Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 141: What is another name for the spring ligament?

A. Calcaneonavicular ligament (Correct Answer)
B. Calcaneocuboid ligament
C. Transverse tibiofibular ligament
D. Talocalcaneal ligament

Explanation: The **Spring Ligament** is a critical structure in the anatomy of the foot, specifically known as the **Plantar Calcaneonavicular Ligament**. ### Why Option A is Correct The spring ligament connects the **sustentaculum tali** of the calcaneus to the plantar surface of the **navicular bone**. It is called the "spring" ligament because it is composed of dense fibroelastic tissue that supports the head of the talus. Its primary function is to maintain the **medial longitudinal arch** of the foot by preventing the talus from dropping downward and medially under the weight of the body. ### Why Other Options are Incorrect * **B. Calcaneocuboid ligament:** This refers to the short and long plantar ligaments. While they support the lateral longitudinal arch, they do not support the head of the talus. * **C. Transverse tibiofibular ligament:** This is part of the distal tibiofibular syndesmosis at the ankle joint, preventing the separation of the tibia and fibula. * **D. Talocalcaneal ligament:** These ligaments (interosseous, medial, lateral) stabilize the subtalar joint but do not form the "spring" mechanism for the arch. ### NEET-PG High-Yield Pearls * **Clinical Correlation:** Chronic stretching or rupture of the spring ligament leads to **Pes Planus (Flat Foot)**, as the head of the talus descends. * **The "Keystone":** In the medial longitudinal arch, the **Talus** is the keystone, but the spring ligament is the main static stabilizer. * **Anatomical Relation:** The tendon of the **Tibialis Posterior** muscle passes immediately inferior to the spring ligament, providing additional dynamic support to the arch.

Question 142: A 46-year-old woman stepped on a broken wine bottle, and sharp glass entered the posterior part of her foot. Physical examination concluded that her lateral plantar nerve had been transected. Which of the following conditions will most likely be confirmed by physical examination?

A. Loss of sensation over the plantar surface of the third toe
B. Paralysis of the abductor hallucis
C. Paralysis of the interossei and adductor hallucis (Correct Answer)
D. Flexor hallucis brevis paralysis

Explanation: ### Explanation The **lateral plantar nerve (LPN)**, a branch of the tibial nerve, is functionally analogous to the **ulnar nerve** in the hand. It supplies the majority of the intrinsic muscles of the foot and provides sensation to the lateral 1.5 digits. #### Why the Correct Answer is Right: * **Muscular Supply:** The LPN supplies the **adductor hallucis**, all **interossei** (plantar and dorsal), the lateral three lumbricals, and the muscles of the little toe (abductor, flexor, and opponens digiti minimi). * **Mechanism:** Transection of the LPN leads to denervation of these muscles, resulting in paralysis of the interossei (responsible for abduction/adduction of toes) and the adductor hallucis. #### Why Other Options are Wrong: * **Option A:** Sensation over the plantar surface of the **third toe** is provided by the **medial plantar nerve** (which covers the medial 3.5 digits). The LPN covers the lateral 1.5 digits (5th and lateral half of 4th). * **Option B:** The **abductor hallucis** is supplied by the **medial plantar nerve** (analogous to the median nerve in the hand). * **Option D:** The **flexor hallucis brevis** is primarily supplied by the **medial plantar nerve**. (Note: The LPN may occasionally supply the lateral head, but the medial plantar nerve is the primary driver). #### High-Yield Clinical Pearls for NEET-PG: * **The "Rule of 4":** The **Medial Plantar Nerve** supplies only **4** muscles: 1. Abductor hallucis 2. Flexor digitorum brevis 3. Flexor hallucis brevis 4. First lumbrical * **The Lateral Plantar Nerve** supplies **all other** intrinsic muscles of the foot. * **Sensory Split:** The division between medial and lateral plantar nerves occurs at the midline of the **4th digit**. * **Clinical Correlation:** Injury to the LPN often presents with "clawing" of the toes due to the loss of interossei and lumbrical function.

Question 143: Which of the following statements about the Anterior Cruciate Ligament (ACL) is true?

A. It attaches to the posterior part of the intercondylar area of the tibia.
B. It is stronger than the posterior cruciate ligament.
C. It attaches upward, backward, and laterally to the posterior aspect of the lateral surface of the medial femoral condyle.
D. It prevents posterior dislocation of the femur on the tibia. (Correct Answer)

Explanation: The **Anterior Cruciate Ligament (ACL)** is a critical stabilizer of the knee joint. It originates from the **anterior** part of the intercondylar area of the tibia and extends upward, backward, and laterally to attach to the posterior part of the **medial surface of the lateral femoral condyle**. ### Why the Correct Answer is Right: The primary function of the ACL is to prevent **anterior translation of the tibia** relative to the femur. Conversely, this means it prevents **posterior dislocation of the femur on the tibia**, especially when the knee is flexed and weight-bearing (e.g., walking downhill). ### Analysis of Incorrect Options: * **Option A:** Incorrect. The ACL attaches to the **anterior** part of the tibial intercondylar area. The Posterior Cruciate Ligament (PCL) attaches to the posterior part. * **Option B:** Incorrect. The **PCL is stronger** and thicker than the ACL. This is why ACL tears are significantly more common in clinical practice. * **Option C:** Incorrect. This is a common "trap" description. The ACL attaches to the **lateral femoral condyle** (specifically the medial surface of its posterior part). The PCL attaches to the medial femoral condyle. ### High-Yield Clinical Pearls for NEET-PG: * **Blood Supply:** Primarily from the **Middle Genicular Artery** (branch of the popliteal artery). * **Nerve Supply:** Tibial nerve. * **Testing:** The **Lachman test** is the most sensitive clinical test for an ACL tear, followed by the Anterior Drawer test. * **Unhappy Triad (O'Donoghue):** Involves injury to the ACL, Medial Collateral Ligament (MCL), and Medial Meniscus (though recent studies suggest the Lateral Meniscus is more commonly involved in acute injuries). * **Mechanism:** Most ACL injuries occur during non-contact deceleration, jumping, or pivoting.

Question 144: The skin and fascia of the great toe drain into which lymph node group?

A. Superficial inguinal lymph nodes, vertical group (Correct Answer)
B. Superficial inguinal lymph nodes, horizontal group
C. Obturator lymph nodes
D. Deep inguinal lymph nodes

Explanation: ### Explanation **1. Why Option A is Correct:** The lymphatic drainage of the lower limb follows a specific pattern based on the venous system. The skin and fascia of the **great toe**, along with the medial side of the foot and the entire medial aspect of the leg and thigh, follow the course of the **Great Saphenous Vein**. These lymphatics drain directly into the **Vertical Group of Superficial Inguinal Lymph Nodes** . This group is situated along the terminal part of the great saphenous vein. **2. Why the Other Options are Incorrect:** * **Option B (Horizontal Group):** This group (further divided into medial and lateral) primarily drains the anterior abdominal wall (below the umbilicus), the perineum, the external genitalia (excluding testes), and the gluteal region. It does not receive direct drainage from the toes. * **Option C (Obturator Nodes):** These are deep pelvic nodes that drain pelvic viscera and the adductor compartment of the thigh; they are not primary drainage sites for cutaneous lymphatics of the foot. * **Option D (Deep Inguinal Nodes):** These nodes (including the Node of Cloquet) receive drainage from the deep structures of the limb (bones/muscles), the glans penis/clitoris, and the efferents from the superficial inguinal nodes. While the vertical group eventually drains into the deep nodes, the *primary* first-order drainage for the great toe is the superficial vertical group . **3. High-Yield Clinical Pearls for NEET-PG:** * **Lateral Side of Foot:** Lymphatics from the lateral side of the foot and the little toe follow the **Small Saphenous Vein** and drain into the **Popliteal Lymph Nodes** first. * **The

Question 145: Which nerve supplies the gluteus medius?

A. Superior Gluteal Nerve (Correct Answer)
B. Inferior Gluteal Nerve
C. Nerve to Obturator Internus
D. Nerve to Quadratus Femoris

Explanation: **Explanation:** The **Superior Gluteal Nerve (L4, L5, S1)** is a branch of the sacral plexus. It exits the pelvis through the greater sciatic foramen, passing *above* the piriformis muscle. It provides motor innervation to three specific muscles: the **Gluteus Medius**, **Gluteus Minimus**, and the **Tensor Fasciae Latae (TFL)**. These muscles are the primary abductors and medial rotators of the hip. **Analysis of Incorrect Options:** * **B. Inferior Gluteal Nerve (L5, S1, S2):** This nerve exits *below* the piriformis and exclusively supplies the **Gluteus Maximus**, the chief extensor of the hip. * **C. Nerve to Obturator Internus (L5, S1, S2):** Supplies the Obturator Internus and the Superior Gemellus. * **D. Nerve to Quadratus Femoris (L4, L5, S1):** Supplies the Quadratus Femoris and the Inferior Gemellus. **High-Yield Clinical Pearls for NEET-PG:** 1. **Trendelenburg Sign:** Injury to the superior gluteal nerve (often due to misplaced intramuscular injections or hip surgery) leads to paralysis of the gluteus medius and minimus. This results in the pelvis dropping on the unsupported side when the patient stands on the affected leg. 2. **Lurching Gait:** To compensate for the pelvic drop, the patient tilts their trunk toward the affected side (compensated Trendelenburg gait). 3. **The "Safe Zone":** Intramuscular injections are given in the **upper outer quadrant** of the gluteal region to avoid injuring the sciatic nerve and the gluteal nerves.

Question 146: Inversion and eversion movements occur at which of the following joints?

A. Ankle joints
B. Subtalar joints (Correct Answer)
C. Tibiotalar joints
D. Transverse tarsal joints

Explanation: The movements of inversion and eversion are complex, multi-planar movements that occur primarily at the **Subtalar joint** and the **Transverse tarsal (Midtarsal) joints**. **1. Why the Subtalar Joint is Correct:** The subtalar joint is the articulation between the talus and the calcaneus. Its primary functional role is to allow the foot to tilt medially (inversion) and laterally (eversion). While the transverse tarsal joints (Chopart's joint) contribute to the range of motion, the subtalar joint is the principal site for these movements, especially during the initial phase of gait on uneven terrain. **2. Analysis of Incorrect Options:** * **Ankle Joint (Tibiotalar Joint):** Options A and C refer to the same anatomical structure. The ankle joint is a **hinge joint** (ginglymus) formed by the tibia, fibula, and talus. It allows only for **dorsiflexion and plantarflexion**. It does not permit side-to-side movements like inversion/eversion. * **Transverse Tarsal Joints:** While these joints (composed of the talonavicular and calcaneocuboid joints) do participate in inversion and eversion, they function in synergy with the subtalar joint. In most standard medical examinations, if both are listed, the **Subtalar joint** is considered the primary and most definitive answer. **Clinical Pearls & High-Yield Facts:** * **Inversion** is performed mainly by the **Tibialis Anterior** and **Tibialis Posterior** muscles. * **Eversion** is performed mainly by the **Peroneus (Fibularis) Longus** and **Brevis**. * **Ligament Injury:** Inversion injuries (the most common type of ankle sprain) typically damage the **Anterior Talofibular Ligament (ATFL)**. * **Axis of Movement:** The axis for inversion/eversion is oblique, running from the lateral-posterior-inferior aspect to the medial-anterior-superior aspect of the tarsals.

Question 147: The peroneal artery is a branch of which artery?

A. Anterior tibial artery
B. Popliteal artery
C. Posterior tibial artery (Correct Answer)
D. Arcuate artery

Explanation: **Explanation:** The **peroneal artery** (also known as the fibular artery) is the largest and most important branch of the **posterior tibial artery**. It typically arises approximately 2.5 cm distal to the lower border of the popliteus muscle. It descends along the medial aspect of the fibula, supplying the lateral compartment of the leg and the calcaneal region. **Analysis of Options:** * **Posterior Tibial Artery (Correct):** After the popliteal artery divides into the anterior and posterior tibial arteries, the posterior tibial artery gives off the peroneal artery via the **tibioperoneal trunk**. * **Anterior Tibial Artery:** This artery passes forward through the opening in the interosseous membrane to supply the anterior compartment. It does not give rise to the peroneal artery. * **Popliteal Artery:** This is the parent trunk that terminates at the lower border of the popliteus by dividing into the anterior and posterior tibial arteries. It does not directly branch into the peroneal artery. * **Arcuate Artery:** This is a branch of the dorsalis pedis artery (the continuation of the anterior tibial artery) located on the dorsum of the foot. **High-Yield Clinical Pearls for NEET-PG:** * **Nutrient Artery:** The peroneal artery provides the nutrient artery to the **fibula**, making the fibula a common site for vascularized bone grafts. * **Termination:** It ends by dividing into the calcaneal branches. * **Tibioperoneal Trunk:** This is the segment of the posterior tibial artery between the origin of the anterior tibial artery and the origin of the peroneal artery. Its occlusion can lead to significant ischemia of both the posterior and lateral compartments.

Question 148: Which nerve supplies the anterior compartment of the leg?

A. Superficial peroneal nerve
B. Deep peroneal nerve (Correct Answer)
C. Saphenous nerve
D. Sural nerve

Explanation: The anterior compartment of the leg is primarily responsible for **dorsiflexion** of the foot and **extension** of the toes. ### Why the Deep Peroneal Nerve is Correct The **Deep Peroneal (Fibular) Nerve** is one of the two terminal branches of the Common Peroneal nerve. It enters the anterior compartment by piercing the anterior intermuscular septum. It provides motor supply to all four muscles of this compartment: 1. Tibialis anterior 2. Extensor digitorum longus 3. Extensor hallucis longus 4. Peroneus tertius Sensory-wise, it supplies only the small area of skin in the **first web space** of the foot. ### Why the Other Options are Incorrect * **A. Superficial Peroneal Nerve:** This nerve supplies the **lateral compartment** of the leg (Peroneus longus and brevis) and provides sensory innervation to the majority of the dorsum of the foot. * **C. Saphenous Nerve:** This is a purely sensory branch of the femoral nerve. it supplies the skin on the medial side of the leg and foot. * **D. Sural Nerve:** Formed by branches of the tibial and common peroneal nerves, it is a purely sensory nerve supplying the skin of the lateral and posterior part of the lower third of the leg and the lateral border of the foot. ### High-Yield Clinical Pearls for NEET-PG * **Foot Drop:** Injury to the Common Peroneal nerve (at the neck of the fibula) or the Deep Peroneal nerve leads to "Foot Drop" due to paralysis of the anterior compartment muscles. * **Anterior Compartment Syndrome:** Increased pressure in this tight fascial space can compress the Deep Peroneal nerve, leading to weakness in dorsiflexion and sensory loss in the first web space. * **The "Nerve of the Anterior Compartment":** Deep Peroneal Nerve. * **The "Nerve of the Lateral Compartment":** Superficial Peroneal Nerve.

Question 149: A 21-year-old man was involved in a motorcycle accident, resulting in destruction of the groove in the lower surface of the cuboid bone. Which of the following muscle tendons is most likely damaged?

A. Flexor hallucis longus
B. Peroneus brevis
C. Peroneus longus (Correct Answer)
D. Tibialis anterior

Explanation: The correct answer is **Peroneus longus (Fibularis longus)**. **Why it is correct:** The cuboid bone features a distinct oblique groove on its plantar (lower) surface. This groove is specifically designed to house the tendon of the **peroneus longus** muscle as it traverses the sole of the foot from the lateral side to its insertion on the base of the first metatarsal and the medial cuneiform. The groove is often converted into a tunnel by the long plantar ligament, providing a smooth pathway for the tendon. **Why other options are incorrect:** * **Flexor hallucis longus:** This tendon passes through a groove on the posterior surface of the **talus** and under the **sustentaculum tali** of the calcaneus, not the cuboid. * **Peroneus brevis:** This muscle inserts directly onto the tubercle at the base of the **5th metatarsal**. It does not cross the plantar surface of the cuboid. * **Tibialis anterior:** This muscle is located in the anterior compartment of the leg and inserts onto the medial cuneiform and the base of the first metatarsal from the **medial/dorsal** aspect, staying far from the cuboid. **NEET-PG High-Yield Pearls:** * **The Os Peroneum:** A sesamoid bone is frequently found within the peroneus longus tendon where it arches around the cuboid; this can be mistaken for a fracture on X-rays. * **Arch Support:** The peroneus longus and tibialis posterior are often called the "stirrup" of the foot because they support the longitudinal and transverse arches. * **Nerve Supply:** All peroneal (fibular) muscles are supplied by the **superficial peroneal nerve**, except for the Peroneus tertius (deep peroneal nerve).

Question 150: Which ossification center appears first?

A. Upper end of femur
B. Lower end of femur (Correct Answer)
C. Greater trochanter
D. Head

Explanation: The correct answer is **B. Lower end of femur.** ### Explanation The ossification of the femur follows a specific chronological sequence. The **lower end of the femur** is unique because its secondary ossification center appears at the **9th month of intrauterine life (36-40 weeks)**. This makes it one of the few secondary centers present at birth, serving as a crucial medico-legal indicator of fetal maturity (viability) [1]. ### Analysis of Options * **Lower end of femur (Correct):** Appears at the end of the 9th month of gestation. It is the first secondary ossification center of the femur to appear. * **Head of femur (Incorrect):** This center appears during the **6th month of postnatal life** (approx. 6 months after birth). * **Greater trochanter (Incorrect):** This center appears much later, typically between **4 to 5 years** of age. * **Upper end of femur (Incorrect):** This is a general term encompassing the head, greater, and lesser trochanters. Since the head appears at 6 months and the trochanters even later, it cannot be the first center. ### NEET-PG High-Yield Pearls 1. **Rule of Ossification at Birth:** The three secondary centers usually present at birth are the **Lower end of the femur**, **Upper end of the tibia**, and sometimes the **Head of the humerus**. 2. **Medico-legal Significance:** The presence of the lower femoral epiphysis in a newborn indicates that the fetus was full-term (at least 38 weeks). 3. **Growth Contribution:** The lower end of the femur is the "growing end" of the bone (it follows the rule: *to the elbow I go, from the knee I flee*). It accounts for approximately 70% of the total femoral length. 4. **Fusion:** While it appears first, it fuses last (around 18–20 years).

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Lower Limb — MCQs

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