WHOLE CHARACTER
医yī
medicine; medical (医疗, 西医); doctor (医生, 医师); to cure; to treat (医治)
医 is medicine and healing — doctors, hospitals, and treatment.
The header's wording pairs 会意 with 矢声; the open-box radical and the arrow graph are shown without a learner rule.
ENCLOSURE FRAME (THE RADICAL 匚)
匚fāng
an open box; container
The open-box radical; a bound form, not a standalone page.
In 医: enclosure frame (the radical 匚) ZDIC lists 匚 as the radical, the open box around the character.
INNER PIECE (矢; NAMED WITH SOUND IN THE HEADER)
矢shǐ
arrow
Standalone meaning is kept separate from its named role in 医.
In 医: inner piece (矢; named with sound in the header) The arrow graph inside; shǐ and yī share neither initial nor final — the link is historical.