa is likely to be involved?

Answer 30

There are four anterior bursae: suprapatellar, prepatellar, superficial infrapatellar and deep infrapatellar. There are two posterior bursae: popliteal and semimembranosus. The deep infrapatellar bursa lies between the ligamentum patellae and the tibia. The superficial infrapatellar bursa lies between the skin and the lower half of the ligamentum patellae. The prepatellar bursa lies in the subcutaneous tissue over the lower half of the patella and upper part of the ligamentum patellae

Question 31

laceration to his foot just anterior to the medial malleolus on the dorsum of the foot.Which clinical structure is likely to be damaged in this injury?

Answer 31

The dorsalis pedis artery lies between the extensor hallucis longus tendon medially, and the deep peroneal nerve lies laterally. The L5 dermatome lies over the medial half of the dorsum of the foot. The great saphenous vein is found anterior to the medial malleolus, and the lower limb of the extensor retinaculum passes under the medial longitudinal arch and blends with the plantar aponeurosis

Question 32

When operating on a femoral hernia in the femoral triangle, care should be taken to avoid damage to which structure?

Answer 32

The superficial epigastric and superficial external pudendal arteries pass through the saphenous opening (the superficial circumflex and deep external pudendal arteries pierce the fascia lata). The femoral artery separates the femoral nerve (laterally) from the femoral vein (medially). The profunda femoris artery is a lateral branch of the femoral artery. The deep inguinal nodes lie medial to the femoral vein. The femoral sheath encloses the femoral vessels for up to 3 cm beyond the inguinal ligament, where the sheath terminates by fusing with the adventitia of both vessels.

Question 33

Absent knee reflex is most likely to be due to

Answer 33

The patellar reflex is mediated by the femoral nerve formed from the posterior divisions of the L2–L4 anterior spinal rami, and is therefore lost after femoral nerve and L2–L4 dorsal root damage. T12 cord lesions result in an upper motor neurone lesion with exaggerated reflexes. Dorsal column lesions only affect central sensory processing since collaterals subserving spinal reflexes are preserved.

Question 34

The posterior approach provides exposure to the acetabulum and hip. Which structure exits the greater sciatic foramen below the piriformis muscle

Answer 34

The piriformis muscle lies partly within the pelvis and emerges through the greater sciatic foramen to enter the gluteal region. The structures passing or emerging from the upper border of the piriformis muscle include the superior gluteal nerve and vessels. Below the lower border of the piriformis emerge the inferior gluteal nerve and muscles, pudendal nerve and vessels, the nerve to obturator internus and the sciatic nerve.