Lower Limb Practice Questions

Q: Peroneus longus is supplied by which nerve?

Superficial peroneal nerve. **Explanation:** The **Peroneus longus** (along with the Peroneus brevis) is a muscle of the **lateral compartment** of the leg. The nerve of the lateral compartment is the **Superficial Peroneal Nerve** (L5, S1), which is a terminal branch of the Common Peroneal Nerve. It provides motor innervation to these muscles and sensory innervation to the lower part of the leg and the dorsum of the foot. **Analysis of Options:** * **Superficial Peroneal Nerve (Correct):** Specifically supplies the lateral compartment (Peroneus longus and brevis). * **Deep Peroneal Nerve:** Supplies the **anterior compartment** of the leg (Tibialis anterior, EHL, EDL, Peroneus tertius) and the EDB on the dorsum of the foot. * **Tibial Nerve:** Supplies the **posterior compartment** of the leg (Gastrocnemius, Soleus, Tibialis posterior, etc.). * **Sural Nerve:** This is a purely **sensory nerve** formed by branches of the tibial and common peroneal nerves; it does not supply motor innervation to any muscles. **High-Yield Clinical Pearls for NEET-PG:** * **Action:** Peroneus longus is a powerful **evertor** of the foot and helps maintain the **lateral longitudinal and transverse arches** of the foot. * **Insertion:** Its tendon crosses the sole of the foot diagonally to insert into the base of the **1st metatarsal** and the **medial cuneiform** (similar to Tibialis anterior). * **Nerve Injury:** Injury to the Common Peroneal Nerve (at the neck of the fibula) affects both deep and superficial branches, leading to **Foot Drop** (loss of dorsiflexion) and loss of eversion. However, an isolated injury to the Superficial Peroneal Nerve would result in loss of eversion but preserved dorsiflexion.

Q: What is the root value for the nerve to the quadratus femoris muscle?

L4, L5, S1. The **nerve to quadratus femoris** is a branch of the **sacral plexus**. It arises from the ventral rami of the **L4, L5, and S1** spinal nerves. It exits the pelvis through the greater sciatic foramen (infra-piriform compartment) and supplies two muscles: the **quadratus femoris** and the **inferior gemellus**. It also provides an articular branch to the hip joint. **Analysis of Options:** * **L4, L5, S1 (Correct):** This is the specific root value for both the nerve to quadratus femoris and the **superior gluteal nerve**. * **L1, L2, L3 (Incorrect):** These roots contribute to the iliohypogastric, ilioinguinal, and genitofemoral nerves (lumbar plexus). * **L2, L3, L4 (Incorrect):** This is the root value for the **femoral nerve** and the **obturator nerve**, which supply the anterior and medial compartments of the thigh, respectively. * **S1, S2, S3 (Incorrect):** These roots contribute to the posterior cutaneous nerve of the thigh. The nerve to obturator internus (which supplies the superior gemellus) has a root value of L5, S1, S2. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of Two":** The nerve to quadratus femoris supplies **two** muscles (Quadratus femoris + Inferior gemellus). Similarly, the nerve to obturator internus supplies **two** muscles (Obturator internus + Superior gemellus). * **Course:** It runs deep to the tendon of the obturator internus and the gemelli muscles. * **Hip Joint Innervation:** It is a key nerve involved in the Hilton’s Law application for the hip joint. * **Mnemonic:** Remember "4-5-1" for both the **S**uperior Gluteal Nerve and the Nerve to **Q**uadratus Femoris (SQ451).

Q: Which of the following arteries is NOT involved in cruciate anastomosis?

Superior gluteal artery. The **cruciate anastomosis** is a vital collateral circulatory pathway located at the level of the lesser trochanter of the femur. It ensures a continuous blood supply to the lower limb if the femoral artery is obstructed between the origin of the profunda femoris and the popliteal artery. ### **Why Option D is Correct** The **Superior Gluteal Artery** is the correct answer because it does **not** participate in the cruciate anastomosis. Instead, it is a primary component of the **trochanteric anastomosis**, which is located higher up near the greater trochanter and supplies the head of the femur. ### **Why the Other Options are Incorrect** The cruciate anastomosis is formed by the "cross-shaped" intersection of four specific arteries: * **Inferior Gluteal Artery (Option A):** Provides the **superior** limb of the anastomosis (descending branch). * **Medial Circumflex Femoral Artery (Option B):** Provides the **medial** limb (transverse branch). * **Lateral Circumflex Femoral Artery (Option C):** Provides the **lateral** limb (transverse branch). * **First Perforating Artery:** A branch of the profunda femoris that provides the **inferior** limb (ascending branch). ### **High-Yield Clinical Pearls for NEET-PG** * **Location:** The cruciate anastomosis lies at the level of the **lesser trochanter**, whereas the trochanteric anastomosis lies in the **trochanteric fossa**. * **Trochanteric Anastomosis Components:** Superior gluteal, Inferior gluteal, Medial circumflex femoral, and Lateral circumflex femoral arteries. * **Key Distinction:** The **Superior Gluteal Artery** is involved in the trochanteric anastomosis but **never** the cruciate anastomosis. * **Clinical Significance:** These anastomoses are crucial in maintaining viability of the femoral head and lower limb in cases of femoral artery ligation or atherosclerotic occlusion.

Q: The talocalcaneonavicular joint is a type of which joint?

Ball and socket joint. ### Explanation The **talocalcaneonavicular (TCN) joint** is a complex, multiaxial joint that functions morphologically and functionally as a **ball and socket joint**. **Why it is correct:** In this joint, the "ball" is formed by the **head of the talus**. The "socket" (often referred to as the *acetabulum pedis*) is a deep, concave receiving surface formed by: 1. The posterior surface of the **navicular** bone. 2. The anterior and middle facets of the **calcaneus**. 3. The **plantar calcaneonavicular (spring) ligament**, which supports the head of the talus and completes the socket inferiorly. This configuration allows for gliding and rotatory movements essential for inversion and eversion of the foot. **Why the other options are incorrect:** * **Saddle joint:** Characterized by opposing surfaces that are reciprocally concavo-convex (e.g., first carpometacarpal joint). The TCN joint has a distinct spherical head fitting into a cup. * **Hinge joint (Ginglymus):** Allows movement in only one plane (e.g., ankle joint/talocrural joint). The TCN joint allows multiaxial movement. * **Plane joint:** Involves flat surfaces that allow only gliding (e.g., intermetatarsal joints). The TCN joint has significant curvature and depth. **High-Yield Clinical Pearls for NEET-PG:** * **Spring Ligament:** The most important static stabilizer of the medial longitudinal arch; it forms the "floor" of the TCN joint. * **Subtalar Joint vs. TCN Joint:** While often discussed together, the anatomical subtalar joint is a plane joint (talus and calcaneus only), whereas the TCN joint is a ball and socket joint. * **Triple Arthrodesis:** Involves the fusion of the subtalar, calcaneocuboid, and talonavicular joints to treat severe hindfoot deformity.

Q: Which tarsal bone is interposed between the proximal and distal rows of the foot?

Navicular. The tarsal bones are organized into two functional rows: a **proximal row** (Talus and Calcaneus) and a **distal row** (Medial, Intermediate, and Lateral Cuneiforms, plus the Cuboid). **Explanation of the Correct Answer:** The **Navicular** bone is anatomically positioned as the "keystone" between these two rows on the medial side of the foot. It articulates posteriorly with the head of the talus (proximal row) and anteriorly with the three cuneiform bones (distal row). This unique interposition makes it essential for the integrity of the **medial longitudinal arch**. **Analysis of Incorrect Options:** * **Talus & Calcaneus (Options A & B):** These constitute the **proximal row** (hindfoot). The talus sits superiorly to transmit body weight from the tibia, while the calcaneus forms the heel. * **Cuboid (Option C):** While the cuboid is sometimes described as being lateral to the navicular, it is functionally part of the **distal row**. It articulates posteriorly with the calcaneus, but unlike the navicular, it does not act as a bridge between rows; rather, it sits directly in the lateral column of the distal tarsus. **High-Yield Clinical Pearls for NEET-PG:** * **The "Boat" Bone:** Navicular is derived from the Latin *navicula* (little ship) due to its concave proximal surface. * **Tibialis Posterior Insertion:** The tuberosity of the navicular is the primary insertion site for the Tibialis Posterior muscle. An accessory navicular bone (Os Tibiale Externum) can sometimes be found here, causing medial foot pain. * **Köhler’s Disease:** This is the avascular necrosis of the navicular bone, typically seen in children. * **Chopart’s Joint:** The mid-tarsal joint (transverse tarsal joint) is formed by the talonavicular and calcancocuboid articulations.

Q: What is the primary action of the obturator externus muscle?

Lateral rotation of the thigh. The **obturator externus** is a deep muscle of the gluteal region, often grouped with the "short lateral rotators" of the hip. ### Why Option B is Correct The muscle originates from the outer surface of the obturator membrane and the surrounding bony margins of the obturator foramen. Its tendon passes **posterior** to the neck of the femur to insert into the **trochanteric fossa**. When the muscle contracts, it pulls the greater trochanter posteriorly, causing the femur to rotate outward around its longitudinal axis. Therefore, its primary action is **lateral (external) rotation** of the thigh. It also helps stabilize the femoral head in the acetabulum. ### 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 flexor of the hip is the iliopsoas. While the obturator externus may weakly assist in adduction, it does not contribute significantly to flexion. * **Option D (Extension):** This is the domain of the gluteus maximus and the hamstring muscles. ### NEET-PG High-Yield Pearls * **Nerve Supply:** Unlike most lateral rotators (supplied by branches of the sacral plexus), the obturator externus is supplied by the **posterior division of the obturator nerve (L3, L4)**. * **Anatomical Relation:** The tendon of the obturator externus is a key landmark; it runs directly inferior to the neck of the femur and is often used by surgeons to locate the hip joint posteriorly. * **The "Short Lateral Rotators":** This group includes the Piriformis, Superior Gemellus, Obturator Internus, Inferior Gemellus, Quadratus Femoris, and Obturator Externus.

Q: What is the number of plantar interossei muscles in the sole of the foot?

3. **Explanation:** The **plantar interossei** are intrinsic muscles of the foot located in the fourth layer of the sole. There are **three** plantar interossei, and they are responsible for **adducting** the toes (moving them toward the axis of the foot). **Why Option B is Correct:** The axis of the foot passes through the **second toe**. The three plantar interossei arise from the medial sides of the 3rd, 4th, and 5th metatarsals and insert into the medial sides of the proximal phalanges of the same toes. Since the second toe is the axis, it does not require a plantar interosseus for adduction; thus, only three muscles are needed for the lateral three toes. **Why Other Options are Incorrect:** * **Option A (2):** This is numerically incorrect. * **Option C (4):** There are **four dorsal interossei** in the foot (responsible for abduction). Students often confuse the number of dorsal (4) with plantar (3) interossei. * **Option D (5):** While there are five metatarsals, the first toe (hallux) has its own dedicated adductor muscle (*Adductor hallucis*), and the second toe is the midline axis, making five interossei unnecessary. **High-Yield NEET-PG Pearls:** * **Mnemonic:** **"PAD DAB"** — **P**lantar **AD**duct / **D**orsal **AB**duct. * **Nerve Supply:** All interossei (both plantar and dorsal) are supplied by the **lateral plantar nerve** (S2, S3), which is a branch of the tibial nerve. * **Action:** They adduct the 3rd, 4th, and 5th toes and assist the lumbricals in flexing the metatarsophalangeal joints and extending the interphalangeal joints. * **Comparison with Hand:** In the hand, there are also 3 (or sometimes 4) palmar interossei, but the axis of the hand is the **middle (3rd) finger**.

Q: Trendelenberg test is positive in palsy of which muscle?

Gluteus medius. ### Explanation **1. Why Gluteus Medius is Correct:** The Trendelenburg test assesses the **hip abductor mechanism**. The primary muscles responsible for hip abduction are the **Gluteus medius** and **Gluteus minimus**, both innervated by the **Superior Gluteal Nerve (L4-S1)**. When standing on one leg, the gluteus medius of the supporting (weight-bearing) limb contracts to stabilize the pelvis, preventing the opposite (non-weight-bearing) side from sagging. If the gluteus medius is weak or paralyzed, it cannot hold the pelvis level; consequently, the pelvis drops toward the unsupported side. This is a **Positive Trendelenburg Sign**. **2. Why Other Options are Incorrect:** * **Gluteus maximus:** This is the chief **extensor** of the hip (and lateral rotator). Paralysis leads to a "Gluteus Maximus Lurch" (difficulty climbing stairs or standing from a sitting position), not a pelvic drop. * **Rectus femoris & Vastus medialis:** These are components of the Quadriceps femoris muscle group. Their primary action is **extension of the knee**. Weakness here affects gait stability and stair climbing but does not control pelvic tilt in the coronal plane. **3. Clinical Pearls for NEET-PG:** * **Nerve Involved:** Superior Gluteal Nerve. Injury often occurs due to misplaced intragluteal injections (upper inner quadrant instead of upper outer). * **Trendelenburg Gait:** Also known as a "Ducking" or "Waddling" gait. If bilateral, it is seen in conditions like Congenital Dislocation of the Hip (CDH). * **The "Sound" Side:** Remember, the pelvis drops on the **healthy side** (the side with the lifted foot), while the pathology lies in the **standing/weight-bearing limb**. * **Other causes of positive test:** Fracture of the greater trochanter, non-union of the femoral neck, or developmental dysplasia of the hip (DDH).

Q: A 32-year-old worker sustains a laceration of the Achilles tendon during an accident. Which of the following bones serves as the insertion site for the Achilles tendon?

Calcaneus. **Explanation:** The **Achilles tendon** (Tendo calcaneus) is the thickest and strongest tendon in the human body. It is formed by the fusion of the tendons of the **Gastrocnemius** and **Soleus** muscles (collectively known as the *Triceps Surae*). **1. Why Calcaneus is correct:** The Achilles tendon descends to insert into the **middle one-third of the posterior surface of the calcaneus**. A small bursa (retrocalcaneal bursa) lies between the tendon and the upper part of the calcaneus to reduce friction during movement. Its primary function is plantarflexion of the foot at the ankle joint. **2. Why the other options are incorrect:** * **Fibula:** This is a bone of the leg. While it serves as the origin for several muscles (like the Peroneus longus and brevis), it does not serve as an insertion point for the Achilles tendon. * **Cuboid:** This is a tarsal bone located on the lateral side of the foot. It provides a groove for the Peroneus longus tendon but is not involved with the Achilles. * **Talus:** This is the "link" bone between the leg and the foot. While it articulates with the calcaneus and tibia, no muscles or major tendons (like the Achilles) insert directly onto the talus. **Clinical Pearls for NEET-PG:** * **Plantaris Muscle:** Often called the "Freshman's Nerve," its small tendon runs medial to the Achilles and may remain intact even during a complete Achilles rupture. * **Simmonds/Thompson Test:** A clinical test where squeezing the calf fails to produce plantarflexion, indicating a ruptured Achilles tendon. * **Reflex:** The Achilles tendon is responsible for the **S1-S2 nerve root** ankle jerk reflex. * **Blood Supply:** The watershed area (2–6 cm proximal to insertion) has a poor blood supply, making it the most common site for spontaneous rupture.

Question 1

Peroneus longus is supplied by which nerve?

Accepted Answer

Superficial peroneal nerve

Answer

Tibial nerve

Answer

Sural nerve

Answer

Deep peroneal nerve

Question 2

What is the root value for the nerve to the quadratus femoris muscle?

Accepted Answer

L4, L5, S1

Answer

L1, L2, L3

Answer

L2, L3, L4

Answer

S1, S2, S3

Question 3

Which of the following arteries is NOT involved in cruciate anastomosis?

Accepted Answer

Superior gluteal artery

Answer

Inferior gluteal artery

Answer

Medial circumflex femoral artery

Answer

Lateral circumflex femoral artery

Question 4

The talocalcaneonavicular joint is a type of which joint?

Accepted Answer

Ball and socket joint

Answer

Saddle joint

Answer

Hinge joint

Answer

Plane joint

Question 5

A patient presents with defective adduction of the hip joint and pain in the hip and knee joint. Which nerve is involved?

Accepted Answer

Obturator nerve

Answer

Femoral nerve

Answer

Saphenous nerve

Answer

Sciatic nerve

Question 6

Which tarsal bone is interposed between the proximal and distal rows of the foot?

Accepted Answer

Navicular

Answer

Talus

Answer

Calcaneus

Answer

Cuboid

Question 7

What is the primary action of the obturator externus muscle?

Accepted Answer

Lateral rotation of the thigh

Answer

Medial rotation of the thigh

Answer

Flexion of the thigh

Answer

Extension of the thigh

Question 8

What is the number of plantar interossei muscles in the sole of the foot?

Accepted Answer

3

Answer

2

Answer

4

Answer

5

Question 9

Trendelenberg test is positive in palsy of which muscle?

Accepted Answer

Gluteus medius

Answer

Gluteus maximus

Answer

Rectus femoris

Answer

Vastus medialis

Question 10

A 32-year-old worker sustains a laceration of the Achilles tendon during an accident. Which of the following bones serves as the insertion site for the Achilles tendon?

Accepted Answer

Calcaneus

Answer

Fibula

Answer

Cuboid

Answer

Talus

Lower Limb — MCQs

Lower Limb — MCQs

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