Lumbricals are small, worm-like muscles located in the deep palm of the hand that play a crucial role in finger movement. Specifically, they flex the metacarpophalangeal joints (the knuckles) and extend the interphalangeal joints (the joints within the fingers).
Anatomy and Function
Here's a more detailed breakdown:
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Location: Found in the palm of the hand, between the tendons of the flexor digitorum profundus muscle.
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Number: There are typically four lumbrical muscles in each hand.
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Attachment: A unique characteristic of the lumbricals is that they don't attach to any bones at their origin. They originate from the tendons of the flexor digitorum profundus and insert onto the extensor hoods of the fingers.
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Function:
- Flexion at the Metacarpophalangeal Joints (MCP): The lumbricals help bend the fingers at the knuckles.
- Extension at the Proximal and Distal Interphalangeal Joints (PIP & DIP): They help straighten the fingers at the joints within the fingers themselves. This is key for fine motor movements.
Table Summarizing Lumbrical Information
| Feature | Description |
|---|---|
| Location | Deep palm of the hand |
| Number | Four in each hand |
| Origin | Tendons of flexor digitorum profundus |
| Insertion | Extensor hoods of the fingers |
| Primary Action | Flexion at MCP joints, extension at PIP and DIP joints |
Clinical Significance
While relatively small, the lumbricals are important for coordinated hand movements. Damage or dysfunction can affect grip strength and dexterity. Conditions affecting the median or ulnar nerve (which innervate the lumbricals) can impact their function.
