Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 241: Which of the following muscles is located in the first layer of the sole of the foot?

A. Adductor hallucis
B. Flexor digitorum brevis (Correct Answer)
C. Flexor digiti minimi brevis
D. Flexor hallucis longus

Explanation: The sole of the foot is organized into **four distinct layers** of muscles and tendons, a high-yield topic for NEET-PG. ### **Explanation of the Correct Answer** The **first (most superficial) layer** consists of three muscles that originate primarily from the calcaneal tuberosity and act as the "intrinsic stabilizers" of the foot. These are: 1. **Abductor hallucis** 2. **Flexor digitorum brevis (FDB)** (The correct answer) 3. **Abductor digiti minimi** The FDB lies centrally in the first layer. It inserts into the middle phalanges of the lateral four toes and is responsible for flexing the proximal interphalangeal joints. ### **Analysis of Incorrect Options** * **Adductor hallucis (Option A):** This muscle belongs to the **third layer**. It has two heads (oblique and transverse) and is crucial for maintaining the transverse arch of the foot. * **Flexor digiti minimi brevis (Option C):** This is also a **third layer** muscle, located on the lateral side of the foot, acting on the little toe. * **Flexor hallucis longus (Option D):** This is an **extrinsic muscle** (originates in the posterior compartment of the leg). Its tendon passes through the **second layer** of the sole, where it is crossed by the tendon of the flexor digitorum longus. ### **NEET-PG High-Yield Pearls** * **Nerve Supply:** All muscles of the first layer are supplied by the **Medial Plantar Nerve**, *except* for the Abductor digiti minimi, which is supplied by the **Lateral Plantar Nerve**. * **Layer 2 Shortcut:** Remember "2 Tendons, 2 Muscles." Tendons: FDL and FHL. Muscles: Quadratus plantae and Lumbricals. * **Master Rule:** Most intrinsic muscles of the foot are supplied by the **Lateral Plantar Nerve** (S2, S3), which is analogous to the Ulnar nerve in the hand. Only four muscles are supplied by the Medial Plantar Nerve (LAFF: 1st **L**umbrical, **A**bductor hallucis, **F**lexor hallucis brevis, and **F**lexor digitorum brevis).

Question 242: Which structure passes deep to the medial malleolus?

A. Posterior tibial artery (Correct Answer)
B. Great saphenous vein
C. Tibialis anterior tendon
D. Peroneus tertius tendon

Explanation: The structures passing deep to the flexor retinaculum (behind the medial malleolus) are organized in a specific anteroposterior sequence. This is a classic high-yield topic for NEET-PG, often remembered by the mnemonic: **"Tom, Dick, And Very Nervous Harry."** 1. **T**ibialis posterior tendon (Most anterior) 2. **D**igitorum longus (Flexor digitorum longus tendon) 3. **A**rtery (Posterior tibial artery) 4. **V**ein (Posterior tibial vein) 5. **N**erve (Tibial nerve) 6. **H**arry (Flexor hallucis longus tendon - Most posterior/deep) **Explanation of Options:** * **A. Posterior tibial artery (Correct):** As per the mnemonic, the artery lies between the flexor digitorum longus and the tibial nerve behind the medial malleolus. * **B. Great saphenous vein:** This structure passes **anterior** to the medial malleolus, accompanied by the saphenous nerve. It is a superficial structure, not deep to the retinaculum. * **C. Tibialis anterior tendon:** This is a structure of the anterior compartment of the leg and passes anterior to the **ankle joint**, medial to the extensor hallucis longus. * **D. Peroneus tertius tendon:** This is also an anterior compartment muscle that inserts onto the base of the 5th metatarsal; it passes anterior to the **lateral malleolus**. **Clinical Pearls for NEET-PG:** * **Tarsal Tunnel Syndrome:** Compression of the tibial nerve as it passes deep to the flexor retinaculum. * **Pulsations:** The posterior tibial artery pulse is best felt midway between the medial malleolus and the medial tubercle of the calcaneus. * **Order:** Tibialis posterior is the first structure encountered immediately behind the medial malleolus and is the most commonly injured tendon in this region.

Question 243: What is the approximate length of the inguinal canal?

A. 2.5 cm
B. 4 cm (Correct Answer)
C. 10 cm
D. 15 cm

Explanation: **Explanation:** The **inguinal canal** is an oblique intramuscular passage located in the lower part of the anterior abdominal wall, situated just above the medial half of the inguinal ligament [1]. **Why 4 cm is correct:** In adults, the inguinal canal measures approximately **4 cm (1.5 inches)** in length. It extends from the **deep inguinal ring** (an opening in the fascia transversalis) to the **superficial inguinal ring** (an opening in the external oblique aponeurosis) [1]. Its oblique course is a protective physiological mechanism; when intra-abdominal pressure rises, the walls of the canal are apposed, acting like a valve to prevent herniation [1]. **Analysis of Incorrect Options:** * **2.5 cm:** This is too short for an adult canal. However, the canal is much shorter and less oblique in newborns, where the two rings almost overlap. * **10 cm & 15 cm:** These dimensions are far too long for the inguinal region. For context, 10-12 cm is the approximate length of the fallopian tube or the ureter’s abdominal portion. **High-Yield Clinical Pearls for NEET-PG:** * **Direction:** The canal runs downwards, forwards, and medially. * **Boundaries (Mnemonic: MALT):** * **M**roof: **M**uscular (Internal oblique and transversus abdominis) [1]. * **A**nterior wall: **A**poneurosis of external oblique [1]. * **L**oor (Floor): Inguinal **L**igament [1]. * **T**osterior (Posterior) wall: Fascia **T**ransversalis [1]. * **Contents:** Spermatic cord (males), Round ligament of the uterus (females), and the **Ilioinguinal nerve** (which enters the canal through the side, not the deep ring) [2]. * **Clinical Significance:** It is the site for **Indirect Inguinal Hernias**, which enter through the deep ring, lateral to the inferior epigastric artery [1].

Question 244: Which of the following muscles is responsible for the locking mechanism of the knee?

A. Popliteus
B. Hamstring
C. Quadriceps (Correct Answer)
D. None of the above

Explanation: The **locking mechanism** of the knee (also known as the "screw-home" mechanism) is a vital biomechanical process that occurs during the terminal stages of knee extension. **1. Why Quadriceps is Correct:** The **Quadriceps femoris** is the primary extensor of the knee. As the knee reaches full extension (0°), the quadriceps contracts to pull the tibia into a position of maximum stability. In a weight-bearing position (closed chain), this involves **internal rotation of the femur** on the tibia. This "locks" the joint by tightening the collateral and cruciate ligaments, allowing a person to stand for long periods with minimal muscular effort. **2. Why Other Options are Incorrect:** * **Popliteus (Option A):** This is the muscle responsible for **unlocking** the knee. To initiate flexion from a fully extended position, the popliteus contracts to rotate the femur laterally (in weight-bearing) or the tibia medially (in non-weight-bearing), thereby "unscrewing" the joint. * **Hamstrings (Option B):** These are the primary flexors of the knee. While they stabilize the joint, they do not participate in the terminal extension required for locking. **Clinical Pearls for NEET-PG:** * **Locking:** Occurs during terminal extension; involves **Medial Rotation of Femur** (on fixed tibia). * **Unlocking:** Occurs at the start of flexion; involves **Lateral Rotation of Femur** (on fixed tibia) by the **Popliteus** (the "Key" to the knee joint). * **Ligamentous Stability:** The Anterior Cruciate Ligament (ACL) is at its tightest during the locked position.

Question 245: Which is the most commonly injured nerve in the leg?

A. Common peroneal nerve (Correct Answer)
B. Femoral nerve
C. Sciatic nerve
D. Tibial nerve

Explanation: **Explanation:** The **Common Peroneal Nerve (CPN)**, also known as the common fibular nerve, is the most commonly injured nerve in the lower limb. The primary reason for its vulnerability is its **superficial anatomical course**. As it winds around the **neck of the fibula**, it lies directly against the bone, covered only by skin and fascia. This makes it highly susceptible to compression (e.g., tight casts, prolonged leg crossing) and direct trauma (e.g., fibular neck fractures). **Analysis of Options:** * **Common Peroneal Nerve (Correct):** Its exposed position at the fibular neck makes it the most frequent site of peripheral nerve entrapment in the leg, typically presenting as **foot drop** due to paralysis of the anterior and lateral compartment muscles. * **Femoral Nerve:** Located deep within the femoral triangle and protected by the inguinal ligament, it is rarely injured except during pelvic fractures or iatrogenic surgical trauma. * **Sciatic Nerve:** While it is the largest nerve, it is well-protected by the gluteus maximus and posterior thigh muscles. It is most commonly injured by posterior hip dislocations or misplaced intramuscular injections, but less frequently than the CPN. * **Tibial Nerve:** This nerve is deeply situated in the popliteal fossa and the posterior compartment of the leg. It is generally protected from external trauma, though it can be compressed in the tarsal tunnel. **Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Injury leads to **Foot Drop** (loss of dorsiflexion) and **Equinovarus** deformity. * **Sensory Loss:** Occurs on the dorsum of the foot and the lateral aspect of the leg. * **High-Yield Association:** Often associated with **Stryker's position** (lithotomy) or "Strawberry picker’s palsy" due to prolonged squatting.

Question 246: Eversion is:

A. Sole of the foot upward
B. Sole of the foot outward (Correct Answer)
C. Sole of the foot inward
D. Sole of the foot downward

Explanation: **Explanation:** **Eversion** is a complex movement of the foot where the **sole of the foot is turned outward**, away from the median plane. This movement occurs primarily at the **subtalar** and **transverse tarsal joints**. * **Why Option B is Correct:** During eversion, the lateral border of the foot is raised, and the sole faces laterally. This movement is primarily executed by the muscles in the lateral compartment of the leg: the **Peroneus (Fibularis) longus** and **Peroneus brevis**, both of which are supplied by the **superficial peroneal nerve**. * **Why Other Options are Incorrect:** * **Option A (Upward):** This describes **Dorsiflexion**, which occurs at the ankle joint (talocrural joint). * **Option C (Inward):** This describes **Inversion**, where the sole faces the midline. This is the opposite of eversion and is performed mainly by the Tibialis anterior and Tibialis posterior. * **Option D (Downward):** This describes **Plantarflexion**, occurring at the ankle joint. **High-Yield Clinical Pearls for NEET-PG:** 1. **Joints Involved:** Remember that Inversion and Eversion occur at the **Subtalar joint** (between talus and calcaneus) and the **Midtarsal/Transverse tarsal joints**, *not* the ankle joint. 2. **Stability:** The foot is more stable in eversion than inversion. Consequently, **Inversion injuries** (sprains) are much more common, often damaging the **Anterior Talofibular Ligament (ATFL)**. 3. **Nerve Supply:** A lesion of the **Common Peroneal Nerve** leads to "Foot Drop" and a loss of eversion, as it supplies both the anterior and lateral compartments.

Question 247: Which muscle is supplied by both the tibial and common peroneal parts of the sciatic nerve?

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

Explanation: **Explanation:** The **Biceps femoris** is a unique muscle of the posterior compartment of the thigh because it possesses a dual nerve supply, making it a "hybrid" or "composite" muscle. * **The Long Head** originates from the ischial tuberosity and is supplied by the **tibial part** of the sciatic nerve. * **The Short Head** originates from the linea aspera of the femur and is supplied by the **common peroneal (fibular) part** of the sciatic nerve. This dual innervation is a high-yield anatomical fact because the short head of the biceps femoris is the *only* muscle in the entire lower limb supplied by the common peroneal nerve before it divides at the neck of the fibula. **Analysis of Incorrect Options:** * **Adductor Magnus (Option A):** This is also a hybrid muscle, but its dual supply comes from the **obturator nerve** (adductor part) and the **tibial part** of the sciatic nerve (hamstring part). It does not receive supply from the common peroneal nerve. * **Semitendinosus & Semimembranosus (Options B & C):** These are "true" hamstring muscles. They originate from the ischial tuberosity and are supplied exclusively by the **tibial part** of the sciatic nerve. **NEET-PG Clinical Pearls:** 1. **Hybrid Muscles of Lower Limb:** Remember the "Big Three": Adductor Magnus (Obturator + Tibial), Pectineus (Femoral + Obturator), and Biceps Femoris (Tibial + Common Peroneal). 2. **Sciatic Nerve Division:** The sciatic nerve typically divides into the tibial and common peroneal nerves at the superior angle of the popliteal fossa, but they are functionally distinct from their origin in the pelvis.

Question 248: Which of the following muscles has an attachment on the capsule of the hip joint?

A. Sartorius
B. Rectus femoris (Correct Answer)
C. Vastus lateralis
D. Vastus medialis

Explanation: **Explanation:** The **Rectus femoris** is a unique component of the Quadriceps femoris muscle because it is the only one that crosses two joints (hip and knee). It arises via two heads: 1. **Straight head:** Originates from the Anterior Inferior Iliac Spine (AIIS). 2. **Reflected head:** Originates from a groove above the acetabulum and the **capsule of the hip joint**. This attachment to the joint capsule is clinically significant as it helps pull the capsule away from the joint space during hip flexion, preventing impingement. **Analysis of Incorrect Options:** * **Sartorius (A):** Originates from the Anterior Superior Iliac Spine (ASIS). It is the longest muscle in the body but has no capsular attachments at the hip. * **Vastus lateralis (C) & Vastus medialis (D):** These muscles originate from the femur (linea aspera, intertrochanteric line, etc.) and only cross the knee joint. They do not have an origin or attachment related to the hip joint capsule. **High-Yield Clinical Pearls for NEET-PG:** * **The "Kick" Muscle:** Rectus femoris is often called the "kicking muscle" because it simultaneously flexes the hip and extends the knee. * **Nerve Supply:** All muscles listed are supplied by the **Femoral Nerve (L2-L4)**. * **Capsular Attachments:** Other muscles with hip capsule attachments include the **Gluteus minimus** (anteriorly) and the **Obturator externus** (inferiorly). * **Avulsion Fracture:** In young athletes, a forceful contraction of the rectus femoris can lead to an avulsion fracture of the **AIIS**.

Question 249: The tendon of which of the following muscles is stretched during the patellar reflex?

A. Quadriceps femoris (Correct Answer)
B. Quadratus femoris
C. Sartorius
D. Pectineus

Explanation: The **patellar reflex** (knee-jerk reflex) is a classic example of a monosynaptic deep tendon reflex [1]. When the patellar ligament is tapped with a reflex hammer, it causes a sudden stretch of the **Quadriceps femoris** muscle. This stretch is detected by muscle spindles, sending an afferent signal via the femoral nerve to the spinal cord (L2–L4), resulting in a compensatory contraction of the quadriceps and extension of the knee [2]. **Analysis of Options:** * **Quadriceps femoris (Correct):** This muscle group (Rectus femoris, Vastus lateralis, medialis, and intermedius) inserts into the patella and, via the patellar ligament, onto the tibial tuberosity. It is the primary extensor of the knee and the effector muscle for this reflex. The muscle spindle and its reflex connections constitute a feedback device that operates to maintain muscle length [2]. * **Quadratus femoris:** Despite the similar name, this is a short lateral rotator of the hip located in the gluteal region. It has no role in knee extension or the patellar reflex. * **Sartorius:** Known as the "tailor's muscle," it acts to flex, abduct, and laterally rotate the hip, and flex the knee. It does not contribute to the quadriceps tendon. * **Pectineus:** This is a flat muscle in the medial compartment of the thigh that primarily adducts and flexes the hip. **Clinical Pearls for NEET-PG:** * **Root Value:** The patellar reflex specifically tests the **L3 and L4** nerve roots (primarily L4). * **Nerve Involved:** The **Femoral nerve** carries both the afferent (sensory) and efferent (motor) limbs of this reflex. * **Westphal’s Sign:** Refers to the absence or decrease of the patellar reflex, often seen in Lower Motor Neuron (LMN) lesions or Tabes dorsalis. * **Hungup Reflex:** A slow-relaxing patellar reflex is a classic sign of **hypothyroidism**.

Question 250: In preparing to isolate the proximal portion of the Femoral Artery, the vascular surgeon gently separated it from surrounding tissues. Posterior to the Femoral Sheath, what muscle forms the lateral portion of the floor of the Femoral Triangle?

A. Adductor Longus
B. Iliopsoas (Correct Answer)
C. Sartorius
D. Pectineus

Explanation: ### Explanation The **Femoral Triangle** is a subfascial space in the upper third of the thigh. Understanding its boundaries and floor is high-yield for surgical anatomy and NEET-PG. **1. Why Iliopsoas is Correct:** The floor of the femoral triangle is gutter-shaped and formed by four muscles. From **lateral to medial**, these are: * **Iliopsoas:** Forms the lateral part of the floor. * **Pectineus:** Forms the medial part of the floor. * (In some texts, the Adductor Longus and Psoas Major are also listed as the most medial and lateral components respectively). Since the question asks for the muscle forming the **lateral portion** of the floor posterior to the femoral sheath, **Iliopsoas** is the correct anatomical landmark. [1] **2. Analysis of Incorrect Options:** * **Adductor Longus (A):** Forms the **medial boundary** of the femoral triangle and the most medial part of the floor. * **Sartorius (C):** Forms the **lateral boundary** of the femoral triangle. It does not form the floor. * **Pectineus (D):** Forms the **medial portion** of the floor. It lies medial to the iliopsoas. **3. Clinical Pearls & High-Yield Facts:** * **Mnemonic for Floor (Lateral to Medial):** "**I** **P**eat **A** lot" (**I**liopsoas, **P**ectineus, **A**dductor longus). * **Femoral Sheath Contents:** The sheath contains the femoral artery (lateral), femoral vein (intermediate), and femoral canal (medial). Note: The **Femoral Nerve** is NOT inside the femoral sheath; it lies lateral to it, resting on the iliopsoas muscle. [1] * **Boundaries:** Superior (Inguinal ligament), Lateral (Sartorius), Medial (Adductor longus). * **Apex:** Formed where the Sartorius crosses the Adductor Longus; it leads into the Adductor (Hunter’s) Canal.

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Lower Limb — MCQs

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