Pseudoganglion on the connecting branch between the deep branch of the lateral plantar nerve and medial plantar nerve.

The connecting branch between the deep branch of the lateral plantar nerve and medial plantar nerve often has an enlarged site. We investigated these enlarged sites of the connecting branches. We observed the 22 human feet of 20 Japanese cadavers. We investigated the connecting branch macroscopically and histologically. We found the connecting branches between the deep branch of the lateral plantar nerve and medial plantar nerve in 19 feet out of 22 feet. This connecting nerve branch was interposed between the tendon of the flexor hallucis longus and the flexor hallucis brevis, and there enlarged in the anteroposterior direction. After penetration, numbers of fascicles of this connecting branch were increased at the enlarged site. In this region, the connective tissues surrounding the nerve fascicles and vessels were more developed compared with the adjoining sides of this branch. A few fascicles at this enlarged site innervated the first metatarsophalangeal joint capsule. Other nerve fascicles arose from the connecting branch and branched off muscular branches to the flexor hallucis brevis. This branch possibly receives the physical exertion or friction during gait due to its position. Deformity and overload of the foot can cause sensory disorders of the foot, but the anatomical basis for the relationship between the deformity/overload and sensory disorders of the foot is unclear. We discussed that this connecting branch can be a potential cause of pressure neuropathies in the human foot.