Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 391: Which of the following tendons is more likely to rupture during violent dorsiflexion of the foot?

A. Extensor hallucis longus (EHL)
B. Extensor digitorum longus (EDL)
C. Flexor hallucis longus (FHL)
D. Plantaris tendon (Correct Answer)

Explanation: The **Plantaris tendon** is the correct answer due to its unique anatomical and functional characteristics. Often referred to as the "Freshman’s Nerve" (because it can be mistaken for a nerve by first-year students), it is a vestigial muscle with a very long, thin, and cord-like tendon. **Why it ruptures:** The plantaris muscle crosses two joints (knee and ankle). During **violent dorsiflexion** of the foot—especially when the knee is simultaneously extended—the tendon is subjected to extreme eccentric loading. Because it is thin and has relatively low tensile strength compared to the robust Achilles or extrinsic extensor tendons, it is prone to sudden rupture. This clinical scenario is often called **"Tennis Leg,"** characterized by a sudden "pop" and sharp pain in the calf, mimicking a more severe Achilles rupture or a gastrocnemius tear. **Analysis of Incorrect Options:** * **A & B (EHL and EDL):** These are anterior compartment muscles. Their primary action is dorsiflexion. They are under tension during plantarflexion, not dorsiflexion. Ruptures of these tendons are rare and usually result from direct trauma or lacerations. * **C (FHL):** While the FHL is a posterior muscle, it is a thick, powerful tendon. It is more commonly associated with chronic "Stenosing Tenosynovitis" (Dancer’s Tendonitis) in ballet dancers rather than acute rupture during dorsiflexion. **High-Yield Clinical Pearls for NEET-PG:** * **Tennis Leg:** Classically involves the rupture of the plantaris tendon or the medial head of the gastrocnemius. * **Graft Source:** Despite its propensity to rupture, the plantaris tendon is a common source for **autologous tendon grafting** (e.g., for hand surgery) because its absence does not result in functional deficit. * **Anatomy:** It is absent in approximately 7–10% of the population.

Question 392: Which of the following movements will not be affected by involvement of the L5 Nerve root?

A. Thigh adduction (Correct Answer)
B. Knee Flexion
C. Knee Extension
D. Toe Extension

Explanation: To answer this question, one must understand the segmental innervation (myotomes) of the lower limb. The **L5 nerve root** is a major contributor to movements of the hip, knee, and foot, but it does not significantly supply the adductor compartment of the thigh. ### 1. Why "Thigh Adduction" is the Correct Answer Thigh adduction is primarily performed by the Adductor group (Longus, Brevis, Magnus) and the Gracilis. These muscles are innervated by the **Obturator nerve**, which carries fibers from the **L2, L3, and L4** nerve roots. Since L5 does not contribute to the obturator nerve or the primary adductor function, this movement remains unaffected in an isolated L5 lesion. ### 2. Analysis of Incorrect Options * **Knee Flexion:** Performed by the Hamstrings. While primarily S1, the hamstrings (especially Semimembranosus and Semitendinosus) receive significant innervation from **L5**. * **Knee Extension:** Performed by the Quadriceps (L2, L3, **L4**). However, the **Tensor Fasciae Latae (TFL)**, which assists in stabilizing the knee during extension, is innervated by the Superior Gluteal Nerve (**L4, L5, S1**). * **Toe Extension:** This is the **classic L5 test**. The Extensor Hallucis Longus (EHL) and Extensor Digitorum Longus are primarily supplied by **L5** via the Deep Peroneal Nerve. ### 3. High-Yield Clinical Pearls for NEET-PG * **L5 Nerve Root Syndrome:** Characterized by weakness in **foot dorsiflexion** (with L4), **big toe extension** (EHL), and **foot eversion**. Sensory loss typically occurs on the lateral leg and the dorsum of the foot. * **Trendelenburg Sign:** L5 supplies the **Gluteus Medius and Minimus** (Superior Gluteal Nerve). An L5 lesion can lead to a positive Trendelenburg sign. * **Mnemonic for Myotomes:** * L2-L3: Hip Flexion * L3-L4: Knee Extension * **L4-L5: Dorsiflexion** * **L5: Big Toe Extension** * S1: Plantarflexion

Question 393: Which of the following is true about the medial meniscus?

A. Made up of hyaline cartilage
B. Injury of the lateral meniscus is more frequent than the medial meniscus
C. C-shaped (Correct Answer)
D. Inner part is more avascular

Explanation: ### Explanation **Correct Answer: C. C-shaped** The **medial meniscus** is a fibrocartilaginous disc located within the knee joint. It is characterized by its **large, semicircular, or "C-shaped"** appearance. In contrast, the lateral meniscus is more circular (nearly a complete ring) and smaller in diameter. #### Analysis of Options: * **A. Made up of hyaline cartilage:** This is incorrect. Menisci are composed of **fibrocartilage**, which provides high tensile strength and elasticity to withstand compressive loads. Hyaline cartilage covers the articular surfaces of the bones, not the menisci themselves. * **B. Injury of the lateral meniscus is more frequent:** This is incorrect. The **medial meniscus is injured 20 times more frequently** than the lateral meniscus. This is because the medial meniscus is firmly attached to the **Medial Collateral Ligament (MCL)** and the joint capsule, making it less mobile and more prone to tearing during rotational stress. * **D. Inner part is more avascular:** While this statement is technically a physiological fact (the inner 2/3rd is avascular and the outer 1/3rd is vascular), it is often considered a general property of *both* menisci. In the context of this specific question, "C-shaped" is the definitive anatomical descriptor that distinguishes the medial from the lateral meniscus. #### NEET-PG High-Yield Pearls: * **Shape:** Medial = C-shaped; Lateral = O-shaped (Circular). * **Mobility:** The lateral meniscus is more mobile because it is not attached to the Lateral Collateral Ligament (separated by the Popliteus tendon). * **Unhappy Triad of O'Donoghue:** Simultaneous injury to the **Anterior Cruciate Ligament (ACL)**, **Medial Collateral Ligament (MCL)**, and **Medial Meniscus**. * **Blood Supply:** The peripheral "Red Zone" has a good blood supply (healing possible), while the central "White Zone" is avascular (requires excision/meniscectomy).

Question 394: Which of the following structures does not drain to the superficial inguinal lymph nodes?

A. Perineum
B. Feet
C. Scrotum
D. Testicle (Correct Answer)

Explanation: The lymphatic drainage of the lower limb and pelvis is a high-yield topic for NEET-PG, primarily governed by the embryological origin of the structures. ### **Why the Testicle is the Correct Answer** The **testicles** do not drain into the superficial inguinal lymph nodes because they develop in the posterior abdominal wall (near the level of L2) and descend into the scrotum during fetal development. Consequently, they carry their lymphatic drainage back to their site of origin: the **Para-aortic (Pre-aortic) lymph nodes**. ### **Analysis of Incorrect Options** The **Superficial Inguinal Lymph Nodes** receive drainage from the skin and superficial structures below the umbilicus (excluding the lateral side of the foot and the glans penis/clitoris). * **A. Perineum:** The skin of the perineum and the anal canal (below the pectinate line) drain into the superficial inguinal nodes. * **B. Feet:** Most of the skin of the foot (except the lateral border, which drains to popliteal nodes) drains via the medial lymphatic vessels to the superficial inguinal nodes. * **C. Scrotum:** Unlike the testicles, the scrotum is a cutaneous structure. Its lymphatic drainage follows the skin of the perineum to the superficial inguinal nodes. ### **High-Yield Clinical Pearls for NEET-PG** * **Testicular Cancer:** Presents with enlargement of para-aortic nodes, not inguinal nodes. * **Scrotal Cancer:** Spreads to superficial inguinal nodes. * **The "Glans" Exception:** The glans penis and glans clitoris bypass the superficial nodes and drain directly into the **Deep Inguinal Lymph Nodes** (Cloquet’s node). * **The "Lateral Foot" Exception:** Lymphatics from the lateral side of the foot follow the small saphenous vein to the **Popliteal nodes**.

Question 395: Which of the following bones is involved in the unlocking of the knee?

A. Navicular
B. Calcaneum
C. Talus (Correct Answer)
D. Cuboid

Explanation: **Explanation:** The "unlocking" of the knee is a critical biomechanical event required to initiate flexion from a fully extended position. In a **weight-bearing (closed chain)** position, unlocking is achieved by the **lateral rotation of the femur** on the tibia. This rotation is primarily driven by the **Popliteus muscle**, often referred to as the "Key to the knee." **Why Talus is the Correct Answer:** In the weight-bearing phase, the tibia is fixed to the foot. For the femur to rotate laterally and unlock the knee, the leg must have a degree of freedom. The **Talus** acts as the crucial link in the kinetic chain. During the initiation of flexion, the talus undergoes slight movement within the ankle mortise and at the subtalar joint to accommodate the rotational forces transmitted from the popliteus through the tibia. Among the options provided, the Talus is the only bone directly involved in the mechanical chain of the ankle/foot complex that facilitates the rotational alignment necessary for the knee to unlock while standing. **Analysis of Incorrect Options:** * **Navicular, Calcaneum, and Cuboid:** While these are essential tarsal bones for foot stability and the longitudinal/transverse arches, they do not play a primary role in the rotational mechanics of the knee joint. They are distal to the talocrural joint and do not serve as the primary pivot point for leg rotation. **High-Yield Clinical Pearls for NEET-PG:** * **Unlocking Muscle:** Popliteus (originates from the lateral femoral condyle). * **Open Chain (Sitting):** Unlocking occurs via **medial rotation of the tibia**. * **Closed Chain (Standing):** Unlocking occurs via **lateral rotation of the femur**. * **Locking:** Occurs during full extension via medial rotation of the femur (closed chain) to increase joint stability.

Question 396: Which of the following is NOT true about the femoral nerve?

A. It lies outside the femoral sheath.
B. The saphenous nerve is its largest cutaneous branch.
C. It supplies the femoral artery.
D. Its root value is L2-L5. (Correct Answer)

Explanation: **Explanation:** The **femoral nerve** is the largest branch of the lumbar plexus and serves as the primary nerve of the anterior compartment of the thigh. **1. Why Option D is the correct answer (The False Statement):** The root value of the femoral nerve is **L2, L3, and L4** (posterior divisions of the ventral rami). It does not involve L5. In the NEET-PG context, root values are high-yield; for instance, the Obturator nerve also shares the L2-L4 roots but arises from the *anterior* divisions. **2. Analysis of Incorrect Options (True Statements):** * **Option A:** The femoral sheath contains the femoral artery, femoral vein, and the femoral canal (lymphatics). The **femoral nerve lies lateral to and outside the sheath**, separated from the vessels by the iliac fascia. * **Option B:** The **saphenous nerve** is indeed the longest and largest cutaneous branch of the femoral nerve. It accompanies the femoral artery in the adductor canal and provides sensation to the medial side of the leg and foot. * **Option C:** The femoral nerve provides vascular branches to the **femoral artery** and its branches, regulating vasomotor tone. **Clinical Pearls for NEET-PG:** * **Nerve Injury:** Injury to the femoral nerve (e.g., by pelvic fractures or hematomas) leads to wasting of the quadriceps, loss of knee extension, and loss of the **patellar reflex (L3-L4)**. * **Meralgia Paraesthetica:** This involves the *Lateral Cutaneous Nerve of Thigh* (L2-L3), not the femoral nerve. * **Hilton’s Law:** The femoral nerve supplies the hip and knee joints, explaining why hip pathology often presents as referred pain to the knee.

Question 397: A 42-year-old mother of three children visits the outpatient clinic complaining that her youngest son cannot walk yet. Radiographic and physical examinations reveal an unstable hip joint. Which of the following ligaments is responsible for stabilization of the hip joint in childhood?

A. Iliofemoral
B. Pubofemoral
C. Ischiofemoral
D. Ligament of the head of the femur (Correct Answer)

Explanation: **Explanation:** The **ligament of the head of the femur** (ligamentum teres) is a triangular, somewhat flattened band that extends from the acetabular notch to the fovea capitis of the femur. **Why it is correct:** In early childhood, the ligament of the head of the femur plays a critical role in hip stability. It contains the **acetabular branch of the obturator artery**, which is the primary blood supply to the epiphysis of the femoral head before the medial and lateral circumflex arteries fully take over this role. Damage or laxity of this ligament in a child can lead to joint instability and potential avascular necrosis. While its mechanical stabilizing role diminishes in adults, it remains a vital structure during the developmental years. **Why the other options are incorrect:** * **A, B, and C (Iliofemoral, Pubofemoral, Ischiofemoral):** These are the three major extracapsular ligaments of the hip. While they provide significant stability in adults (especially the **Iliofemoral ligament**, which is the strongest ligament in the body and prevents hyperextension), they are not the primary structures responsible for the specific developmental stability and vascular integrity required in early childhood. **High-Yield Clinical Pearls for NEET-PG:** * **Iliofemoral Ligament (Y-ligament of Bigelow):** Strongest ligament in the body; prevents hyperextension of the hip. * **Ischiofemoral Ligament:** Weakest of the three extracapsular ligaments; limits internal rotation. * **Blood Supply:** In adults, the main blood supply to the femoral head is the **medial circumflex femoral artery** (via retinacular arteries). In children, the artery within the ligamentum teres is crucial. * **Clinical Correlation:** Damage to the acetabular branch in the ligamentum teres during childhood can lead to **Legg-Calvé-Perthes disease**.

Question 398: A 'saphenous vein cutdown' is a procedure used to locate the great saphenous vein at the ankle. To find this vein, the skin would be incised where?

A. Anterior to the lateral epicondyle
B. Posterior to the medial epicondyle
C. Anterior to the medial malleolus (Correct Answer)
D. Posterior to the lateral malleolus

Explanation: The **Great Saphenous Vein (GSV)** is the longest vein in the body and is a critical site for emergency venous access (venous cutdown) when peripheral veins are collapsed [1]. **1. Why Option C is Correct:** At the level of the ankle, the GSV consistently passes **anterior to the medial malleolus**. This anatomical landmark is highly reliable. During a cutdown, a transverse incision is made roughly 2.5 cm anterior and superior to the medial malleolus. At this specific location, the vein is superficial and can be easily isolated from the surrounding subcutaneous fat. **2. Analysis of Incorrect Options:** * **Option A (Anterior to lateral epicondyle):** This refers to the knee region. While the GSV passes medial to the knee (posterior to the medial condyle), it has no relation to the lateral epicondyle. * **Option B (Posterior to medial epicondyle):** At the knee, the GSV passes about a hand’s breadth **posterior** to the medial border of the patella and the medial condyle/epicondyle of the femur. However, the question specifically asks for the location at the **ankle**. * **Option D (Posterior to the lateral malleolus):** This is the anatomical landmark for the **Small Saphenous Vein**, which runs along the lateral aspect of the foot and ascends behind the lateral malleolus to eventually drain into the popliteal vein [1]. **3. Clinical Pearls for NEET-PG:** * **Nerve at Risk:** The **Saphenous Nerve** (a branch of the femoral nerve) runs immediately adjacent to the GSV at the ankle [2]. Injury during a cutdown leads to loss of sensation along the medial border of the foot. * **Course:** The GSV originates from the medial end of the dorsal venous arch, passes anterior to the medial malleolus, ascends the medial leg/thigh, and terminates at the **saphenous opening** (cribriform fascia) by joining the femoral vein. * **Valves:** It contains approximately 10–12 valves, with the most functional one located at the saphenofemoral junction.

Question 399: What is true about the iliotibial tract?

A. Thickening of the fascia lata (Correct Answer)
B. Gluteus medius is inserted into it
C. Insertion at the medial aspect of the tibia
D. Runs along the medial aspect of the thigh

Explanation: ### Explanation **1. Why the Correct Answer is Right:** The **iliotibial tract (ITT)** is a longitudinal fibrous reinforcement of the **fascia lata** (the deep fascia of the thigh). It is formed by the thickening of this fascia on the lateral aspect of the thigh. Superiorly, it splits into two layers to enclose the tensor fasciae latae and receives the insertion of the gluteus maximus. It acts as a stabilizer for the knee joint during walking and running. **2. Why the Other Options are Wrong:** * **Option B:** The **gluteus medius** inserts into the lateral surface of the **greater trochanter** of the femur, not the ITT. It is the **gluteus maximus** (superficial 3/4th) and the **tensor fasciae latae** that insert into the iliotibial tract. * **Option C:** The ITT inserts into the **lateral condyle of the tibia** at a specific bony prominence known as **Gerdy’s tubercle**. It does not insert on the medial aspect. * **Option D:** The ITT is located strictly on the **lateral aspect** of the thigh, extending from the iliac crest to the lateral tibial condyle. **3. High-Yield Clinical Pearls for NEET-PG:** * **Gerdy’s Tubercle:** Always remember this specific insertion point on the lateral tibial condyle; it is a frequent "one-liner" question. * **Iliotibial Band Syndrome:** An overuse injury common in runners and cyclists caused by friction of the ITT against the **lateral femoral epicondyle**. * **Function:** It helps maintain the knee in extension and stabilizes the pelvis while standing on one leg. * **Nerve Supply:** Since it encloses the tensor fasciae latae, it is functionally associated with the **superior gluteal nerve (L4, L5, S1)**.

Question 400: Which artery supplies the gluteus medius muscle?

A. Obturator artery
B. Ilio-inguinal artery
C. Superior gluteal artery (Correct Answer)
D. Inferior gluteal artery

Explanation: **Explanation:** The **superior gluteal artery (SGA)** is the largest branch of the internal iliac artery. It exits the pelvis through the greater sciatic foramen, passing superior to the piriformis muscle. It divides into a superficial branch (supplying the gluteus maximus) and a **deep branch**, which runs between the gluteus medius and minimus, providing the primary blood supply to both these muscles as well as the tensor fasciae latae. **Analysis of Incorrect Options:** * **Obturator artery:** A branch of the internal iliac artery that passes through the obturator canal to supply the medial compartment (adductors) of the thigh and the head of the femur via the ligamentum teres. * **Ilio-inguinal artery:** This is a distractor; the *ilio-inguinal* is a nerve (L1), not an artery. The *iliolumbar* artery exists but supplies the iliacus and psoas muscles. * **Inferior gluteal artery:** While it also exits the greater sciatic foramen (inferior to the piriformis), it primarily supplies the **gluteus maximus**, the pelvic diaphragm, and the proximal hamstrings. **High-Yield Clinical Pearls for NEET-PG:** * **The Piriformis Landmark:** The piriformis is the "key" muscle of the gluteal region. The **Superior** gluteal artery/nerve exit **above** it, while the **Inferior** gluteal artery/nerve and the **Sciatic nerve** exit **below** it. * **Trendelenburg Sign:** The superior gluteal **nerve** (which accompanies the artery) innervates the gluteus medius and minimus. Injury to this nerve leads to a positive Trendelenburg sign (pelvic tilt toward the unsupported side during walking). * **Cruciate Anastomosis:** The inferior gluteal artery participates in the cruciate anastomosis of the thigh, providing collateral circulation between the internal iliac and femoral systems.

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Lower Limb — MCQs

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