Lower Limb Practice Questions

Q: A 55-year-old man is admitted to the hospital after falling from his roof. Radiographic examination reveals a fracture of the talus bone in one foot. From what artery does this bone receive its primary vascular supply?

Posterior tibial. **Explanation:** The talus is a unique bone in the foot as it has no muscular or tendinous attachments and is largely covered by articular cartilage. Its blood supply is precarious and follows a retrograde pattern, making it highly susceptible to **avascular necrosis (AVN)** following fractures, particularly of the talar neck. **1. Why Posterior Tibial is Correct:** The primary vascular supply to the talus comes from the **artery of the tarsal canal**, which is a branch of the **posterior tibial artery**. This artery enters through the tarsal canal on the medial side and supplies the majority of the talar body. Additionally, the posterior tibial artery gives off deltoid branches that supply the medial aspect of the talar body. **2. Analysis of Incorrect Options:** * **Anterior Tibial:** While it contributes to the blood supply via the superior neck vessels, it is not the *primary* source for the talar body. * **Dorsalis Pedis:** This artery (a continuation of the anterior tibial) gives off the **artery of the sinus tarsi** (along with the perforating peroneal artery). While it supplies the talar head and neck, it is secondary to the posterior tibial's contribution to the body. * **Lateral Plantar:** This is a terminal branch of the posterior tibial artery that primarily supplies the sole of the foot and digits, not the talus bone itself. **Clinical Pearls for NEET-PG:** * **Hawkins’ Sign:** A subcortical radiolucency of the talar dome seen 6–8 weeks post-fracture; it indicates intact vascularity (a good prognostic sign). * **Retrograde Flow:** Like the scaphoid and the femoral head, the talus has a retrograde blood supply, increasing the risk of non-union and AVN. * **Most common site of fracture:** The talar neck.

Q: All of the following are hybrid muscles except?

Tensor fascia lata. ### Explanation A **hybrid (or composite) muscle** is defined as a muscle supplied by two or more different nerves, usually reflecting its development from different embryological compartments. **Why Tensor Fascia Lata (TFL) is the correct answer:** The TFL is **not** a hybrid muscle. It is derived from the gluteal morphogenetic field and is supplied solely by the **superior gluteal nerve (L4, L5, S1)**. It acts as a flexor, abductor, and medial rotator of the hip. **Analysis of Incorrect Options (Hybrid Muscles):** * **Pectineus:** It is a hybrid muscle supplied by the **femoral nerve** (anterior compartment) and occasionally the **obturator nerve** (medial compartment). * **Adductor Magnus:** This is a classic hybrid muscle. Its adductor part is supplied by the **obturator nerve**, while its "hamstring" (ischiocondylar) part is supplied by the **tibial component of the sciatic nerve**. * **Biceps Femoris:** It has a dual nerve supply. The long head is supplied by the **tibial part of the sciatic nerve**, whereas the short head is supplied by the **common peroneal part of the sciatic nerve**. **High-Yield NEET-PG Pearls:** * **Other Hybrid Muscles to Remember:** * **Upper Limb:** Brachialis (Musculocutaneous & Radial), Flexor Digitorum Profundus (Ulnar & Median). * **Head & Neck:** Digastric (Anterior: V3; Posterior: VII). * **Adductor Magnus** is often called the "Clinician's Hamstring" because of its dual nerve supply and origin from the ischial tuberosity. * **Pectineus** is unique as it is functionally an adductor but developmentally and nerve-wise primarily associated with the extensors (femoral nerve).

Q: Which of the following nerves is NOT a branch of the lumbar plexus?

Sciatic nerve. **Explanation:** The **Lumbar Plexus** is formed by the ventral rami of spinal nerves **L1 to L4** (with a contribution from T12). It is situated within the posterior part of the Psoas major muscle. **Why Sciatic Nerve is the correct answer:** The **Sciatic nerve (L4–S3)** is the largest nerve in the body and is the primary branch of the **Sacral Plexus**, not the lumbar plexus. It enters the gluteal region via the greater sciatic foramen and supplies the posterior compartment of the thigh and all muscles of the leg and foot. **Analysis of incorrect options:** * **Obturator nerve (L2–L4):** A major branch of the lumbar plexus (anterior divisions). it supplies the medial (adductor) compartment of the thigh. * **Femoral nerve (L2–L4):** The largest branch of the lumbar plexus (posterior divisions). It supplies the anterior compartment of the thigh (extensors of the knee). * **Lateral cutaneous nerve of thigh (L2–L3):** A purely sensory branch of the lumbar plexus that supplies the skin of the lateral thigh. **High-Yield Clinical Pearls for NEET-PG:** 1. **Meralgia Paraesthetica:** Compression of the *Lateral cutaneous nerve of thigh* under the inguinal ligament, causing pain/numbness on the outer thigh. 2. **Lumbosacral Trunk:** Formed by the union of part of the **L4 and L5** rami; it connects the lumbar plexus to the sacral plexus. 3. **Nerve to Psoas Major:** Arises directly from the ventral rami of **L2 and L3**. 4. **Root Value Tip:** Both the Femoral and Obturator nerves share the same root value (**L2, L3, L4**), but the Femoral comes from posterior divisions while the Obturator comes from anterior divisions.

Q: Which of the following is a component of the deltoid ligament?

Tibiotalar ligament. The **Deltoid ligament** (Medial ligament of the ankle) is a strong, triangular band of fibers that stabilizes the medial aspect of the ankle joint. It originates from the apex and borders of the **medial malleolus** and fans out to attach to the tarsal bones. ### Why Option B is Correct: The deltoid ligament is composed of four distinct parts, categorized into superficial and deep layers. The **Tibiotalar ligament** (both anterior and posterior fibers) is a core component. * **Superficial Layer:** Tibionavicular, Tibiocalcaneal, and Posterior Superficial Tibiotalar fibers. * **Deep Layer:** Anterior Deep Tibiotalar and **Posterior Deep Tibiotalar** fibers. The deep layer is the strongest and primarily prevents lateral displacement of the talus. ### Why Other Options are Incorrect: * **A. Talofibular ligament:** This is a component of the **Lateral ligament** of the ankle (along with the calcaneofibular ligament). It is the most commonly injured ligament in inversion ankle sprains. * **C. Talonavicular ligament:** This is part of the dorsal ligaments of the foot, connecting the neck of the talus to the navicular bone; it is not part of the deltoid complex. * **D. Calcaneo-navicular ligament:** Also known as the **Spring ligament**, it supports the head of the talus and maintains the medial longitudinal arch. While the deltoid ligament (tibionavicular part) blends with it, they are distinct anatomical structures. ### NEET-PG High-Yield Pearls: * **Strength:** The deltoid ligament is so strong that in eversion injuries, the medial malleolus usually fractures (avulsion) before the ligament tears. * **Stability:** It is the primary stabilizer against **eversion** of the ankle. * **Spring Ligament:** Always remember that the "Spring ligament" (Plantat calcaneonavicular) is the main supporter of the **Medial Longitudinal Arch**. Loss of this support leads to flat foot (Pes Planus).

Q: Which nerve supplies the gamellus inferior muscle?

Nerve to quadratus femoris. The **Gemellus inferior** is one of the small lateral rotators of the hip. Its nerve supply is determined by its anatomical proximity and shared embryological origin with the muscle immediately below it. ### **Why Option C is Correct** The **Nerve to quadratus femoris (L4, L5, S1)**, a branch of the sacral plexus, descends deep to the tendon of the obturator internus and the gemelli muscles. As it passes down to reach the quadratus femoris, it provides a motor branch to the **gemellus inferior**. This is a classic "two-for-one" nerve supply pattern seen in the gluteal region. ### **Analysis of Incorrect Options** * **Option A (Nerve to obturator internus):** This nerve supplies the **Gemellus superior** and the Obturator internus. A common mnemonic is "Superior nerve for superior muscle." * **Option B (Nerve to obturator externus):** This is a branch of the **posterior division of the obturator nerve** (L3, L4). It supplies the obturator externus, which is located in the medial compartment of the thigh, not the gluteal region. * **Option D (Ventral rami S1, S2):** While these segments contribute to the sacral plexus, they do not directly supply the gemellus inferior. The specific segmental origin for the nerve to quadratus femoris is **L4, L5, S1**. ### **High-Yield NEET-PG Pearls** * **The "Sandwich" Rule:** The Obturator internus tendon is "sandwiched" between the Gemellus superior (above) and Gemellus inferior (below). * **Nerve Supply Mnemonic:** * **S**uperior Gemellus = Nerve to Obturator **I**nternus (**S-I**) * **I**nferior Gemellus = Nerve to **Q**uadratus femoris (**I-Q**) * **Action:** All these muscles (Gemelli, Obturator internus, Quadratus femoris) act as **lateral rotators** of the extended thigh and abductors of the flexed thigh.

Q: A fracture of the neck of the fibula is most likely to result in injury to which nerve?

Common peroneal nerve. **Explanation:** **1. Why Common Peroneal Nerve (CPN) is correct:** The common peroneal nerve (also known as the common fibular nerve) is the most frequently injured nerve in the lower limb due to its superficial and vulnerable anatomical course. After branching from the sciatic nerve, it winds laterally around the **neck of the fibula**. At this specific site, the nerve lies directly against the bone, covered only by skin and fascia, making it highly susceptible to injury from fibular neck fractures, tight casts, or direct lateral trauma. **2. Why other options are incorrect:** * **Obturator nerve:** This nerve arises from the lumbar plexus (L2-L4) and supplies the medial compartment (adductors) of the thigh. It does not descend below the knee. * **Genitofemoral nerve:** This is a branch of the lumbar plexus (L1-L2) providing sensory innervation to the upper anterior thigh and motor supply to the cremaster muscle; it is anatomically distant from the fibula. * **Posterior tibial nerve:** This nerve passes through the popliteal fossa and travels deep in the **posterior compartment** of the leg, well-protected by the gastrocnemius and soleus muscles. It is more commonly injured in distal tibial fractures or tarsal tunnel syndrome. **3. Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Injury to the CPN leads to **Foot Drop** (loss of dorsiflexion) and loss of sensation over the first dorsal web space and lateral aspect of the leg. * **Gait:** Patients exhibit a **High Steppage Gait** to prevent toes from dragging. * **Branches:** The CPN divides into the **Deep Peroneal Nerve** (muscles of the anterior compartment) and the **Superficial Peroneal Nerve** (muscles of the lateral compartment). * **Deformity:** The characteristic deformity is **Equinovarus** (due to unopposed action of the tibialis posterior and calf muscles).

Question 1

Which of the following statements about the menisci is not true?

Accepted Answer

The medial meniscus is more mobile than the lateral meniscus.

Answer

The lateral meniscus covers more tibial articular surface than the medial meniscus.

Answer

The medial meniscus is more commonly injured than the lateral meniscus.

Answer

Menisci are predominantly made up of Type I collagen.

Question 2

Which statement best describes the common femoral artery?

Accepted Answer

The common femoral artery initially lies lateral to the femoral vein and moves to lie posteriorly as it descends.

Answer

Gives the profunda femoris branch within the femoral sheath.

Answer

Lies between the saphenous vein and femoral vein below the level of the thigh.

Answer

Lies over the pectineus muscle as it passes under the inguinal ligament.

Question 3

A 55-year-old man is admitted to the hospital after falling from his roof. Radiographic examination reveals a fracture of the talus bone in one foot. From what artery does this bone receive its primary vascular supply?

Accepted Answer

Posterior tibial

Answer

Anterior tibial

Answer

Dorsalis pedis

Answer

Lateral plantar

Question 4

All of the following are hybrid muscles except?

Accepted Answer

Tensor fascia lata

Answer

Pectineus

Answer

Adductor magnus

Answer

Biceps femoris

Question 5

Which of the following nerves is NOT a branch of the lumbar plexus?

Accepted Answer

Sciatic nerve

Answer

Obturator nerve

Answer

Femoral nerve

Answer

Lateral cutaneous nerve of thigh

Question 6

Which of the following is a component of the deltoid ligament?

Accepted Answer

Tibiotalar ligament

Answer

Talofibular ligament

Answer

Talonavicular ligament

Answer

Calcaneo-navicular ligament

Question 7

Which nerve supplies the gamellus inferior muscle?

Accepted Answer

Nerve to quadratus femoris

Answer

Nerve to obturator internus

Answer

Nerve to obturator externus

Answer

Ventral rami to S1 and S2

Question 8

A fracture of the neck of the fibula is most likely to result in injury to which nerve?

Accepted Answer

Common peroneal nerve

Answer

Obturator nerve

Answer

Genitofemoral nerve

Answer

Posterior tibial nerve

Question 9

Which of the following statements regarding knee movements is incorrect?

Accepted Answer

The posterior horns of the menisci move more than the anterior horns during knee movement.

Answer

Flexion is coupled with lateral rotation of the tibia.

Answer

There is differential motion between the lateral and medial compartments of the knee.

Answer

In full extension, the collateral ligaments of the knee are taut.

Question 10

A 31-year-old female presents with a complaint of Bell's palsy, which had appeared a year earlier and resulted in paralysis of muscles of one side of her face. A nerve graft was performed using a cutaneous nerve from the lower limb to replace the defective facial nerve, and the surgery was successful with restoration of facial muscle function six months post-procedure. The patient reports an area of skin on the lateral aspect of the leg and lateral side of the foot with no sensation. What nerve was likely used in the grafting procedure?

Accepted Answer

Sural

Answer

Superficial fibular (peroneal)

Answer

Tibial

Answer

Common fibular (peroneal)

Lower Limb — MCQs

Lower Limb — MCQs

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