Lower Limb — MCQs
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A football player has suffered severe trauma to the lateral part of the left leg just below the knee. He drags his left toe when he walks and cannot feel the dorsum of the foot. Which of the following functions or sensations will still be intact?
What is the primary action of the popliteus muscle?
The lateral cutaneous nerve of the thigh arises from which of the following?
Which component of the lateral collateral ligament complex is most commonly affected in an ankle sprain?
What is the normal angle of the neck of the femur to its shaft?
Damage to which of the following nerves leads to sensory loss on the adjacent sides of the great and second toes and impaired dorsiflexion of the foot?
What is the primary action of the quadratus femoris muscle?
Which muscles are responsible for the flexion of the knee joint?
Which statement about the Posterior Cruciate Ligament is true?
Lateral meniscus is less prone to injury than medial meniscus because of the following reasons, except?
Lower Limb Indian Medical PG Practice Questions and MCQs
Question 121: A football player has suffered severe trauma to the lateral part of the left leg just below the knee. He drags his left toe when he walks and cannot feel the dorsum of the foot. Which of the following functions or sensations will still be intact?
- A. Dorsiflexion
- B. Eversion
- C. Cutaneous sensation of the medial leg (Correct Answer)
- D. Cutaneous sensation between the great toe and the second toe
Explanation: **Explanation:** The clinical presentation describes an injury to the **Common Peroneal (Fibular) Nerve**. This nerve is highly vulnerable to trauma as it winds around the **neck of the fibula**, just below the lateral aspect of the knee. **1. Why the Correct Answer is Right:** The **cutaneous sensation of the medial leg** is provided by the **Saphenous nerve**, which is a branch of the **Femoral nerve** (L2-L4). Since the injury is localized to the Common Peroneal nerve (L4-S2), the Saphenous nerve remains unaffected. Therefore, sensation on the medial side of the leg and foot remains intact. **2. Why Incorrect Options are Wrong:** * **Dorsiflexion (A):** This is performed by the muscles of the anterior compartment of the leg, supplied by the **Deep Peroneal nerve**. Injury to this nerve leads to "Foot Drop," explaining why the patient drags his toe. * **Eversion (B):** This is performed by the Peroneus longus and brevis in the lateral compartment, supplied by the **Superficial Peroneal nerve**. * **Sensation between the 1st and 2nd toes (D):** This specific area (the first dorsal web space) is the sensory territory of the **Deep Peroneal nerve**. **Clinical Pearls for NEET-PG:** * **Common Peroneal Nerve (CPN):** The most commonly injured nerve in the lower limb. * **Mnemonic for CPN branches:** **PED** (**P**eroneal **E**verts and **D**orsiflexes). If damaged, the foot is **DIP**ed (**D**orsiflexion and **I**nversion **P**aralyzed). * **Foot Drop:** Characterized by a "High Steppage Gait" to prevent the toes from dragging. * **Sensory Loss:** Superficial peroneal nerve supplies the majority of the dorsum of the foot; Deep peroneal nerve supplies only the first web space.
Question 122: What is the primary action of the popliteus muscle?
- A. Medial rotation of the femur
- B. Lateral rotation of the femur (Correct Answer)
- C. Locking of the knee
- D. Extension of the knee
Explanation: ### Explanation The **Popliteus muscle** is often referred to as the **"Key to the knee"** because its primary function is to initiate the process of **unlocking** the knee joint to allow flexion. **1. Why "Lateral rotation of the femur" is correct:** The action of the popliteus depends on whether the limb is weight-bearing or non-weight-bearing: * **Weight-bearing (Closed Chain):** When standing with the knee fully extended (locked), the popliteus contracts to **laterally rotate the femur** on the fixed tibia. This rotation "unlocks" the joint, allowing flexion to occur. * **Non-weight-bearing (Open Chain):** It medially rotates the tibia on the femur. Since the question asks for the primary action (typically referring to the unlocking mechanism in a standing position), lateral rotation of the femur is the definitive answer. **2. Analysis of Incorrect Options:** * **A. Medial rotation of the femur:** This occurs during the "locking" mechanism (Screw-home movement) at the end of extension, performed by the quadriceps, not the popliteus. * **C. Locking of the knee:** This is a passive mechanism occurring at full extension involving medial rotation of the femur. The popliteus does the exact opposite (unlocking). * **D. Extension of the knee:** This is primarily performed by the Quadriceps femoris. The popliteus is a weak flexor. **3. NEET-PG High-Yield Clinical Pearls:** * **Origin:** It is unique because it is **intracapsular but extrasynovial**. It originates from the lateral condyle of the femur. * **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 in lower animals. * **Tendon Fact:** The tendon of the popliteus separates the **Lateral Meniscus** from the Fibular Collateral Ligament, which is why the lateral meniscus is more mobile and less frequently injured than the medial meniscus.
Question 123: The lateral cutaneous nerve of the thigh arises from which of the following?
- A. Femoral nerve
- B. Lumbar plexus (Correct Answer)
- C. Obturator nerve
- D. Sciatic nerve
Explanation: The **Lateral Cutaneous Nerve of the Thigh (LCNT)** is a purely sensory nerve that arises directly from the **Lumbar Plexus**, specifically from the posterior divisions of the ventral rami of **L2 and L3** spinal nerves. It emerges from the lateral border of the psoas major muscle, crosses the iliacus, and enters the thigh by passing posterior to the inguinal ligament, just medial to the anterior superior iliac spine (ASIS). **Analysis of Options:** * **Option B (Correct):** The LCNT is a direct branch of the lumbar plexus (L2, L3). It provides sensation to the skin of the anterior and lateral aspects of the thigh down to the knee. * **Option A (Femoral Nerve):** While the femoral nerve also arises from the lumbar plexus (L2–L4), the LCNT is a separate branch and does not originate from the femoral nerve itself. * **Option C (Obturator Nerve):** This nerve arises from the anterior divisions of L2–L4 and supplies the medial (adductor) compartment of the thigh. * **Option D (Sciatic Nerve):** This is the largest nerve of the body, arising from the sacral plexus (L4–S3), and supplies the posterior thigh and the entire leg and foot. **Clinical Pearls for NEET-PG:** * **Meralgia Paraesthetica:** This is a high-yield clinical condition caused by the compression of the LCNT as it passes under the inguinal ligament. It presents with tingling, numbness, or burning pain on the outer aspect of the thigh. Common causes include tight clothing (belts), obesity, and pregnancy. * **Root Value:** Remember the LCNT is **L2, L3**. In contrast, the Femoral and Obturator nerves are **L2, L3, L4**. * **Purely Sensory:** The LCNT carries no motor fibers; therefore, its injury results in sensory loss only, with no muscle weakness.
Question 124: Which component of the lateral collateral ligament complex is most commonly affected in an ankle sprain?
- A. Middle component
- B. Anterior component (Correct Answer)
- C. Posterior component
- D. Deeper component
Explanation: The lateral collateral ligament (LCL) complex of the ankle consists of three distinct bands: the **Anterior Talofibular Ligament (ATFL)**, the **Calcaneofibular Ligament (CFL)**, and the **Posterior Talofibular Ligament (PTFL)**. ### 1. Why the Anterior Component is Correct The **Anterior Talofibular Ligament (ATFL)** is the **anterior component** of the LCL. It is the weakest of the three ligaments and is the first to be stressed during **inversion of a plantar-flexed foot** (the most common mechanism of an ankle sprain). Because it is thin and intracapsular, it is the most frequently injured ligament in the body. ### 2. Why Other Options are Incorrect * **Middle component (CFL):** The Calcaneofibular ligament is the middle band. It is stronger than the ATFL and is typically injured only after the ATFL has already ruptured (Grade II or III sprains). * **Posterior component (PTFL):** This is the strongest and deepest part of the lateral complex. It is rarely injured except in complete ankle dislocations because it is only under tension during extreme dorsiflexion. * **Deeper component:** While some ligaments have deep fibers (like the deltoid ligament on the medial side), the lateral complex is generally described by its anterior-to-posterior orientation. This is not a standard anatomical classification for the primary site of injury in a typical sprain. ### 3. Clinical Pearls for NEET-PG * **Mechanism of Injury:** Inversion + Plantarflexion. * **Sequence of Tear:** ATFL (most common) → CFL → PTFL (least common). * **Anterior Drawer Test:** Used clinically to assess the integrity of the ATFL. * **Talar Tilt Test:** Used to assess the integrity of the CFL. * **Medial Side:** The **Deltoid ligament** is much stronger than the lateral complex, which is why eversion sprains are less common but often involve avulsion fractures of the medial malleolus.
Question 125: What is the normal angle of the neck of the femur to its shaft?
- A. 110°
- B. 125° (Correct Answer)
- C. 170°
- D. 100°
Explanation: ### Explanation **1. Understanding the Correct Answer (B: 125°)** The **angle of inclination** (neck-shaft angle) is the angle formed between the long axis of the femoral neck and the long axis of the femoral shaft. In a normal adult, this angle typically ranges from **120° to 135°**, with **125°** being the most commonly cited average. This angle is crucial as it allows the femur to move freely away from the pelvis, facilitating limb mobility and providing a mechanical advantage to the hip abductors. **2. Analysis of Incorrect Options** * **A (110°):** This is significantly lower than normal. An angle less than 120° is termed **Coxa Vara**. * **C (170°):** This is excessively high. An angle greater than 135° is termed **Coxa Valga**. Note that in infants, the angle is naturally higher (around 150°) but decreases with weight-bearing. * **D (100°):** This represents a severe degree of Coxa Vara, often seen in pathological conditions like rickets or congenital deformities. **3. High-Yield Clinical Pearls for NEET-PG** * **Age Variation:** The angle is widest at birth (~150°) and gradually decreases to ~125° in adults due to the stresses of walking. It may further decrease in old age (predisposing to fractures). * **Coxa Vara (<120°):** Leads to shortening of the limb and a "Trendelenburg gait" because the abductors (Gluteus medius/minimus) become slack. * **Coxa Valga (>135°):** Leads to lengthening of the limb and increases the risk of hip dislocation. * **Angle of Anteversion:** Do not confuse the neck-shaft angle with the **angle of femoral torsion (anteversion)**, which is normally **15°** in adults (the angle the neck makes with the transverse axis of the femoral condyles).
Question 126: Damage to which of the following nerves leads to sensory loss on the adjacent sides of the great and second toes and impaired dorsiflexion of the foot?
- A. Superficial peroneal
- B. Lateral plantar
- C. Deep peroneal (Correct Answer)
- D. Sural
Explanation: ### Explanation The correct answer is **Deep peroneal nerve** (also known as the Deep Fibular nerve). #### 1. Why the Deep Peroneal Nerve is Correct The deep peroneal nerve is one of the two terminal branches of the common peroneal nerve. It is responsible for: * **Motor Supply:** It innervates the muscles of the anterior compartment of the leg (Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus, and Peroneus tertius). These muscles are the primary **dorsiflexors** of the foot. Damage leads to "Foot Drop." * **Sensory Supply:** Its cutaneous distribution is very specific—it supplies only the **first interdigital cleft** (the adjacent sides of the great and second toes). #### 2. Why Other Options are Incorrect * **A. Superficial peroneal nerve:** It supplies the lateral compartment of the leg (fibularis longus/brevis) for eversion. Its sensory distribution covers the majority of the **dorsum of the foot**, excluding the first web space. * **B. Lateral plantar nerve:** A branch of the tibial nerve, it supplies the intrinsic muscles of the sole and the skin of the lateral 1.5 toes on the **plantar surface**, not the dorsum. * **C. Sural nerve:** Formed by branches of the tibial and common peroneal nerves, it provides purely sensory innervation to the **lateral border of the foot** and the little toe. #### 3. Clinical Pearls for NEET-PG * **Anterior Compartment Syndrome:** Increased pressure in the anterior compartment can compress the deep peroneal nerve, leading to the symptoms described. * **Foot Drop:** Characterized by a "high-stepping gait." Remember: **P**eroneal **D**orsiflexes and **E**verts (**PED**); **T**ibial **P**lantarflexes and **I**nverts (**TIP**). * **Nerve Compression:** The common peroneal nerve is the most commonly injured nerve in the lower limb due to its superficial course around the **neck of the fibula**.
Question 127: What is the primary action of the quadratus femoris muscle?
- A. Extension
- B. Flexion
- C. Lateral rotation (Correct Answer)
- D. Medial rotation
Explanation: The **quadratus femoris** is a flat, quadrilateral muscle located in the gluteal region, belonging to the group of "short lateral rotators" of the hip. ### Why Lateral Rotation is Correct The muscle originates from the lateral border of the **ischial tuberosity** and inserts into the **quadrate tubercle** on the intertrochanteric crest of the femur. Due to its horizontal orientation and posterior position relative to the hip joint axis, its contraction pulls the greater trochanter posteriorly, resulting in the **lateral (external) rotation** of the thigh. It also assists in adduction. ### Why Other Options are Incorrect * **Extension:** This is primarily the function of the Gluteus maximus and the Hamstring group. * **Flexion:** This is the primary action of the Iliopsoas and Rectus femoris. * **Medial rotation:** This is performed by the Gluteus medius, Gluteus minimus (anterior fibers), and Tensor fasciae latae. ### NEET-PG High-Yield Pearls * **Nerve Supply:** It is supplied by the **Nerve to Quadratus Femoris** (L4, L5, S1), which also supplies the **Inferior gemellus**. * **Cruciate Anastomosis:** The quadratus femoris serves as the anatomical landmark for the cruciate anastomosis of the thigh; the transverse branch of the medial circumflex femoral artery runs across its superior border. * **The "Short Rotator" Group:** Includes the Piriformis, Obturator internus, Superior/Inferior gemelli, and Quadratus femoris. All are lateral rotators.
Question 128: Which muscles are responsible for the flexion of the knee joint?
- A. Rectus femoris
- B. Vastus medialis
- C. Hamstrings (Correct Answer)
- D. Vastus lateralis
Explanation: **Explanation:** The primary movement of the knee joint is flexion and extension. **Flexion** (decreasing the angle between the thigh and leg) is primarily executed by the **Hamstring group** of muscles located in the posterior compartment of the thigh. **1. Why Hamstrings are correct:** The Hamstrings consist of three muscles: **Biceps femoris, Semitendinosus, and Semimembranosus**. They originate from the ischial tuberosity (except the short head of biceps) and insert around the proximal tibia and fibula. Because they cross posterior to the knee joint axis, their contraction pulls the leg backward, resulting in flexion. They are innervated by the sciatic nerve. **2. Why the other options are incorrect:** * **Rectus femoris, Vastus medialis, and Vastus lateralis:** These are components of the **Quadriceps femoris muscle group** located in the anterior compartment of the thigh. They insert into the tibial tuberosity via the patellar ligament. Since they cross anterior to the knee joint, they act as the primary **extensors** of the knee, not flexors. **3. Clinical Pearls & High-Yield Facts:** * **Unlocker of the Knee:** While hamstrings are the main flexors, the **Popliteus** muscle is known as the "Key to the knee" because it initiates flexion by laterally rotating the femur on the fixed tibia (unlocking the joint). * **Sartorius & Gracilis:** These muscles also assist in knee flexion and form the **Pes Anserinus** (Goose's foot) insertion on the medial tibia along with the Semitendinosus. * **Nerve Supply:** A common NEET-PG trap is the nerve supply of the Biceps Femoris; the long head is supplied by the tibial part of the sciatic nerve, while the short head is supplied by the common peroneal part.
Question 129: Which statement about the Posterior Cruciate Ligament is true?
- A. It is attached to the lateral femoral condyle.
- B. It is an intrasynovial structure.
- C. It prevents posterior dislocation of the tibia. (Correct Answer)
- D. It is relaxed in full flexion.
Explanation: ### Explanation The **Posterior Cruciate Ligament (PCL)** is one of the two major intra-articular ligaments of the knee, playing a vital role in joint stability. **Why Option C is Correct:** The primary function of the PCL is to prevent **posterior displacement of the tibia** relative to the femur. It acts as the main stabilizer against posterior tibial translation. Clinically, a deficiency or tear in the PCL results in a "posterior sag" of the tibia (Sag Sign). **Analysis of Incorrect Options:** * **Option A:** The PCL attaches to the **medial femoral condyle** (specifically the anterolateral aspect). A common mnemonic to remember cruciate attachments is **LAMP**: **L**ateral femoral condyle = **A**nterior cruciate; **M**edial femoral condyle = **P**osterior cruciate. * **Option B:** While the PCL is intra-articular (inside the joint capsule), it is **extrasynovial**. The synovial membrane reflects around the cruciate ligaments, excluding them from the synovial cavity. * **Option D:** The PCL becomes **taut (stretched) during full flexion** of the knee. In contrast, the ACL is taut in full extension. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Injury:** The most common cause is a "dashboard injury" (direct blow to the proximal tibia while the knee is flexed). * **Clinical Test:** The **Posterior Drawer Test** is the most specific clinical examination for PCL integrity. * **Blood Supply:** Both cruciate ligaments are primarily supplied by the **middle genicular artery** (a branch of the popliteal artery). * **Strength:** The PCL is significantly thicker and stronger than the ACL.
Question 130: Lateral meniscus is less prone to injury than medial meniscus because of the following reasons, except?
- A. Lateral meniscus is less mobile than medial meniscus.
- B. Lateral meniscus is opened outwards by the popliteus. (Correct Answer)
- C. Lateral meniscus is more adapted to sustain injury.
- D. Lateral meniscus undergoes less excursion during rotatory movement.
Explanation: The **Medial Meniscus** is fixed and C-shaped, making it 20 times more prone to injury than the **Lateral Meniscus**, which is nearly circular and highly mobile. ### **Explanation of the Correct Option** **Option B** is the correct answer because it is a **false statement** regarding the mechanism. The popliteus muscle does not "open it outwards" to prevent injury; rather, the **popliteus tendon** is attached to the posterior horn of the lateral meniscus. During knee flexion, the popliteus pulls the lateral meniscus **posteriorly**, moving it out of the way of the compressing femoral condyles. This active retraction is a protective mechanism, not an "opening outwards." ### **Analysis of Other Options** * **Option A:** This is incorrect because the lateral meniscus is actually **more mobile** than the medial meniscus. The medial meniscus is firmly attached to the Tibial Collateral Ligament (MCL), restricting its movement. The lateral meniscus is not attached to the LCL, allowing it to glide and escape entrapment. * **Option C:** The lateral meniscus is structurally more "adapted" to sustain stress because its circular shape covers a larger percentage of the articular surface compared to the medial meniscus. * **Option D:** During rotatory movements, the lateral meniscus undergoes controlled excursion due to its lack of rigid peripheral attachments, allowing it to adapt to the femoral condyle's position without tearing. ### **High-Yield Clinical Pearls for NEET-PG** * **O’Donoghue’s Unhappy Triad:** Consists of injury to the **Anterior Cruciate Ligament (ACL)**, **Medial Collateral Ligament (MCL)**, and **Medial Meniscus**. * **McMurray Test:** Used to diagnose meniscal tears (Internal rotation for lateral meniscus; External rotation for medial meniscus). * **Blood Supply:** The peripheral 1/3 (Red zone) is vascularized and can heal; the central 2/3 (White zone) is avascular and requires surgical excision if torn.
Practice by Chapter
Gluteal Region and Hip
Practice Questions
Thigh and Popliteal Fossa
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Leg and Foot
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Joints of Lower Limb
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Nerves of Lower Limb
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Arterial Supply and Venous Drainage
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Lymphatic Drainage
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Muscles and Their Actions
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Gait Analysis and Biomechanics
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Applied Anatomy and Clinical Correlations
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