Lower Limb Practice Questions

Q: Medial rotation of the tibia in a flexed leg is brought about by which muscle?

Popliteus. **Explanation:** The **Popliteus** is a thin, triangular muscle located at the floor of the popliteal fossa. It is often referred to as the **"Key to the knee"** because of its essential role in initiating the process of **unlocking** the knee joint. 1. **Mechanism of Action:** When the knee is in full extension (locked), the femur is medially rotated on the tibia. To initiate flexion, the Popliteus must "unlock" the joint. * **In a non-weight-bearing position (flexed/free leg):** It acts as a **medial rotator of the tibia** on the femur. * **In a weight-bearing position (standing):** It acts as a lateral rotator of the femur on the tibia. **Analysis of Incorrect Options:** * **Vastus medialis & Quadriceps femoris:** These are primarily **extensors** of the knee joint. While the Vastus medialis helps in stabilizing the patella, it does not contribute to the rotation of the tibia. * **Adductor magnus:** This is a powerful adductor of the hip (thigh). Its "hamstring part" helps in hip extension, but it has no direct action on the rotation of the tibia at the knee joint. **High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Lateral surface of the lateral condyle of the femur (intracapsular but extrasynovial). * **Insertion:** Posterior surface of the tibia above the soleal line. * **Nerve Supply:** Tibial nerve (L4, L5, S1). * **Morphology:** It is considered the "remnant" of the long flexor of the hallux (morphologically significant). * **Function:** Besides unlocking, it protects the lateral meniscus by pulling it posteriorly during flexion.

Q: A 49-year-old man is admitted to the emergency department with a cold and pale foot. Physical examination reveals that the patient suffers from peripheral vascular disease and his popliteal artery is occluded and no pulse is felt upon palpation. What is the landmark to feel the pulse of the femoral artery?

Femoral triangle. The **femoral artery** is the primary arterial supply to the lower limb. To palpate its pulse, the artery must be superficial and rest against a firm structure. In the **femoral triangle**, the artery lies just deep to the fascia lata and is positioned directly anterior to the psoas major tendon and the superior pubic ramus [1]. The specific landmark for palpation is the **mid-inguinal point** (halfway between the anterior superior iliac spine and the pubic symphysis), just inferior to the inguinal ligament. This is a high-yield clinical site for arterial blood gas (ABG) sampling and cardiac catheterization. **Analysis of Incorrect Options:** * **Adductor canal (Hunter’s canal):** This is a narrow fascial tunnel located deep to the sartorius muscle in the middle third of the thigh [2]. The artery is too deep here to be palpated. * **Popliteal fossa:** This is where the popliteal pulse is felt (deep between the two heads of the gastrocnemius). In this patient, the popliteal artery is occluded [3], making this site irrelevant for feeling the femoral pulse. * **Inguinal canal:** This is a passage in the anterior abdominal wall containing the spermatic cord (in males) or round ligament (in females). It does not contain the femoral artery. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Femoral Triangle (Lateral to Medial):** **N**erve, **A**rtery, **V**ein, **E**mpty space, **L**ymphatics (**NAVEL**). * **Mid-inguinal point:** Site of femoral pulse (midway between ASIS and pubic symphysis) [1]. * **Mid-point of inguinal ligament:** Site of deep inguinal ring (midway between ASIS and pubic tubercle). * **Profunda femoris artery:** The largest branch of the femoral artery, arising within the femoral triangle.

Q: Which of the following is NOT a content of Hunter's canal?

Femoral nerve. **Explanation:** The **Hunter’s canal** (also known as the Adductor canal or Subsartorial canal) is an aponeurotic tunnel in the middle third of the thigh. It serves as a passageway for structures moving from the femoral triangle to the popliteal fossa. **Why the Femoral Nerve is the Correct Answer:** The **femoral nerve** itself is not a content of the Hunter's canal. It terminates within the femoral triangle by dividing into several anterior and posterior divisions. While some of its branches (like the saphenous nerve and the nerve to vastus medialis) enter the canal, the main trunk of the femoral nerve does not. **Analysis of Other Options:** * **Femoral Artery:** It enters the canal at the apex of the femoral triangle and leaves through the adductor hiatus to become the popliteal artery. * **Femoral Vein:** It lies posterior to the artery in the upper part of the canal and lateral to it in the lower part. * **Saphenous Nerve:** This is the longest cutaneous branch of the femoral nerve. It enters the canal, crosses the femoral artery from lateral to medial, and eventually exits by piercing the roof (vasoadductor fascia) to become superficial. **High-Yield Clinical Pearls for NEET-PG:** * **Boundaries:** Anterolaterally by the **Vastus medialis**, posteriorly by **Adductor longus and magnus**, and medially (roof) by the **Sartorius** muscle. * **Contents mnemonic:** "Vast Safe Femurs" (Nerve to **Vast**us medialis, **Saphenous** nerve, **Fem**oral artery, and **Fem**oral vein). * **Clinical Significance:** The canal is a common site for **Adductor Canal Blocks**, used for regional anesthesia in knee surgeries (e.g., TKR) because it provides sensory blockade via the saphenous nerve while sparing the motor fibers of the femoral nerve, allowing for early mobilization.

Q: Which is the most lateral structure passing through the tarsal tunnel?

Flexor hallucis longus tendon. The **tarsal tunnel** is a fibro-osseous canal located on the posteromedial aspect of the ankle, formed by the medial malleolus and the overlying flexor retinaculum. Understanding the spatial arrangement of structures passing through this tunnel is high-yield for NEET-PG. ### **Anatomical Arrangement (Anterior to Posterior / Medial to Lateral)** The structures pass behind the medial malleolus in a specific order, which can be remembered by the popular mnemonic: **"Tom, Dick, And Very Nervous Harry."** 1. **T**ibialis posterior tendon (Most Anterior/Medial) 2. **D**igitorum longus (Flexor digitorum longus tendon) 3. **A**rtery (Posterior tibial artery) 4. **V**ein (Posterior tibial veins) 5. **N**erve (Tibial nerve) 6. **H**allucis longus (**Flexor hallucis longus tendon**) — **Most Posterior/Lateral** ### **Analysis of Options** * **Flexor hallucis longus (Correct):** It is the deepest and most posterior/lateral structure in the tunnel. It occupies its own groove on the posterior surface of the talus and the sustentaculum tali. * **Tibialis posterior:** This is the most anterior structure, lying immediately behind the medial malleolus. * **Flexor digitorum longus:** Positioned between the Tibialis posterior and the neurovascular bundle. * **Posterior tibial vessels and nerve:** These lie between the Flexor digitorum longus and the Flexor hallucis longus. ### **Clinical Pearls for NEET-PG** * **Tarsal Tunnel Syndrome:** Compression of the **Tibial nerve** within this tunnel, often causing paresthesia in the sole of the foot. * **Pulse Point:** The posterior tibial artery pulse is clinically palpated halfway between the medial malleolus and the heel. * **Roof of the Tunnel:** Formed by the **Flexor retinaculum**, which attaches from the medial malleolus to the calcaneus.

Q: What is the root value of the ankle jerk reflex?

S1. **Explanation:** The **Ankle Jerk (Achilles reflex)** is a deep tendon reflex mediated by the **S1 nerve root**. When the Achilles tendon is tapped, it triggers a stretch reflex in the gastrocnemius and soleus muscles, leading to plantar flexion of the foot. While S2 also contributes to this reflex arc, **S1 is the predominant functional component** tested clinically. **Analysis of Options:** * **S1 (Correct):** This is the primary root value for the ankle jerk. The reflex arc travels via the tibial nerve to the S1 spinal segment. * **L3-L4 (Incorrect):** This is the root value for the **Knee Jerk (Patellar reflex)**. It is mediated by the femoral nerve. * **L1-L2 (Incorrect):** This is the root value for the **Cremasteric reflex** (a superficial reflex). * **L4-L5 (Incorrect):** These roots are primarily involved in foot dorsiflexion (Tibialis anterior) and big toe extension (EHL), but they do not mediate a major deep tendon reflex. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mnemonic for Reflexes:** Think of the body from bottom to top in numerical order: * **S1-S2:** Ankle (S1) * **L3-L4:** Knee (L4) * **C5-C6:** Biceps and Brachioradialis * **C7-C8:** Triceps 2. **Clinical Significance:** A diminished or absent ankle jerk is often the first sign of **S1 radiculopathy** (commonly due to an L5-S1 disc prolapse) or peripheral neuropathy (e.g., Diabetic neuropathy). 3. **Wartenberg’s Sign:** In patients with upper motor neuron lesions, the ankle jerk may show **clonus** (rhythmic oscillations) [1].

Q: A needle biopsy of the sural nerve resulted in the formation of a hematoma. Which of the following veins closely adjacent to the nerve was accidentally injured?

Lesser saphenous vein. **Explanation:** The correct answer is **D. Lesser (Small) saphenous vein.** The **sural nerve** is a sensory nerve formed by the union of the medial sural cutaneous nerve (from the tibial nerve) and the peroneal communicating branch (from the common peroneal nerve). In the lower leg, it descends along the lateral border of the Achilles tendon. Crucially, it runs in close anatomical proximity to the **lesser saphenous vein (LSV)** as they both pass posterior to the lateral malleolus. Because of this intimate relationship, the sural nerve is frequently harvested for nerve grafts or biopsied, and the adjacent LSV is the most likely vessel to be injured during such procedures, leading to hematoma formation. **Analysis of Incorrect Options:** * **A. Accessory saphenous vein:** This vein drains the medial and posterior parts of the thigh and joins the Great Saphenous Vein (GSV) near the saphenofemoral junction; it is not located near the sural nerve in the lower leg. * **B. Femoral vein:** This is a deep vein of the thigh located in the femoral triangle, far removed from the superficial course of the sural nerve. * **C. Greater saphenous vein:** This vein runs anterior to the medial malleolus and is accompanied by the **saphenous nerve** (a branch of the femoral nerve), not the sural nerve. **NEET-PG High-Yield Pearls:** * **Nerve-Vein Pairs:** * Greater Saphenous Vein + Saphenous Nerve (Medial side). * Lesser Saphenous Vein + Sural Nerve (Lateral side). * **Sural Nerve Distribution:** Provides sensation to the lateral aspect of the foot and the fifth toe. * **Clinical Significance:** The sural nerve is the most common donor site for autologous nerve grafting because its loss results in only a minor sensory deficit.

Q: Locking of the knee joint occurs with all except?

Popliteus. **Explanation:** The mechanism of the knee joint involves two distinct processes: **Locking** and **Unlocking**. **1. Why Popliteus is the correct answer:** Locking is the final stage of knee extension where the femur undergoes **medial rotation** (on a fixed tibia) to tighten the ligaments, making the joint stable and rigid. This process is driven by the **Quadriceps femoris** group. In contrast, **Popliteus** is the "Key to the knee." Its primary function is **Unlocking** the knee by initiating **lateral rotation** of the femur on the tibia (or medial rotation of the tibia if the foot is free) at the start of flexion. Therefore, it is not involved in locking; it is the essential muscle for reversing it. **2. Why the other options are incorrect:** * **Vastus medialis (specifically the VM Obliquus):** This is the most crucial muscle for the final 10–15 degrees of extension and the terminal locking of the knee. * **Vastus intermedius & Rectus femoris:** As components of the Quadriceps femoris, these muscles are powerful extensors of the knee. Since locking is a phenomenon of terminal extension, all components of the quadriceps contribute to the force required to achieve a locked position. **Clinical Pearls for NEET-PG:** * **Locking:** Occurs in full extension; involves **Medial rotation** of the femur. * **Unlocking:** Occurs at the start of flexion; involves **Lateral rotation** of the femur, performed by the **Popliteus**. * **Popliteus Origin/Insertion:** It is unique because it is an **intracapsular but extrasynovial** muscle, originating from the lateral condyle of the femur. * **Nerve Supply:** Tibial Nerve (L4, L5, S1).

Q: Trendelenburg's sign is positive in injury to which muscle?

Gluteus medius. **Explanation:** The **Trendelenburg sign** is a clinical indicator of dysfunction in the **hip abductor mechanism**. **1. Why Gluteus Medius is Correct:** The primary abductors of the hip are the **Gluteus medius** and **Gluteus minimus**, both supplied by the **Superior Gluteal Nerve (L4-S1)**. In a normal gait, when one foot is lifted off the ground (swing phase), the abductors of the weight-bearing leg (stance phase) contract to pull the pelvis down toward the femur, effectively keeping the pelvis level or slightly elevated on the unsupported side. If the Gluteus medius is weak or paralyzed, it cannot stabilize the pelvis, causing the pelvis to **drop on the unsupported (opposite) side**. This is a "Positive Trendelenburg Sign." **2. Why Other Options are Incorrect:** * **Gluteus maximus:** Supplied by the Inferior Gluteal Nerve, it is the chief extensor of the hip (used for climbing stairs or rising from a chair), not abduction. * **Quadriceps femoris:** Located in the anterior compartment of the thigh, its primary function is knee extension and hip flexion (rectus femoris). * **Quadratus lumborum:** A muscle of the posterior abdominal wall that assists in lateral flexion of the vertebral column and fixing the 12th rib; it does not maintain pelvic stability during the gait cycle. **Clinical Pearls for NEET-PG:** * **Trendelenburg Gait:** To compensate for the pelvic drop, the patient tilts their trunk *toward* the affected side to shift the center of gravity (known as a **Gluteal lurch**). * **Nerve Involved:** Injury to the **Superior Gluteal Nerve** (e.g., due to misplaced intragluteal injections or hip surgery) is the most common cause. * **The "Sound-Side" Rule:** In a positive sign, the pelvis drops on the **healthy/normal side**, indicating weakness on the **contralateral (standing) side**.

Question 1

What is true about the saphenous vein?

Accepted Answer

Located 1 cm anterior to the medial malleolus process

Answer

Located 1 cm inferior to the medial malleolus process

Answer

Located 1 cm posterior to the medial malleolus process

Answer

Located 1 cm superior to the medial malleolus process

Question 2

Medial rotation of the tibia in a flexed leg is brought about by which muscle?

Accepted Answer

Popliteus

Answer

Vastus medialis

Answer

Quadriceps femoris

Answer

Adductor magnus

Question 3

A 49-year-old man is admitted to the emergency department with a cold and pale foot. Physical examination reveals that the patient suffers from peripheral vascular disease and his popliteal artery is occluded and no pulse is felt upon palpation. What is the landmark to feel the pulse of the femoral artery?

Accepted Answer

Femoral triangle

Answer

Adductor canal

Answer

Popliteal fossa

Answer

Inguinal canal

Question 4

Which of the following is NOT a content of Hunter's canal?

Accepted Answer

Femoral nerve

Answer

Femoral artery

Answer

Femoral vein

Answer

Saphenous nerve

Question 5

Which is the most lateral structure passing through the tarsal tunnel?

Accepted Answer

Flexor hallucis longus tendon

Answer

Flexor digitorum longus tendon

Answer

Tibialis posterior tendon

Answer

Posterior tibial vessels and nerve

Question 6

What is the root value of the ankle jerk reflex?

Accepted Answer

S1

Answer

L1-L2

Answer

L3-L4

Answer

L4-L5

Question 7

Trendelenburg test is positive in injury to which nerve?

Accepted Answer

Superior gluteal nerve

Answer

Inferior gluteal nerve

Answer

Lateral popliteal nerve

Answer

Sciatic nerve

Question 8

A needle biopsy of the sural nerve resulted in the formation of a hematoma. Which of the following veins closely adjacent to the nerve was accidentally injured?

Accepted Answer

Lesser saphenous vein

Answer

Accessory saphenous vein

Answer

Femoral vein

Answer

Greater saphenous vein

Question 9

Locking of the knee joint occurs with all except?

Accepted Answer

Popliteus

Answer

Vastus intermedius

Answer

Vastus medialis

Answer

Rectus femoris

Question 10

Trendelenburg's sign is positive in injury to which muscle?

Accepted Answer

Gluteus medius

Answer

Gluteus maximus

Answer

Quadriceps femoris

Answer

Quadratus lumborum

Lower Limb — MCQs

Lower Limb — MCQs

On this page

Practice by Chapter

Want unlimited practice?