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Lumbricals of the Hand and Foot: Learn Your Muscles

The lumbricals are another muscle that appears in both the hand and the foot. If you have any difficulty bending your fingers or toes at the middle knuckle or where they join your hands or feet, you’ll want to learn more about these muscles. Here’s more information about the lumbricals and how to keep them healthy.

Location

According to my Flash Anatomy Muscles Flash Cards, the points of origin for the lumbricals in the hand are on the tendons of the flexor digitorum profundus in the center of the palm. From the center of the palm, the muscles insert “around the radial side of the metacarpal bone and into the extensor expansion.” Basically, this means that the muscles insert on the inside of each finger (the side closest to the thumb), just above the knuckle where the finger joins the palm.

lumbrical muscles of the hand

Thanks to Orthobullets for the image.

In the foot, the lumbricals originate from some of the tendons from the flexor digitorum longus. Similarly to the hand, these muscles insert on the inside of the four smaller toes, just above the joint where the toe joins the foot. However, in the foot, this ends up being near to the tendons of the extensor digitorum longus.

lumbricals muscles in the foot

Thanks to How to Relief for the image.

Function

In the hand, the lumbricals are the primary extensors of the middle joints of your fingers in the spot that you might call your knuckles. When you fingers extend, it means that they bend backward. (An example of finger extension is when you lace your fingers and press them away to pop your knuckles.)

These muscles also weakly flex the metacarpophalangeal joints, which are where your fingers join the palm of your hand. Whenever your finger flexes, it bends toward the palm of your hand.

Similarly to the hand, the lumbricals in the foot extend the interphalangeal joints, which are the middle toe knuckle joints. Here, the lumbricals help reach the toes back toward the top of the foot.

Also, they assist in flexing the metatarsophalangeal joints where the toes join the foot. This means that this muscle helps the four smaller toes bend toward the sole of the foot at the joint where the toe meets the foot.

Common Dysfunction

If your lumbricals are dysfunctional, you might feel pain or weakness when you try to reach your fingers or toes backward from the middle knuckle. Also, you might have pain or weakness when you try to bend your fingers or toes forward at their point of attachment to the hand or foot.

Restoring or Maintaining Health

If you believe you have injured your lumbricals in your hand or foot, you should contact your doctor. He or she can order the appropriate imaging, medicine, and therapy necessary for you to make a speedy and complete recovery.

However, if you’re wanting to keep these muscles healthy and strong, I have some suggestions. Any time you want to strengthen a muscle, you should perform its action. This means that you should practice bending your fingers toward your palm and your toes toward the sole of your foot.

Also, carefully stretch each knuckle. (Technically, this is a strengthening exercise, but it feels like a stretch to me.) To do this, I place my thumb on the back of the knuckle and my pointer finger on the other side of the finger or toe just above the knuckle. Then, I apply a slight pressure to create a mild stretch. This stretch can be done on all four of your fingers and all four of your smaller toes.

To stretch these muscles, you would do the opposite. Bend your knuckles so that your fingers and toes seem to fold in half. Also, use your fingers to carefully extend your fingers and toes where they join the hand or foot.

More Information

For those who are more interested in technical terminology and smaller muscles, I recommend Flash Anatomy Muscles Flash Cards. Any time a client comes to me with pain, I use these flash cards.

Do you have any other suggestions for strengthening or stretching the lumbricals of the hand and foot? Let us know in the comments below.

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About Sarah Stockett

Hi, I'm Sarah! I'm a certified Pilates and yoga instructor with a passion for pain relief. I believe you can use simple exercises to relieve your aches + pains. AND, I believe I can teach you how.

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