Lower Limb — MCQs

During a football game, a 21-year-old wide receiver was illegally blocked by a linebacker, who threw himself against the posterolateral aspect of the runner's left knee. As he lay on the ground, the wide receiver grasped his knee in obvious pain. Which of the following structures is frequently subject to injury from this type of force against the knee?

Q430Easy

The deltoid ligament is attached to all of the following except?

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 421: A 32-year-old man presents with multiple tendinous tears in his foot after an injury. Which of the following bones is associated with the muscles involved in these tears?

A. Navicular
B. Cuboid
C. Calcaneus (Correct Answer)
D. Sustentaculum tali

Explanation: **Explanation:** The **calcaneus** (heel bone) is the largest bone of the foot and serves as a major site for muscle and tendon attachments. It provides the structural leverage necessary for walking and posture. **Why Calcaneus is correct:** The calcaneus is associated with several major tendons and muscles that are frequently involved in foot injuries: * **Tendo Achilles (Calcaneal tendon):** The strongest tendon in the body, formed by the Gastrocnemius and Soleus, inserts into the posterior surface. * **Plantaris:** Inserts medial to the Achilles tendon. * **Extensor Digitorum Brevis:** Originates from the superolateral surface. * **Flexor Digitorum Brevis & Abductor Hallucis:** Originate from the medial tubercle of the calcaneal tuberosity. * **Quadratus Plantae:** Originates by two heads from the medial and lateral surfaces of the calcaneus. **Why other options are incorrect:** * **Navicular:** Primarily serves as the insertion for the **Tibialis posterior** tendon. While clinically important for the medial longitudinal arch, it has fewer muscle attachments compared to the calcaneus. * **Cuboid:** Provides a groove for the **Peroneus longus** tendon but is not the primary site for multiple tendinous origins/insertions. * **Sustentaculum tali:** This is a shelf-like projection of the *calcaneus* itself. While it supports the talus and acts as a pulley for the **Flexor Hallucis Longus**, the question asks for the "bone." The calcaneus as a whole is the more comprehensive and correct anatomical answer. **NEET-PG High-Yield Pearls:** * **Fracture:** Calcaneal fractures (e.g., Lover’s fracture) often occur after a fall from height and are associated with compression fractures of the lumbar spine. * **Bohler’s Angle:** A decrease in this angle (normal 20-40°) on X-ray indicates a calcaneal fracture. * **Peroneal Trochlea:** A small tubercle on the lateral surface of the calcaneus that separates the tendons of Peroneus brevis (above) and Peroneus longus (below).

Question 422: All of the following muscles are supplied by the tibial component of the sciatic nerve except?

A. Adductor magnus
B. Semimembranosus
C. Semitendinosus
D. Short head of Biceps femoris (Correct Answer)

Explanation: The sciatic nerve (L4-S3) is the largest nerve in the body and consists of two distinct components wrapped in a single connective tissue sheath: the **Tibial nerve** and the **Common Peroneal (Fibular) nerve**. **1. Why the Correct Answer is Right:** The **Short head of Biceps femoris** is the only muscle in the posterior compartment of the thigh that is **not** supplied by the tibial component. Instead, it is supplied by the **Common Peroneal component** of the sciatic nerve. This is a classic anatomical "exception" often tested in exams. **2. Why the Other Options are Incorrect:** The tibial component of the sciatic nerve supplies the "true" hamstring muscles and the hamstring part of the adductor magnus. * **Semitendinosus & Semimembranosus:** These are true hamstring muscles (originating from the ischial tuberosity) and are supplied by the tibial nerve. * **Adductor Magnus:** This is a "hybrid" or "composite" muscle. Its **hamstring part** (ischial part) is supplied by the tibial nerve, while its adductor part is supplied by the obturator nerve. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hybrid Muscles of Lower Limb:** Always remember Adductor Magnus (Obturator + Tibial n.), Pectineus (Femoral + Obturator n.), and Biceps Femoris (Tibial + Common Peroneal n.). * **The "Hamstring" Definition:** To be a true hamstring, a muscle must originate from the ischial tuberosity, insert into a bone of the leg, and be supplied by the tibial nerve. The **short head of biceps femoris fails all three criteria** (originates from linea aspera, supplied by common peroneal n.). * **Sciatic Nerve Bifurcation:** The sciatic nerve typically divides into its two terminal branches at the superior angle of the popliteal fossa.

Question 423: Which of the following movements would be affected in case of paralysis of the quadriceps femoris muscle?

A. Adduction at the hip
B. Extension at the hip
C. Extension at the knee (Correct Answer)
D. Flexion at the knee

Explanation: **Explanation:** The **Quadriceps Femoris** is the primary extensor of the knee joint. It is a large muscle group located in the anterior compartment of the thigh, consisting of four heads: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. All four muscles converge into the quadriceps tendon, which inserts into the tibial tuberosity via the patellar ligament. **Why Option C is Correct:** The fundamental action of the quadriceps is **extension at the knee**. When these muscles contract, they pull on the tibia to straighten the leg. Paralysis of this group (often due to femoral nerve injury) results in an inability to extend the knee against gravity and significant instability while walking. **Analysis of Incorrect Options:** * **A. Adduction at the hip:** This is primarily performed by the **Adductor group** (Adductor longus, brevis, and magnus) located in the medial compartment of the thigh, supplied by the obturator nerve. * **B. Extension at the hip:** This movement is executed by the **Gluteus maximus** and the **Hamstring muscles** (posterior compartment). Interestingly, the rectus femoris (part of the quadriceps) actually assists in hip *flexion*, not extension. * **D. Flexion at the knee:** This is the function of the **Hamstring muscles** (Biceps femoris, Semitendinosus, and Semimembranosus) located in the posterior compartment. **High-Yield NEET-PG Pearls:** * **Nerve Supply:** The quadriceps is supplied by the **Femoral Nerve (L2-L4)**. * **Clinical Sign:** Loss of the **Patellar Reflex (Knee-jerk)** is a classic sign of femoral nerve damage or L3-L4 nerve root compression. * **Vastus Medialis Obliquus (VMO):** This specific part of the quadriceps is crucial for maintaining patellar tracking; weakness here leads to lateral subluxation of the patella. * **Rectus Femoris:** It is the only component of the quadriceps that crosses two joints (hip and knee), acting as a hip flexor and knee extensor.

Question 424: What is the primary blood supply to the great toe?

A. Dorsalis pedis artery (Correct Answer)
B. Dorsalis pedis artery
C. Metatarsal artery
D. Posterior tibial artery

Explanation: The **Dorsalis pedis artery (DPA)** is the primary source of blood supply to the dorsal aspect of the foot and the great toe. It is the direct continuation of the **anterior tibial artery** distal to the level of the malleoli. ### Why Dorsalis Pedis Artery is Correct: The DPA gives off several branches, but its terminal distribution is crucial for the great toe. It provides the **First Dorsal Metatarsal Artery**, which further divides to supply the medial and lateral sides of the great toe (hallux) and the medial side of the second toe. This makes it the dominant arterial supply for the hallux. ### Analysis of Incorrect Options: * **Metatarsal Artery:** While the first dorsal metatarsal artery specifically supplies the great toe, "metatarsal artery" is a general term. The DPA is the parent trunk and the standard answer in clinical anatomy for the primary source. * **Posterior Tibial Artery:** This artery supplies the sole of the foot via the medial and lateral plantar arteries. While it contributes to the plantar digital arteries, the primary landmark for the great toe's supply in standard anatomical teaching (and pulse palpation) is the DPA. ### High-Yield Clinical Pearls for NEET-PG: * **Palpation Point:** The DPA pulse is best felt on the dorsum of the foot, lateral to the tendon of **Extensor Hallucis Longus (EHL)**. * **Clinical Significance:** In Buerger’s disease or Peripheral Arterial Disease (PAD), the DPA pulse is often absent, leading to ischemia of the great toe. * **Arcuate Artery:** This is a branch of the DPA that gives rise to the 2nd, 3rd, and 4th dorsal metatarsal arteries. * **Deep Plantar Artery:** A branch of the DPA that enters the sole between the two heads of the first dorsal interosseous muscle to complete the **plantar arch**.

Question 425: Third tubercle of the femur provides attachment to which muscle?

A. Gluteus maximus (Correct Answer)
B. Gluteus medius
C. Gluteus minimis
D. Piriformis

Explanation: ### Explanation The **third tubercle of the femur** (also known as the **gluteal tuberosity**) is a rough, elongated ridge located on the posterior aspect of the proximal femoral shaft, lateral to the pectineal line. It serves as the primary site for the distal insertion of the superficial and inferior fibers of the **Gluteus maximus**. #### Why Option A is Correct: The Gluteus maximus has two main insertions: 1. **Superficial/Superior fibers:** Insert into the **iliotibial tract** (IT band). 2. **Deep/Inferior fibers:** Insert into the **gluteal tuberosity** (third tubercle) of the femur. In some individuals, this tuberosity is significantly enlarged, resembling the third trochanter found in other mammals (like horses). #### Why Other Options are Incorrect: * **B. Gluteus medius:** Inserts onto the lateral surface of the **Greater Trochanter**. * **C. Gluteus minimus:** Inserts onto the anterior surface of the **Greater Trochanter**. * **D. Piriformis:** Inserts onto the apex (superior border) of the **Greater Trochanter**. #### NEET-PG High-Yield Pearls: * **The "Trochanteric" Rule:** Most gluteal muscles and short lateral rotators (Piriformis, Obturators, Gemelli) insert on the **Greater Trochanter**. The Gluteus maximus is the notable exception, inserting lower down on the shaft (gluteal tuberosity). * **Nerve Supply:** Gluteus maximus is the only muscle supplied by the **Inferior Gluteal Nerve (L5, S1, S2)**. * **Clinical Significance:** The Gluteus maximus is the chief extensor of the hip when rising from a sitting position or climbing stairs. Its paralysis results in a "Gluteus Maximus Lurch."

Question 426: Which nerve is affected in the Trendelenburg test?

A. Superior gluteal nerve (Correct Answer)
B. Inferior gluteal nerve
C. Obturator nerve
D. Pudendal nerve

Explanation: ### Explanation **1. Why the Superior Gluteal Nerve is Correct:** The Trendelenburg test assesses the integrity of the **hip abductor mechanism**. The **superior gluteal nerve (L4–S1)** supplies the **Gluteus medius, Gluteus minimus**, and Tensor fasciae latae. * **Mechanism:** During normal walking, when one foot is lifted off the ground, the abductors on the **supported (weight-bearing) side** contract to prevent the pelvis from sagging toward the unsupported side. * **Positive Sign:** If the superior gluteal nerve is damaged, the abductors on the standing leg fail to stabilize the pelvis. Consequently, the pelvis drops toward the **opposite (healthy) side**. This is a "Positive Trendelenburg Sign." **2. Why the Other Options are Incorrect:** * **B. Inferior Gluteal Nerve (L5–S2):** Supplies the **Gluteus maximus**. Damage results in difficulty climbing stairs or rising from a seated position (Gluteus maximus lurch), but does not cause a pelvic drop. * **C. Obturator Nerve (L2–L4):** Supplies the **adductor compartment** of the thigh. Injury leads to weakness in leg adduction and sensory loss on the medial thigh. * **D. Pudendal Nerve (S2–S4):** Supplies the perineum and external genitalia. It is involved in fecal/urinary continence and sexual function, not hip stability. **3. Clinical Pearls for NEET-PG:** * **Nerve Root:** Superior Gluteal Nerve (L4, L5, S1) – remember it exits the pelvis via the **greater sciatic foramen**, *above* the piriformis muscle. * **Trendelenburg Gait:** Also known as a "waddling gait" if bilateral (seen in congenital hip dislocation or muscular dystrophy). * **Iatrogenic Injury:** The most common cause of superior gluteal nerve injury is an **intramuscular injection** given in the wrong quadrant of the buttock (safe zone is the upper outer quadrant). * **Rule of Thumb:** The lesion is always on the side of the **standing leg** (the side the patient is leaning toward to compensate).

Question 427: Injury of the common peroneal nerve at the lateral aspect of the head of the fibula results in all of the following except?

A. Weakness of ankle dorsiflexion
B. Foot drop
C. Loss of ankle reflex (Correct Answer)
D. Sensory impairment on the lateral aspect of the leg extending to the dorsum of the foot

Explanation: The **Common Peroneal Nerve (CPN)** is the most frequently injured nerve in the lower limb due to its superficial course as it winds around the **neck of the fibula**. **1. Why "Loss of ankle reflex" is the correct answer:** The ankle reflex (Achilles tendon reflex) tests the **S1 nerve root**. The motor component of this reflex is mediated by the **Tibial nerve**, which innervates the gastrocnemius and soleus muscles (plantarflexors). Since the CPN is a branch of the sciatic nerve distinct from the tibial nerve, an injury at the fibular head will **not** affect the ankle reflex. **2. Analysis of incorrect options:** * **Weakness of ankle dorsiflexion & Foot drop:** The CPN divides into the Deep and Superficial Peroneal nerves. The **Deep Peroneal nerve** supplies the anterior compartment of the leg (tibialis anterior, etc.). Paralysis of these muscles leads to a loss of dorsiflexion, clinically manifesting as **foot drop**. * **Sensory impairment:** The CPN gives off the lateral sural cutaneous nerve, and its branches (Superficial Peroneal nerve) supply the skin of the **lower lateral leg and the dorsum of the foot** (except the first web space, which is deep peroneal, and the lateral border, which is sural). **Clinical Pearls for NEET-PG:** * **Gait:** Patients with CPN injury exhibit a **"High-steppage gait"** to prevent toes from dragging. * **First Web Space:** Sensory loss specifically in the first interdigital cleft indicates isolated **Deep Peroneal Nerve** injury. * **Inversion vs. Eversion:** In CPN injury, **eversion** is lost (Superficial Peroneal), but **inversion** is preserved (Tibial nerve/Tibialis posterior). * **Common Causes:** Tight plaster casts, leg crossing, or fibular neck fractures.

Question 428: All the following muscles are supplied by the anterior division of the obturator nerve except?

A. Pectineus
B. Adductor longus
C. Gracilis
D. Adductor magnus (Correct Answer)

Explanation: **Explanation:** The **obturator nerve (L2–L4)** is the primary nerve of the medial compartment of the thigh. After passing through the obturator canal, it divides into **anterior and posterior divisions**, separated by the adductor brevis muscle. **1. Why Adductor Magnus is the correct answer:** The **Adductor magnus** is a "hybrid" or "composite" muscle with a dual nerve supply. Its **adductor part** is supplied by the **posterior division** of the obturator nerve, while its **hamstring part** is supplied by the **tibial component of the sciatic nerve**. It is never supplied by the anterior division. **2. Analysis of incorrect options (Supplied by the Anterior Division):** * **Adductor longus:** A superficial muscle of the medial compartment, consistently supplied by the anterior division. * **Gracilis:** The most medial muscle of the thigh, supplied by the anterior division. * **Pectineus:** While primarily supplied by the femoral nerve, it frequently receives a branch from the **anterior division** of the obturator nerve (accessory obturator nerve when present). In the context of standard NEET-PG patterns, it is grouped with the anterior division's distribution. **High-Yield Clinical Pearls for NEET-PG:** * **Adductor Brevis:** This muscle acts as the "sandwich filling"; the anterior division runs anterior to it, and the posterior division runs posterior to it. It can be supplied by either or both divisions. * **Obturator Externus:** This is the only muscle supplied by the **trunk** of the obturator nerve (or the posterior division) before it splits significantly. * **Hilton’s Law:** The obturator nerve supplies the hip and knee joints, explaining why hip pathology often presents as referred pain to the medial knee.

Question 429: During a football game, a 21-year-old wide receiver was illegally blocked by a linebacker, who threw himself against the posterolateral aspect of the runner's left knee. As he lay on the ground, the wide receiver grasped his knee in obvious pain. Which of the following structures is frequently subject to injury from this type of force against the knee?

A. Fibular collateral ligament
B. Anterior cruciate ligament (Correct Answer)
C. Lateral meniscus and posterior cruciate ligament
D. Fibular collateral and posterior cruciate ligament

Explanation: ### Explanation The clinical scenario describes a classic **"Clipping Injury"** or a blow to the **posterolateral aspect** of the knee. This mechanism of injury results in a force that pushes the femur posteriorly relative to the tibia, or more commonly, creates a **valgus stress** combined with internal rotation. **1. Why the Anterior Cruciate Ligament (ACL) is correct:** The ACL is the primary stabilizer preventing anterior translation of the tibia on the femur. When a force is applied to the posterolateral aspect of the knee, it often results in a **valgus strain**. This puts immense tension on the "Unhappy Triad" (O'Donoghue's Triad), which consists of the **Anterior Cruciate Ligament**, **Medial Collateral Ligament (MCL)**, and the **Medial Meniscus** (though recent studies suggest the lateral meniscus is more commonly injured in acute ACL tears). The ACL is the most frequently ruptured of these structures in contact sports involving sudden deceleration or lateral impact. **2. Why the other options are incorrect:** * **Option A (Fibular collateral ligament):** The FCL (Lateral Collateral Ligament) is injured by a **varus force** (impact to the medial side of the knee), not a lateral/valgus force. * **Option C & D (Posterior Cruciate Ligament):** The PCL is typically injured by a direct blow to the **anterior** aspect of the proximal tibia (e.g., "Dashboard injury") or extreme hyperextension. It is much stronger than the ACL and less likely to be injured by a posterolateral blow. ### NEET-PG High-Yield Pearls: * **Unhappy Triad (O'Donoghue):** ACL + MCL + Medial Meniscus (Classic teaching) or Lateral Meniscus (Modern clinical finding). * **Lachman Test:** The most sensitive clinical test for an acute ACL tear. * **Pivot Shift Test:** Most specific test for ACL deficiency. * **Segond Fracture:** An avulsion fracture of the lateral tibial condyle; it is pathognomonic for an ACL tear.

Question 430: The deltoid ligament is attached to all of the following except?

A. Medial malleolus
B. Talus
C. Calcaneum
D. Lateral malleolus (Correct Answer)

Explanation: **Explanation:** The **Deltoid ligament** (Medial ligament of the ankle) is a strong, triangular-shaped fibrous band located on the **medial side** of the ankle joint. Its primary function is to resist over-eversion of the foot. **1. Why "Lateral Malleolus" is the correct answer:** The lateral malleolus is a feature of the **fibula** on the lateral aspect of the ankle. It serves as the attachment point for the **Lateral Ligament complex** (comprising the Anterior Talofibular, Posterior Talofibular, and Calcaneofibular ligaments). Since the deltoid ligament is strictly a medial structure, it has no attachment to the lateral malleolus. **2. Analysis of incorrect options (Attachments of the Deltoid Ligament):** The deltoid ligament is divided into superficial and deep layers, all originating from the **Medial Malleolus (Option A)** of the tibia. * **Talus (Option B):** The ligament attaches to the talus via the *Anterior Tibiotalar* and *Posterior Tibiotalar* bands. * **Calcaneum (Option C):** The *Tibiocalcaneal* part of the ligament attaches to the **Sustentaculum tali** of the calcaneus. * *Note:* It also attaches to the **Navicular bone** via the *Tibionavicular* part. **Clinical Pearls for NEET-PG:** * **Strength:** The deltoid ligament is significantly stronger than the lateral ligaments; therefore, eversion sprains often result in an **avulsion fracture** of the medial malleolus rather than a ligamentous tear. * **Spring Ligament:** The deltoid ligament blends with the plantar calcaneonavicular (spring) ligament, helping to support the medial longitudinal arch of the foot. * **Stability:** It is the primary stabilizer of the talar shift.

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Lower Limb — MCQs

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