Lumbricals Flashcards

Examine the four plantar lumbrical muscles, their tendon attachments, distinctive innervation, joint actions, and anatomical relationships.

Card 1 of 28Question

How many lumbrical muscles are present in each foot?

Four lumbrical muscles.

In This Section

1. How many lumbrical muscles are present in each foot?

Four lumbrical muscles.

2. Which layer of plantar foot muscles contains the lumbricals?

The second plantar muscle layer.

3. Are the lumbricals intrinsic or extrinsic muscles of the foot?

Intrinsic muscles of the foot.

4. Which toes are acted upon by the four lumbrical muscles?

The second, third, fourth, and fifth toes.

5. From which tendons do the foot lumbricals originate?

The tendons of flexor digitorum longus.

6. What is the specific origin of the first lumbrical?

The medial side of the flexor digitorum longus tendon to the second toe.

7. How do the origins of the second through fourth lumbricals differ from that of the first?

They typically arise from adjacent sides of two neighboring flexor digitorum longus tendons.

8. Which lumbrical is typically unipennate?

The first lumbrical.

9. What is the typical muscle fiber arrangement of the second through fourth lumbricals?

Bipennate, with fibers arising from adjacent flexor tendons.

10. Where do the lumbrical tendons insert?

Into the medial sides of the extensor expansions of toes two through five.

11. On which side of their respective toes do the lumbrical tendons pass?

The medial side.

12. What action do the lumbricals produce at the metatarsophalangeal joints?

Flexion of the second through fifth toes.

13. What action do the lumbricals produce at the interphalangeal joints?

Extension of the interphalangeal joints of toes two through five.

14. How do the lumbricals produce interphalangeal extension despite originating from flexor tendons?

They insert into the dorsal extensor expansions of the toes.

15. Which nerve innervates the first lumbrical of the foot?

The medial plantar nerve.

16. Which nerve innervates the second, third, and fourth lumbricals?

The deep branch of the lateral plantar nerve.

17. Which major peripheral nerve gives rise to both plantar nerves supplying the lumbricals?

The tibial nerve.

18. Which spinal nerve roots primarily contribute to the medial plantar nerve supplying the first lumbrical?

L4 and L5.

19. Which spinal nerve roots primarily contribute to the lateral plantar nerve supplying the remaining lumbricals?

S2 and S3.

20. Which arteries supply the lumbrical muscles of the foot?

Branches of the medial and lateral plantar arterial systems.

21. Which veins drain blood from the plantar lumbrical muscles?

Plantar veins accompanying the supplying arteries.

22. Which muscle shares the second plantar layer with the lumbricals?

Quadratus plantae.

23. Which long flexor tendons are closely associated with the lumbricals in the second plantar layer?

The four tendons of flexor digitorum longus.

24. What is the anatomical relationship of the lumbricals to the deep transverse metatarsal ligament?

Their tendons pass plantar to the deep transverse metatarsal ligament.

25. How do the lumbricals contribute to toe position during walking?

They help coordinate metatarsophalangeal flexion with interphalangeal extension.

26. What functional imbalance may result from weakness or paralysis of the lumbricals?

Reduced intrinsic toe control, potentially contributing to claw toe deformity.

27. What joint posture characterizes a typical claw toe deformity?

Metatarsophalangeal hyperextension with flexion of the interphalangeal joints.

28. Which anatomical feature distinguishes the lumbricals from most other skeletal muscles?

They originate from the tendons of another muscle rather than directly from bone.