Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 101: A 24-year-old female sustained a small-caliber bullet wound to the popliteal fossa. The bullet severed the tibial nerve. What is the most likely functional deficit resulting from this injury?

A. Inability to extend the leg at the knee
B. Foot drop
C. A dorsiflexed and everted foot (Correct Answer)
D. A plantar flexed and inverted foot

Explanation: ### Explanation **1. Why Option C is Correct:** The **tibial nerve** (L4-S3) is the larger terminal branch of the sciatic nerve. It supplies the muscles of the **posterior compartment of the leg** (gastrocnemius, soleus, plantaris, popliteus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus) and the intrinsic muscles of the sole. * **Action of Tibial Nerve:** It is responsible for **plantar flexion** (via gastrocnemius/soleus) and **inversion** (via tibialis posterior). * **Effect of Injury:** Paralysis of these muscles leads to an inability to plantar flex and invert the foot. Consequently, the **unopposed action** of the antagonist muscles (supplied by the common peroneal nerve)—the dorsiflexors and everters—pulls the foot into a **dorsiflexed and everted** position (Calcaneovalgus). **2. Why Other Options are Incorrect:** * **Option A:** Extension of the leg at the knee is performed by the quadriceps femoris, supplied by the **femoral nerve**. * **Option B:** **Foot drop** is the hallmark of **common peroneal nerve** injury. It results from the loss of dorsiflexion (deep peroneal nerve) and eversion (superficial peroneal nerve), causing the foot to remain plantar flexed and inverted (Equinovarus). * **Option D:** A plantar flexed and inverted foot describes the deformity seen in common peroneal nerve injury, not tibial nerve injury. **3. Clinical Pearls for NEET-PG:** * **Tarsal Tunnel Syndrome:** Compression of the tibial nerve behind the medial malleolus, causing pain/paresthesia in the sole. * **Mnemonic for Deformity:** * **T**ibial nerve injury = **T**alipes **C**alcaneovalgus (Dorsiflexed/Everted). * **P**eroneal nerve injury = **P**lantar flexion/Equinovarus (Foot Drop). * **Sensory Loss:** In tibial nerve injury at the popliteal fossa, sensation is lost on the **sole of the foot** (medial and lateral plantar nerves).

Question 102: What is the blood supply of the femoral head?

A. Femoral artery
B. Obturator artery
C. Medial and lateral circumflex arteries
D. All of the above (Correct Answer)

Explanation: The blood supply to the femoral head is a classic high-yield topic in Anatomy, characterized by a complex collateral network essential for bone viability. ### **Explanation of the Correct Answer** The femoral head receives its blood supply from three primary sources, making **Option D** the correct answer: 1. **Medial and Lateral Circumflex Femoral Arteries (MCFA & LCFA):** These are branches of the *Profunda Femoris*. They form an extracapsular arterial ring at the base of the femoral neck. The **MCFA** is the most significant contributor, giving off **retinacular arteries** (mainly posterosuperior and posteroinferior) that pierce the capsule to supply the majority of the head. 2. **Obturator Artery:** It gives rise to the **Artery of Ligamentum Teres** (acetabular branch). While critical in children, its contribution diminishes in adults, supplying only a small area around the fovea capitis. 3. **Femoral Artery:** It acts as the primary source by giving rise to the *Profunda Femoris*, which subsequently branches into the circumflex arteries mentioned above. ### **Analysis of Options** * **Options A, B, and C** are all individual components of the supply. Since all three contribute to the vascularity of the femoral head, selecting any single one would be incomplete. ### **Clinical Pearls for NEET-PG** * **Avascular Necrosis (AVN):** Intracapsular fractures of the femoral neck frequently tear the retinacular vessels (from MCFA). Because the femoral head has a "retrograde" blood supply, these fractures carry a high risk of AVN. * **Cruciate Anastomosis:** Located at the level of the lesser trochanter, it connects the Internal Iliac (via inferior gluteal) and Femoral systems (via MCFA, LCFA, and first perforator). * **Trochanteric Anastomosis:** Provides the main supply to the femoral head; it involves the MCFA, LCFA, Superior Gluteal, and Inferior Gluteal arteries.

Question 103: What percentage of total height does the length of the tibia typically represent?

A. 10% of height
B. 20% of height (Correct Answer)
C. 30% of height
D. 40% of height

Explanation: The length of the tibia is a critical parameter in anthropometry and forensic medicine for estimating an individual's total stature. In a standard adult, the **tibia represents approximately 20% (one-fifth) of the total body height.** **Why Option B is Correct:** The tibia is the second longest bone in the body. Anatomical studies and regression formulas (like those by Trotter and Gleser) establish that the ratio of tibial length to total height is roughly 1:5. For example, in an individual who is 175 cm tall, the tibia typically measures around 35 cm. **Analysis of Incorrect Options:** * **Option A (10%):** This is too short; 10% of height would correspond to smaller bones like the clavicle or the length of the hand. * **Option C (30%):** This is an overestimation for a single bone. However, the entire lower leg (including the foot height) might approach this, but the tibia alone does not. * **Option D (40%):** This value is closer to the length of the **entire lower limb** (from the hip joint to the ground), not just the tibia. **High-Yield Clinical Pearls for NEET-PG:** * **The Femur Factor:** The femur is the longest and strongest bone, representing approximately **26-27%** of total height. * **Nutrient Foramen:** The tibia's nutrient foramen is located in the upper one-third of the posterior surface; the nutrient artery is a branch of the **posterior tibial artery**. * **Clinical Significance:** The lower one-third of the tibia is the most common site for **non-union fractures** due to its relatively poor blood supply compared to the proximal segments. * **Ossification:** The tibia ossifies from one primary center (shaft) and two secondary centers (upper and lower epiphyses). The upper epiphysis is often used in forensics to determine if a newborn is full-term.

Question 104: The femoral nerve supplies all of the following muscles except?

A. Pectineus
B. Sartorius
C. Vastus medialis
D. Obturator externus (Correct Answer)

Explanation: The **femoral nerve (L2–L4)** is the largest branch of the lumbar plexus, primarily responsible for supplying the muscles of the **anterior compartment of the thigh** and the hip flexors. ### **Why Obturator Externus is the Correct Answer** The **Obturator externus** is located in the medial compartment of the thigh. It is supplied by the **posterior division of the obturator nerve (L2–L4)**, not the femoral nerve. Its primary function is the external rotation of the hip. ### **Analysis of Incorrect Options** * **Pectineus:** This is a "hybrid" or "composite" muscle. It is primarily supplied by the **femoral nerve** (anterior division), though it occasionally receives a small branch from the accessory obturator nerve. * **Sartorius:** Known as the "tailor's muscle," it is the most superficial muscle of the anterior compartment and is supplied by the **anterior division of the femoral nerve**. * **Vastus Medialis:** Part of the Quadriceps femoris group, it is supplied by the **posterior division of the femoral nerve**. Notably, the nerve to the vastus medialis also provides sensory innervation to the knee joint. ### **NEET-PG High-Yield Pearls** * **Divisions:** The femoral nerve divides into anterior and posterior divisions via the **lateral circumflex femoral artery**. * **Sensory Supply:** The anterior division gives off the medial and intermediate cutaneous nerves of the thigh; the posterior division gives off the **saphenous nerve** (the longest cutaneous nerve in the body). * **Clinical Sign:** Injury to the femoral nerve results in the inability to extend the knee and loss of the patellar reflex (Knee jerk). * **Hybrid Muscles of Lower Limb:** Pectineus (Femoral + Obturator), Adductor Magnus (Obturator + Sciatic/Tibial), and Biceps Femoris (Tibial + Common Peroneal).

Question 105: Which bony landmark of the femur serves as a site for muscle attachments?

A. fovea capitis
B. lesser trochanter (Correct Answer)
C. head
D. medial condyle

Explanation: The **lesser trochanter** is a conical eminence located on the posteromedial aspect of the femur at the junction of the neck and shaft. It serves as the primary insertion site for the **Iliopsoas muscle** (the combined tendon of psoas major and iliacus), which is the most powerful flexor of the hip joint. In anatomy, "trochanters" and "tuberosities" are specifically designed as leverage points for muscle pull. **Analysis of Incorrect Options:** * **A. Fovea Capitis:** This is a small, pit-like depression on the head of the femur. It does not provide muscle attachment; instead, it serves as the attachment site for the **Ligamentum Teres** (ligament of the head of the femur), which carries a small branch of the obturator artery to the femoral head. * **C. Head:** The femoral head is a smooth, globular structure covered in hyaline cartilage designed for articulation with the acetabulum to form the hip joint. It is an articular surface, not a site for muscle attachment. * **D. Medial Condyle:** This is a large, rounded projection at the distal end of the femur. While the *epicondyles* serve as attachment points for ligaments (like the MCL), the condyles themselves are smooth articular surfaces that form the knee joint. **High-Yield Clinical Pearls for NEET-PG:** * **Avulsion Fracture:** In adolescent athletes, sudden forceful contraction of the iliopsoas can lead to an avulsion fracture of the lesser trochanter. * **Psoas Sign:** Pain during hip extension (stretching the iliopsoas) is a classic sign of retrocecal appendicitis. * **Greater Trochanter:** In contrast, the greater trochanter is the insertion site for the gluteus medius, gluteus minimus, and piriformis muscles.

Question 106: Inversion of the foot is produced by which of the following muscles?

A. Peroneus longus
B. Soleus
C. Popliteus
D. Tibialis anterior (Correct Answer)

Explanation: **Explanation:** The movements of inversion and eversion occur primarily at the **subtalar** and **transverse tarsal joints**. Inversion is the movement where the sole of the foot faces medially. **Why Tibialis Anterior is Correct:** The **Tibialis anterior** (supplied by the Deep Peroneal Nerve) is a primary inverter of the foot. It inserts into the medial cuneiform and the base of the first metatarsal. Because its tendon passes medial to the axis of the subtalar joint, its contraction pulls the medial border of the foot upwards and inwards. It also acts as the chief dorsiflexor of the ankle. **Analysis of Incorrect Options:** * **Peroneus longus:** This muscle is a primary **everter** of the foot and a weak plantarflexor. It inserts on the lateral side of the medial cuneiform and first metatarsal, pulling the lateral border of the foot upwards. * **Soleus:** This is a powerful **plantarflexor** of the ankle joint. It does not cross the tarsal joints in a way that significantly contributes to inversion or eversion. * **Popliteus:** This muscle acts on the **knee joint**. It "unlocks" the knee by laterally rotating the femur on the fixed tibia (or medially rotating the tibia in a non-weight-bearing position). It has no action on the foot. **High-Yield Clinical Pearls for NEET-PG:** * **The "Tibialis" Rule:** Both Tibialis muscles (**Anterior and Posterior**) are **Inverters**. * **The "Peroneus" Rule:** All Peroneal muscles (**Longus, Brevis, and Tertius**) are **Everters**. * **Nerve Supply:** Injury to the **Common Peroneal Nerve** leads to loss of eversion and dorsiflexion, resulting in **Foot Drop** and a characteristic "Equinovarus" position (the foot remains inverted due to the unopposed action of Tibialis posterior).

Question 107: What is the largest and most important branch of the posterior tibial artery?

A. Circumflex fibular artery
B. Peroneal artery (Correct Answer)
C. Medial plantar artery
D. Lateral plantar artery

Explanation: **Explanation:** The **posterior tibial artery** is the larger terminal branch of the popliteal artery. It descends in the posterior compartment of the leg, deep to the gastrocnemius and soleus muscles. **Why the Peroneal (Fibular) Artery is correct:** The **peroneal artery** is the largest and most significant branch of the posterior tibial artery. It arises approximately 2.5 cm distal to the lower border of the popliteus muscle. It runs obliquely toward the fibula and descends along its medial side, supplying the lateral compartment of the leg and the calcaneal region. Its clinical importance lies in its role in providing collateral circulation to the foot if the tibial arteries are occluded. **Analysis of Incorrect Options:** * **Circumflex fibular artery:** This is a small branch that usually arises from the beginning of the posterior tibial artery (or sometimes the anterior tibial artery) and winds around the neck of the fibula. * **Medial and Lateral plantar arteries:** These are the **terminal branches** of the posterior tibial artery, formed deep to the flexor retinaculum (at the level of the porta pedis). While important for foot vascularity, they are divisions of the parent artery rather than its "largest branch" along its course in the leg. **High-Yield Clinical Pearls for NEET-PG:** * **Nutrient Artery to Tibia:** The posterior tibial artery gives off the nutrient artery to the tibia, which is the largest nutrient artery in the body. * **Palpation:** The posterior tibial pulse is best felt halfway between the **medial malleolus** and the **medial tubercle of the calcaneus**. * **Pirogoff’s Artery:** Another name for the peroneal artery in older texts. * **Grafting:** The peroneal artery is often spared in atherosclerotic disease, making it a vital source for distal bypass or free flap surgery (e.g., fibular osteocutaneous flap).

Question 108: Which of the following ligaments is not attached to the talus?

A. Talonavicular ligament
B. Spring ligament (Correct Answer)
C. Deltoid ligament
D. Cervical ligament

Explanation: The **Spring ligament** (Plantar calcaneonavicular ligament) is the correct answer because it does not have a direct attachment to the talus. Instead, it spans the gap between the **sustentaculum tali** of the calcaneus and the **navicular bone**. Its primary function is to support the head of the talus from below, acting as a "hammock" to maintain the medial longitudinal arch of the foot. ### Evaluation of Options: * **Talonavicular ligament (Option A):** As the name implies, it connects the neck of the talus to the dorsal surface of the navicular bone. * **Deltoid ligament (Option C):** This strong, medial collateral ligament of the ankle has four parts. Two of these—the **anterior tibiotalar** and **posterior tibiotalar** fibers—attach directly to the talus. * **Cervical ligament (Option D):** This is a strong extracapsular ligament located in the sinus tarsi that connects the neck of the talus to the neck of the calcaneus. It is crucial for subtalar joint stability. ### NEET-PG High-Yield Pearls: * **The "Hammock" Concept:** The Spring ligament is the main supporter of the **medial longitudinal arch**. If it fails or overstretches, the head of the talus descends, leading to **Pes Planus (Flat Foot)**. * **The Talus Paradox:** The talus is unique because it has **no muscular or tendinous attachments**; it relies entirely on ligamentous support and bony articulation. * **Blood Supply:** The talus has a retrograde blood supply (mainly via the artery of the tarsal canal). Fractures of the neck often lead to **Avascular Necrosis (AVN)**.

Question 109: Ligation of which nerve will lead to paresthesia and pain on the dorsum of the foot during venesection of the great saphenous vein?

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

Explanation: **Explanation:** The **Saphenous nerve** is the correct answer because of its intimate anatomical relationship with the **Great Saphenous Vein (GSV)**. 1. **Anatomical Basis:** The saphenous nerve is the longest cutaneous branch of the femoral nerve ($L3, L4$). It descends through the adductor canal and becomes superficial at the medial side of the knee. Crucially, as it descends into the leg, it runs immediately **anterior** to the medial malleolus, closely accompanying the GSV [1]. 2. **Clinical Correlation:** Venesection (cut-down) of the GSV is typically performed just anterior to the medial malleolus. During this procedure, the saphenous nerve is at high risk of being accidentally ligated or injured [1]. Since it provides sensory innervation to the **medial side of the leg and the medial border of the dorsum of the foot**, injury results in paresthesia and pain in these regions [1]. **Analysis of Incorrect Options:** * **Sural Nerve:** Accompanies the **Small Saphenous Vein** behind the lateral malleolus. Injury affects the lateral border of the foot. * **Genicular Nerve:** These are branches (from femoral, obturator, and sciatic nerves) that supply the knee joint capsule and ligaments, not the distal dorsum of the foot. * **Deep Peroneal Nerve:** Supplies the web space between the first and second toes. It is located deep in the anterior compartment and is not involved in superficial venesection. **High-Yield Clinical Pearls for NEET-PG:** * **GSV Location:** Starts at the medial end of the dorsal venous arch, passes **anterior** to the medial malleolus. * **Nerve-Vein Pairs:** * Great Saphenous Vein + Saphenous Nerve [1]. * Small Saphenous Vein + Sural Nerve. * **Saphenous Nerve Block:** Often used for procedures on the medial leg/foot; it is a purely sensory nerve (no motor deficit if injured).

Question 110: A patient presents with sensory loss on adjacent sides of the great and second toes and impaired dorsiflexion of the foot. These signs probably indicate damage to which of the following nerves?

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

Explanation: The clinical presentation points toward a lesion of the **Deep Peroneal Nerve (Deep Fibular Nerve)**, a branch of the Common Peroneal nerve. This nerve is responsible for both specific motor and sensory functions in the lower limb: 1. **Motor Function:** It innervates the muscles of the anterior compartment of the leg (Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus, and Peroneus tertius). Damage leads to the loss of **dorsiflexion**, resulting in **foot drop**. 2. **Sensory Function:** Its cutaneous distribution is highly specific—it supplies only the **first interdigital cleft** (adjacent sides of the great and second toes). **Analysis of Incorrect Options:** * **Superficial Peroneal Nerve:** Supplies the lateral compartment (eversion) and provides sensation to the majority of the dorsum of the foot, *excluding* the first web space. * **Tibial Nerve:** Supplies the posterior compartment (plantarflexion). Injury causes loss of plantarflexion and sensory loss on the sole of the foot. * **Sural Nerve:** A purely sensory nerve supplying the lateral aspect of the foot and the little toe. It has no motor component, so it would not cause impaired dorsiflexion. **NEET-PG High-Yield Pearls:** * **Site of Injury:** The Common Peroneal nerve is most commonly injured at the **neck of the fibula**. * **Anterior Compartment Syndrome:** The Deep Peroneal nerve is the nerve most commonly compressed in this surgical emergency. * **Gait:** Foot drop caused by Deep Peroneal nerve injury results in a **"High Steppage Gait"** to prevent the toes from dragging.

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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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