There are four dorsal interossei muscles in the foot. These muscles are bi-penniform, which means they are attached in two places. The dorsal interossei muscles arise from the metatarsal shafts (the long section of the metatarsal bones, located behind the toe bones) and are attached to the bones near the ankle and between the bases of the first sets of bones in the toes.
This group of muscles pulls the second, third, and fourth toes away from the axis of the second toe. The muscles also help the lumbricals to extend the joints in the toes during flexion of the metatarsal phalangeal joints.
The deep branch of the lateral plantar nerve sends signals to the muscle group from the brain to control movement.
The dorsal artery extends from the anterior tibial artery and branches out into the deep plantar nerve branch inside the soles of the feet. It enters through the first dorsal interossei muscle and supplies blood to the dorsal interossei muscles. The pulsations of this artery are used to assess peripheral circulation in the foot.