Lower Limb Practice Questions

Q: Foot drop results as a result of injury to which nerve?

Deep peroneal nerve. **Explanation:** **Foot drop** is a clinical condition characterized by the inability to dorsiflex the foot at the ankle joint, leading to a "dragging" gait. **Why Deep Peroneal Nerve (DPN) is the correct answer:** The Deep Peroneal Nerve (a branch of the Common Peroneal Nerve) supplies the muscles of the **anterior compartment of the leg**, including the Tibialis anterior, Extensor digitorum longus, and Extensor hallucis longus. The Tibialis anterior is the primary dorsiflexor of the foot. Damage to the DPN results in paralysis of these muscles, causing the foot to remain in a plantar-flexed position (Foot Drop). **Analysis of Incorrect Options:** * **Superficial Peroneal Nerve:** Supplies the lateral compartment of the leg (Peroneus longus and brevis). Injury leads to loss of **eversion**, but dorsiflexion remains intact. * **Tibial Nerve:** Supplies the posterior compartment (plantar flexors). Injury results in "calcaneovalgus" deformity (inability to plantar flex), not foot drop. * **Deltoid Ligament:** This is a strong medial ligament of the ankle joint. Its rupture (often in Pott’s fracture) affects joint stability but does not cause nerve-related motor deficits like foot drop. **Clinical Pearls for NEET-PG:** 1. **Common Peroneal Nerve (CPN):** The most common site of injury is at the **neck of the fibula**. Since the CPN divides into the Deep and Superficial branches, a proximal injury here causes **both** foot drop and loss of eversion. 2. **Gait:** Patients with foot drop exhibit a **High Steppage Gait** to prevent their toes from scraping the ground. 3. **Sensory Loss:** Isolated DPN injury causes sensory loss specifically in the **first web space** of the foot.

Q: A 45-year-old intoxicated male was struck by a tour bus while walking in the middle of the street. The man was admitted to the emergency department and during physical examination was diagnosed with "scissor gait," in which an individual crosses one limb in front of the other, due to powerful hip adduction. Which of the following nerves was most likely involved in this condition?

Obturator. ### Explanation **1. Why the Correct Answer is Right:** The **Obturator nerve (L2–L4)** supplies the muscles of the **medial compartment of the thigh**, which are primarily responsible for hip adduction (Adductor longus, brevis, magnus, and Gracilis). A **"Scissor Gait"** is characterized by excessive activation or spasticity of these adductor muscles, causing the legs to cross over each other during the swing phase of walking. While this condition is most commonly associated with **Upper Motor Neuron (UMN) lesions** (like Cerebral Palsy), the question asks which nerve is "involved" in the mechanism of this gait. Since the Obturator nerve provides the motor innervation to the adductors, it is the anatomical structure responsible for the powerful hip adduction described. **2. Why the Incorrect Options are Wrong:** * **Tibial Nerve:** Supplies the posterior compartment of the leg and hamstrings. Injury leads to loss of plantar flexion and "calcaneovalgus" deformity, not adduction. * **Inferior Gluteal Nerve:** Supplies the Gluteus maximus. Injury results in difficulty climbing stairs or rising from a seated position (weak hip extension). * **Superior Gluteal Nerve:** Supplies the Gluteus medius and minimus (hip abductors). Injury leads to a **Trendelenburg gait**, where the pelvis drops on the unsupported side. **3. Clinical Pearls for NEET-PG:** * **Obturator Nerve Injury:** Can occur during pelvic surgeries or due to compression by a fetal head during labor. It results in loss of thigh adduction and sensory loss over the **medial aspect of the thigh**. * **Scissor Gait vs. Trendelenburg Gait:** Scissor gait is due to **overactive adductors** (Obturator nerve), whereas Trendelenburg gait is due to **weak abductors** (Superior Gluteal nerve). * **Adductor Magnus:** This is a "hybrid" muscle. Its adductor part is supplied by the Obturator nerve, while its hamstring part is supplied by the Tibial component of the Sciatic nerve.

Q: All of the following are contents of the second layer of the sole, except?

Flexor hallucis brevis. The sole of the foot is organized into four distinct layers. To answer this question, one must distinguish between the extrinsic tendons passing through the sole and the intrinsic muscles located within specific layers. ### **Why Flexor Hallucis Brevis is the Correct Answer** **Flexor hallucis brevis (FHB)** is a component of the **third layer** of the sole, not the second. The third layer consists of three short muscles: Flexor hallucis brevis, Adductor hallucis, and Flexor digiti minimi brevis. ### **Analysis of Incorrect Options (Contents of the Second Layer)** The second layer is characterized by "2 tendons and 2 muscles" (the "Layer of Tendons"): * **Flexor digitorum longus (B):** An extrinsic tendon that enters the second layer and serves as the insertion point for the lumbricals and flexor accessorius. * **Flexor hallucis longus (A):** An extrinsic tendon that passes deep to the flexor digitorum longus within this layer. * **Flexor digitorum accessorius (C):** Also known as *Quadratus plantae*, this intrinsic muscle originates from the calcaneus and inserts into the tendon of the flexor digitorum longus. * **Lumbricals (4):** These originate from the tendons of the flexor digitorum longus. ### **High-Yield NEET-PG Pearls** * **Layer 1 (Superficial):** Abductor hallucis, Flexor digitorum brevis, Abductor digiti minimi. * **Layer 4 (Deepest):** Interossei (3 Plantar, 4 Dorsal) and the tendons of Peroneus longus and Tibialis posterior. * **Nerve Supply:** Most intrinsic muscles are supplied by the **Lateral Plantar Nerve**, except for the "LAFF" muscles (1st **L**umbrical, **A**bductor hallucis, **F**lexor digitorum brevis, **F**lexor hallucis brevis), which are supplied by the **Medial Plantar Nerve**. * **Clinical Note:** The Flexor digitorum accessorius is unique because it corrects the oblique pull of the flexor digitorum longus tendon, ensuring the toes flex straight.

Q: The tibial nerve supplies all of the following muscles except:

Peroneus longus. Explanation: The **Tibial nerve (L4–S3)** is one of the two terminal branches of the sciatic nerve. It descends through the popliteal fossa to enter the posterior compartment of the leg. It provides motor innervation to all muscles in the **posterior compartment** (both superficial and deep groups). **Why Peroneus Longus is the correct answer:** The **Peroneus (Fibularis) longus** belongs to the **lateral compartment** of the leg. Muscles in the lateral compartment are exclusively supplied by the **Superficial Peroneal nerve** (a branch of the Common Peroneal nerve). Therefore, the tibial nerve does not supply it. **Analysis of incorrect options:** * **Gastrocnemius:** A superficial muscle of the posterior compartment; supplied by the tibial nerve in the popliteal fossa. * **Plantaris:** A vestigial superficial muscle of the posterior compartment; supplied by the tibial nerve. * **Tibialis posterior:** The deepest muscle of the posterior compartment; supplied by the tibial nerve as it descends toward the ankle. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of Posterior":** The Tibial nerve supplies all muscles on the posterior aspect of the leg and the sole of the foot (via medial and lateral plantar nerves). * **Exception to remember:** The **Short head of Biceps Femoris** is the only muscle in the posterior thigh NOT supplied by the tibial part of the sciatic nerve (it is supplied by the **common peroneal** part). * **Clinical Correlation:** Injury to the tibial nerve results in the inability to plantarflex the foot and "clawing" of the toes, leading to a **calcaneovalgus** deformity.

Q: Surgical exploration of the ankle and foot demonstrates a muscle arising from the medial and lateral processes of the tuberosity of the calcaneus and inserting into the lateral side of the base of the proximal phalanx of the 5th toe. How does this muscle act on the 5th toe?

Abduction. ### Explanation **1. Why the Correct Answer is Right:** The muscle described is the **Abductor Digiti Minimi (ADM)**. It is the most lateral muscle of the first layer of the sole. * **Origin:** Medial and lateral processes of the tuberosity of the calcaneus. * **Insertion:** Lateral side of the base of the proximal phalanx of the 5th toe. * **Action:** Due to its lateral insertion relative to the axis of the 5th digit, its primary action is **abduction** of the little toe at the metatarsophalangeal joint. It also assists in flexion. **2. Why the Incorrect Options are Wrong:** * **B. Adduction:** Adduction of the toes (moving toward the 2nd toe axis) is performed by the **Plantar Interossei**. The 5th toe has its own plantar interosseus for adduction, which originates from the 5th metatarsal, not the calcaneus. * **C. Extension:** Extension of the 5th toe is primarily performed by the **Extensor Digitorum Longus** and **Brevis** (dorsal muscles), not muscles of the plantar first layer. * **D. Flexion of the middle phalanx on the proximal phalanx:** This is the specific action of the **Flexor Digitorum Brevis** (which inserts into the middle phalanges of the lateral four toes). The ADM inserts into the *proximal* phalanx. **3. High-Yield Clinical Pearls for NEET-PG:** * **Nerve Supply:** The Abductor Digiti Minimi is supplied by the **Lateral Plantar Nerve** (S2, S3), a branch of the Tibial nerve. * **Layering of the Sole:** Remember the "1-2-3-4" rule for muscles. The 1st layer contains three muscles: Abductor Hallucis, Flexor Digitorum Brevis, and Abductor Digiti Minimi. * **Functional Axis:** In the foot, the axis for abduction/adduction is the **2nd toe**, unlike the hand where it is the 3rd finger.

Q: Which of the following structures is not a part of the knee extensor mechanism?

Biceps femoris. ### Explanation The **knee extensor mechanism** is a complex functional unit of the anterior compartment of the thigh designed to extend the leg at the knee joint. It consists of a series of structures that transmit the force generated by the quadriceps muscle to the tibia. **Why Biceps Femoris is the correct answer:** The **Biceps femoris** is a member of the hamstring group located in the **posterior compartment** of the thigh. Its primary functions are knee flexion and lateral rotation of the leg (when the knee is flexed). Since it acts as an antagonist to extension, it is not part of the extensor mechanism. **Analysis of Incorrect Options:** * **Quadriceps tendon (A):** This is the collective tendon of the four quadriceps muscles (rectus femoris, vastus lateralis, medialis, and intermedius). It inserts into the superior pole of the patella and is the primary driver of extension. * **Patellar tendon/ligament (D):** This structure connects the inferior pole of the patella to the tibial tuberosity. It acts as the final link in transmitting the contractile force of the quadriceps to the lower leg. * **Tibial tubercle (C):** This is the bony insertion point for the patellar tendon. Without this stable distal attachment, the extensor mechanism cannot function. **High-Yield Clinical Pearls for NEET-PG:** * **The Patella:** The largest sesamoid bone in the body, it acts as a fulcrum to increase the mechanical advantage (leverage) of the quadriceps by about 30%. * **Innervation:** The entire extensor mechanism is supplied by the **Femoral Nerve (L2-L4)**. * **Clinical Sign:** A rupture at any point in this mechanism (quadriceps tendon tear, patellar fracture, or patellar tendon rupture) results in an **inability to perform an active straight leg raise**. * **Jumper’s Knee:** Clinical term for patellar tendonitis, often seen in athletes due to repetitive stress on the extensor mechanism.

Q: Which ligament is primarily responsible for supporting the medial arch of the foot?

Spring ligament. **Explanation:** The **Spring ligament** (Plantar Calcaneonavicular ligament) is the primary dynamic and static stabilizer of the **medial longitudinal arch**. It spans the gap between the sustentaculum tali of the calcaneus and the tuberosity of the navicular bone. Its critical function is to support the head of the talus, which acts as the "keystone" of the medial arch. By preventing the talus from descending inferiorly and medially under weight-bearing conditions, it maintains the arch's height and integrity. **Analysis of Options:** * **Deltoid Ligament (Option A):** This is a strong, triangular ligament on the medial side of the ankle joint. While it provides medial stability to the ankle, it is not the primary supporter of the plantar arch. * **Short Plantar Ligament (Option C):** Also known as the plantar calcaneocuboid ligament, it supports the **lateral longitudinal arch**, not the medial. * **Long Plantar Ligament (Option D):** This is the longest ligament of the tarsus. It converts the sulcus of the cuboid into a canal for the Fibularis longus tendon and primarily supports the **lateral longitudinal arch**. **Clinical Pearls for NEET-PG:** * **Flat Foot (Pes Planus):** Chronic stretching or rupture of the Spring ligament leads to the collapse of the medial longitudinal arch, resulting in a "flat foot" deformity. * **Keystone Concept:** The **Talus** is the keystone of the medial arch, while the **Cuboid** is the keystone of the lateral arch. * **Dynamic Support:** While the Spring ligament is the most important *passive* stabilizer, the **Tibialis posterior tendon** is the most important *dynamic* stabilizer of the medial arch. Its dysfunction is a common cause of acquired flat foot in adults.

Q: A 49-year-old man is admitted to the emergency department with a cold and pale foot. Physical examination reveals that the patient suffers from peripheral vascular disease and his popliteal artery is occluded and no pulse is felt upon palpation. What is the landmark to feel the pulse of the femoral artery?

Femoral triangle. The **femoral artery** is the primary arterial supply to the lower limb. To palpate its pulse, the artery must be superficial and rest against a firm structure. In the **femoral triangle**, the artery lies just deep to the fascia lata and is positioned directly anterior to the psoas major tendon and the superior pubic ramus [1]. The specific landmark for palpation is the **mid-inguinal point** (halfway between the anterior superior iliac spine and the pubic symphysis), just inferior to the inguinal ligament. This is a high-yield clinical site for arterial blood gas (ABG) sampling and cardiac catheterization. **Analysis of Incorrect Options:** * **Adductor canal (Hunter’s canal):** This is a narrow fascial tunnel located deep to the sartorius muscle in the middle third of the thigh [2]. The artery is too deep here to be palpated. * **Popliteal fossa:** This is where the popliteal pulse is felt (deep between the two heads of the gastrocnemius). In this patient, the popliteal artery is occluded [3], making this site irrelevant for feeling the femoral pulse. * **Inguinal canal:** This is a passage in the anterior abdominal wall containing the spermatic cord (in males) or round ligament (in females). It does not contain the femoral artery. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Femoral Triangle (Lateral to Medial):** **N**erve, **A**rtery, **V**ein, **E**mpty space, **L**ymphatics (**NAVEL**). * **Mid-inguinal point:** Site of femoral pulse (midway between ASIS and pubic symphysis) [1]. * **Mid-point of inguinal ligament:** Site of deep inguinal ring (midway between ASIS and pubic tubercle). * **Profunda femoris artery:** The largest branch of the femoral artery, arising within the femoral triangle.

Q: Which of the following is NOT a content of Hunter's canal?

Femoral nerve. **Explanation:** The **Hunter’s canal** (also known as the Adductor canal or Subsartorial canal) is an aponeurotic tunnel in the middle third of the thigh. It serves as a passageway for structures moving from the femoral triangle to the popliteal fossa. **Why the Femoral Nerve is the Correct Answer:** The **femoral nerve** itself is not a content of the Hunter's canal. It terminates within the femoral triangle by dividing into several anterior and posterior divisions. While some of its branches (like the saphenous nerve and the nerve to vastus medialis) enter the canal, the main trunk of the femoral nerve does not. **Analysis of Other Options:** * **Femoral Artery:** It enters the canal at the apex of the femoral triangle and leaves through the adductor hiatus to become the popliteal artery. * **Femoral Vein:** It lies posterior to the artery in the upper part of the canal and lateral to it in the lower part. * **Saphenous Nerve:** This is the longest cutaneous branch of the femoral nerve. It enters the canal, crosses the femoral artery from lateral to medial, and eventually exits by piercing the roof (vasoadductor fascia) to become superficial. **High-Yield Clinical Pearls for NEET-PG:** * **Boundaries:** Anterolaterally by the **Vastus medialis**, posteriorly by **Adductor longus and magnus**, and medially (roof) by the **Sartorius** muscle. * **Contents mnemonic:** "Vast Safe Femurs" (Nerve to **Vast**us medialis, **Saphenous** nerve, **Fem**oral artery, and **Fem**oral vein). * **Clinical Significance:** The canal is a common site for **Adductor Canal Blocks**, used for regional anesthesia in knee surgeries (e.g., TKR) because it provides sensory blockade via the saphenous nerve while sparing the motor fibers of the femoral nerve, allowing for early mobilization.

Question 1

Foot drop results as a result of injury to which nerve?

Accepted Answer

Deep peroneal nerve

Answer

Superficial peroneal nerve

Answer

Tibial nerve

Answer

Deltoid ligament

Question 2

A 45-year-old intoxicated male was struck by a tour bus while walking in the middle of the street. The man was admitted to the emergency department and during physical examination was diagnosed with "scissor gait," in which an individual crosses one limb in front of the other, due to powerful hip adduction. Which of the following nerves was most likely involved in this condition?

Accepted Answer

Obturator

Answer

Tibial

Answer

Inferior gluteal

Answer

Superior gluteal

Question 3

All of the following are contents of the second layer of the sole, except?

Accepted Answer

Flexor hallucis brevis

Answer

Flexor hallucis longus

Answer

Flexor digitorum longus

Answer

Flexor digitorum accessorius

Question 4

The tibial nerve supplies all of the following muscles except:

Accepted Answer

Peroneus longus

Answer

Gastrocnemius

Answer

Plantaris

Answer

Tibialis posterior

Question 5

Which quadrant of the gluteal region is considered safe for intramuscular injections?

Accepted Answer

Upper and outer

Answer

Upper and inner

Answer

Lower and inner

Answer

Lower and outer

Question 6

Surgical exploration of the ankle and foot demonstrates a muscle arising from the medial and lateral processes of the tuberosity of the calcaneus and inserting into the lateral side of the base of the proximal phalanx of the 5th toe. How does this muscle act on the 5th toe?

Accepted Answer

Abduction

Answer

Adduction

Answer

Extension

Answer

Flexion of the middle phalanx on the proximal phalanx

Question 7

Which of the following structures is not a part of the knee extensor mechanism?

Accepted Answer

Biceps femoris

Answer

Quadriceps tendon

Answer

Tibial tubercle

Answer

Patellar tendon

Question 8

Which ligament is primarily responsible for supporting the medial arch of the foot?

Accepted Answer

Spring ligament

Answer

Deltoid ligament

Answer

Short plantar ligament

Answer

Long plantar ligament

Question 9

A 49-year-old man is admitted to the emergency department with a cold and pale foot. Physical examination reveals that the patient suffers from peripheral vascular disease and his popliteal artery is occluded and no pulse is felt upon palpation. What is the landmark to feel the pulse of the femoral artery?

Accepted Answer

Femoral triangle

Answer

Adductor canal

Answer

Popliteal fossa

Answer

Inguinal canal

Question 10

Which of the following is NOT a content of Hunter's canal?

Accepted Answer

Femoral nerve

Answer

Femoral artery

Answer

Femoral vein

Answer

Saphenous nerve

Lower Limb — MCQs

Lower Limb — MCQs

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