LOWER LIMB MCQs Flashcards
67-year-old obese female presents with to her physician’s office with complaints of severe pain behind her knee. Ultrasound reveals a thrombosis in the popliteal vein.
This thrombosis most likely causes reduction of blood flow in which of the following veins?
This is the correct answer - The popliteal vein drains blood into the femoral vein; thus, blood flow in the femoral vein is reduced.
Takeaway: the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor hiatus and is a continuation of the popliteal vein.
A 76-year-old male presents to the emergency room after being hit in the leg by an electric scooter. Physical examination reveals trauma to the right lower extremity. Imaging of the affected limb reveals a fracture of the proximal fibula. Further examination exhibits a loss of skin sensation on the lateral surface of the leg and dorsum of the foot as well as impaired pronation of the foot.
Which of the following nerve branches is most likely damaged?
This is the correct answer - Superficial peroneal nerve, which innervates the lateral muscles of the leg and supplies the skin on the side of the lower leg and the dorsum of the ankle and foot. The superficial peroneal nerve innervates the peroneus longus and peroneus brevis muscles and the skin over the antero-lateral aspect of the leg along with the greater part of the dorsum of the foot (with the exception of the first web space, which is innervated by the deep peroneal nerve). Superficial peroneal nerve is the main nerve of the lateral compartment of the leg. It begins at the lateral side of the neck of fibula, and runs through the peroneal muscles.
Takeaway: The superficial peroneal nerve is a nerve of the lower extremity that innervates the lateral compartment of the leg (foot eversion) and the skin that overlies the anteromedial leg and dorsal foot, exclusive of the first web space. A branch of the common peroneal nerve. Injury to this nerve is commonly secondary to entrapment at the lateral ankle or via fibular fracture. Injury to the nerve can result in an inability to evert the foot and loss of sensation over the dorsum of the foot (with the exception of the first web space between the great toe and the second toe, where the deep fibular nerve innervates)
A 19-year-old soccer player is taken down from behind while running, causing him to twist suddenly. He goes to the ground in obvious pain and is unable to continue. He tells the trainer that he felt a pop in his left knee when it happened. Examination reveals anterior displacement of the knee while in 90-degree flexion along with excessive anterior movement of the tibia when pulled anteriorly with the knee in 30-degree flexion and while stabilizing the distal femur.
This is the connection points for the anterior cruciate ligament (ACL), which is most likely the damaged structure in this patient. The anterior cruciate ligament (ACL) prevents the tibia from moving anteriorly. An ACL tear commonly occurs when the knee is stressed from the outside or hyperextended. It is the most common ligamentous injury in the United States. The “terrible triad” is a term referring to damage resulting from a lateral blow to the knee. It may lead to injury to: anterior cruciate ligament, lateral collateral ligament, lateral meniscus. Preventive measures for ACL tears include equally strengthening muscles around the knee and proper biomechanics when running, and jumping.
Takeaway - Damage to the anterior cruciate ligament (ACL) results in anterior dispalcement of the knee.
A football player is trying out for the NFL. During the physical by the NFL physician, the young man is tested for stability of his joints before tryouts. Presentation show a tall male with significant muscle mass with no past medical history.
Which of the following ligaments is important in preventing forward displacement of the femur on the tibia when the weight-bearing knee is flexed?
This is the correct answer - The posterior cruciate ligament prevents posterior displacement of the tibia on the femur; therefore, prevents anterior displacement of the femur on the tibia.
TAKEAWAY - The posterior cruciate ligament is the largest and strongest ligament of the knee. It originates on the lateral border of the medial femoral condyle and inserts on the posterior tibia between the two tibial plateaus. Its primary function is to prevent posterior translation of the tibia and forward displacement of the femur. Common injuries with the PCL are seen in athletes when the knee hyperflexion with a plantar-flexed foot as well as persons involved in motor vehicle accidents when they experience a direct posterior force to the tibia from the dashboard.
A 65-year-old man with a history of smoking 2 packs of cigarettes/ day for the last 20 years is seen in the clinic with symptoms suggestive of peripheral vascular disease. Physical examination reveals decreased pulsation of the artery on the dorsum of the foot between the two malleoli.
Which of the following nerves innervates the muscle whose tendon lies immediately medial to the artery at the site of palpation?
Deep fibular nerve - This is the correct answer. Deep fibular nerve innervates the extensor hallucis longus muscle on the anterior compartment of leg. The tendon of this muscle lies medial to the dorsalis pedis artery (the artery that lies between the two malleoli).
A 19-year-old man is struck by an automobile while crossing a road. He is brought to the emergency department. On examination, the physician notes that the patient is having a high stepping gait and is unable to dorsiflex his foot on the injured side. It is also noted that he is having sensory loss on the dorsum of the foot. An X-ray of the patient reveals a fracture of the proximal fibula.
Which of the following nerves is most likely injured in this patient?
Common fibular - This is the correct answer. In this case the patient is unable to dorsiflex his foot and is having a high stepping gait. This is a sign of “Foot drop”. In this case the muscles of anterior compartment of the leg, which are innervated by deep fibular nerve, a branch of common fibular nerve is paralyzed. The actions of this group of muscles are to dorsiflex the foot. The patient is also having sensory loss on the dorsum of the foot. The sensations from the dorsum of foot are carried by superficial fibular nerve, a branch of common fibular nerve. The sensation from the web space between the 1st and the 2nd toe is carried by the deep fibular nerve. The site of injury indicates that the patient is having a fracture of the proximal part of fibula. The common fibular nerve is closely related to the proximal part (neck) of the fibula. Therefore, this fracture is likely to injure the common fibular nerve or its branches. In this case the motor deficit is due to paralysis of anterior compartment muscles and sensory deficit is on the dorsum of foot. Both can happen only if the common fibular nerve is injured, not its branches alone.
