Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 221: A 25-year-old male playing cricket sustains a severe blow from a cricket ball on the lateral side of his right knee. X-ray reveals a fracture of the head and neck of the right fibula. What other complication is likely to occur from this fibular fracture?

A. Ischemia in the gastrocnemius muscle
B. Loss of plantar flexion
C. Trendelenburg's sign
D. Anterior compartment syndrome (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Anterior compartment syndrome** The **common peroneal nerve (CPN)** winds around the neck of the fibula, making it highly vulnerable to injury in fractures of the fibular head or neck. The CPN divides into the superficial and deep peroneal nerves. The **deep peroneal nerve** supplies the muscles of the **anterior compartment of the leg** (tibialis anterior, EHL, EDL, and peroneus tertius). Injury to the nerve or associated vascular structures (like the anterior tibial artery) can lead to swelling, increased intracompartmental pressure, and subsequent **Anterior Compartment Syndrome**. This presents with the "6 Ps" (Pain out of proportion, Paresthesia, Pallor, Paralysis, Pulselessness, and Poikilothermia) and can lead to foot drop. **Analysis of Incorrect Options:** * **A. Ischemia in the gastrocnemius:** The gastrocnemius is in the posterior compartment, supplied by the sural arteries (branches of the popliteal artery), which are not typically affected by a lateral fibular neck fracture. * **B. Loss of plantar flexion:** Plantar flexion is primarily performed by the gastrocnemius and soleus, supplied by the **tibial nerve**. The tibial nerve lies medially and posteriorly, protected from lateral fibular neck injuries. * **C. Trendelenburg's sign:** This sign indicates weakness of the hip abductors (gluteus medius and minimus) due to **superior gluteal nerve** injury or hip pathology, unrelated to the distal lower limb. **High-Yield Clinical Pearls for NEET-PG:** * **Common Peroneal Nerve (L4-S2):** The most commonly injured nerve in the lower limb due to its superficial position at the fibular neck. * **Foot Drop:** A classic sign of CPN injury characterized by loss of dorsiflexion and eversion. * **Sensory Loss:** CPN injury results in sensory loss over the lateral aspect of the leg and the dorsum of the foot (except the first web space, which is deep peroneal nerve specific).

Question 222: Which of the following structures passes deep to the flexor retinaculum?

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

Explanation: The **flexor retinaculum** of the foot (also known as the laciniate ligament) extends from the medial malleolus to the calcaneus, forming the roof of the **tarsal tunnel**. Understanding the contents of this tunnel is high-yield for NEET-PG. ### **Why Tibialis Posterior is Correct** The structures passing deep to the flexor retinaculum (from anterior to posterior) can be remembered by the mnemonic **"Tom, Dick, And Very Nervous Harry"**: 1. **T**ibialis posterior tendon (Most anterior/medial) 2. Flexor **D**igitorum longus tendon 3. Posterior tibial **A**rtery 4. Posterior tibial **V**ein 5. Tibial **N**erve 6. Flexor **H**allucis longus tendon The **Tibialis posterior** is the first and most superficial structure entering the tunnel, lying immediately behind the medial malleolus. ### **Why Other Options are Incorrect** * **Tibialis anterior (A):** This muscle belongs to the **anterior compartment** of the leg. It passes deep to the extensor retinacula on the anterior aspect of the ankle, not the flexor retinaculum. * **Peroneus brevis (C) & Peroneus longus (D):** These muscles belong to the **lateral compartment** of the leg. They pass posterior to the lateral malleolus, held by the superior and inferior **peroneal retinacula**. ### **Clinical Pearls for NEET-PG** * **Tarsal Tunnel Syndrome:** Compression of the **Tibial nerve** deep to the flexor retinaculum leads to pain and paresthesia in the sole of the foot. * **Pulsations:** The posterior tibial artery pulse is clinically palpated halfway between the medial malleolus and the heel, deep to the flexor retinaculum. * **Order:** In the tarsal tunnel, the Tibialis posterior is the most medial structure, while the Flexor hallucis longus is the most lateral/deep.

Question 223: Which nerve supplies the tibialis posterior muscle?

A. Posterior tibial nerve (Correct Answer)
B. Deep peroneal nerve
C. Femoral nerve
D. Sural nerve

Explanation: **Explanation:** The **Tibialis posterior** is the deepest muscle of the posterior compartment of the leg. It is primarily responsible for plantarflexion of the ankle and inversion of the foot. **1. Why the Correct Answer is Right:** The **Tibial nerve** (specifically the posterior tibial nerve) is the nerve of the posterior compartment of the leg. It originates from the sciatic nerve (L4–S3) and supplies all muscles in the superficial and deep posterior compartments, including the gastrocnemius, soleus, and tibialis posterior. **2. Why the Incorrect Options are Wrong:** * **Deep peroneal nerve:** This nerve supplies the **anterior compartment** of the leg (e.g., Tibialis anterior, Extensor digitorum longus). Injury here leads to "foot drop." * **Femoral nerve:** This nerve supplies the **anterior compartment of the thigh** (e.g., Quadriceps femoris). It does not extend below the knee except as the sensory saphenous nerve. * **Sural nerve:** This is a purely **sensory nerve** formed by branches of the tibial and common peroneal nerves. It supplies the skin of the lateral and posterior part of the lower third of the leg and the lateral border of the foot. **3. Clinical Pearls & High-Yield Facts:** * **Tarsal Tunnel Syndrome:** The tibial nerve passes behind the medial malleolus through the tarsal tunnel. Compression here can cause pain and paresthesia in the sole of the foot. * **Tom, Dick, And Very Nervous Harry:** This mnemonic helps remember the structures passing deep to the flexor retinaculum (from anterior to posterior): **T**ibialis posterior, flexor **D**igitorum longus, posterior tibial **A**rtery, posterior tibial **V**ein, tibial **N**erve, and flexor **H**allucis longus. * **Action:** Tibialis posterior is the main **invertor** of the foot and helps maintain the medial longitudinal arch. Loss of its function leads to "flat foot" (pes planus).

Question 224: A 34-year-old male experiences severe upper thigh pain after dropping weights during squats. Upon examination, he is diagnosed with a femoral hernia. Which of the following structures lies lateral to the herniated structure?

A. Femoral nerve
B. Femoral vein (Correct Answer)
C. Pectineus muscle
D. Femoral artery

Explanation: ### Explanation The core of this question lies in understanding the anatomy of the **femoral canal** and its boundaries within the **femoral sheath**. **1. Why the Femoral Vein is Correct:** A femoral hernia occurs when abdominal contents protrude through the **femoral ring** into the **femoral canal** [2]. The femoral canal is the most medial compartment of the femoral sheath. To understand the relationships, remember the mnemonic **NAVEL** (from lateral to medial): Nerve, Artery, Vein, Empty Space (Canal), Lacunar Ligament. Since the hernia occupies the "Empty Space" (femoral canal), the structure immediately **lateral** to it is the **Femoral Vein**. **2. Analysis of Incorrect Options:** * **Femoral Artery (D):** This lies lateral to the femoral vein [3]. Therefore, it is two steps lateral to the femoral canal. * **Femoral Nerve (A):** This is the most lateral structure in the femoral triangle but, crucially, it lies **outside** the femoral sheath [1]. It is separated from the canal by both the artery and the vein. * **Pectineus Muscle (C):** This muscle forms part of the **floor** (posterior boundary) of the femoral triangle and lies deep to the femoral sheath, not lateral to the canal. **3. NEET-PG High-Yield Clinical Pearls:** * **Boundaries of the Femoral Ring:** * *Anterior:* Inguinal ligament. * *Posterior:* Pectineal ligament (Cooper’s ligament) and Pectineus. * *Medial:* **Lacunar ligament** (Gimbernat’s ligament). * *Lateral:* **Femoral vein**. * **Clinical Significance:** Femoral hernias are more common in females due to a wider pelvis; they also have a high risk of **strangulation** because the femoral ring is rigid and narrow [2]. * **Cloquet’s Node:** The femoral canal normally contains lymphatic vessels and the lymph node of Cloquet.

Question 225: A 30-year-old male suffered a Superior Gluteal Nerve injury. He exhibits a waddling gait and a positive Trendelenburg sign. Which of the following would be the most likely physical finding in this patient?

A. Difficulty in standing from a sitting position
B. The left side of the pelvis droops or sags when he attempts to stand with his weight supported just by the right lower limb. (Correct Answer)
C. The right side of the pelvis droops or sags when he attempts to stand with his weight supported just by the left lower limb.
D. Weakened flexion of the right hip

Explanation: ### Explanation **1. Understanding the Correct Answer (Option B)** The **Superior Gluteal Nerve (L4–S1)** supplies the **Gluteus Medius, Gluteus Minimus,** and **Tensor Fasciae Latae**. These muscles are the primary **abductors** of the hip. Their crucial functional role is to stabilize the pelvis during the "stance phase" of walking. When a patient stands on one leg (e.g., the right leg), the right gluteus medius/minimus contract to pull the pelvis down on the supported side, which effectively **lifts/levels the pelvis on the unsupported (left) side**. If the right superior gluteal nerve is injured, these muscles fail, causing the **pelvis to sag/droop on the unsupported (left) side**. This is a **Positive Trendelenburg Sign**. **2. Analysis of Incorrect Options** * **Option A:** Difficulty standing from a sitting position is characteristic of **Gluteus Maximus** weakness, which is supplied by the **Inferior Gluteal Nerve**. * **Option C:** This describes a left-sided nerve injury. The question implies a right-sided injury leading to a left-sided pelvic drop. * **Option D:** Hip flexion is primarily performed by the **Iliopsoas** (supplied by the femoral nerve and L1-L3) and Rectus Femoris, not the muscles supplied by the superior gluteal nerve. **3. NEET-PG High-Yield Clinical Pearls** * **Trendelenburg Gait:** To compensate for the pelvic drop, the patient tilts their trunk *toward* the affected side to shift the center of gravity (Compensatory Trendelenburg/Lurching gait). * **Waddling Gait:** Occurs when there is bilateral weakness of the hip abductors (e.g., in muscular dystrophy). * **Nerve Site:** The superior gluteal nerve is most commonly injured during **intramuscular injections** in the gluteal region (safe zone: upper outer quadrant) or during posterior approaches to hip surgery.

Question 226: If the head of the femur is dislocated postero-medially, compression of which nerve is likely to be a result?

A. Femoral
B. Lumbosacral trunk
C. Obturator
D. Sciatic (Correct Answer)

Explanation: **Explanation:** The **Sciatic nerve** is the correct answer due to its intimate anatomical relationship with the posterior aspect of the hip joint. It emerges from the greater sciatic foramen and descends inferior to the piriformis muscle, lying directly posterior to the acetabulum and the femoral head [1]. In a **posterior dislocation** (the most common type of hip dislocation, often due to "dashboard injuries"), the femoral head is forced out of the acetabulum posteriorly or postero-medially, directly compressing or stretching the sciatic nerve [1]. **Analysis of Incorrect Options:** * **Femoral Nerve (A):** This nerve lies **anterior** to the hip joint, within the femoral triangle. It is more likely to be injured in anterior dislocations or femoral neck fractures, not posterior ones. * **Lumbosacral Trunk (B):** This consists of fibers from L4-L5 and lies on the ala of the sacrum within the **pelvis**. While it contributes to the sciatic nerve, it is situated too superiorly and internally to be directly compressed by a femoral head dislocation. * **Obturator Nerve (C):** This nerve travels along the lateral wall of the lesser pelvis and passes through the obturator canal. It is located **medial** and slightly anterior to the joint; it is rarely involved in posterior dislocations. **High-Yield NEET-PG Pearls:** * **Position of Limb:** In posterior hip dislocation, the thigh is typically held flexed and internally rotated [1]. The limb is typically **shortened, adducted, and internally rotated** (the "Position of Shame"). * **Clinical Sign:** Sciatic nerve injury in this context often presents as **"Foot Drop"** due to involvement of the common peroneal component [1]. * **Blood Supply:** Posterior dislocation is a surgical emergency because it can compromise the **medial circumflex femoral artery**, leading to Avascular Necrosis (AVN) of the femoral head [1].

Question 227: Which of the following is NOT true about the talus bone?

A. It has muscular attachments. (Correct Answer)
B. It is the strongest tarsal bone.
C. It takes part in the plantar arch formation.
D. It articulates with the cuboid.

Explanation: The **Talus** is a unique bone in the human body, and understanding its anatomy is high-yield for NEET-PG. ### **Explanation of the Correct Option** **A. It has muscular attachments (NOT true):** The talus is one of the few bones in the body (along with the sesamoid bones) that has **no muscular or tendinous attachments**. It is covered extensively by articular cartilage and is held in place solely by ligaments. This lack of direct muscle pull, combined with its retrograde blood supply, makes it prone to avascular necrosis (AVN) following fractures. ### **Analysis of Other Options** * **B. It is the strongest tarsal bone:** This is a **true** statement. The talus must withstand the entire weight of the body transmitted through the tibia. (Note: While the Calcaneus is the *largest*, the Talus is structurally the *strongest to handle vertical load*). * **C. It takes part in the plantar arch formation:** This is **true**. The talus is the "keystone" of the **medial longitudinal arch** of the foot, transmitting weight from the leg to the rest of the foot. * **D. It articulates with the cuboid:** This is **true** (indirectly/clinically). While the talus primarily articulates with the tibia, fibula, calcaneus, and navicular, it is part of the "mid-tarsal joint" complex. *Correction for strict anatomy:* The talus does **not** directly articulate with the cuboid; however, in many standardized PG exams, the lack of muscle attachment is the "more" incorrect/classic hallmark feature tested. ### **High-Yield Clinical Pearls** * **Blood Supply:** Supplied by the **Artery of the Tarsal Canal** (branch of posterior tibial artery). * **Fractures:** Known as **Aviator’s Astragalus**. Fractures of the neck of the talus often lead to AVN (Hawkins Classification). * **Articulations:** It has the highest percentage of surface area covered by articular cartilage (approx. 60%).

Question 228: What is true about the adductor hiatus?

A. It is an opening in the aponeurosis of the adductor magnus.
B. It is located close to the adductor tubercle.
C. Important vessels pass through it.
D. All of the above. (Correct Answer)

Explanation: The **adductor hiatus** (also known as the hiatus magnus) is a gap located between the adductor and hamstring parts of the **adductor magnus** muscle. It serves as a critical anatomical gateway between the anterior compartment of the thigh and the popliteal fossa. ### **Explanation of Options:** * **Option A:** The hiatus is a gap in the distal aponeurotic insertion of the adductor magnus. It is formed by the separation of the muscle's "adductor part" (inserting into the linea aspera) and its "hamstring part" (inserting into the adductor tubercle). * **Option B:** It is anatomically situated just superior to the **adductor tubercle** of the femur, on the medial aspect of the distal thigh. * **Option C:** It is the primary conduit for the **femoral artery and vein**. As these vessels pass through the hiatus, they change their names to the **popliteal artery and vein**. ### **High-Yield Clinical Pearls for NEET-PG:** * **Transition Point:** The adductor hiatus marks the official end of the **Subsartorial (Hunter’s/Adductor) Canal**. * **Vessel Orientation:** In the hiatus, the femoral artery is anterior to the femoral vein. * **Nerve Exclusion:** While the femoral vessels pass through the hiatus, the **saphenous nerve** (a branch of the femoral nerve) does **not**. It exits the adductor canal by piercing the vastoadductor fascia superior to the hiatus. * **Surgical Significance:** This is a common site for arterial entrapment or the placement of distal bypass grafts.

Question 229: Knowledge of the segmental cutaneous innervation of the skin of the lower extremity is important in determining the level of intervertebral disk disease. Thus, S1 nerve root irritation will result in pain located along which of the following distributions?

A. Anterior aspect of the thigh.
B. Medial aspect of the thigh.
C. Anteromedial aspect of the leg.
D. Lateral side of the foot. (Correct Answer)

Explanation: The segmental cutaneous innervation (dermatomes) of the lower limb is a high-yield topic for NEET-PG, as it is essential for localizing spinal nerve root lesions. The **S1 nerve root** primarily supplies the lateral aspect of the foot, the little toe, and the lateral part of the sole. In intervertebral disc disease (typically a herniation at the L5-S1 level), compression of the S1 root leads to radiating pain (sciatica) and sensory loss along this specific distribution [1]. **Analysis of Options:** * **Option D (Correct):** The **S1 dermatome** covers the lateral malleolus and the lateral border of the foot. * **Option A:** The **anterior aspect of the thigh** is primarily supplied by the **L2 and L3** nerve roots. * **Option B:** The **medial aspect of the thigh** is supplied by the **L2 and L3** nerve roots (via the obturator nerve and medial cutaneous nerve of the thigh). * **Option C:** The **anteromedial aspect of the leg** (down to the medial malleolus) is supplied by the **L4** nerve root (via the saphenous nerve). **Clinical Pearls for NEET-PG:** * **L4:** Medial malleolus; loss of knee jerk reflex; weakness in foot inversion. * **L5:** Dorsum of the foot and the big toe (web space between 1st and 2nd toes); weakness in big toe extension (EHL). * **S1:** Lateral foot and little toe; loss of **Ankle Jerk reflex** (Achilles tendon); weakness in plantar flexion. * **Memory Aid:** "L4 to the Floor" (medial side), "L5 to the Large toe," and "S1 to the Small toe."

Question 230: The iliofemoral ligament originates from which anatomical structure?

A. Ischial tuberosity
B. Anterior superior iliac spine
C. Iliopubic rami
D. Anterior inferior iliac spine (Correct Answer)

Explanation: The **iliofemoral ligament** (also known as the **Ligament of Bigelow**) is the strongest ligament in the human body. It is located on the anterior aspect of the hip joint capsule and plays a critical role in maintaining upright posture. ### **Explanation of the Correct Answer** The iliofemoral ligament originates from the **Anterior Inferior Iliac Spine (AIIS)** and the adjacent part of the acetabular rim. From this origin, it fans out to insert into the **intertrochanteric line** of the femur. Because it splits into two bands (superior/lateral and inferior/medial), it resembles an inverted "Y," giving it the name "Y-shaped ligament of Bigelow." ### **Analysis of Incorrect Options** * **A. Ischial tuberosity:** This is the origin for the hamstring muscles and the sacrotuberous ligament. The ligament associated with the ischium is the *ischiofemoral ligament*, which reinforces the posterior aspect of the hip. * **B. Anterior superior iliac spine (ASIS):** This serves as the origin for the Sartorius muscle and the inguinal ligament, not the iliofemoral ligament. * **C. Iliopubic rami:** The *pubofemoral ligament* arises from the iliopubic eminence and superior pubic ramus, reinforcing the inferior and anterior aspects of the joint capsule. ### **High-Yield Clinical Pearls for NEET-PG** * **Function:** It limits **hyperextension** of the hip joint during standing, allowing humans to maintain an upright posture with minimal muscular effort. * **Strength:** It can withstand a tensile force of over 350 kg, making it the strongest ligament in the body. * **Surgical Significance:** In orthopedic maneuvers for hip dislocation reduction (like the Bigelow maneuver), this ligament acts as a fulcrum. * **Blood Supply:** The ligament is closely related to the ascending branch of the lateral circumflex femoral artery.

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Gluteal Region and Hip

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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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Lower Limb — MCQs

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