Lower Limb Practice Questions

Q: Which muscles are collectively known as 'Triceps surae'?

Gastrocnemius and soleus. ### Explanation **Concept Overview:** The term **Triceps surae** (Latin for "three-headed muscle of the calf") refers to a pair of muscles located in the superficial posterior compartment of the leg. It is composed of the **two heads of the Gastrocnemius** (medial and lateral) and the **single head of the Soleus**. These muscles share a common insertion point via the **Tendo calcaneus (Achilles tendon)** onto the posterior surface of the calcaneum. **Why Option A is Correct:** * **Gastrocnemius:** A two-headed, superficial muscle that crosses both the knee and ankle joints. * **Soleus:** A broad, flat muscle lying deep to the gastrocnemius. It is often called the "Peripheral Heart" because its venous sinuses are crucial for pumping blood back to the heart against gravity. * Together, they act as the primary **plantar flexors** of the foot. **Why Other Options are Incorrect:** * **B. Popliteus:** This is a deep muscle of the posterior compartment known as the "Key of the knee" because it unlocks the knee joint by rotating the femur laterally on a fixed tibia. * **C & D. Extensor hallucis longus & Extensor digitorum longus:** These are muscles of the **anterior compartment** of the leg. They are responsible for dorsiflexion of the foot and extension of the toes, not plantar flexion. **High-Yield Clinical Pearls for NEET-PG:** * **Nerve Supply:** All muscles of the posterior compartment, including the triceps surae, are supplied by the **Tibial nerve (S1, S2)**. * **Achilles Tendon Reflex:** Tests the **S1-S2** nerve roots. * **Plantaris:** Often called the "Freshman’s Nerve," it is a vestigial muscle located between the gastrocnemius and soleus; its tendon is a common graft source for reconstructive surgery. * **Soleus Fact:** Unlike the gastrocnemius, the soleus is a **multipennate** muscle and consists predominantly of slow-twitch (Type I) muscle fibers, making it highly resistant to fatigue.

Q: Which of the following does NOT supply the femoral head?

Profunda femoris artery. The blood supply to the femoral head is a high-yield topic in Anatomy and Orthopaedics, primarily because of its clinical relevance in femoral neck fractures and avascular necrosis (AVN). ### **Explanation** The femoral head receives its blood supply from three main sources: the **Medial Circumflex Femoral Artery (MCFA)**, the **Lateral Circumflex Femoral Artery (LCFA)**, and the **Artery of Ligamentum Teres**. While the **Profunda Femoris Artery** is the parent vessel that gives rise to the circumflex arteries, it does not directly supply the femoral head itself. * **Option C (Correct):** The Profunda femoris artery provides the branches (MCFA and LCFA) that form the extracapsular arterial ring, but the main trunk of the artery continues down the thigh to supply the musculature via perforating branches. It has no direct distribution to the femoral head. ### **Analysis of Other Options** * **Option A (MCFA):** This is the **most important** source. Its retinacular branches (especially the posterosuperior group) provide the bulk of the blood supply to the femoral head. * **Option B (LCFA):** It contributes to the extracapsular arterial ring at the base of the neck. Its branches must traverse the thick anterior capsule, making it less significant than the MCFA. * **Option C (Artery of Ligamentum Teres):** A branch of the **obturator artery**, it supplies a small area around the fovea centralis. While vital in children, its contribution diminishes in adults. ### **NEET-PG High-Yield Pearls** 1. **Crucial Vessel:** The **Medial Circumflex Femoral Artery** is the primary source of blood; damage to this vessel in intracapsular fractures leads to **Avascular Necrosis (AVN)**. 2. **Anastomosis:** The extracapsular ring is formed by the MCFA (posteriorly) and LCFA (anteriorly). 3. **Pediatric Note:** In children, the artery of the ligamentum teres is more significant as the epiphyseal plate acts as a barrier to the retinacular vessels.

Q: Obturator nerve arises from which spinal nerve roots?

Ventral divisions of L2, L3, L4. ### Explanation The **Obturator nerve** is a major branch of the lumbar plexus. It is formed within the psoas major muscle by the fusion of the **ventral (anterior) divisions of the ventral rami of L2, L3, and L4** spinal nerves. **1. Why Option A is Correct:** The lumbar plexus is formed by the ventral rami of L1–L4. These rami split into anterior (ventral) and posterior (dorsal) divisions. The **Obturator nerve** arises from the **ventral divisions**, which typically supply the adductor (pre-axial) compartment of the thigh. **2. Why the other options are incorrect:** * **Option B:** The **dorsal divisions** of L2, L3, and L4 join to form the **Femoral nerve**. This is a common point of confusion; remember: *Ventral = Obturator, Dorsal = Femoral.* * **Options C & D:** The L1 and L2 roots contribute to the Iliohypogastric, Ilioinguinal (L1), and Genitofemoral (L1, L2) nerves, but not the obturator nerve. **Clinical Pearls & High-Yield Facts for NEET-PG:** * **Course:** It emerges from the medial border of the psoas major and enters the thigh through the **obturator canal**. * **Supply:** It provides motor innervation to the **adductor group** (Adductor longus, brevis, magnus, and gracilis) and sensory innervation to the medial aspect of the thigh. * **Howship-Romberg Sign:** Pain down the medial aspect of the thigh due to compression of the obturator nerve (often by an obturator hernia). * **Referred Pain:** Since the obturator nerve supplies both the **hip and knee joints** (Hilton’s Law), pathology in the hip (like Perthes disease) often presents as referred pain to the medial knee.

Q: Which of the following muscles primarily assists in the flexion of the hip joint?

Psoas. ### Explanation **Correct Answer: A. Psoas** The **Psoas major** is the primary and most powerful flexor of the hip joint. It originates from the transverse processes and bodies of the T12–L5 vertebrae and inserts into the **lesser trochanter** of the femur via the iliopsoas tendon (combined with the Iliacus muscle). Because of its anatomical position crossing the anterior aspect of the hip joint, its contraction pulls the femur upward, making it essential for activities like walking, climbing stairs, and sitting up from a supine position. **Why the other options are incorrect:** * **B. Piriformis:** This is a member of the "short lateral rotators" of the hip. Its primary action is **lateral (external) rotation** and abduction of the hip when the thigh is flexed. * **C. Pectoralis major:** This is a muscle of the **upper limb** (pectoral region) responsible for adduction, medial rotation, and flexion of the humerus at the shoulder joint. * **D. External oblique abdominis:** This is a muscle of the **anterior abdominal wall** [1]. Its functions include compressing abdominal viscera and aiding in trunk rotation and lateral flexion, but it does not cross the hip joint to act as a primary flexor. **High-Yield Clinical Pearls for NEET-PG:** * **The "Psoas Sign":** Pain on passive extension of the hip is a classic clinical sign of **Acute Appendicitis** (due to the inflamed appendix irritating the underlying psoas muscle). * **Psoas Abscess:** Infections (often TB of the spine/Pott’s disease) can track down the psoas fascia and present as a swelling in the **femoral triangle** (groin). * **Nerve Supply:** The Psoas major is supplied by the **ventral rami of L1–L3**, whereas the Iliacus is supplied by the **Femoral nerve (L2–L4)**.

Q: The saphenous vein is a tributary of which of the following veins?

Lateral marginal vein. The **Small Saphenous Vein (SSV)** is formed by the union of the **lateral marginal vein** of the foot and the lateral end of the dorsal venous arch [1]. It travels posterior to the lateral malleolus, ascends along the midline of the calf, and typically terminates by piercing the popliteal fascia to drain into the **popliteal vein**. **Analysis of Options:** * **B. Lateral marginal vein (Correct):** The small saphenous vein is the direct upward continuation of the lateral marginal vein [1]. * **A. Medial marginal vein:** This vein continues as the **Great Saphenous Vein (GSV)**, passing anterior to the medial malleolus [2]. * **C. Posterior tibial vein:** This is a deep vein of the leg. While the SSV has communicating branches to deep veins, it is not a tributary of the posterior tibial vein. * **D. Dorsal venous arch:** While the SSV originates at the lateral end of this arch, it is specifically defined as the continuation of the lateral marginal vein. **High-Yield NEET-PG Pearls:** * **Course:** SSV is accompanied by the **Sural nerve** in the leg (Clinical: Nerve injury during vein stripping leads to loss of sensation on the lateral aspect of the foot). * **Termination:** The most common site of termination is the Popliteal vein, but it can occasionally drain into the GSV or deep femoral veins (Giacomini vein) [1]. * **Valves:** The SSV contains approximately 7–13 valves to prevent backflow. * **Position:** SSV is **posterior** to the lateral malleolus; GSV is **anterior** to the medial malleolus [2].

Q: What is the nerve supply of the Tibialis anterior muscle?

Deep peroneal nerve. **Explanation:** The **Tibialis anterior** is the most medial muscle of the **anterior compartment of the leg**. Muscles in this compartment are primarily responsible for dorsiflexion of the foot and extension of the toes. 1. **Why the Correct Answer is Right:** The **Deep Peroneal Nerve** (L4, L5) is the nerve of the anterior compartment of the leg. It arises from the common peroneal nerve at the neck of the fibula. It supplies all muscles in this compartment: Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus, and Peroneus tertius. The Tibialis anterior specifically acts as the primary dorsiflexor and invertor of the foot. 2. **Why the Incorrect Options are Wrong:** * **Tibial nerve:** This nerve supplies the **posterior compartment** of the leg (e.g., Gastrocnemius, Soleus, Tibialis posterior). Its primary functions are plantarflexion and toe flexion. * **Femoral nerve:** This nerve supplies the **anterior compartment of the thigh** (e.g., Quadriceps femoris), facilitating hip flexion and knee extension. * **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. **Clinical Pearls & High-Yield Facts:** * **Foot Drop:** Injury to the Common Peroneal Nerve (at the fibular neck) or the Deep Peroneal Nerve leads to paralysis of the Tibialis anterior, resulting in "Foot Drop" and a "High-steppage gait." * **Anterior Compartment Syndrome:** The Tibialis anterior is the muscle most commonly involved in this surgical emergency, which can lead to ischemic necrosis and deep peroneal nerve palsy. * **Inversion vs. Eversion:** While Tibialis anterior (Deep Peroneal Nerve) and Tibialis posterior (Tibial Nerve) both **invert** the foot, they have opposite actions on the ankle joint (Dorsiflexion vs. Plantarflexion).

Q: The saphenous nerve is a branch of which of the following nerves?

Femoral nerve. The **saphenous nerve** is the longest and largest cutaneous branch of the **femoral nerve (L2–L4)**. It arises in the femoral triangle, descends through the adductor canal (subsartorial canal) alongside the femoral artery, and eventually pierces the fascia between the sartorius and gracilis muscles to provide sensory innervation to the medial aspect of the leg and foot. **Why the other options are incorrect:** * **Tibial nerve:** This is a terminal branch of the sciatic nerve. It supplies the posterior compartment of the leg and the sole of the foot. * **Sciatic nerve:** This is the largest nerve in the body (L4–S3). While it gives rise to the nerves of the lower leg, it does not directly branch into the saphenous nerve. * **Common peroneal (fibular) nerve:** This is the other terminal branch of the sciatic nerve. It supplies the lateral and anterior compartments of the leg and the dorsal surface of the foot. **High-Yield Clinical Pearls for NEET-PG:** * **Course:** The saphenous nerve is the only branch of the femoral nerve that extends below the knee. * **Adductor Canal:** It is a key content of the adductor canal but, unlike the femoral artery and vein, it **does not** pass through the adductor hiatus. * **Clinical Correlation:** The nerve is closely related to the **great saphenous vein** anterior to the medial malleolus. It is at high risk of injury during **venesection** or varicose vein stripping, leading to numbness along the medial border of the foot. * **Nerve Block:** A saphenous nerve block is often performed at the level of the adductor canal for surgeries involving the distal leg or foot.

Q: Which is the locking muscle of the knee joint?

Vastus Medialis. ### Explanation **1. Why Vastus Medialis is the Correct Answer:** The "locking" of the knee joint refers to the terminal phase of extension. During the last 10–15 degrees of extension, the femur undergoes **medial rotation** (in a closed kinetic chain) or the tibia undergoes **lateral rotation** (in an open kinetic chain) on the other bone. This mechanism tightens the ligaments, making the joint stable and rigid. The **Vastus Medialis**, specifically its distal horizontal fibers known as the **Vastus Medialis Obliquus (VMO)**, is the primary muscle responsible for achieving these final degrees of extension. By completing the extension and facilitating the terminal rotation, it effectively "locks" the knee. **2. Why Other Options are Incorrect:** * **Vastus Lateralis (A):** This is the largest and most powerful part of the Quadriceps. While it is a strong extensor, it tends to pull the patella laterally and does not contribute to the terminal locking rotation. * **Vastus Intermedius (C):** Located deep to the Rectus Femoris, it acts as a pure extensor of the knee but lacks the specific orientation to facilitate the locking mechanism. * **Rectus Femoris (D):** This is a bipennate, superficial muscle that crosses two joints (hip and knee). It is primarily involved in hip flexion and general knee extension but is not the specific driver for terminal locking. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Locking vs. Unlocking:** While Vastus Medialis is the **locking** muscle, the **Popliteus** is the **unlocking** muscle (it initiates flexion by laterally rotating the femur on the tibia). * **VMO Atrophy:** The Vastus Medialis is the first muscle to atrophy in knee injuries or chronic effusions, often leading to patellar maltracking. * **Screw-Home Mechanism:** This is the anatomical term for the locking of the knee, which increases joint stability while standing for long periods with minimal muscular effort.

Q: Following a car accident with a deep laceration on the medial side of the right knee, the patient notices numbness along the medial side of the right leg and foot. There is no motor deficit. Which nerve appears to have been injured?

Saphenous nerve. **Explanation:** The correct answer is **B. Saphenous nerve.** **Why it is correct:** The saphenous nerve is the longest cutaneous branch of the **femoral nerve** (L2-L4). It becomes superficial on the medial side of the knee after piercing the roof of the adductor canal (subsartorial canal). It descends along the medial side of the leg alongside the **great saphenous vein** and provides sensory innervation to the **medial side of the leg and the medial border of the foot** up to the ball of the great toe. Since the patient has a medial knee laceration and purely sensory symptoms in this specific distribution, the saphenous nerve is the most likely structure injured. **Why the other options are incorrect:** * **Femoral nerve:** While it is the parent nerve, a femoral nerve injury would cause motor deficits (weakness in knee extension/quadriceps) and sensory loss in the anterior thigh, not just the lower leg. * **Sural nerve:** This nerve supplies the **lateral** aspect of the ankle and the lateral border of the foot. It is formed by branches of the tibial and common fibular nerves. * **Superficial fibular nerve:** This nerve supplies the lateral compartment of the leg (motor) and the skin over the **lower lateral leg and the dorsum of the foot** (sensory). **High-Yield Clinical Pearls for NEET-PG:** * **Anatomical Landmark:** The saphenous nerve passes between the Sartorius and Gracilis muscles at the knee. * **Surgical Correlation:** The saphenous nerve is at high risk of injury during **venesection of the great saphenous vein** or during orthopedic surgeries involving the medial aspect of the knee. * **Purely Sensory:** It is a purely sensory nerve; any motor deficit rules out an isolated saphenous nerve injury.

Q: Which of the following structures does not form the covering of a femoral hernia?

External spermatic fascia. To understand the coverings of a **femoral hernia**, one must trace the path of the hernia sac as it passes through the femoral canal and exits via the saphenous opening [1]. ### **Why Option C is Correct** The **External spermatic fascia** is a covering derived from the external oblique aponeurosis. It is a specific layer of the **spermatic cord** (in males) or the round ligament (in females) and is associated with **inguinal hernias**, not femoral hernias. Since the femoral canal is located lateral to the pubic tubercle and below the inguinal ligament, it does not involve the layers of the inguinal canal. ### **Analysis of Other Options** * **A. Peritoneum:** This is the innermost layer of any abdominal hernia sac. As the abdominal contents protrude, they always push the parietal peritoneum ahead of them. * **B. Cribriform fascia:** This is the modified deep fascia of the thigh (fascia lata) that covers the saphenous opening. As a femoral hernia expands anteriorly, it must push through or stretch this fascia to become visible in the subcutaneous tissue of the thigh [1]. ### **Coverings of a Femoral Hernia (Inside to Outside):** 1. Extraperitoneal fat (Femoral septum) 2. Parietal peritoneum 3. Transversalis fascia (Femoral sheath) 4. Cribriform fascia 5. Skin and subcutaneous tissue ### **NEET-PG High-Yield Pearls** * **Anatomy:** The femoral canal is the medial compartment of the femoral sheath. Its boundaries are: *Anterior:* Inguinal ligament; *Posterior:* Pectineal ligament (Cooper’s); *Medial:* Lacunar ligament (Gimbernat’s); *Lateral:* Femoral vein. * **Clinical:** Femoral hernias are more common in **females** due to a wider pelvis [1]. * **Complication:** They have the **highest risk of strangulation** among all abdominal hernias because of the rigid boundaries of the femoral ring (specifically the sharp edge of the lacunar ligament) [1].

Question 1

Which muscles are collectively known as 'Triceps surae'?

Accepted Answer

Gastrocnemius and soleus

Answer

Popliteus

Answer

Extensor hallucis longus

Answer

Extensor digitorum longus

Question 2

Which of the following does NOT supply the femoral head?

Accepted Answer

Profunda femoris artery

Answer

Medial circumflex artery

Answer

Lateral circumflex artery

Answer

Artery of the ligamentum teres

Question 3

Obturator nerve arises from which spinal nerve roots?

Accepted Answer

Ventral divisions of L2, L3, L4

Answer

Dorsal divisions of L2, L3, L4

Answer

Ventral rami of L1, L2

Answer

Dorsal rami of L1, L2

Question 4

Which of the following muscles primarily assists in the flexion of the hip joint?

Accepted Answer

Psoas

Answer

Piriformis

Answer

Pectoralis major

Answer

External oblique abdominis

Question 5

The saphenous vein is a tributary of which of the following veins?

Accepted Answer

Lateral marginal vein

Answer

Medial marginal vein

Answer

Posterior tibial vein

Answer

Dorsal venous arch

Question 6

What is the nerve supply of the Tibialis anterior muscle?

Accepted Answer

Deep peroneal nerve

Answer

Tibial nerve

Answer

Femoral nerve

Answer

Sural nerve

Question 7

The saphenous nerve is a branch of which of the following nerves?

Accepted Answer

Femoral nerve

Answer

Tibial nerve

Answer

Sciatic nerve

Answer

Common peroneal nerve

Question 8

Which is the locking muscle of the knee joint?

Accepted Answer

Vastus Medialis

Answer

Vastus Lateralis

Answer

Vastus Intermedius

Answer

Rectus Femoris

Question 9

Following a car accident with a deep laceration on the medial side of the right knee, the patient notices numbness along the medial side of the right leg and foot. There is no motor deficit. Which nerve appears to have been injured?

Accepted Answer

Saphenous nerve

Answer

Femoral nerve

Answer

Sural nerve

Answer

Superficial fibular nerve

Question 10

Which of the following structures does not form the covering of a femoral hernia?

Accepted Answer

External spermatic fascia

Answer

Peritoneum

Answer

Cribriform fascia

Answer

None of the above

Lower Limb — MCQs

Lower Limb — MCQs

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