Lumbricals of the hand

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==Lumbricals of the hand ==

The lumbricals of the hand are four small, worm-like muscles located in the palm of the hand. These muscles play a crucial role in the fine motor movements of the fingers.

Anatomy

The lumbricals originate from the tendons of the flexor digitorum profundus muscle. Each lumbrical muscle arises from the radial side of the tendons of the flexor digitorum profundus and inserts into the extensor expansion on the dorsal aspect of the corresponding finger.

There are four lumbricals in each hand:

• The first and second lumbricals are unipennate muscles, originating from the lateral two tendons of the flexor digitorum profundus.
• The third and fourth lumbricals are bipennate muscles, originating from the medial three tendons of the flexor digitorum profundus.

Innervation

The lumbricals are innervated by two different nerves:

• The first and second lumbricals are innervated by the median nerve.
• The third and fourth lumbricals are innervated by the ulnar nerve.

Function

The primary function of the lumbricals is to flex the metacarpophalangeal joints and extend the interphalangeal joints of the fingers. This action is essential for the intricate movements required for tasks such as writing, typing, and playing musical instruments.

Clinical significance

Dysfunction of the lumbricals can lead to difficulties in performing fine motor tasks. Conditions such as carpal tunnel syndrome and ulnar nerve entrapment can affect the lumbricals, leading to muscle weakness and impaired hand function.

See also

• Hand muscles
• Flexor digitorum profundus
• Median nerve
• Ulnar nerve
• Carpal tunnel syndrome
• Ulnar nerve entrapment