Lower Limb Practice Questions

Q: The obturator nerve enters the thigh by passing through which anatomical structure?

Obturator canal. **Explanation:** The **obturator nerve** (L2–L4) is a branch of the lumbar plexus that descends through the psoas major muscle and enters the pelvis. It exits the pelvis to enter the medial compartment of the thigh via the **obturator canal**. This canal is a small opening in the superior part of the obturator membrane, which covers the obturator foramen. Upon entering the thigh, the nerve divides into anterior and posterior divisions, providing motor supply to the adductor muscles and sensory innervation to the medial thigh. **Analysis of Incorrect Options:** * **Adductor canal (Hunter’s canal):** This is a fascial tunnel in the middle third of the thigh. It contains the femoral artery, femoral vein, and the saphenous nerve, but not the obturator nerve. * **Superficial inguinal ring:** This is an opening in the external oblique aponeurosis. It serves as the exit for the spermatic cord (in males) or the round ligament (in females) and the ilioinguinal nerve. * **Femoral canal:** This is the most medial compartment of the femoral sheath. It contains lymphatic vessels and Cloquet’s node; it is a common site for femoral hernias but does not transmit the obturator nerve. **High-Yield Clinical Pearls for NEET-PG:** * **Howship-Romberg Sign:** Pain or paresthesia on the medial aspect of the thigh due to compression of the obturator nerve (often by an obturator hernia). * **Referred Pain:** Pathology in the hip joint can cause referred pain to the knee because the obturator nerve supplies both joints. * **Adductor reflex:** The obturator nerve is the efferent and afferent limb for the adductor reflex (L2-L4).

Q: What is the main action of the Gemellus muscle?

Lateral rotation of the thigh. **Explanation:** The **Gemellus muscles** (Superior and Inferior) belong to the group of **short lateral rotators** of the hip. They are located in the gluteal region, situated superior and inferior to the tendon of the Obturator internus. **1. Why Option B is Correct:** The Gemelli muscles originate from the ischial spine (Superior) and ischial tuberosity (Inferior) and insert into the medial surface of the greater trochanter of the femur. Due to their posterior position relative to the hip joint axis, their contraction pulls the greater trochanter posteriorly, resulting in the **lateral (external) rotation** of the extended thigh. They also help stabilize the femoral head in the acetabulum. **2. Why Other Options are Incorrect:** * **Option A (Medial rotation):** This is primarily performed by the Gluteus medius, Gluteus minimus, and Tensor fasciae latae. * **Option C (Flexion):** The primary hip flexors are the Iliopsoas, Pectineus, and Rectus femoris. * **Option D (Extension):** Hip extension is the main action of the Gluteus maximus and the Hamstring muscles. **3. High-Yield NEET-PG Clinical Pearls:** * **Innervation:** The Superior Gemellus is supplied by the **nerve to obturator internus** (L5, S1), while the Inferior Gemellus is supplied by the **nerve to quadratus femoris** (L4, L5, S1). * **The "Triceps Coxae":** The Superior Gemellus, Obturator Internus, and Inferior Gemellus are often referred to as the *Triceps Coxae* because they share a common insertion. * **Surgical Landmark:** These muscles are vital landmarks during the posterior approach to the hip joint; the sciatic nerve lies superficial to them.

Q: The dorsalis pedis artery is the continuation of which artery?

Anterior tibial artery. ### Explanation **Correct Option: A. Anterior Tibial Artery** The **dorsalis pedis artery** is the direct continuation of the **anterior tibial artery**. This transition occurs at the level of the **ankle joint**, specifically midway between the two malleoli. It runs along the dorsum of the foot to the proximal end of the first intermetatarsal space, where it terminates by dividing into the first dorsal metatarsal artery and the deep plantar artery (which completes the plantar arch). **Analysis of Incorrect Options:** * **B. Posterior Tibial Artery:** This artery passes behind the medial malleolus and terminates by dividing into the medial and lateral plantar arteries on the sole of the foot. * **C. Popliteal Artery:** This is the parent vessel located in the popliteal fossa. It terminates at the lower border of the popliteus muscle by dividing into the anterior and posterior tibial arteries. * **D. Lateral Tarsal Artery:** This is a **branch** of the dorsalis pedis artery, not its origin. It helps supply the tarsal bones and joints. **Clinical Pearls for NEET-PG:** * **Palpation:** The dorsalis pedis pulse is clinically palpated on the dorsum of the foot, just lateral to the tendon of the **Extensor Hallucis Longus (EHL)**. * **Surface Marking:** It is represented by a line joining the midpoint between the malleoli to the proximal end of the first intermetatarsal space. * **Vascular Significance:** Absence of this pulse may indicate peripheral arterial disease (PAD) or Buerger’s disease. However, note that the pulse is congenitally absent in approximately 10% of the population. * **Anastomosis:** The deep plantar branch of the dorsalis pedis joins the lateral plantar artery to form the **Deep Plantar Arch**.

Q: What is the root value of the common peroneal nerve?

L4, L5, S1, S2. **Explanation:** The **Common Peroneal Nerve** (also known as the common fibular nerve) is one of the two terminal branches of the sciatic nerve. The sciatic nerve originates from the sacral plexus (L4 to S3). It is composed of two distinct functional components: the tibial part and the common peroneal part, which are bundled together by a common connective tissue sheath. 1. **Why L4, L5, S1, S2 is correct:** The common peroneal nerve is derived specifically from the **dorsal (posterior) divisions** of the anterior rami of spinal nerves **L4, L5, S1, and S2**. In contrast, the tibial nerve is derived from the ventral (anterior) divisions of L4, L5, S1, S2, and S3. Therefore, the common peroneal component lacks the S3 contribution. 2. **Analysis of Incorrect Options:** * **A (S1, S2, S3):** These roots contribute to the tibial nerve and the posterior cutaneous nerve of the thigh, but do not represent the full span of the common peroneal nerve. * **B (L1, L2, L3):** These are primarily associated with the lumbar plexus (e.g., iliohypogastric, genitofemoral, and lateral cutaneous nerve of the thigh). * **D (S3, S4, S5):** These roots contribute to the pudendal nerve and the coccygeal plexus, supplying the pelvic floor and perineum. **High-Yield Clinical Pearls for NEET-PG:** * **Vulnerability:** The common peroneal nerve is the most commonly injured nerve in the lower limb because of its superficial course as it winds around the **neck of the fibula**. * **Clinical Presentation:** Injury here leads to **Foot Drop** (loss of dorsiflexion) and **Equinovarus** deformity, as it supplies the muscles of the anterior and lateral compartments of the leg. * **Sensory Loss:** Anesthesia occurs over the dorsum of the foot and the lateral aspect of the leg.

Q: The deep peroneal nerve provides sensory innervation to which of the following areas?

The first web space. **Explanation:** The **deep peroneal nerve (DPN)**, a terminal branch of the common peroneal nerve, primarily serves the anterior compartment of the leg. While its function is predominantly motor (innervating the dorsiflexors of the foot and extensors of the toes), its **sensory distribution is highly localized and specific.** 1. **Why Option C is Correct:** After passing deep to the extensor retinaculum, the DPN terminates by supplying the skin of the **first interdigital cleft (the first web space)** and the adjacent sides of the great toe and second toe. This is a high-yield anatomical landmark frequently tested in exams. 2. **Analysis of Incorrect Options:** * **Option A (Anterolateral dorsum of the foot):** This area is primarily supplied by the **superficial peroneal nerve**, which provides sensory innervation to the majority of the dorsal surface of the foot (except the first web space and the lateral edge). * **Option B (Lateral aspect of the leg):** This is supplied by the **lateral sural cutaneous nerve** (a branch of the common peroneal nerve). * **Option D (The fifth web space):** The lateral border of the foot and the fifth digit area are supplied by the **sural nerve**. **Clinical Pearls for NEET-PG:** * **Anterior Compartment Syndrome:** Increased pressure in the anterior compartment can compress the DPN, leading to "foot drop" (motor loss) and sensory loss specifically in the **first web space**. * **Ski Boot Neuropathy:** Compression of the DPN under the extensor retinaculum causes pain and paresthesia in the first web space. * **Mnemonic:** Remember **"Deep = Digits"** (specifically the first two) and **"Superficial = Surface"** (most of the dorsal surface).

Q: During pronation of the foot, the axes of which two joints become parallel?

Talonavicular and calcaneocuboid. The **Talonavicular** and **Calcaneocuboid** joints together constitute the **Midtarsal (Transverse Tarsal) joint**. The mobility of the foot is heavily dependent on the alignment of the axes of these two joints. **1. Why the Correct Answer is Right:** * **Pronation (Eversion):** During pronation, the axes of the talonavicular and calcaneocuboid joints become **parallel**. This alignment "unlocks" the midtarsal joint, making the foot flexible and supple. This allows the foot to act as a shock absorber and adapt to uneven terrain during the loading phase of gait. * **Supination (Inversion):** Conversely, during supination, these axes **converge** (become non-parallel). This "locks" the joint, turning the foot into a rigid lever necessary for efficient propulsion during toe-off. **2. Why Other Options are Incorrect:** * **Talocrural and Subtalar:** The talocrural (ankle) joint is a hinge joint primarily for plantarflexion/dorsiflexion, while the subtalar joint is for inversion/eversion. Their axes are anatomically distinct and do not become parallel to facilitate motion in this manner. * **Talonavicular and Subtalar:** While both are involved in complex foot movements, they do not function as a parallel-axis unit to lock/unlock the midfoot. * **Midtarsal and Tarsometatarsal:** The midtarsal joint is the functional unit itself; the tarsometatarsal (Lisfranc) joints are distal and provide stability rather than the dynamic locking mechanism described. **High-Yield Clinical Pearls for NEET-PG:** * **Chopart’s Joint:** Another name for the Midtarsal joint. Amputations through this line are called Chopart amputations. * **The "Rigid Lever" Concept:** Remember: **S**upination = **S**table/Stiff (Axes converge); **P**ronation = **P**liable (Axes parallel). * **Subtalar Joint:** Occurs between the talus and calcaneus; it is the primary site for inversion and eversion.

Q: Which of the following is NOT a branch of the lumbar plexus?

Subcostal nerve. The **Lumbar Plexus** is formed by the ventral rami of spinal nerves **L1 to L4**, with a contribution from T12. It is situated within the posterior part of the Psoas major muscle. ### Why Subcostal Nerve is the Correct Answer: The **Subcostal nerve** is the ventral ramus of the **T12** spinal nerve. It is classified as a thoracic nerve because it runs below the 12th rib, outside the formal structure of the lumbar plexus. While T12 sends a small communicating branch to the L1 nerve root, the subcostal nerve itself remains distinct and supplies the abdominal wall muscles and skin over the hip. ### Analysis of Incorrect Options: * **Obturator Nerve (L2, L3, L4):** This is a major branch of the lumbar plexus (posterior division). it enters the thigh through the obturator canal to supply the adductor compartment. * **Iliohypogastric Nerve (L1):** This is the first branch of the lumbar plexus. it supplies the abdominal muscles and skin above the pubis. * **Ilioinguinal Nerve (L1):** Also a branch of the L1 root, it passes through the inguinal canal to supply the skin of the scrotum/labia majora and the adjacent thigh. ### High-Yield NEET-PG Pearls: * **Mnemonic for Lumbar Plexus:** "**I** **I** **G**et **L**unch **F**or **O**thers" (**I**liohypogastric, **I**lioinguinal, **G**enitofemoral, **L**ateral cutaneous nerve of thigh, **F**emoral, **O**bturator). * **Femoral Nerve (L2-L4):** The largest branch of the lumbar plexus. * **Nerve through Psoas Major:** The **Genitofemoral nerve (L1, L2)** is the only nerve that pierces the Psoas major muscle. * **Lumbosacral Trunk:** Formed by part of **L4 and all of L5**; it connects the lumbar plexus to the sacral plexus.

Q: Which of the following is NOT found in the contents of the Adductor canal?

Popliteal artery. The **Adductor canal** (also known as Hunter’s canal or the subsartorial canal) is an aponeurotic tunnel in the middle third of the thigh. It serves as a passage for structures moving from the femoral triangle to the popliteal fossa. ### Why Popliteal Artery is the Correct Answer: The **Femoral artery** enters the adductor canal at its apex. It only becomes the **Popliteal artery** *after* it exits the canal by passing through the **adductor hiatus** (an opening in the Adductor magnus muscle). Therefore, the popliteal artery is a content of the popliteal fossa, not the adductor canal. ### Explanation of Other Options: * **Femoral Artery (A):** It is the primary arterial content of the canal, accompanied by the femoral vein (which lies posterior to the artery). * **Nerve to Vastus Medialis (C):** This is the thickest muscular branch of the femoral nerve. It enters the canal and terminates by supplying the vastus medialis muscle. * **Saphenous Nerve (D):** This is the longest cutaneous branch of the femoral nerve. It traverses the canal but exits by piercing the roof (vastoadductor fascia) to become superficial. ### High-Yield Clinical Pearls for NEET-PG: * **Boundaries:** Anterolaterally (Vastus medialis), Posteriorly (Adductor longus/magnus), and Medially/Roof (Sartorius). * **Sub-sartorial Plexus:** Located on the roof of the canal; formed by branches of the saphenous nerve, obturator nerve, and medial cutaneous nerve of the thigh. * **Clinical Significance:** The canal is a common site for **Adductor Canal Blocks** (used for post-operative analgesia in knee surgeries) because it provides sensory blockade to the saphenous nerve while sparing the motor nerves to the quadriceps (except vastus medialis).

Q: The posterior cutaneous nerve of the thigh supplies the skin overlying which of the following areas EXCEPT?

Lateral aspect of the thigh. The **posterior cutaneous nerve of the thigh (S1, S2, S3)** is a purely sensory branch of the sacral plexus. It descends through the greater sciatic foramen, deep to the gluteus maximus, and runs down the back of the thigh just beneath the fascia lata. ### **Why "Lateral aspect of the thigh" is the correct answer:** The skin of the **lateral aspect of the thigh** is supplied by the **Lateral Cutaneous Nerve of the Thigh (L2, L3)**, which is a branch of the lumbar plexus. The posterior cutaneous nerve specifically supplies the midline posterior strip of the limb, making the lateral aspect the exception. ### **Analysis of Incorrect Options:** * **Posterior inferior aspect of the buttock:** The nerve gives off **inferior cluneal nerves** that loop around the lower border of the gluteus maximus to supply this region. * **Scrotum:** The nerve gives off **perineal branches** that supply the skin of the posterior part of the scrotum (or labia majora in females) and the root of the penis. * **Popliteal fossa:** The nerve continues its descent to supply the skin over the entire back of the thigh and the popliteal fossa, often extending to the upper part of the calf. ### **High-Yield NEET-PG Pearls:** * **Root Value:** S1, S2, S3 (Remember: "1, 2, 3 – back of the knee"). * **Longest Cutaneous Nerve:** It has one of the longest cutaneous distributions in the body. * **Meralgia Paraesthetica:** This clinical condition involves compression of the *Lateral* Cutaneous Nerve of the Thigh (not the posterior) under the inguinal ligament, causing numbness/pain on the lateral thigh. * **Relationship to Gluteus Maximus:** It enters the gluteal region through the infrapiriform compartment, medial to the sciatic nerve.

Question 1

The obturator nerve enters the thigh by passing through which anatomical structure?

Accepted Answer

Obturator canal

Answer

Adductor canal

Answer

Superficial inguinal ring

Answer

Femoral canal

Question 2

What is the main action of the Gemellus muscle?

Accepted Answer

Lateral rotation of the thigh

Answer

Medial rotation of the thigh

Answer

Flexion of the hip

Answer

Extension of the hip

Question 3

The dorsalis pedis artery is the continuation of which artery?

Accepted Answer

Anterior tibial artery

Answer

Posterior tibial artery

Answer

Popliteal artery

Answer

Lateral tarsal artery

Question 4

What is the root value of the common peroneal nerve?

Accepted Answer

L4, L5, S1, S2

Answer

S1, S2, S3

Answer

L1, L2, L3

Answer

S3, S4, S5

Question 5

The deep peroneal nerve provides sensory innervation to which of the following areas?

Accepted Answer

The first web space

Answer

Anterolateral dorsum of the foot

Answer

Lateral aspect of the leg

Answer

The fifth web space

Question 6

During pronation of the foot, the axes of which two joints become parallel?

Accepted Answer

Talonavicular and calcaneocuboid

Answer

Talocrural and subtalar

Answer

Talonavicular and subtalar

Answer

Midtarsal and tarsometatarsal

Question 7

Which of the following statements about the menisci is not true?

Accepted Answer

The menisci are made up of Collagen Type I.

Answer

The lateral meniscus is more mobile than the medial meniscus.

Answer

The lateral meniscus covers more area of the tibial articular surface than the medial meniscus.

Answer

The menisci are composed of around 75% water.

Question 8

Which of the following is NOT a branch of the lumbar plexus?

Accepted Answer

Subcostal nerve

Answer

Obturator nerve

Answer

Iliohypogastric nerve

Answer

Ilioinguinal nerve

Question 9

Which of the following is NOT found in the contents of the Adductor canal?

Accepted Answer

Popliteal artery

Answer

Femoral artery

Answer

Nerve to Vastus medialis

Answer

Saphenous nerve

Question 10

The posterior cutaneous nerve of the thigh supplies the skin overlying which of the following areas EXCEPT?

Accepted Answer

Lateral aspect of the thigh

Answer

Posterior inferior aspect of the buttock

Answer

Scrotum

Answer

Popliteal fossa

Lower Limb — MCQs

Lower Limb — MCQs

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