Lumbricals Hand Anatomy

Lumbrical Hand Muscles O, I, A

Origin:  From the tendons of flexor digitorum profundus.First and second lumbricals: radial sides of the palmar surfaces of the tendons of the second and  third digit, respectively
Third lumbrical: adjacent sides of the tendons of the third and fourth digits.
Fourth lumbrical: adjoining sides of the tendons of the fourth and fifth digits.
Insertion:  To the radial surface of the extensor apparatus of the same digits as the tendons of origin
Actions: Flexion of the digits
Innervation: First and second lumbricals: median nerve (C8, T1). Third and fourth lumbricals: ulnar nerve (C8, T1)
Blood Supply: Deep palmar arch of the radial artery

Primary Actions of the Lumbrical Muscles Of The Hand

1. Flexion of the digits at the metacarpophalangeal joints

Agonists:

  • Dorsal Interossei
  • Palmar Interossei
  • Flexor Digiti Minimi
  • Flexor Digitorum Superficialis
  • Flexor Digitorum Profundus

  Antagonists:

  • Extensor Digitorum
  • Extensor Indicis
  • Extensor Digiti Minimi

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Secondary Actions of the Lumbrical Muscles Of The Hand

1. Assists with extension of the digits at the proximal interphalangeal joints

  Agonists:

  • Dorsal Interossei
  • Palmar Interossei
  • Extensor Digitorum
  • Extensor Indicis
  • Extensor Digiti Minimi

  Antagonists:

  • Flexor Digitorum Superficialis
  • Flexor Digitorum Profundus

2. Assists with extension of the digits at the proximal interphalangeal joints

  Agonists:

  • Dorsal Interossei
  • Palmar Interossei
  • Extensor Digitorum
  • Extensor Indicis
  • Extensor Digiti Minimi

  Antagonists:

  • Flexor Digitorum Superficialis
  • Flexor Digitorum Profundus

3. Assists with extension of the digits at the distal interphalangeal joints

  Agonists:

  • Dorsal Interossei
  • Palmar Interossei
  • Extensor Digitorum
  • Extensor Indicis
  • Extensor Digiti Minimi

  Antagonists:

  • Flexor Digitorum Profundus