Posterior interosseus nerve, one of the two terminal branches of Radial and the Radial itself (it supply only one muscle)

the radius and ulna along its length

Interosseus Membrane

Plantaris, palmaris longus, 1st palmar interosseus. There may be more, but that is all I can recall

eye starts with an E, iris and intestines starts with an I. index finger, illium, ileum, inguinal ligament (...canal, ligament, region, etc), intercostal muscles (some of which are Internal), Illiacus muscle, Illeocecal valve, Inner ear, Integumentary system, Interosseus membrane, etc.