Section 01 of 20
Introduction
Flexor digiti minimi brevis (foot) is a small intrinsic muscle in the third layer of the sole, on the lateral side of the forefoot. It lies along the plantar surface of the fifth metatarsal, deep to abductor digiti minimi.
It is often thin or partly fused with the interossei, and it is easily confused with abductor digiti minimi, which runs along the lateral border of the foot from the heel.
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Origin
| Origin | Base of the fifth metatarsal and the sheath of the fibularis longus tendon (long plantar ligament region). |
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An anatomical image for this section will be added when verified source media becomes available.
Section 03 of 20
Insertion
| Insertion | Lateral side of the base of the proximal phalanx of the fifth toe. |
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An anatomical image for this section will be added when verified source media becomes available.
Section 04 of 20
Actions
No dedicated action video is currently available. This movement is explained below and video will be added when verified source media becomes available.
| Primary action | Flexion of the fifth toe at the metatarsophalangeal joint. |
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| Secondary actions | Contributes to stability of the lateral forefoot. |
| Movement at the joint | Fifth metatarsophalangeal joint. |
| Heads / fiber groups | Single small muscle belly; no separate heads. |
| Functional examples | Gripping the ground with the little toe; stabilizing the outer forefoot during push-off; balancing. |
Flexes the fifth toe
Flexes the metatarsophalangeal joint of the fifth toe.
Lateral forefoot support
Contributes to stability of the lateral forefoot during push-off.
Small-muscle role
Its contribution is modest and overlaps with the interossei and other plantar muscles.
Section 05 of 20
Nerve Innervation
| Nerve | Superficial branch of the lateral plantar nerve, a branch of the tibial nerve (S2–S3). |
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The lateral plantar nerve passes behind the medial malleolus through the tarsal tunnel. Lateral forefoot burning, tingling, or numbness may reflect the nerve or a nearby structure, not the muscle.
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Blood Supply
| Blood | Lateral plantar artery and plantar metatarsal branches. |
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Section 07 of 20
Pictures and Visual Anatomy
An anatomical image for this section will be added when verified source media becomes available.
Section 08 of 20
Functional Movement
Together with the other intrinsic foot muscles, it helps the fifth toe grip the ground and keeps the lateral forefoot stable in walking, running, and balance tasks.
Section 09 of 20
Synergists and Antagonists
Synergists: abductor digiti minimi, the plantar and dorsal interossei, and the long toe flexors. Antagonists: extensor digitorum longus and brevis, which extend the toes.
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Palpation and Location
Client position and technique
This is a small deep muscle and cannot be palpated individually with confidence. Position the client supine or seated with the foot supported. Locate the fifth metatarsal base (the bony prominence on the lateral midfoot) and the plantar surface of the fifth metatarsal shaft, and feel the soft tissue along the lateral sole while the client gently curls the fifth toe.
Protect nearby structures
Use light-to-moderate pressure only. Avoid sustained pressure on the base of the fifth metatarsal, where fracture and tendon injury are common, and on a tender bunionette, wound, or callus.
Section 11 of 20
Massage Therapy Relevance
Lateral forefoot pain is common in people who stand or walk for long periods or wear tight shoes. Because this muscle is small and deep, treatment focuses on the whole lateral foot rather than isolating it.
Section 12 of 20
Dysfunction: What Happens When Movement Goes Wrong
Changes in how a muscle works can change how a joint moves. The points below describe possibilities that may be associated with altered muscle function; they are not diagnoses, and one muscle is never assumed to be the sole cause of a problem.
When the muscle is weak
Weakness may reduce fifth-toe grip and outer-forefoot stability and may shift load to other plantar muscles.
When it is tight or shortened
Tightness may be associated with an aching outer forefoot and reduced fifth-toe extension.
When it is overused
Prolonged standing or narrow footwear may overload the outer forefoot and may contribute to lateral forefoot ache.
When it is strained
A strain may cause pain under the fifth metatarsal; the same area is affected by bunionette, neuroma, and stress injuries.
When it is inhibited or others compensate
Reduced activation may be associated with less lateral forefoot control and compensation from the other intrinsic muscles.
When it does not coordinate well with synergists and antagonists
Poor coordination with abductor digiti minimi and the interossei may alter outer-forefoot stability during push-off.
Section 13 of 20
Conditions, Pathologies, and Pain Relationships
Bunionette (tailor's bunion)
Enlargement at the head of the fifth metatarsal can cause lateral forefoot pain. Massage does not correct the deformity.
Metatarsalgia and forefoot overload
Pain under the metatarsal heads can involve the intrinsic muscles, fat pad, and joints.
Fifth metatarsal base injury
Pain and swelling at the base of the fifth metatarsal after a twisting injury may indicate a fracture and needs assessment.
Differential considerations
Interdigital neuroma, tarsal tunnel syndrome, peripheral neuropathy, gout, and stress fracture can all cause lateral forefoot pain.
Section 14 of 20
Example Clinical Relationship
A nurse who stands for long shifts in narrow shoes reports aching under the outer forefoot and little toe. The small plantar muscles of the fifth toe may be overloaded, and the pattern may be associated with forefoot overload, but bunionette, interdigital neuroma, and fifth metatarsal stress injury can look similar. Pain and swelling after a twisting injury needs referral.
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Massage and Treatment Approaches
For healthy, non-acute tissue, support the foot in a neutral posture and begin with broad effleurage over the sole and lateral border. Progress to gentle compression and short strokes along the lateral plantar surface, keeping pressure comfortable.
| Movement | Use gentle active toe curling and spreading within comfort. |
|---|---|
| Regional work | Consider the plantar fascia, abductor digiti minimi, fibularis muscles, calf, and footwear when history supports it. |
| Avoid | Deep pressure over acute pain, a tender fifth metatarsal base, swelling, or open skin. |
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Precautions and Contraindications
Precautions and contraindications
- Acute injury, suspected stress fracture, or recent foot surgery.
- Use caution with diabetes, peripheral neuropathy, poor circulation, or reduced sensation.
- Avoid open wounds, infection, plantar warts, and tender bunionettes.
- Ask about anticoagulant use and easy bruising.
Section 17 of 20
Red Flags and When to Refer
Red flags and referral
- Foot or ankle that is red, hot, swollen, and painful, especially with fever.
- Pain and swelling at the outer midfoot after a twisting injury, or inability to bear weight.
- Progressive numbness, weakness, or burning that does not settle.
- Cold, pale, or blue toes, non-healing sores, or unilateral calf swelling.
Section 18 of 20
Study Summary
Attachments
Origin: base of the fifth metatarsal. Insertion: base of the fifth-toe proximal phalanx.
Actions
Flexes the fifth toe and supports the lateral forefoot.
Supply
Lateral plantar nerve (S2–S3); lateral plantar artery.
Section 19 of 20
Instructor Narration
Open narration transcript
Flexor digiti minimi brevis in the foot is a small muscle in the third layer of the sole, on the outer side of the forefoot.
It arises from the base of the fifth metatarsal and the sheath of the fibularis longus tendon, and it inserts on the lateral side of the base of the fifth toe's proximal phalanx.
It flexes the fifth toe at the metatarsophalangeal joint and helps stabilize the lateral forefoot. Abductor digiti minimi and the interossei work with it, and the toe extensors oppose it.
The superficial branch of the lateral plantar nerve, from S2 to S3, supplies it. Blood comes from the lateral plantar artery and plantar metatarsal branches.
Because this muscle is small and deep, it cannot be palpated separately with confidence. Support the foot, find the base of the fifth metatarsal, and feel the soft tissue along the lateral sole while the client curls the little toe. Stay away from the fifth metatarsal base if it is tender.
Bunionettes, forefoot overload, fifth metatarsal base fractures, interdigital neuroma, and tarsal tunnel problems can all cause lateral forefoot pain. Refer a hot, red, swollen foot, outer midfoot pain after a twisting injury, progressive numbness, or cold or blue toes. The pictures supplied for this muscle appeared to show a neighboring muscle, so this course is text-only.
Remember: base of the fifth metatarsal to the fifth toe, fifth-toe flexion, and the lateral plantar nerve.
Section 20 of 20