Lower Limb Practice Questions

Q: A 62-year-old woman slips and falls, resulting in a posterior hip dislocation and a fractured neck of the femur. If the acetabulum is fractured at its posterosuperior margin due to hip dislocation, which of the following bones could be involved?

Ilium. The acetabulum is a cup-shaped socket formed by the fusion of three primary bones: the **ilium, ischium, and pubis**. These bones meet at the **triradiate cartilage**, which ossifies in early adulthood. Understanding the anatomical contribution of each bone is crucial for localizing fractures. 1. **Why Ilium is correct:** The **Ilium** forms the **superior and posterosuperior** part of the acetabulum (approximately 2/5ths of the structure). In a posterior hip dislocation, the femoral head is driven backward and upward. If this force fractures the posterosuperior rim, the ilium is the bone involved. 2. **Why Ischium is incorrect:** The **Ischium** forms the **posteroinferior** part of the acetabulum (approximately 2/5ths). While it is involved in posterior dislocations, it does not form the superior margin. 3. **Why Pubis is incorrect:** The **Pubis** forms the **anteromedial** part of the acetabulum (approximately 1/5th). It is typically involved in anterior dislocations or direct pelvic trauma. 4. **Why Sacrum is incorrect:** The sacrum is part of the pelvic girdle but does **not** contribute to the formation of the acetabulum. **Clinical Pearls for NEET-PG:** * **Acetabular Contributions:** Ilium (Superior/Posterosuperior), Ischium (Posteroinferior), Pubis (Anterior). * **Posterior Dislocation:** Most common type of hip dislocation (90%). The limb is typically held in **Internal Rotation, Adduction, and Flexion** [1]. * **Nerve Injury:** The **Sciatic nerve** is the most commonly injured structure in posterior acetabular fractures/dislocations [1]. * **Blood Supply:** The fracture of the femoral neck (mentioned in the stem) poses a high risk of **Avascular Necrosis (AVN)** due to disruption of the medial circumflex femoral artery [1].

Q: A 72-year-old woman complains of cramplike pain in her thigh and leg. She was diagnosed with severe intermittent claudication. Following surgery, an infection was found in the adductor canal, damaging the enclosed structures. Which of the following structures remains intact?

Great saphenous vein. ### Explanation The **adductor canal (Hunter’s canal)** is an aponeurotic tunnel located in the middle third of the medial thigh. It serves as a passageway for structures moving from the femoral triangle to the popliteal fossa. **1. Why the Great Saphenous Vein (GSV) is the Correct Answer:** The GSV is a **superficial vein** that runs within the subcutaneous tissue of the medial thigh [1]. It does **not** enter the adductor canal. Instead, it remains superficial until it pierces the cribriform fascia at the saphenous opening (much higher up in the femoral triangle) to drain into the femoral vein. Therefore, an infection or surgical trauma localized within the adductor canal will not affect the GSV. **2. Why the Other Options are Incorrect:** The adductor canal contains the following structures, all of which would be at risk in this scenario: * **Femoral Artery (A):** Enters the canal and exits through the adductor hiatus to become the popliteal artery. * **Femoral Vein (B):** Lies posterior to the artery within the canal. * **Saphenous Nerve (C):** A branch of the femoral nerve that travels within the canal before exiting by piercing the vastoadductor membrane to provide cutaneous sensation to the medial leg. * **Nerve to Vastus Medialis:** Also travels within the proximal part of the canal. **3. NEET-PG High-Yield Pearls:** * **Boundaries:** Anterolateral (Vastus medialis), Posterior (Adductor longus and magnus), and Medial/Roof (Sartorius). * **Clinical Significance:** The adductor canal is a common site for **"Adductor Canal Blocks"** (used for knee surgery) because it provides sensory blockade via the saphenous nerve while sparing the motor components of the femoral nerve (allowing early mobilization). * **Subsartorial Plexus:** Located deep to the sartorius muscle, it is formed by branches of the saphenous, obturator, and medial femoral cutaneous nerves.

Q: The demonstrated abnormality is seen in paralysis of which muscles?

Gluteus medius and Gluteus minimus. ***Gluteus medius and Gluteus minimus*** - The **Trendelenburg sign** occurs when both **hip abductors** (gluteus medius and minimus) are paralyzed, causing the pelvis to drop on the **opposite side** during single-leg stance. - Both muscles are innervated by the **superior gluteal nerve** and work together to stabilize the pelvis during walking and standing on one leg. *Gluteus maximus* - Primarily functions as a **hip extensor** rather than an abductor, so its paralysis doesn't cause Trendelenburg sign. - Paralysis leads to difficulty with **hip extension** activities like climbing stairs or rising from a chair, not pelvic instability. *Gluteus medius* - While it is a **hip abductor**, paralysis of gluteus medius alone typically produces a **mild** or **incomplete** Trendelenburg sign. - The **gluteus minimus** can partially compensate for its function, preventing the classic positive Trendelenburg test. *Gluteus minimus* - Acts as a **hip abductor** but is smaller and weaker than gluteus medius, so isolated paralysis rarely causes obvious Trendelenburg sign. - The **gluteus medius** provides the majority of abduction strength and can compensate for gluteus minimus weakness.

Q: The dorsalis pedis artery terminates at which location?

Proximal part of the first intermetatarsal space. ### Explanation **Correct Answer: D. Proximal part of the first intermetatarsal space** The **dorsalis pedis artery** is the direct continuation of the anterior tibial artery, beginning at the level of the ankle joint (midway between the two malleoli). It travels along the dorsum of the foot, lateral to the tendon of the extensor hallucis longus. The artery terminates at the **proximal part of the first intermetatarsal space** by dividing into two terminal branches: 1. **Deep Plantar Artery:** This dives between the two heads of the first dorsal interosseous muscle to enter the sole of the foot, where it completes the **plantar arch** by joining the lateral plantar artery. 2. **First Dorsal Metatarsal Artery:** This continues forward to supply the adjacent sides of the big toe and second toe. --- ### Why the other options are incorrect: * **Option A & B:** These locations are too distal. The artery terminates and "dives" into the sole at the base (proximal end) of the metatarsals, long before reaching the phalanges or the metatarsophalangeal joints. * **Option C:** This is the **origin** of the dorsalis pedis artery, not its manifestation. It begins at the dorsum of the ankle joint as a continuation of the anterior tibial artery. --- ### High-Yield NEET-PG Pearls: * **Surface Marking:** The pulse is best felt on the dorsum of the foot, just lateral to the **Extensor Hallucis Longus (EHL)** tendon, against the tarsal bones. * **Clinical Significance:** Absence of the dorsalis pedis pulse is a classic sign of **Peripheral Arterial Disease (PAD)** or Buerger’s disease. * **Anatomical Variation:** In about 10% of individuals, the dorsalis pedis artery is absent or replaced by a large perforating branch of the peroneal artery. * **The Plantar Arch:** Remember that the **Deep Plantar Artery** (terminal branch of dorsalis pedis) + **Lateral Plantar Artery** = Plantar Arch.

Q: Perforators are not present at which of the following locations?

Below inguinal ligament. The venous system of the lower limb consists of superficial and deep veins connected by **perforating veins** [1]. These perforators contain valves that ensure blood flows in one direction: from the superficial system to the deep system [2]. **Why Option D is Correct:** There are no significant anatomical perforators located immediately **below the inguinal ligament**. The connection between the superficial and deep systems at this level is the **Saphenofemoral Junction (SFJ)**, where the Great Saphenous Vein (GSV) terminates directly into the Common Femoral Vein [1]. This is a terminal junction, not a "perforator" in the traditional sense. **Analysis of Incorrect Options:** * **A. Ankle:** These are known as **May’s or Kuster’s perforators**. They connect the GSV/tributaries to the posterior tibial veins. * **B. Medial Calf:** These are the **Cockett’s perforators** (Lower, Middle, and Upper). They are clinically significant as they are often involved in the pathogenesis of venous ulcers [2]. * **C. Distal to Calf (Adductor Canal):** These are the **Dodd’s perforators**, located in the distal third of the thigh/upper calf area, connecting the GSV to the femoral vein [2]. **NEET-PG High-Yield Pearls:** 1. **Boyd’s Perforators:** Located at the medial aspect of the knee (connecting GSV to posterior tibial veins). 2. **Hunterian Perforators:** Located in the mid-thigh (proximal adductor canal). 3. **Direction of Flow:** Normally superficial to deep [2]. If valves fail (perforator incompetence), flow becomes **bidirectional or reversed**, leading to varicose veins and "Gaiter zone" skin changes [2]. 4. **Clinical Sign:** Incompetent perforators can be identified using the **Multiple Tourniquet Test**.

Q: A patient suddenly experienced pain radiating along the medial border of the dorsum of the foot. Which of the following nerves is most likely to be involved?

Saphenous nerve. ### Explanation The correct answer is **B. Saphenous nerve**. **1. Why the Saphenous Nerve is Correct:** The saphenous nerve is the longest cutaneous branch of the **femoral nerve (L2-L4)**. It descends through the adductor canal, becomes superficial at the medial side of the knee, and accompanies the great saphenous vein. It provides sensory innervation to the medial side of the leg and extends down to the **medial border of the foot**, reaching as far as the ball of the great toe (metatarsophalangeal joint). Pain or paresthesia along this specific distribution indicates involvement of the saphenous nerve. **2. Why the Other Options are Incorrect:** * **Sural Nerve:** Formed by branches of the tibial and common peroneal nerves, it supplies the skin of the **lateral border of the foot** and the lateral side of the little toe. * **Deep Peroneal Nerve:** This nerve primarily supplies the muscles of the anterior compartment of the leg. Its sensory distribution is limited to the **first interdigital cleft** (the skin between the 1st and 2nd toes). * **Superficial Peroneal Nerve:** It supplies the skin of the **distal third of the anterior leg and the majority of the dorsum of the foot**, excluding the medial border (saphenous), lateral border (sural), and first web space (deep peroneal). **3. NEET-PG High-Yield Clinical Pearls:** * **Saphenous Nerve Injury:** Often occurs during **varicose vein stripping** or harvesting of the great saphenous vein for CABG, leading to numbness along the medial leg/foot. * **Adductor Canal Syndrome:** The saphenous nerve can be compressed as it exits the adductor canal (Hunter’s canal). * **Nerve-Vein Pairs:** * Saphenous Nerve + Great Saphenous Vein (Medial) * Sural Nerve + Small Saphenous Vein (Lateral)

Q: Which nerve supplies the tensor fascia lata?

Superior gluteal nerve. **Explanation:** The **Superior Gluteal Nerve (L4, L5, S1)** is a branch of the sacral plexus that exits the pelvis through the greater sciatic foramen, passing *above* the piriformis muscle. It provides motor innervation to three specific muscles: the **gluteus medius**, **gluteus minimus**, and the **tensor fascia lata (TFL)**. These muscles act together to abduct the hip and stabilize the pelvis during the stance phase of walking. **Analysis of Options:** * **Superior Gluteal Nerve (Correct):** It is the sole nerve supply to the TFL. Damage to this nerve leads to a "Trendelenburg gait" due to the failure of the hip abductor mechanism. * **Inferior Gluteal Nerve (Incorrect):** This nerve (L5, S1, S2) passes *below* the piriformis and exclusively supplies the **gluteus maximus**, the chief extensor of the hip. * **Nerve to Quadratus Femoris (Incorrect):** This nerve (L4, L5, S1) supplies the quadratus femoris and the inferior gemellus muscles. * **Nerve to Obturator Internus (Incorrect):** This nerve (L5, S1, S2) supplies the obturator internus and the superior gemellus muscles. **High-Yield Clinical Pearls for NEET-PG:** * **The "Above/Below" Rule:** The Superior Gluteal Nerve is the only major nerve exiting the greater sciatic foramen *above* the piriformis. All others (Sciatic, Inferior Gluteal, Pudendal) exit below it. * **Trendelenburg Sign:** If the right superior gluteal nerve is injured, the left side of the pelvis drops when the patient stands on the right leg. * **Safe Injection Site:** Intramuscular injections are given in the superolateral quadrant of the gluteal region to avoid the sciatic nerve, but deep injections can still potentially injure the superior gluteal nerve branches.

Q: Ankle is most stable in dorsiflexion due to which anatomical factor?

Wedge shape of the talus. ### Explanation The ankle (talocrural) joint is a hinge-type synovial joint formed by the distal ends of the tibia and fibula (the mortise) and the trochlea of the talus. **1. Why the Correct Answer is Right:** The **wedge shape of the talus** is the primary anatomical factor for stability. The superior articular surface (trochlea) of the talus is **wider anteriorly** than posteriorly. * **In Dorsiflexion:** The wider anterior part of the talus moves backward to wedge tightly into the narrower space between the medial and lateral malleoli. This "close-packed" position provides maximum bony stability and limits side-to-side movement. * **In Plantarflexion:** The narrower posterior part of the talus sits loosely within the mortise, making the joint relatively unstable and more prone to sprains. **2. Why Other Options are Incorrect:** * **B. Muscle Pull:** While muscles (like the Tibialis anterior) facilitate the movement of dorsiflexion, they do not provide the primary structural stability compared to the bony architecture. * **C. Presence of Malleoli:** The malleoli form the mortise, which is essential for the joint's existence, but they are present in both dorsiflexion and plantarflexion. The stability change is specifically due to how the talus fits *between* them. * **D. Ligament Pull:** Ligaments (like the Deltoid and Lateral ligaments) provide passive stability, but they are actually more stretched and prone to injury during plantarflexion/inversion rather than being the defining factor for dorsiflexion stability. ### NEET-PG High-Yield Pearls: * **Close-packed position of the ankle:** Full dorsiflexion. * **Most common ankle injury:** Inversion sprain (occurs during plantarflexion because the narrow part of the talus is in the mortise). * **Ligament most commonly torn:** Anterior Talofibular Ligament (ATFL). * **The

Q: Which nerve supplies the posterior femoral muscles?

Sciatic nerve. **Explanation:** The **posterior femoral muscles**, commonly known as the **hamstrings**, consist of the Biceps Femoris, Semitendinosus, and Semimembranosus. These muscles are primarily supplied by the **Sciatic nerve (L4-S3)**. Specifically, the tibial component of the sciatic nerve supplies the semitendinosus, semimembranosus, and the long head of the biceps femoris. The common peroneal (fibular) component supplies the short head of the biceps femoris. **Analysis of Options:** * **A. Femoral nerve:** Supplies the **anterior compartment** of the thigh (e.g., Quadriceps femoris, Sartorius) and provides sensation to the anterior thigh and medial leg. * **B. Obturator nerve:** Supplies the **medial compartment** of the thigh (adductor group), including the Adductor longus, brevis, and gracilis. * **D. Sural nerve:** This is a purely **sensory nerve** formed by branches of the tibial and common peroneal nerves; it supplies the skin of the lateral and posterior part of the lower third of the leg and the lateral border of the foot. **High-Yield Clinical Pearls for NEET-PG:** * **The "Hybrid" Muscle:** The **Adductor Magnus** is a composite muscle. Its adductor part is supplied by the obturator nerve, while its "hamstring part" is supplied by the tibial part of the sciatic nerve. * **Short Head of Biceps:** It is the only muscle in the posterior compartment supplied by the **common peroneal** part of the sciatic nerve; all others are supplied by the tibial part. * **Action:** The hamstrings are unique because they cross two joints, acting as powerful flexors of the knee and extensors of the hip.

Question 1

A 62-year-old woman slips and falls, resulting in a posterior hip dislocation and a fractured neck of the femur. If the acetabulum is fractured at its posterosuperior margin due to hip dislocation, which of the following bones could be involved?

Accepted Answer

Ilium

Answer

Pubis

Answer

Ischium

Answer

Sacrum

Question 2

A 72-year-old woman complains of cramplike pain in her thigh and leg. She was diagnosed with severe intermittent claudication. Following surgery, an infection was found in the adductor canal, damaging the enclosed structures. Which of the following structures remains intact?

Accepted Answer

Great saphenous vein

Answer

Femoral artery

Answer

Femoral vein

Answer

Saphenous nerve

Question 3

Which of the following tendons passes under the extensor retinaculum?

Accepted Answer

Superficial peroneal nerve

Answer

Extensor digitorum brevis

Answer

Extensor hallucis

Answer

Tibialis anterior

Question 4

The demonstrated abnormality is seen in paralysis of which muscles?

Accepted Answer

Gluteus medius and Gluteus minimus

Answer

Gluteus maximus

Answer

Gluteus medius

Answer

Gluteus minimus

Question 5

The dorsalis pedis artery terminates at which location?

Accepted Answer

Proximal part of the first intermetatarsal space

Answer

Base of the proximal phalanx of the hallux

Answer

First metatarsophalangeal joint

Answer

Dorsum of ankle joint

Question 6

Perforators are not present at which of the following locations?

Accepted Answer

Below inguinal ligament

Answer

Ankle

Answer

Medial calf

Answer

Distal to calf

Question 7

A patient suddenly experienced pain radiating along the medial border of the dorsum of the foot. Which of the following nerves is most likely to be involved?

Accepted Answer

Saphenous nerve

Answer

Sural nerve

Answer

Deep peroneal nerve

Answer

Superficial peroneal nerve

Question 8

Which nerve supplies the tensor fascia lata?

Accepted Answer

Superior gluteal nerve

Answer

Inferior gluteal nerve

Answer

Nerve to quadratus femoris

Answer

Nerve to obturator internus

Question 9

Ankle is most stable in dorsiflexion due to which anatomical factor?

Accepted Answer

Wedge shape of the talus

Answer

Muscle pull during dorsiflexion

Answer

Presence of malleoli

Answer

Ligament pull

Question 10

Which nerve supplies the posterior femoral muscles?

Accepted Answer

Sciatic nerve

Answer

Femoral nerve

Answer

Obturator nerve

Answer

Sural nerve

Lower Limb — MCQs

Lower Limb — MCQs

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