Structure
The extensor tendons entering the toes are anchored together at the level of the metatarsophalangeal joint by an aponeurotic expansion called the extensor expansion. The proximal part of the expansion, the transverse lamina or extensor sling, is composed of transversely orientated fibers that extend around the capsule of the metatarsophalangeal joint. The fibers extend around the toes to blend on the plantar aspect with the deep transverse metatarsal ligament.
The distal part of the extensor expansion, the extensor wing or hood, is formed by obliquely orientated fibers. Near the proximal interphalangeal joint, the hood trifurcates into a central and two lateral parts. The central part inserts into the base of the middle phalanges, while the collateral parts insert into the base of the distal phalanges (Standring, 2016).
Related parts of the anatomy
Anatomical Relations
The extensor expansion receives tendinous insertions from the extensor digitorum longus, extensor digitorum brevis, and extensor hallucis longus muscles, while tendinous contributions from the lumbricals and plantar and dorsal interossei muscles (Kelikian, 2012).
Function
The attachment of the extensor muscles into the extensor expansion allows for flexion of the Metatarsophalangeal joint and extension at the interphalangeal joints.
References
Kelikian, A. S. (2012) Sarrafian's Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional. Wolters Kluwer Health.
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
