Lower Limb — MCQs

Lower Limb Indian Medical PG Practice Questions and MCQs

Question 551: Which metatarsal is known for its significant mobility in the foot?

A. 3rd metatarsal
B. 4th metatarsal
C. 1st metatarsal (Correct Answer)
D. 2nd metatarsal

Explanation: ***1st metatarsal*** - The **first metatarsal** is highly mobile, articulated with the **medial cuneiform** by a saddle-shaped joint, allowing for significant motion critical for foot adaptation during gait. - Its mobility is crucial for **pronation and supination** of the foot, impacting load distribution and stability, especially during toe-off. *2nd metatarsal* - The **second metatarsal** is the **least mobile** of the metatarsals, deeply recessed and articulated with the three cuneiforms, forming a key part of the **Lisfranc joint complex**. - Its relative rigidity contributes to the **stability** of the midfoot and acts as a central pillar, providing a stable base for the other metatarsals. *3rd metatarsal* - The **third metatarsal** has **limited mobility**, articulating primarily with the **lateral cuneiform**. - While it has some translational and rotational movement, it is significantly less mobile than the first metatarsal and plays a role in the stability of the central ray of the foot. *4th metatarsal* - The **fourth metatarsal** exhibits **moderate mobility**, greater than the second and third but less than the first. - It articulates with the **cuboid** and **lateral cuneiform**, providing flexibility important for adapting the forefoot to uneven surfaces.

Question 552: Which structure passes deep to the inguinal ligament in the vascular compartment?

A. Psoas major
B. Femoral vein (Correct Answer)
C. Femoral branch of genitofemoral nerve
D. Superficial epigastric artery

Explanation: ***Femoral vein*** - The **femoral vein** passes deep to the inguinal ligament within the **femoral sheath** in the **vascular compartment (lacuna vasorum)**. - It lies medial to the **femoral artery** within the femoral triangle and continues superiorly as the external iliac vein. - The femoral vein is the major venous structure passing through this compartment. *Psoas major* - The **psoas major muscle** (along with iliacus as the iliopsoas) passes deep to the inguinal ligament through the **muscular compartment (lacuna musculorum)**, which is lateral to the vascular compartment. - It is separated from the vascular structures by the iliopectineal arch. *Femoral branch of genitofemoral nerve* - The **femoral branch of the genitofemoral nerve** does pass through the vascular compartment, but it is a small nerve branch that accompanies the vessels, not the primary structure defining this compartment [1]. - It supplies sensation to the skin of the upper anterior thigh. *Superficial epigastric artery* - The **superficial epigastric artery** arises from the **femoral artery** approximately 1 cm **distal to** (below) the inguinal ligament [2]. - It does **not** pass deep to the inguinal ligament but rather originates below it and ascends superficially on the anterior abdominal wall [2].

Question 553: Which of the following statements accurately describes the location of the saphenous vein?

A. 1cm anterior and 1cm superior to the medial malleolus (Correct Answer)
B. 1cm posterior to the medial malleolus
C. 1cm inferior to the medial malleolus
D. 1cm superior to the medial malleolus

Explanation: ***1cm anterior and 1cm superior to the medial malleolus*** [1] - This is the classic anatomical landmark for the **great saphenous vein (GSV)** at the ankle level [1]. - The vein passes both **anterior** and **superior** to the medial malleolus, making this dual landmark the most accurate for surgical identification [1]. - This position is crucial for procedures such as **venous cutdown**, **cannulation**, or assessing for **venous insufficiency**. *1cm posterior to the medial malleolus* - The structures posterior to the medial malleolus include the **tibial nerve**, **posterior tibial artery**, and **tibialis posterior tendon** (contents of the tarsal tunnel). - The **great saphenous vein** is not located in this area; attempting to access it there could damage surrounding neurovascular structures. *1cm inferior to the medial malleolus* - The area inferior to the medial malleolus refers to the plantar aspect of the foot or the distal ankle region. - The **great saphenous vein** is not consistently found in this location at the ankle level. *1cm superior to the medial malleolus* - While the vein does pass superior to the malleolus, this description is **incomplete** without also specifying the anterior position. - The precise landmark requires both coordinates: anterior AND superior to the medial malleolus.

Question 554: Muscles taking origin from the ischial tuberosity are all except:

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

Explanation: ***Adductor longus*** - The **adductor longus** originates from the anterior surface of the **pubic body**, inferior to the pubic crest. - It is part of the **adductor compartment of the thigh** but does not originate from the ischial tuberosity. *Semimembranosus* - The **semimembranosus** muscle originates from the **ischial tuberosity**, specifically from its upper and outer part. - It is one of the three **hamstring muscles**. *Semitendinosus* - The **semitendinosus** originates from the **ischial tuberosity**, sharing a common origin with the long head of the biceps femoris. - It is also a **hamstring muscle**. *Adductor magnus* - The **adductor magnus** has a dual origin; its adductor (anterior) part originates from the **inferior pubic ramus** and **ischial ramus**, while its hamstring (posterior) part originates directly from the **ischial tuberosity**. - Its origin is therefore partially from the ischial tuberosity, making it an incorrect answer for the "except" question.

Question 555: Which of the following brain structures does not contribute to the Mickey Mouse sign on axial brain imaging?

A. Interpeduncular cistern
B. Substantia nigra
C. Superior colliculus (Correct Answer)
D. Cerebral peduncles

Explanation: ***Superior colliculus*** - The superior colliculus is located **dorsal to the cerebral peduncles** and substantia nigra, at a higher axial level, and therefore does not contribute to the "Mickey Mouse" appearance on axial imaging formed by the substantia nigra and red nucleus within the midbrain tegmentum. - The "Mickey Mouse" sign specifically refers to the configuration of structures visible on **axial T2-weighted MRI brain images** at the level of the midbrain, depicting the red nucleus and substantia nigra as the "ears" and the cerebral peduncles as the "face." *Cerebral peduncles* - The cerebral peduncles form the **"face" or main body** of the Mickey Mouse sign, evident on axial imaging due to their ventral position in the midbrain. - These are large bundles of nerve fibers descending from the cerebrum to the brainstem and spinal cord, creating a prominent structure in the anterior midbrain. *Interpeduncular cistern* - The interpeduncular cistern is the **CSF-filled space** located between the cerebral peduncles. - While it doesn't form part of Mickey's face or ears, its presence and surrounding structures help define the arrangement that creates the "Mickey Mouse" sign on imaging. *Substantia nigra* - The substantia nigra forms the **"ears" of the Mickey Mouse** sign on axial imaging, positioned dorsally to the cerebral peduncles. - Its high iron content causes it to be **hypointense on T2-weighted images**, contributing to its distinct appearance in this characteristic sign.

Question 556: Trendelenburg test is positive due to injury to which of the following nerves?

A. Superior Gluteal nerve (Correct Answer)
B. Obturator nerve
C. Inferior Gluteal nerve
D. Sciatic nerve

Explanation: ***Superior Gluteal nerve*** - A positive **Trendelenburg test** indicates weakness of the **gluteus medius** and **gluteus minimus** muscles, which are innervated by the **superior gluteal nerve**. - Injury to this nerve leads to the characteristic pelvic drop on the unsupported side during ambulation or unilateral stance. *Obturator nerve* - The **obturator nerve** primarily innervates the **adductor muscles** of the thigh. - Injury to this nerve would cause weakness in **thigh adduction**, not gluteal muscle dysfunction or a positive Trendelenburg sign. *Inferior Gluteal nerve* - The **inferior gluteal nerve** supplies the **gluteus maximus**, which is a powerful extensor and external rotator of the hip. - Damage to this nerve primarily affects hip extension, making rising from a seated position or climbing stairs difficult, but does not cause a positive Trendelenburg test. *Sciatic nerve* - The **sciatic nerve** is the largest nerve in the body, innervating the posterior thigh muscles and all muscles below the knee. - Injury to the sciatic nerve would cause widespread motor and sensory deficits in the leg and foot, but not specifically the weakness typical of a positive Trendelenburg sign.

Question 557: The blood supply of the anterior cruciate ligament (ACL) is primarily derived from?

A. Middle genicular artery (Correct Answer)
B. Descending genicular artery
C. Circumflex fibular artery
D. Superior medial genicular artery

Explanation: ***Middle genicular artery*** - This artery, a branch of the **popliteal artery**, is the **primary blood supply** to the ACL and PCL. - It directly penetrates the **posterior capsule of the knee joint** to reach the cruciate ligaments. *Descending genicular artery* - This artery, a branch of the **femoral artery**, primarily supplies the **vastus medialis muscle** and the medial aspect of the knee joint. - It does not directly contribute significantly to the **intraligamentous blood flow** of the ACL. *Circumflex fibular artery* - This artery typically branches from the **posterior tibial artery** or the **fibular artery**. - It supplies structures in the **proximal leg** around the fibular head, not the cruciate ligaments within the knee joint. *Superior medial genicular artery* - This artery is one of the five genicular branches of the **popliteal artery**. - It primarily supplies the **medial epicondyle of the femur**, the **medial collateral ligament**, and the **medial head of the gastrocnemius**, with minimal contribution to the ACL.

Question 558: Sartorius muscle takes origin from which structure?

A. Pectinate line
B. Anterior superior iliac spine (Correct Answer)
C. Body of the ilium
D. Ischial tuberosity

Explanation: ***Anterior superior iliac spine*** - The **sartorius muscle**, the longest muscle in the body, originates from the **anterior superior iliac spine (ASIS)** and the upper half of the notch just below it. - This anatomical landmark is crucial for its function in **flexing, abducting, and laterally rotating the thigh**, as well as flexing the knee. *Pectinate line* - The **pectinate line** is an anatomical landmark found in the anal canal, marking the transition between the visceral and somatic innervation. - It plays no role in the origin of any major limb muscles. *Body of the ilium* - While other muscles like the **gluteus medius** and **minimus** originate from the external surface of the ala (body) of the ilium, the sartorius does not. - The **body of the ilium** contributes to the acetabulum and provides origin points for various hip muscles. *Ischial tuberosity* - The **ischial tuberosity** is the origin point for the **hamstring muscles** (semitendinosus, semimembranosus, and biceps femoris long head). - It is located on the ischium, which is part of the pelvic bone, but distinct from the origin of the sartorius.

Question 559: Anterior gliding of the tibia on the femur is prevented by

A. Anterior cruciate ligament (Correct Answer)
B. Ligament of Humphrey
C. Ligament of Wrisberg
D. Posterior cruciate ligament

Explanation: ***Anterior cruciate ligament*** - The **anterior cruciate ligament (ACL)** is a crucial stabilizer of the knee joint, preventing the **anterior translation of the tibia** relative to the femur. - It also limits **hyperextension** and internal rotation of the tibia. *Posterior cruciate ligament (PCL)* - The **PCL** primarily prevents posterior displacement or **gliding of the tibia** on the femur. - It is often injured by direct trauma to the anterior tibia or through vehicular accidents. *Ligament of Humphrey* - The **ligament of Humphrey** is an accessory ligament of the knee that runs anterior to the **posterior cruciate ligament (PCL)**. - It arises from the posterior horn of the lateral meniscus and inserts into the medial femoral condyle, potentially augmenting PCL function. *Ligament of Wrisberg* - The **ligament of Wrisberg** is another accessory ligament that runs posterior to the **posterior cruciate ligament (PCL)**. - It also originates from the posterior horn of the lateral meniscus and inserts into the medial femoral condyle, serving a similar function to the ligament of Humphrey in stabilizing the knee.

Question 560: Coronary ligament is present between which two structures?

A. Femur and meniscus
B. Posterior horns of menisci
C. Tibia and meniscus (Correct Answer)
D. Femur and tibia

Explanation: ***Tibia and meniscus*** - The **coronary ligaments** are fibrous bands that connect the inferior edges of the **menisci** to the **tibia**. - These ligaments play a crucial role in stabilizing the menisci on the tibial plateau, limiting their movement during knee joint activity. *Posterior horns of menisci* - The posterior horns of the menisci are connected to the tibia by other attachments, but the **coronary ligaments** specifically describe the circumferential attachments of the menisci to the tibial plateau. - While there are various attachments for the posterior horns, the coronary ligament is distinct in its **peripheral connection** to the tibia. *Femur and meniscus* - The menisci are primarily attached to the **tibia** via coronary ligaments and to each other by the **transverse ligament of the knee**. - There are no direct ligamentous connections between the femur and meniscus referred to as **coronary ligaments**. *Femur and tibia* - The femur and tibia are connected by major ligaments such as the **cruciate ligaments** (anterior and posterior) and the **collateral ligaments** (medial and lateral). - The **coronary ligaments** specifically connect the menisci to the tibia, not directly the femur to the tibia.

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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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