Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 381: Which of the following is not a part of the chest wall?

A. Pectoralis major
B. Pectoralis minor
C. Serratus anterior
D. Coracobrachialis (Correct Answer)

Explanation: ### Explanation The **chest wall** (thoracic wall) consists of the rib cage and the muscles that either form the intercostal spaces or attach the upper limb to the axial skeleton (extrinsic muscles). **Why Coracobrachialis is the correct answer:** The **Coracobrachialis** is a muscle of the **arm (brachium)**, located in the anterior compartment. It originates from the tip of the coracoid process of the scapula and inserts into the middle third of the medial surface of the humerus. Its primary functions are flexion and adduction of the arm at the glenohumeral joint. It does not have any attachment to the ribs or the sternum and is therefore not considered a part of the chest wall. **Analysis of Incorrect Options:** * **Pectoralis major:** A large, fan-shaped extrinsic muscle that forms the bulk of the anterior chest wall [1]. It originates from the clavicle, sternum, and upper costal cartilages. * **Pectoralis minor:** Located deep to the pectoralis major, it originates from the 3rd, 4th, and 5th ribs and forms part of the anterior wall of the axilla [1]. * **Serratus anterior:** Known as the "boxer's muscle," it originates from the outer surfaces of the upper eight ribs and forms the medial wall of the axilla and the lateral aspect of the chest wall. **High-Yield Clinical Pearls for NEET-PG:** * **Musculocutaneous Nerve:** This nerve pierces the **Coracobrachialis** muscle. Injury to this nerve leads to loss of forearm flexion and sensory loss over the lateral forearm. * **Serratus Anterior:** Innervated by the **Long Thoracic Nerve (of Bell)**. Damage to this nerve (often during axillary lymph node dissection) results in **"Winging of Scapula."** * **Pectoral Fascia:** The pectoralis major is covered by pectoral fascia, which forms the base of the breast; the space between them is the **retromammary space**, crucial for breast mobility.

Question 382: All of the following can be involved in an injury to the head of the fibula, EXCEPT?

A. Anterior tibial nerve
B. Common peroneal nerve
C. Superficial peroneal nerve
D. Tibial nerve (Correct Answer)

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**. Any trauma to the head or neck of the fibula (fractures, tight casts, or compression) directly impacts this nerve and its branches. ### **Explanation of Options:** * **Tibial Nerve (Correct Answer):** The tibial nerve is the larger terminal branch of the sciatic nerve. It descends vertically through the midline of the popliteal fossa, deep between the two heads of the gastrocnemius. Because it is situated medially and protected by bulky muscles, it is **not** involved in injuries localized to the fibular head. * **Common Peroneal Nerve (CPN):** This nerve passes laterally across the posterior aspect of the fibular head before winding around the neck. It is the primary structure at risk. * **Deep Peroneal Nerve (Anterior Tibial Nerve):** This is one of the two terminal branches of the CPN. It begins at the neck of the fibula; therefore, a proximal injury to the CPN at the fibular head will manifest as deep peroneal nerve palsy. * **Superficial Peroneal Nerve:** This is the other terminal branch of the CPN. Like the deep peroneal nerve, it originates at the fibular neck and is compromised in fibular head injuries. ### **Clinical Pearls for NEET-PG:** * **Foot Drop:** Injury to the CPN at the fibular head leads to paralysis of the anterior and lateral compartment muscles, resulting in "Foot Drop" (loss of dorsiflexion and eversion) and a **"Stamping/High-steppage gait."** * **Sensory Loss:** Occurs on the dorsum of the foot and the lateral aspect of the leg. * **Mnemonic:** **PED** (Peroneal Everts and Dorsiflexes; if injured, the foot is **P**lantarflexed and **I**nverted).

Question 383: The neurovascular bundle of the anterior compartment of the leg passes between the tendons of which muscles?

A. Extensor hallucis longus and Extensor digitorum longus (Correct Answer)
B. Extensor digitorum longus and peroneus tertius
C. Tibialis anterior and Extensor hallucis longus
D. Tibialis anterior and Extensor digitorum longus

Explanation: ### Explanation The neurovascular bundle of the anterior compartment of the leg consists of the **Deep Peroneal Nerve** and the **Anterior Tibial Artery**. Understanding its anatomical course is crucial for identifying structures during surgery or in trauma cases like compartment syndrome. **Why Option A is Correct:** In the upper part of the leg, the neurovascular bundle lies between the **Tibialis anterior** and **Extensor digitorum longus (EDL)**. However, as it descends toward the ankle, the **Extensor hallucis longus (EHL)** crosses the bundle from lateral to medial. Consequently, in the lower third of the leg (just above the extensor retinaculum), the bundle is positioned specifically between the **tendons of EHL (medially)** and **EDL (laterally)**. This is the standard anatomical landmark often tested in exams. **Analysis of Incorrect Options:** * **Option B:** The Peroneus tertius is a small muscle often continuous with the EDL; the bundle does not pass between them. * **Option C:** This describes the relationship in the middle of the leg, but at the level of the ankle (where tendons are most prominent), the EHL has moved medially, placing the bundle between EHL and EDL. * **Option D:** This describes the relationship in the upper third of the leg before the EHL muscle belly becomes the primary medial boundary. **NEET-PG High-Yield Pearls:** * **Nerve Supply:** The Deep Peroneal Nerve (L4-S1) supplies all muscles of the anterior compartment. Injury leads to **Foot Drop**. * **Surface Marking:** The Anterior Tibial Artery continues as the **Dorsalis Pedis Artery** midway between the two malleoli, lateral to the EHL tendon. * **Clinical Correlation:** The anterior compartment is the most common site for **Acute Compartment Syndrome** in the leg. The first sign of nerve involvement is often sensory loss in the **first web space**.

Question 384: Which of the following is NOT a flexor of the hip joint?

A. Psoas major
B. Sartorius
C. Gluteus maximus (Correct Answer)
D. Rectus femoris

Explanation: **Explanation:** The hip joint is a multiaxial ball-and-socket joint where movement is determined by the muscle's position relative to the joint's axis. **Why Gluteus Maximus is the correct answer:** The **Gluteus maximus** is the chief **extensor** of the hip joint, not a flexor. It is located posterior to the joint axis and is particularly active during powerful movements like climbing stairs, running, or rising from a sitting position. It also acts as a lateral rotator of the thigh. **Analysis of incorrect options (Flexors of the Hip):** * **Psoas major:** This is the **primary and most powerful flexor** of the hip. Along with the Iliacus (forming the Iliopsoas), it is essential for lifting the limb during walking. * **Sartorius:** Known as the "tailor's muscle," it is a multi-joint muscle that acts as a flexor, abductor, and lateral rotator of the hip, as well as a flexor of the knee. * **Rectus femoris:** As part of the Quadriceps femoris, it is the only head that crosses the hip joint (originating from the AIIS), making it a potent hip flexor and knee extensor. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Hip Flexor:** Iliopsoas (Psoas major + Iliacus). * **Primary Hip Extensor:** Gluteus maximus. * **Primary Hip Abductor:** Gluteus medius (Trendelenburg sign occurs if paralyzed). * **Nerve Supply:** Gluteus maximus is supplied by the **Inferior Gluteal Nerve (L5, S1, S2)**, while the Gluteus medius and minimus are supplied by the Superior Gluteal Nerve. * **Thomas Test:** Used clinically to assess fixed flexion deformity of the hip.

Question 385: At what level does the common peroneal nerve divide?

A. Popliteal fossa
B. Neck of fibula (Correct Answer)
C. Tibial tuberosity
D. Upper pole of patella

Explanation: The **Common Peroneal Nerve (CPN)**, also known as the common fibular nerve, is a terminal branch of the sciatic nerve. It descends through the popliteal fossa along the medial border of the biceps femoris. The nerve then winds around the **posterolateral aspect of the neck of the fibula**, where it pierces the peroneus longus muscle. At this specific anatomical landmark, it divides into its two terminal branches: the **Superficial Peroneal Nerve** and the **Deep Peroneal Nerve**. **Analysis of Options:** * **Popliteal Fossa (Option A):** While the CPN originates at the apex of the popliteal fossa (from the sciatic nerve), it does not divide here; it travels along the lateral boundary. * **Tibial Tuberosity (Option C):** This is an anterior midline landmark of the tibia and is not anatomically related to the course or division of the peroneal nerve. * **Upper Pole of Patella (Option D):** This level is too superior; the sciatic nerve usually hasn't even bifurcated into the CPN and Tibial nerve at this height. **Clinical Pearls for NEET-PG:** 1. **Vulnerability:** The neck of the fibula is the most common site for CPN injury due to its superficial location against the bone. 2. **Clinical Presentation:** Injury at the fibular neck leads to **Foot Drop** (loss of dorsiflexion) and "Equinovarus" deformity, along with sensory loss on the dorsum of the foot. 3. **Nerve Supply:** The Deep Peroneal nerve supplies the anterior compartment of the leg (dorsiflexors), while the Superficial Peroneal nerve supplies the lateral compartment (evertors).

Question 386: Which muscle is supplied by the inferior gluteal nerve?

A. Obturator externus
B. Gluteus maximus (Correct Answer)
C. Gluteus medius
D. Quadratus femoris

Explanation: The **inferior gluteal nerve (L5, S1, S2)** is a branch of the sacral plexus that provides motor innervation to only one muscle: the **Gluteus maximus**. This muscle is the largest and most superficial of the gluteal group, acting as the primary extensor of the hip joint. ### Analysis of Options: * **Gluteus maximus (Correct):** It is the sole muscle supplied by the inferior gluteal nerve. It is essential for powerful movements like climbing stairs or rising from a sitting position. * **Obturator externus (Incorrect):** This muscle belongs to the medial compartment of the thigh and is supplied by the **posterior division of the obturator nerve (L3, L4)**. * **Gluteus medius (Incorrect):** Along with the gluteus minimus and tensor fasciae latae, it is supplied by the **superior gluteal nerve (L4, L5, S1)**. * **Quadratus femoris (Incorrect):** This is supplied by its own dedicated nerve, the **nerve to quadratus femoris (L4, L5, S1)**, which also supplies the inferior gemellus. ### High-Yield Clinical Pearls for NEET-PG: * **Trendelenburg Sign:** Damage to the **superior gluteal nerve** leads to paralysis of the gluteus medius and minimus, causing the pelvis to drop on the unsupported (opposite) side during walking. * **Gluteus Maximus Gait:** Damage to the **inferior gluteal nerve** results in difficulty extending the hip. Patients compensate by leaning their trunk backward during the heel-strike phase to maintain balance. * **Nerve Roots:** Remember the "Superior is Higher" rule: Superior gluteal (L4-S1) vs. Inferior gluteal (L5-S2).

Question 387: Extensor hallucis longus is supplied by which nerve?

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

Explanation: ### Explanation The **Extensor Hallucis Longus (EHL)** is a muscle located in the **anterior compartment** of the leg. The fundamental anatomical principle to remember for the lower limb is that each compartment has a specific nerve supply. **1. Why Deep Peroneal Nerve is Correct:** The anterior compartment of the leg (which includes the Tibialis Anterior, Extensor Digitorum Longus, Extensor Hallucis Longus, and Peroneus Tertius) is exclusively supplied by the **Deep Peroneal Nerve** (L4, L5, S1), a branch of the Common Peroneal Nerve. This nerve is often referred to as the "nerve of the anterior compartment." **2. Why Other Options are Incorrect:** * **Superficial Peroneal Nerve:** This nerve supplies the **lateral compartment** of the leg (Peroneus Longus and Brevis). It primarily handles eversion of the foot. * **Tibial Nerve:** This nerve supplies the **posterior compartment** of the leg (e.g., Gastrocnemius, Soleus, Tibialis Posterior). These muscles are responsible for plantarflexion and toe flexion. * **Sciatic Nerve:** This is the parent nerve that divides into the Tibial and Common Peroneal nerves in the popliteal fossa. It does not directly supply the muscles of the leg. **Clinical Pearls for NEET-PG:** * **Foot Drop:** Injury to the Common Peroneal Nerve (often at the neck of the fibula) or the Deep Peroneal Nerve leads to "Foot Drop" due to paralysis of the anterior compartment muscles (including EHL). * **Testing EHL:** To clinically test the **L5 nerve root**, ask the patient to perform resisted extension of the great toe. * **Anterior Compartment Syndrome:** The Deep Peroneal Nerve can be compressed in this syndrome, leading to sensory loss in the **first web space** of the foot (a high-yield diagnostic sign).

Question 388: Which of the following muscles plays an important role in lifting the left foot off the ground while walking?

A. Left gluteus medius
B. Left gluteus maximus
C. Right adductor longus
D. Right gluteus medius (Correct Answer)

Explanation: ### Explanation The correct answer is **Right gluteus medius**. #### 1. The Underlying Concept: Pelvic Stability during Gait To lift the **left foot** off the ground (the "swing phase"), the body must balance on the **right leg** (the "stance phase"). When the left foot is raised, gravity naturally tends to pull the unsupported left side of the pelvis downward. To prevent this pelvic tilt and allow the left foot to clear the ground, the **abductors of the supporting hip** (primarily the **Right Gluteus Medius** and **Gluteus Minimus**) must contract. This contraction pulls the pelvis down on the right side, effectively counter-levering and elevating the pelvis on the left side. #### 2. Analysis of Incorrect Options * **A. Left gluteus medius:** This muscle is relaxed during the left swing phase. If it were the supporting leg (right foot lifted), the left gluteus medius would be the primary stabilizer. * **B. Left gluteus maximus:** This is the chief extensor of the hip, used for climbing stairs or rising from a sitting position; it does not provide lateral pelvic stability. * **C. Right adductor longus:** Adductors move the limb toward the midline. They do not prevent the pelvic drop required for foot clearance. #### 3. Clinical Pearls for NEET-PG * **Trendelenburg Sign:** If the right superior gluteal nerve or gluteus medius is damaged, the pelvis will drop on the **opposite (left) side** when standing on the right leg. This is a "Positive Trendelenburg Sign." * **Trendelenburg Gait (Lurching Gait):** To compensate for this drop, the patient tilts their trunk toward the **affected side** (the side they are standing on) to shift the center of gravity. * **Nerve Supply:** Both the gluteus medius and minimus are supplied by the **Superior Gluteal Nerve (L4, L5, S1)**. Injury to this nerve (e.g., via misplaced intramuscular injections) is the most common cause of this gait abnormality.

Question 389: Which nerve winds around the neck of the fibula?

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

Explanation: ### Explanation **Correct Answer: D. Common peroneal nerve** The **Common Peroneal Nerve (CPN)**, also known as the common fibular nerve, is a terminal branch of the sciatic nerve. After originating in the popliteal fossa, it descends obliquely along the medial border of the biceps femoris muscle. Its most clinically significant anatomical landmark is where it **winds laterally around the neck of the fibula**. At this specific site, the nerve lies subcutaneously against the bone before dividing into its two terminal branches (deep and superficial peroneal nerves) within the fibers of the peroneus longus muscle. **Why the other options are incorrect:** * **A. Tibial nerve:** This is the larger branch of the sciatic nerve. it descends vertically through the popliteal fossa and enters the posterior compartment of the leg, staying well away from the fibular neck. * **B. Deep peroneal nerve:** This is a terminal branch of the CPN. It begins *after* the CPN has already rounded the fibular neck and travels in the anterior compartment of the leg. * **C. Superficial peroneal nerve:** This is the other terminal branch of the CPN. Like the deep peroneal nerve, it originates within the peroneus longus muscle *after* the CPN has passed the fibular neck. **Clinical Pearls for NEET-PG:** * **Most Common Site of Injury:** The CPN is the most commonly injured nerve in the lower limb due to its superficial position at the fibular neck. * **Mechanism of Injury:** Compression (tight casts, leg crossing), knee dislocations, or fibular neck fractures. * **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 Fact:** The CPN is the nerve most frequently involved in **Leprosy** (Hansen's disease) in the lower limb, where it becomes thickened and palpable at the fibular neck.

Question 390: Which muscle is attached to the navicular tuberosity?

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

Explanation: Explanation: The **Tibialis posterior** is the principal invertor and stabilizer of the medial longitudinal arch of the foot. Its insertion is extensive to ensure structural support; the primary (superficial) portion of its tendon inserts directly onto the **tuberosity of the navicular bone** and the medial cuneiform. This specific attachment point is a frequent high-yield target in anatomy exams. Analysis of Options: * **Tibialis anterior (A):** Inserts onto the medial and plantar surfaces of the **medial cuneiform** and the base of the **1st metatarsal**. It is the primary dorsiflexor of the foot. * **Peroneus longus (C):** Passes under the foot to insert onto the lateral side of the **medial cuneiform** and the base of the **1st metatarsal**. It acts as an antagonist to the Tibialis anterior regarding eversion/inversion. * **Extensor hallucis longus (D):** Inserts onto the base of the **distal phalanx of the great toe**. Its primary action is the extension of the big toe and dorsiflexion of the ankle. Clinical Pearls for NEET-PG: 1. **Medial Longitudinal Arch:** The Tibialis posterior is the "dynamic stabilizer" of this arch. Dysfunction or rupture of its tendon leads to **Acquired Flatfoot (Pes Planus)**. 2. **Accessory Navicular:** Occasionally, a secondary ossification center exists near the navicular tuberosity (Os Tibiale Externum), which can cause pain due to Tibialis posterior tension. 3. **Tom, Dick, and Harry:** Remember the order of structures passing behind the medial malleolus (Ant to Post): **T**ibialis posterior, flexor **D**igitorum longus, posterior tibial **A**rtery, tibial **N**erve, and flexor **H**allucis longus.

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Lower Limb — MCQs

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