Kalmar "medial rectus" kalma ce da aka fi amfani da ita a fagen ilimin halittar jiki, musamman dangane da tsokar ido. tsakiya, yayin da "rectus" yana nufin madaidaiciya ko a daidaitawa.Saboda haka, tsokoki na tsakiya na tsakiya yana daya daga cikin tsokoki shida masu sarrafa motsin ido, wanda ke kusa da kusurwar ido na ciki. Babban aikinsa shi ne motsa ido zuwa ciki, zuwa hanci, da taimakawa tare da haɗuwa, ko ikon mayar da hankali ga idanu biyu akan wani abu kusa.