incus; anvil (ear bone)
Anatomical term for the middle ear bone shaped like an anvil. The reading きぬたこつ is standard; ちんこつ is a less common alternative reading.
The incus is one of the auditory ossicles and transmits vibrations from the eardrum to the inner ear.
Standard kanji spelling for the incus bone. The reading ちんこつ is also valid for this form.
Mixed kana-kanji spelling that clarifies the reading きぬたこつ.
From 砧 (kinuta, 'fulling block/anvil') + 骨 (kotsu, 'bone'), referring to the anvil-like shape of the incus bone in the middle ear.