Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 111: Which of the following forms the tendinous sling in the superficial arch of the foot?

A. Peroneus longus and peroneus brevis
B. Peroneus longus and flexor hallucis longus
C. Peroneus longus and tibialis posterior (Correct Answer)
D. Peronius brevis and tibialis posterior

Explanation: The arches of the foot are maintained by four main factors: bony architecture, ligaments, muscles, and the "tie-beams" or slings. The **tendinous sling** is a crucial mechanism for maintaining the **medial and lateral longitudinal arches**, as well as the **transverse arch**. ### Why Option C is Correct: The "sling" is formed by the tendons of the **Peroneus longus** and **Tibialis posterior** crossing in the sole of the foot. * **Peroneus Longus:** Enters the sole from the lateral side, passes through the groove of the cuboid, and runs medially to insert into the base of the 1st metatarsal and medial cuneiform. * **Tibialis Posterior:** Enters from the medial side and inserts primarily into the navicular tuberosity, with slips spreading to almost all tarsal bones (except the talus) and the bases of the middle metatarsals. * **The Mechanism:** These two tendons meet and cross like a "stirrup" or "sling" under the midfoot. When they contract, they pull the midfoot upward, effectively supporting the longitudinal arches and preventing the collapse of the transverse arch. ### Why Other Options are Incorrect: * **Option A & D:** The **Peroneus brevis** inserts into the tubercle at the base of the 5th metatarsal. It does not cross the sole of the foot and therefore cannot contribute to the sling mechanism. * **Option B:** The **Flexor hallucis longus** acts as a "tie-beam" for the medial longitudinal arch, but it runs anteroposteriorly and does not form a transverse sling with the peroneus longus. ### High-Yield Clinical Pearls for NEET-PG: * **Main Supporter:** The **Spring Ligament** (Plantar calcaneonavicular) is the most important *static* stabilizer of the medial longitudinal arch. * **Keystone:** The **Talus** is the keystone of the medial longitudinal arch; the **Cuboid** is the keystone of the lateral arch. * **Dynamic Support:** Tibialis anterior and Peroneus longus together form a "functional stirrup" that lifts the sole during gait. * **Clinical Correlation:** Paralysis or dysfunction of the Tibialis posterior is a leading cause of **acquired flat foot** (Pes Planus).

Question 112: Tibialis posterior has insertion to all of the following bones except?

A. 2nd metatarsal
B. 1st metatarsal (Correct Answer)
C. Medial Cuneiform
D. 3rd Metatarsal

Explanation: The **Tibialis Posterior** is the deepest muscle of the posterior compartment of the leg and is often referred to as the "key stabilizer" of the medial longitudinal arch. ### **Anatomical Basis of Insertion** The tendon of the Tibialis Posterior passes behind the medial malleolus and spreads out into a wide, fan-like insertion in the sole of the foot. It is unique because it attaches to almost every tarsal bone (except the talus) and several metatarsals. * **Primary Insertion:** The Tuberosity of the **Navicular** bone and the **Medial Cuneiform**. * **Secondary Insertions (Expansion):** It sends slips to the Intermediate and Lateral Cuneiforms, the Cuboid, and the bases of the **2nd, 3rd, and 4th metatarsals**. ### **Why Option B is Correct** The **1st Metatarsal** is the correct answer because the Tibialis Posterior does **not** attach to it. The base of the 1st metatarsal is the primary insertion site for the **Tibialis Anterior** and the **Peroneus (Fibularis) Longus**. ### **Analysis of Incorrect Options** * **Option A & D (2nd and 3rd Metatarsals):** These are incorrect because the Tibialis Posterior specifically sends fibrous expansions to the bases of the 2nd, 3rd, and 4th metatarsals to maintain the transverse arch of the foot. * **Option C (Medial Cuneiform):** This is incorrect because the medial cuneiform is one of the two primary insertion points of the muscle. ### **High-Yield NEET-PG Pearls** * **Main Function:** It is the principal **invertor** and plantarflexor of the foot. * **Clinical Correlation:** Dysfunction or rupture of the Tibialis Posterior tendon is the most common cause of **Acquired Flat Foot (Pes Planus)** due to the collapse of the medial longitudinal arch. * **Nerve Supply:** Tibial Nerve (L4, L5). * **The "Tom, Dick, and Harry" Mnemonic:** Reminds you of the structures passing deep to the flexor retinaculum (Medial to Lateral): **T**ibialis posterior, flexor **D**igitorum longus, posterior tibial **A**rtery, tibial **N**erve, and flexor **H**allucis longus.

Question 113: Which bursa communicates with the knee joint?

A. Infrapatellar bursa
B. Prepatellar bursa
C. Suprapatellar bursa (Correct Answer)
D. Lateral patellar bursa

Explanation: ### Explanation The knee joint is the largest and most complex joint in the body, characterized by an extensive synovial membrane. The correct answer is the **Suprapatellar bursa**. **1. Why Suprapatellar Bursa is Correct:** The suprapatellar bursa (or suprapatellar pouch) is located superior to the patella, between the femur and the tendon of the quadriceps femoris. During fetal development, it starts as a separate bursa but eventually fuses with the synovial cavity of the knee joint. Therefore, in adults, it represents a **direct extension of the joint cavity**. This communication is clinically significant because joint effusions (fluid collection) will typically accumulate here first. **2. Analysis of Incorrect Options:** * **Prepatellar bursa:** Located subcutaneously between the skin and the anterior surface of the patella. It does **not** communicate with the joint. Inflammation here is known as "Housemaid’s knee." * **Infrapatellar bursa:** There are two (superficial and deep). The **Deep infrapatellar bursa** is located between the tibia and the ligamentum patellae, separated from the joint by the infrapatellar fat pad. Neither communicates with the joint cavity. * **Lateral patellar bursa:** This is not a standard anatomical term for the major bursae around the knee; however, bursae related to the lateral collateral ligament do not communicate with the main synovial cavity. **3. NEET-PG High-Yield Clinical Pearls:** * **Popliteus Bursa:** This is another important bursa that **always communicates** with the knee joint. * **Semimembranosus Bursa:** Often communicates with the joint; its enlargement is a common cause of a **Baker’s Cyst** (Popliteal cyst). * **Articularis Genu:** This small muscle (derived from vastus intermedius) inserts into the suprapatellar bursa to pull it superiorly during extension, preventing the synovial membrane from being trapped in the joint.

Question 114: Identify the muscle that is not in relation with the structure marked A.

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

Explanation: ***Gluteus maximus*** - The **gluteus maximus** does not insert into the **greater trochanter** but instead inserts into the **gluteal tuberosity** of the femur and the **iliotibial tract**. - It is the largest gluteal muscle responsible for **hip extension** and **external rotation**, but has no direct relation to the greater trochanter. *Gluteus medius* - The **gluteus medius** inserts directly into the **lateral surface of the greater trochanter**, making it closely related to structure A. - This muscle is crucial for **hip abduction** and **pelvic stabilization** during walking, with its insertion site being the greater trochanter. *Gluteus minimus* - The **gluteus minimus** inserts into the **anterior aspect of the greater trochanter**, establishing a direct anatomical relationship with structure A. - It works synergistically with gluteus medius for **hip abduction** and **medial rotation** of the thigh. *Piriformis* - The **piriformis muscle** inserts into the **superior border of the greater trochanter**, making it anatomically related to structure A. - This deep muscle is important for **hip external rotation** and **hip stabilization**, with its insertion directly on the greater trochanter.

Question 115: What is the origin of the Posterior Cruciate Ligament (PCL)?

A. Posterior part of the intercondylar area of the tibia (Correct Answer)
B. Anterior part of the intercondylar area of the tibia
C. Medial part of the medial femoral condyle
D. Lateral part of the medial femoral condyle

Explanation: The **Posterior Cruciate Ligament (PCL)** is one of the two major intra-articular ligaments of the knee, essential for maintaining posterior stability. ### **Explanation of the Correct Answer** **Option A** is correct because the PCL originates from the **posterior part of the intercondylar area of the tibia**, specifically from a depression behind the intercondylar eminence. From this tibial attachment, it passes upwards, forwards, and medially to insert into the **anterolateral aspect of the medial femoral condyle**. Its primary function is to prevent the tibia from sliding posteriorly relative to the femur. ### **Analysis of Incorrect Options** * **Option B:** The anterior part of the intercondylar area of the tibia is the site of origin for the **Anterior Cruciate Ligament (ACL)**. * **Option C & D:** These options refer to the **insertion** points on the femur, not the origin. The PCL inserts onto the lateral surface of the medial femoral condyle. A common mnemonic to remember the femoral insertions is **LAMP**: **L**ateral condyle = **A**CL; **M**edial condyle = **P**CL. ### **NEET-PG High-Yield Pearls** * **Strength:** The PCL is thicker and stronger than the ACL. * **Blood Supply:** Both cruciate ligaments are supplied by the **middle genicular artery** (branch of the popliteal artery). * **Clinical Sign:** Injury to the PCL results in a **Positive Posterior Drawer Sign** or "Sag sign." * **Mechanism of Injury:** Often occurs due to a direct blow to the proximal tibia while the knee is flexed (e.g., **"Dashboard injury"** in motor vehicle accidents).

Question 116: Which muscle is responsible for unlocking the knee?

A. Adductor magnus
B. Biceps femoris
C. Popliteus (Correct Answer)
D. Sartorius

Explanation: The **Popliteus** is famously known as the **"Key to the knee"** because of its essential role in initiating flexion from a fully extended position. **1. Why Popliteus is correct:** When the knee is fully extended, it undergoes "locking"—a mechanism where the femur rotates medially on the tibia (in a closed chain) to increase stability. To initiate flexion, the knee must first be "unlocked." The Popliteus muscle achieves this by: * **Non-weight bearing (Open chain):** Rotating the tibia medially on the femur. * **Weight-bearing (Closed chain):** Rotating the femur **laterally** on the tibia. This rotation relaxes the tension in the ligaments (specifically the ACL and collateral ligaments), allowing flexion to proceed. **2. Why other options are incorrect:** * **Adductor magnus:** Primarily an adductor of the thigh. Its "hamstring part" aids in hip extension, but it has no role in the rotational unlocking of the knee. * **Biceps femoris:** A member of the hamstrings that flexes the knee and laterally rotates the leg when the knee is semi-flexed. It does not initiate the unlocking process. * **Sartorius:** Known as the "Tailor’s muscle," it flexes, abducts, and laterally rotates the hip, and flexes the knee. It is not involved in the biomechanical unlocking mechanism. **Clinical Pearls for NEET-PG:** * **Origin:** Lateral condyle of the femur (intracapsular but extrasynovial). * **Insertion:** Posterior surface of the tibia above the soleal line. * **Innervation:** Tibial nerve (L4, L5, S1). * **Action:** Unlocks the knee, protects the lateral meniscus (by pulling it posteriorly during flexion), and acts as a weak knee flexor.

Question 117: The obturator nerve innervates all of the following muscles except?

A. Adductor longus
B. Pectineus
C. Obturator internus (Correct Answer)
D. Obturator externus

Explanation: **Explanation:** The **obturator nerve (L2–L4)** is the primary nerve of the medial compartment of the thigh. It supplies the adductor group of muscles and the obturator externus. **Why Obturator Internus is the correct answer:** Despite its similar name, the **Obturator internus** is a muscle of the gluteal region, not the medial thigh. It is innervated by the **Nerve to Obturator Internus (L5, S1, S2)**, which arises from the sacral plexus. This is a common "trap" in anatomy exams due to the nomenclature. **Analysis of Incorrect Options:** * **Adductor longus:** This is a classic medial compartment muscle supplied by the anterior division of the obturator nerve. * **Pectineus:** This is a "hybrid" or "composite" muscle. While it is primarily supplied by the **femoral nerve**, it frequently receives a small contribution from the **obturator nerve** (accessory obturator nerve). In the context of this question, it is considered part of the obturator's distribution compared to the obturator internus, which has a completely different nerve origin. * **Obturator externus:** This muscle is supplied by the posterior division of the obturator nerve. It is the only external rotator of the hip supplied by this nerve. **High-Yield Clinical Pearls for NEET-PG:** 1. **Hybrid Muscles of Lower Limb:** * **Adductor Magnus:** Obturator nerve (adductor part) and Sciatic nerve/Tibial component (hamstring part). * **Pectineus:** Femoral nerve and Obturator nerve. 2. **Referred Pain:** Irritation of the obturator nerve (e.g., in ovarian cancer or obturator hernia) can cause referred pain to the medial side of the knee (Howship-Romberg sign). 3. **Obturator Externus:** It is the "key" to the medial compartment, and the obturator nerve divisions (anterior and posterior) pass around it.

Question 118: A 45-year-old male presents with fractures of the tibia and fibula after a bicycle fall. On physical examination, he has a foot drop but normal foot eversion. Which of the following nerves is most likely injured?

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

Explanation: ### **Explanation** The clinical presentation of **foot drop** with **preserved eversion** is the diagnostic key to this question. **1. Why the Deep Fibular Nerve is Correct:** The common fibular nerve (CFN) bifurcates into the superficial and deep fibular nerves. The **deep fibular nerve** innervates the muscles of the **anterior compartment** of the leg (Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus). The Tibialis anterior is the primary dorsiflexor of the foot; its paralysis leads to **foot drop**. Since the superficial fibular nerve remains intact, the muscles of the lateral compartment (fibularis longus and brevis) can still perform **eversion**, which matches the patient's presentation. **2. Why the Other Options are Incorrect:** * **Tibial Nerve:** This nerve innervates the posterior compartment (plantarflexors). Injury would result in an inability to plantarflex the foot ("heel walk" deficit) and loss of sensation on the sole, not foot drop. * **Common Fibular Nerve:** Injury here (typically at the neck of the fibula) would cause **both** foot drop (deep branch) and loss of eversion (superficial branch), along with sensory loss in the first web space and lateral leg. * **Superficial Fibular Nerve:** This nerve supplies the lateral compartment. Injury would cause a loss of eversion, but dorsiflexion (and thus foot drop) would be unaffected. **3. Clinical Pearls for NEET-PG:** * **Deep Fibular Nerve:** Supplies the **first interdigital cleft** (web space) for sensation. This is the most high-yield sensory landmark. * **Common Fibular Nerve:** The most commonly injured nerve in the lower limb due to its superficial course around the **fibular neck**. * **Mnemonic for Gait:** **PED** (**P**eroneal **E**verts and **D**orsiflexes; if injured, the foot drops) vs. **TIP** (**T**ibial **I**nverts and **P**lantarflexes; if injured, you cannot stand on your toes).

Question 119: What is the nerve supply of the obturator internus muscle?

A. L1-L3
B. L4-S1
C. L5-S2 (Correct Answer)
D. S1-S3

Explanation: The **Obturator Internus** is a key lateral rotator of the hip. It is supplied by the **Nerve to Obturator Internus**, which arises from the **sacral plexus** with root values **L5, S1, and S2**. **Why C is correct:** The nerve to obturator internus originates from the ventral rami of L5-S2. A high-yield anatomical fact is its unique course: it leaves the pelvis through the **greater sciatic foramen**, passes over the ischial spine (lateral to the internal pudendal vessels), and re-enters the pelvis through the **lesser sciatic foramen** to supply the muscle on its pelvic surface. It also supplies the **Superior Gemellus** muscle. **Why incorrect options are wrong:** * **A (L1-L3):** These roots contribute to the lumbar plexus (e.g., femoral and obturator nerves). The obturator nerve (L2-L4) supplies the adductor compartment, not the obturator internus. * **B (L4-S1):** This is the root value for the **Superior Gluteal Nerve** (supplying gluteus medius/minimus) and the **Nerve to Quadratus Femoris** (which also supplies the Inferior Gemellus). * **D (S1-S3):** This range is more characteristic of the **Posterior Cutaneous Nerve of the Thigh** (S1-S3) or the **Pudendal Nerve** (S2-S4). **High-Yield Clinical Pearls for NEET-PG:** * **The "Triceps Coxae":** The Obturator Internus, Superior Gemellus, and Inferior Gemellus function together; however, they have different nerve supplies (Nerve to Obturator Internus for the first two; Nerve to Quadratus Femoris for the third). * **Exit/Entry:** The Nerve to Obturator Internus is one of the structures that exits the greater and enters the lesser sciatic foramen. * **Action:** It is a powerful lateral rotator of the extended thigh and an abductor of the flexed thigh.

Question 120: Which tarsal bone articulates with the tibia and fibula?

A. calcaneus
B. cuboid
C. navicular
D. talus (Correct Answer)

Explanation: The **talus** is the correct answer because it is the only tarsal bone that articulates with the leg bones (tibia and fibula) to form the **ankle joint (talocrural joint)**. The superior surface of the talus, known as the **trochlea**, is wedge-shaped and fits into the mortise formed by the medial malleolus (tibia), the lateral malleolus (fibula), and the inferior surface of the tibia. This articulation is primarily responsible for dorsiflexion and plantarflexion of the foot. **Why other options are incorrect:** * **Calcaneus:** This is the largest tarsal bone (heel bone). It articulates superiorly with the talus (subtalar joint) and anteriorly with the cuboid, but it has no direct contact with the tibia or fibula. * **Cuboid:** Located on the lateral aspect of the foot, it articulates with the calcaneus, the lateral cuneiform, and the 4th and 5th metatarsals. * **Navicular:** Positioned on the medial side between the talus and the three cuneiform bones. It does not reach the ankle joint complex. **Clinical Pearls for NEET-PG:** 1. **No Muscular Attachments:** The talus is unique because **no muscles or tendons** originate from or insert onto it. Its position is maintained entirely by ligaments and bony articulations. 2. **Blood Supply:** The blood supply to the talus is retrograde (from distal to proximal), primarily via the **artery of the tarsal canal** (branch of the posterior tibial artery). 3. **Avascular Necrosis (AVN):** Due to its precarious blood supply, fractures of the **talar neck** (Hawkins classification) carry a high risk of AVN. 4. **Subtalar Joint:** Inversion and eversion of the foot occur at the subtalar and transverse tarsal joints, not at the ankle joint.

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Arterial Supply and Venous Drainage

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Lower Limb — MCQs

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