Description
The base is the expanded proximal end of the middle (intermediate) phalanx of the index finger. It is the proximal continuation of its body and contains a proximal articular facet, which articulates with the distal articular facet of the proximal phalanx of the index finger, forming the proximal interphalangeal joint of the index finger.
The base of the middle phalanx of the index finger provides insertion sites for the extensor digitorum and extensor indicis muscles. It also provides attachment sites for the collateral and palmar ligaments for the proximal interphalangeal joint of the index finger.
