Advanced Lumbricals Quiz

Q1. How can dysfunction of the lumbricals contribute to abnormal toe posture?

• It paralyzes the quadriceps
• Loss of balanced metatarsophalangeal flexion and interphalangeal extension can promote deforming forces
• It directly causes ankle dislocation
• It eliminates calcaneal inversion

Q2. Why can a lateral plantar nerve lesion affect several lumbricals while sparing the first?

• The first lumbrical is an extrinsic leg muscle
• The lateral three are supplied by the femoral nerve
• The first lumbrical has a different plantar nerve supply
• The first lumbrical has no innervation

Q3. What feature allows a lumbrical to coordinate forces between the flexor and extensor systems of a toe?

• Origin from a flexor tendon with insertion into the extensor expansion
• Insertion into the Achilles tendon
• Origin and insertion both on the calcaneus
• Origin from the extensor retinaculum

Q4. Why might lumbrical function become altered when flexor digitorum longus tendon excursion changes?

• They originate from the dorsal metatarsals
• Their origins move with the flexor digitorum longus tendons
• They are independent of all tendon motion
• They are fused to the tibia

Q5. Which anatomical arrangement explains why the lateral three lumbricals can be described as bipennate?

• They are supplied by two unrelated nerves
• They cross two ankle joints
• They have two insertions on the calcaneus
• They arise from two neighboring flexor digitorum longus tendons

Q6. Why can intrinsic muscle imbalance be relevant in claw-toe deformity?

• It produces isolated ankle eversion
• Reduced lumbrical action can permit metatarsophalangeal hyperextension with interphalangeal flexion
• Lumbrical weakness primarily causes knee hyperextension
• It fuses the interphalangeal joints

Q7. Why is the medial course of each lumbrical tendon important to its distal mechanics?

• It makes the tendon insert on the fibula
• It converts the muscle into an ankle plantarflexor
• It allows the tendon to enter the tarsal tunnel
• It positions the tendon to join the medial aspect of the extensor expansion

Q8. How can anatomical variation complicate identification of the lumbricals during dissection?

• Their origins and slips can vary among individuals
• They normally arise from the patella
• They are absent from all adult feet
• They always have identical morphology

Q9. Which examination finding would better support a broader lateral plantar nerve lesion than an isolated lumbrical injury?

• Weakness of additional lateral plantar nerve supplied intrinsic muscles
• Normal strength in every neighboring intrinsic muscle
• Normal motor function with no neurological findings
• An isolated skin abrasion over one toe

Q10. Which statement best integrates the anatomy of the foot lumbricals?

• They are dorsal muscles supplied entirely by the deep fibular nerve
• They link the long flexor tendons to the extensor expansions and coordinate flexion at metatarsophalangeal joints with extension at interphalangeal joints
• They are first-layer muscles that extend the ankle
• They arise from the calcaneus and insert on the great toe only