Although the flexor hallucis brevis and flexor digitorum brevis are not the most common foot muscles, they play an important role in your structure and stability. People who struggle with bunions and hammer toes should be particularly interested in these muscles. Here’s more about these small-but-important foot muscles.
Flexor Hallucis Brevis
According to Flash Anatomy Muscle Flash Cards, the flexor hallucis brevis originates on the “medial portion of the plantar surface of the cuboid bone, adjacent portion of the lateral cuneiform bone and prolongation of the tendon of the tibialis posterior.” Let’s take a moment to break that down and understand what it says.
The plantar surface of the cuboid bone is the top of a square-shaped bone in your foot. This bone is located toward the outside of your foot, back toward your heel.
The lateral cuneiform bone is right beside the cuboid bone, toward the middle of your foot. Actually, it’s nearly in the center of your foot.
Right next to the lateral cuneiform is the intermediate cuneiform. Then, on the other side of that is the medial cuneiform. On the medial cuneiform is where the tendon of the tibialis posterior inserts. Those are all the points of origin for the flexor hallucis brevis.
The insertion point for the flexor hallucis brevis is on the medial and lateral sides of the bottom bone of the big toe. Technically, this insertion site is called the proximal phalanx of the big toe.
Flexor Digitorum Brevis
The flexor digitorum brevis originates in two places. They are the:
- Medial process of the tuberosity of the calcaneus–This is the lower half of the calcaneus that is closer to what you would identify as your heel bone.
- Center part of the plantar aponeurosis and the internuscular septa–The plantar aponeurosis is another name for the plantar fascia, which you might be familiar with if you’ve ever had plantar fasciitis. This fascia supports the arch of your foot. Intermuscular septa is the medical way to include all the other aponeurotic sheets that separate the various muscles in that area.
The Flash Anatomy Muscle Flash Cards note that “the entire muscle belly is firmly united with the plantar aponeurosis.” If the muscle belly of the flexor digitorum brevis is united with the plantar aponeurosis, you can imagine that you might be able to feel the flexor digitorum brevis when you palpate the center of the bottom of your foot.
Flexor digitorum brevis inserts on the four tendons that insert into the middle phalanges of the 2nd-5th toes. There are three bones that make up your four smaller toes, or phalanges. These insertion points are on the middle bone.
The flexor hallucis brevis flexes the metatarsophalangeal joint of the big toe. When you lift your big toe, that joint where the big toe lifts from the ground is the matatarsophalangeal joint. However, when you use the flexor hallucis brevis, you’re performing the opposite movement; you’re flexing your big toe or pressing it further into the ground if you’re standing.
The flexor digitorum brevis works in a little bit different way. Yes, it flexes, which means that it helps reach your toes away or press them into the ground if you’re standing. However, because the flexor digitorum brevis has to work with three toe joints, its function is a little different. It flexes the middle phalanges on the proximal phalanges and flexes the proximal phalanges on the metatarsals.
If either of these two muscles are dysfunctional, you might notice reduced ability to flex your toes. This might feel like a tightness on the top of your feet, particularly near the joints where your toes attach to your feet. It’s also possible that dysfunction of either of these two muscles could cause pain on the top of your foot.
Restoring or Maintaining Health
If you think you have injured your flexor hallucis brevis or flexor digitorum brevis, you should contact your doctor. He or she can order the appropriate imaging, medicine, and therapy necessary for you to make a full recovery.
However, if you’re looking for exercises to keep these two muscles healthy, I have some ideas.
- Thunderbolt pose–I love this pose to stretch out the top of the foot. Plus, because there’s no rotation from the hip, it’s really easy to check to make sure that your foot keeps straight alignment throughout.
- Lifting your toes while standing in Tadasana–Every yoga class I teach, we do this. When you lift your toes, you can really activate the muscles in your feet and get them to hug to the bones of your feet and ankles. This neutral foot position is essential for neutral body alignment.
For those who are more interested in technical terminology and smaller muscles, I recommend. Any time a client comes to me with pain, I use these flash cards.
Thanks again to Madeinkibera.com for the image. Here is a link to their website.
Do you have any other suggestions for strengthening or stretching the flexor hallucis brevis and flexor digitorum brevis? Let us know in the comments below.
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