Lumbricales

The Lumbricales are a group of four small skeletal muscles found in the human hand. They are part of the intrinsic muscle group, which also includes the interossei and the thenar and hypothenar muscles. The lumbricales originate from the Flexor digitorum profundus and insert into the extensor expansion. They are responsible for flexing the metacarpophalangeal joints and extending the interphalangeal joints.

Structure

The lumbricales are unique among the muscles of the hand in that they do not have any bony attachments. Instead, they originate from the tendons of the flexor digitorum profundus and insert into the extensor expansion, a fibrous structure on the dorsal side of the fingers. The lumbricales are numbered from lateral to medial, with the first lumbrical being the most lateral and the fourth the most medial.

Function

The primary function of the lumbricales is to flex the metacarpophalangeal joints and extend the interphalangeal joints. This action is important for the fine motor control of the fingers, particularly during tasks such as writing and typing.

Clinical significance

Damage to the lumbricales can result in a loss of fine motor control in the fingers. This can be caused by a variety of conditions, including Carpal tunnel syndrome, Dupuytren's contracture, and Rheumatoid arthritis. Treatment typically involves physical therapy and, in severe cases, surgery.

See also

• Hand anatomy
• Flexor digitorum profundus
• Carpal tunnel syndrome
• Dupuytren's contracture
• Rheumatoid arthritis

External links

• Lumbricales at the US National Library of Medicine Medical Subject Headings (MeSH)