Dorsal interossei muscles of the foot
Dorsal interossei are the four feather-like muscles found in the central compartment of the sole of the foot. Concerning that the plantar foot muscles can be divided either into layers (superficial to deep) or into groups (medial to lateral), dorsal interossei can be grouped under;
- The central plantar muscles, along with the flexor digitorum brevis, quadratus plantae, lumbricals and plantar interossei
- The fourth (and deepest) layer of the plantar foot muscles, together with the plantar and dorsal interossei of the foot
Going from medial to lateral (in transverse plane) dorsal interossei are counted from one to four; the first being the most medial and the fourth being the most lateral. These muscles are known as bipennate muscles, which means that they consist of two muscle bellies that converge towards the centrally positioned tendon. The functions of dorsal interossei are the toe flexion and abduction on the metatarsophalangeal joints, and toe extension on the interphalangeal joints.
|Origin||Opposing sides of metatarsal bones 1-5|
|Insertion||1: Medial base of proximal phalanx of digit
2-4: Lateral bases of proximal phalanges and extensor expansion of digits 2-4
|Action||Metatarsophalangeal joints 2-4: toe flexion, toe abduction; Interphalangeal joints 2-4: toe extension|
|Innervation||Lateral plantar nerve (S2-S3)|
|Blood supply||Arcuate artery, dorsal and plantar metatarsal arteries|
In this article, we will discuss the anatomy and function of the dorsal interossei muscles of the foot.
Origin and insertion
Dorsal interossei muscles are the two-headed muscles found between the metatarsal bones 1-5. The heads of each dorsal interossei originate from the opposing surfaces of metatarsal bones. The muscle fibers converge toward each other to give off a narrow tendon that continues its course towards the phalanges.
The tendon of the first (most medial) dorsal interosseus muscle inserts onto the medial base of the second proximal phalanx, while the lateral three muscles insert onto the lateral bases of second to fourth proximal phalanges. Due to this inserting pattern, the second proximal phalanx is the only one with two dorsal interossei muscles (first and second) attached to its respective sides.
Since the heads of dorsal interossei converge toward each other in an anteromedial fashion, they bound the angular spaces in the proximal parts of intermetatarsal intervals. These openings between the heads of second to fourth muscles serve as passageways for posterior perforating arteries on their way to the sole of foot, while the corresponding opening between the heads of the first dorsal interosseus muscle transmits the dorsalis pedis artery.
Dorsal interossei muscles of the foot are innervated by lateral plantar nerve (S2-S3), which is a branch of the tibial nerve.
The vascularization of dorsal interossei muscles comes from several small arteries in the foot;
Although small, the dorsal interossei are strong muscles that in synergy with the plantar interossei flex the lateral three toes at the metatarsophalangeal joints. This action is important as it positions the toes in a way that flexor digitorum longus and brevis can perform their activity during jumping and running.
Besides being involved in flexion, dorsal interossei also assist to the extensor digitorum longus and extensor digitorum brevis muscles in toe extension at the interphalangeal joints of second, third and fourth toes. Although it is of less importance, it is worth mentioning that these muscles also abduct the same three toes at metatarsophalangeal joints. Dorsal interossei muscles also contribute to the stability of the foot by supporting the anterior metatarsal, medial and lateral arches of the foot in running, walking and jumping.
To expand your knowledge check out our video about central muscles of the sole of foot, and then test your knowledge with our quiz about muscles of the foot.