Dorsal Interosseous Muscles – Anatomy, Nerve Supply

Dorsal Interosseous muscles are a group of paired intrinsic muscles of the foot located between the metatarsals. They consist of four dorsal muscles that abduct the fingers. The dorsal interossei additionally assist in flexion of the metacarpophalangeal joints and extension of the interphalangeal joints. All interossei muscles receive innervation by the lateral plantar nerve. As such, any injury to the lateral plantar nerve may have debilitating implications on specific intrinsic foot muscle functions, including finger abduction and adduction, which are primarily controlled by the interossei muscles.

Dorsal Interosseous

• The dorsal interossei muscles (3) exist between digits two through five – the two adjacent muscles form a central tendon and act to abduct the metatarsal-phalangeal joints and innervation comes from the lateral plantar nerve

Origin and Insertion of Dorsal Interosseous Muscles

The four interossei muscles are bipenniform muscles each originating by two heads from the proximal half of the sides of adjacent metatarsal bones.

The two heads of each muscle form a central tendon that passes forwards deep to the deep transverse metatarsal ligament.^[rx] The tendons are inserted on the bases of the second, third, and fourth proximal phalanges and into the aponeurosis of the tendons of the extensor digitorum longus^[rx] without attaching to the extensor hoods of the toes.^[rx] Thus, the first is inserted into the medial side of the second toe; the other three are inserted into the lateral sides of the second, third, and fourth toes.^[rx]

Nerve Supply of Dorsal Interosseous Muscles

All dorsal interossei are innervated by the lateral plantar nerve (S2–3). Those in the fourth interosseous space are innervated by the superficial branch and the other by the deep branch. ^[rx] The first and second dorsal interossei muscles additionally receive innervation from the lateral branch of the deep fibular nerve.^[rx]

The Function of Dorsal Interosseous Muscles

The dorsal interossei abduct at the metatarsophalangeal joints of the third and fourth toes. Because there is a pair of dorsal interossei muscles attached on both sides of the second toe, the simultaneous contraction of these muscles results in no movement. This arrangement of dorsal interossei makes the second toe the midline of the foot, whereas the midline of the hand (marked by dorsal interossei of hand) is in the third finger. ^[rx]

Abduction is of little importance in the foot, but, together with the plantar interossei, the dorsal interossei also produce flexion at the metatarsophalangeal joints. Although small, the dorsal interossei are powerful muscles that, together with their plantar counterparts, control the direction of the toes during violent activity, thus allowing the long and short flexors to perform their actions. ^[rx]

Because of the relationship to the metatarsophalangeal joints, the interossei muscles also contribute to maintaining the anterior metatarsal arch of the foot and also, to a limited extent, the medial and lateral longitudinal arches of the foot. ^[rx]

References

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