Second Dorsal Interosseous (Foot)
Foot · Lower Limb
The second dorsal interosseous of the foot is a bipennate muscle lying between the second and third metatarsals, from whose adjacent sides it arises. Unlike the first dorsal interosseous, it inserts on the lateral side of the proximal phalanx of the second toe, so it draws the second toe laterally away from the reference axis of that same toe. As with the whole interosseous group, it also flexes the metatarsophalangeal joint and extends the interphalangeal joints by way of the dorsal digital expansion. It is supplied by the lateral plantar nerve (S2, S3), with an additional contribution from the deep fibular nerve shared by the first two dorsal interossei. Because both the first and second dorsal interossei attach to the second toe, that toe can be moved to either side, unlike toes three and four.
Origin, Insertion, Action & Nerve
Origin
Adjacent sides of the 2nd and 3rd metatarsals (bipennate)
Insertion
Lateral side of proximal phalanx of the 2nd toe
Action
Abducts the 2nd toe laterally; flexes MTP and extends IP joints
Nerve
Lateral plantar nerve (S2, S3); first and second also receive the deep fibular nerve
Attachments explained
The Second Dorsal Interosseous (Foot) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Adjacent sides of the 2nd and 3rd metatarsals (bipennate)
Insertion
Lateral side of proximal phalanx of the 2nd toe
Action & function
When the Second Dorsal Interosseous (Foot) contracts, it produces the following movements: Abducts the 2nd toe laterally; flexes MTP and extends IP joints.
As part of the Foot group of the Lower Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Second Dorsal Interosseous (Foot) receives its nerve supply from the Lateral plantar nerve (S2, S3); first and second also receive the deep fibular nerve. This nerve carries fibres from spinal segment(s) S2, S3.
Because a muscle can only contract when its nerve is intact, injury to the Lateral plantar nerve or to its spinal roots (S2, S3) can weaken or paralyse the Second Dorsal Interosseous (Foot), impairing the movements it normally produces (abducts the 2nd toe laterally). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Second Dorsal Interosseous (Foot) (the OIANS method)
Study this muscle as the mirror partner of the first dorsal interosseous. Both insert on the second toe, but the first pulls it medially and the second pulls it laterally, so the second toe is the only digit with a dorsal interosseous on each side. Visualising that opposing pair explains why the second toe can be abducted in both directions from its own axis.
Reinforce the nerve pattern here: the second dorsal interosseous is the last of the group to keep the extra deep fibular twig, since only the first and second receive it. Bundling that detail with its bipennate origin from the second and third metatarsals and its lateral insertion on the second toe keeps it distinct from the third and fourth dorsal interossei, which are purely lateral plantar in supply.
Frequently asked questions
Where is the Second Dorsal Interosseous (Foot) located?
The Second Dorsal Interosseous (Foot) is a muscle of the Foot group, located in the Lower Limb.
What is the origin of the Second Dorsal Interosseous (Foot)?
Adjacent sides of the 2nd and 3rd metatarsals (bipennate)
What is the insertion of the Second Dorsal Interosseous (Foot)?
Lateral side of proximal phalanx of the 2nd toe
What movements does the Second Dorsal Interosseous (Foot) produce?
Abducts the 2nd toe laterally; flexes MTP and extends IP joints
What nerve supplies the Second Dorsal Interosseous (Foot)?
Lateral plantar nerve (S2, S3); first and second also receive the deep fibular nerve
Is the Second Dorsal Interosseous (Foot) free to study in OIANS?
The Second Dorsal Interosseous (Foot) is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Lower Limb is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
Study the Second Dorsal Interosseous (Foot)
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