Lower Limb Practice Questions

Q: What anatomical considerations should an orthopedic surgeon take into account to minimize the risk of damaging the sciatic nerve during hip replacement surgery?

Avoid deep dissection near the piriformis muscle. ***Avoid deep dissection near the piriformis muscle*** - The **sciatic nerve** typically exits the pelvis below the **piriformis muscle**, making this a crucial area to protect during deep dissection. - Excessive retraction or direct injury to the nerve in this region can lead to **postoperative sciatica** or neurological deficits. *Identify and protect the nerve as it courses anterior to the piriformis* - The sciatic nerve almost always courses **posterior** (or inferior) to the piriformis muscle, not anterior. - An anomalous high division of the nerve or an atypical course through the piriformis can occur but a normally positioned nerve is posterior. *Maintain dissection superficial to the gluteus maximus* - The gluteus maximus is the most superficial muscle in the gluteal region, and while a superficial approach minimizes nerve damage, it would not provide adequate access for **hip replacement surgery**. - Hip replacement requires deeper dissection to access the **acetabulum** and **femoral head**. *Understand the nerve's path in relation to the acetabulum for surgical planning.* - While it is generally important to understand the overall anatomy, focusing solely on the relationship with the **acetabulum** overlooks the most common site of injury, which is usually in the vicinity of the **piriformis** and **posterior capsule**. - The nerve's relationship to the acetabulum becomes more critical with specific approaches (e.g., direct anterior) or implant placement, but the **piriformis region** is a more universal concern.

Q: Which ligament is primarily responsible for stabilizing the anterior aspect of the knee joint?

Anterior cruciate ligament. ***Anterior cruciate ligament*** - The **ACL** is crucial for preventing the **anterior displacement of the tibia** relative to the femur and controlling rotational stability. - It arises from the posterior aspect of the lateral femoral condyle and inserts into the anterior intercondylar area of the tibia. *Posterior cruciate ligament* - The PCL primarily prevents the **posterior displacement of the tibia** on the femur. - It is stronger and thicker than the ACL and is less frequently injured. *Lateral collateral ligament* - The **LCL** provides stability against **varus stress** (forces pushing the knee inward). - It is located on the outer side of the knee, connecting the femur to the fibula. *Medial collateral ligament* - The **MCL** resists **valgus stress** (forces pushing the knee outward) and stabilizes the inner side of the knee. - It connects the medial femoral condyle to the medial tibia.

Q: Weakness of extensor Hallucis longus is due to which nerve root mainly?

L5. ***L5*** - The **extensor hallucis longus** muscle, primarily responsible for **dorsiflexion of the great toe**, is predominantly innervated by the **L5 nerve root** via the deep fibular nerve. - Weakness in this muscle is a classic sign of **L5 radiculopathy**. - L5 radiculopathy typically presents with **foot drop** (due to tibialis anterior weakness), **great toe extensor weakness**, and sensory loss over the dorsum of the foot. *L4* - The **L4 nerve root** primarily innervates the **quadriceps** muscles and contributes to the **tibialis anterior**. - Weakness in **knee extension** and diminished **patellar reflex** are more indicative of L4 radiculopathy. - L4 lesions do not typically cause isolated extensor hallucis longus weakness. *S1* - The **S1 nerve root** primarily innervates the **gastrocnemius and soleus** muscles. - Weakness in **plantarflexion** and loss of the **Achilles reflex** are characteristic of S1 radiculopathy. - S1 radiculopathy presents with difficulty walking on toes, not great toe dorsiflexion weakness. *S2* - The **S2 nerve root** contributes to the innervation of the **hamstrings** and intrinsic foot muscles. - Involvement of S2 would typically manifest as weakness in **knee flexion** and sensory changes in the posterior thigh and perineum. - S2 does not innervate the extensor hallucis longus.

Q: Which of the following structures is common between the medial and lateral plantar arch?

Plantar Fascia. ***Plantar Fascia*** - The **plantar fascia** is a thick aponeurosis that extends along the sole of the foot, forming a crucial biomechanical link that is common to both the medial and lateral plantar arches. - It plays a vital role in maintaining the **longitudinal arches** of the foot, acting as a tie-rod that prevents their collapse during weight-bearing. *Flexor Digitorum Brevis* - The **flexor digitorum brevis** is one of the intrinsic muscles of the foot, situated superficially in the central compartment of the sole. - While it contributes to toe flexion, it is primarily located within the **central arch region** and is not considered a common structural component directly spanning both medial and lateral arches in the same way as the plantar fascia. *Spring Ligament* - The **spring ligament** (plantar calcaneonavicular ligament) is critical for supporting the **medial longitudinal arch** of the foot. - It connects the calcaneus to the navicular bone and supports the head of the talus, but it is specific to the medial arch and does not extend to the lateral arch. *Deltoid Ligament* - The **deltoid ligament** is a strong, multi-banded ligament located on the medial side of the **ankle joint**. - Its primary function is to stabilize the ankle joint and prevent excessive eversion, therefore it is not a structure common to the plantar arches of the foot.

Q: All of the following are true about tibialis anterior except?

It is supplied by the superficial peroneal nerve. ***It is supplied by the superficial peroneal nerve*** - The **tibialis anterior muscle** is innervated by the **deep peroneal nerve** (L4, L5, S1), not the superficial peroneal nerve. - The superficial peroneal nerve primarily supplies the **lateral compartment muscles** of the leg (peroneus longus and brevis) and provides sensation to the dorsum of the foot. *It dorsiflexes the foot* - The tibialis anterior is the **primary dorsiflexor of the foot** at the ankle joint. - This action is crucial for **foot clearance** during the swing phase of gait. *It is closely related to the anterior tibial vessels* - The tibialis anterior muscle lies in the **anterior compartment of the leg**, immediately lateral to the **anterior tibial artery and vein**. - These structures run together in the anterior compartment, making them vulnerable in trauma or compartment syndrome. *It inserts on the medial cuneiform* - The tibialis anterior tendon inserts onto the **medial cuneiform bone** and the base of the **first metatarsal bone**. - This insertion point allows it to powerfully dorsiflex and invert the foot.

Q: Lateral aspect of the plantar surface of the foot receives its sensory supply from ?

Lateral plantar nerve. ***Lateral plantar nerve*** - The **lateral plantar nerve** is a terminal branch of the **tibial nerve** and is primarily responsible for the sensory innervation of the **lateral one-third** of the plantar aspect of the foot. - It also supplies sensation to the **fourth and fifth toes**, consistent with its lateral distribution. *Medial plantar nerve* - The **medial plantar nerve** innervates the **medial two-thirds** of the plantar aspect of the foot, including the first, second, and third toes, and the medial half of the fourth toe. - It is a branch of the **tibial nerve** and is distinct from the lateral plantar nerve's sensory distribution. *Superficial peroneal nerve* - The **superficial peroneal nerve** (also known as the musculocutaneous nerve) primarily provides sensory innervation to the **dorsum of the foot** (top of the foot), excluding the web space between the first and second toes. - It does not supply the plantar surface of the foot. *Tibial nerve* - While the **tibial nerve** gives rise to both the medial and lateral plantar nerves as its terminal branches, it does not directly innervate the plantar surface of the foot for sensation. - The plantar surface sensation is specifically provided by its terminal branches: the medial and lateral plantar nerves.

Q: Which muscle is the source of the oblique popliteal ligament?

Semimembranosus. ***Semimembranosus*** - The **oblique popliteal ligament** is a strong, flat fibrous band that strengthens the posterior capsule of the knee joint. - It arises from the tendon of the **semimembranosus muscle** as it inserts onto the medial tibial condyle, reflecting superiorly and laterally across the posterior aspect of the knee. - This is a direct anatomical extension of the semimembranosus tendon. *Semitendinosus* - This muscle's distal tendon contributes to the **pes anserinus**, along with the gracilis and sartorius, inserting on the medial aspect of the tibia. - It does not directly contribute to the formation of the oblique popliteal ligament. *Biceps femoris* - The **long head** originates from the ischial tuberosity and the **short head** from the linea aspera; they insert on the head of the fibula. - Its tendon passes laterally to the knee joint and does not form the oblique popliteal ligament. *Adductor magnus* - This muscle is located in the **medial compartment of the thigh** with origins from the pubic ramus and ischial tuberosity, inserting along the linea aspera and adductor tubercle of the femur. - It is primarily involved in **adduction and extension of the thigh** and has no anatomical connection to the oblique popliteal ligament.

Q: Which tendon is lodged in the groove on posterior surface of lateral malleolus?

Peroneus brevis. ***Peroneus brevis*** - The **peroneus brevis** tendon runs in the groove on the **posterior surface of the lateral malleolus**. - It lies **deeper** than the peroneus longus tendon in this groove and is the primary occupant of the fibular groove. - After passing the lateral malleolus, the **peroneus brevis** inserts into the base of the **fifth metatarsal**. - It functions in **eversion** and **plantarflexion** of the foot. *Peroneus longus* - The **peroneus longus** tendon passes behind the lateral malleolus but is more **superficial and lateral** to the groove. - While it shares the same compartment, the peroneus brevis is the tendon actually lodged in the groove itself. *Tibialis anterior* - The **tibialis anterior** tendon is located on the **anterior aspect of the ankle**, passing over the front of the tibia. - It functions in **dorsiflexion** and **inversion** of the foot, far from the lateral malleolus. *Tibialis posterior* - The **tibialis posterior** tendon passes behind the **medial malleolus**, not the lateral malleolus. - It is a primary inverter and **plantarflexor** of the foot. *Flexor Hallucis Longus* - The **flexor hallucis longus** tendon passes behind the **medial malleolus** and then beneath the sustentaculum tali, extending to the great toe. - Its primary function is **flexion of the great toe**.

Q: What is the longest cutaneous nerve in the body?

Saphenous nerve. ***Saphenous nerve*** - The saphenous nerve is the **longest cutaneous nerve** in the body, originating from the femoral nerve and providing sensory innervation to the skin on the **medial side of the leg and foot**. - It accompanies the **great saphenous vein** down the leg, giving off several cutaneous branches. *Lateral cutaneous nerve of thigh* - This nerve provides sensation to the **anterolateral aspect of the thigh**. - Its length is significantly shorter than the saphenous nerve, and it is primarily associated with conditions like **meralgia paresthetica**. *Medial cutaneous nerve of thigh* - This nerve supplies sensation to the **medial aspect of the thigh**. - It is a branch of the **femoral nerve** but is not as extensive in its course as the saphenous nerve. *Sural nerve* - The sural nerve provides sensory innervation to the **posterolateral aspect of the leg** and the lateral side of the foot. - Formed from branches of the **tibial and common fibular nerves**, it is considerably shorter than the saphenous nerve.

Question 1

What anatomical considerations should an orthopedic surgeon take into account to minimize the risk of damaging the sciatic nerve during hip replacement surgery?

Accepted Answer

Avoid deep dissection near the piriformis muscle

Answer

Identify and protect the nerve as it courses anterior to the piriformis

Answer

Maintain dissection superficial to the gluteus maximus

Answer

Understand the nerve's path in relation to the acetabulum for surgical planning.

Question 2

Which ligament is primarily responsible for stabilizing the anterior aspect of the knee joint?

Accepted Answer

Anterior cruciate ligament

Answer

Posterior cruciate ligament

Answer

Lateral collateral ligament

Answer

Medial collateral ligament

Question 3

Weakness of extensor Hallucis longus is due to which nerve root mainly?

Accepted Answer

L5

Answer

L4

Answer

S1

Answer

S2

Question 4

Which of the following structures is common between the medial and lateral plantar arch?

Accepted Answer

Plantar Fascia

Answer

Flexor Digitorum Brevis

Answer

Deltoid Ligament

Answer

Spring Ligament

Question 5

Which of the following statements is true regarding the lateral tibial condyle?

Accepted Answer

The iliotibial tract is attached to the lateral condyle of the tibia.

Answer

The ligamentum patellae inserts on the anterior tubercle of the tibia.

Answer

The medial collateral ligament attaches only to the medial epicondyle of the femur.

Answer

The semimembranosus muscle is part of the pes anserinus insertion.

Question 6

All of the following are true about tibialis anterior except?

Accepted Answer

It is supplied by the superficial peroneal nerve

Answer

It is closely related to the anterior tibial vessels

Answer

It inserts on the medial cuneiform

Answer

It dorsiflexes the foot

Question 7

Lateral aspect of the plantar surface of the foot receives its sensory supply from ?

Accepted Answer

Lateral plantar nerve

Answer

Medial plantar nerve

Answer

Superficial peroneal nerve

Answer

Tibial nerve

Question 8

Which muscle is the source of the oblique popliteal ligament?

Accepted Answer

Semimembranosus

Answer

Biceps femoris

Answer

Adductor magnus

Answer

Semitendinosus

Question 9

Which tendon is lodged in the groove on posterior surface of lateral malleolus?

Accepted Answer

Peroneus brevis

Answer

Tibialis anterior

Answer

Tibialis posterior

Answer

Flexor Hallucis Longus

Question 10

What is the longest cutaneous nerve in the body?

Accepted Answer

Saphenous nerve

Answer

Lateral cutaneous nerve of thigh

Answer

Medial cutaneous nerve of thigh

Answer

Sural nerve

Lower Limb — MCQs

Lower Limb — MCQs

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