Classica Sinica Medica

真牙

zhēn yá

The wisdom teeth · zhen ya

Also rendered: The true teeth (this site; it keeps 真 as true, and the chapter's point is that these are the teeth that complete the set) · Zhen ya (transliteration; used where the word is being read against the other 真 compounds of the book)

Life stages

Reviewed · 2026-10-08

At a glance

Pinyin
zhēn yá
Simplified
真牙
Literal
真 zhēn — true, genuine, what is complete of its kind (《說文》: 真，仙人變形而登天也); 牙 yá — a molar, the grinding teeth at the back (《說文》: 牙，牡齒也). 真牙 is the true teeth: the last to come, the ones that complete the set. In this chapter they arrive at twenty-one in the woman's count and at twenty-four in the man's, and both times the chapter adds the same words — and growth reaches its extreme. The teeth that finish the mouth are the sign that the body has finished growing.
Shuowen
**「真」讀 zhēn，本篇6見**；**「牙」讀 yá，本篇2見**；**「真牙」本篇2見**；**《說文》：真，仙人變形而登天也；牙，牡齒也**；**本篇真牙生而長極凡2見，男女各一**

In brief

The wisdom teeth, the last teeth to come and the sign that growth has reached its extreme. Suwen 1 names them twice, at twenty-one in the woman’s count and at twenty-four in the man’s, and both times with the same clause: the wisdom teeth come and growth reaches its extreme. They are the only sign in either count that is the same for both sexes — the counts differ by seven and eight, but the teeth that close growth come to both.

Senses in the classical corpus

1
The graphs 真牙
真者真也，牙者牡齒；真牙謂最後生之齒
故真牙生而長極 — Suwen 1
2
The last teeth 真牙生
齒之最後生者，俗謂盡根牙
故真牙生而長極 — Suwen 1
3
At twenty-one 三七腎氣平均，故真牙生而長極
女子三七而真牙生
三七腎氣平均，故真牙生而長極 — Suwen 1
4
At twenty-four 三八腎氣平均，筋骨勁強，故真牙生而長極
丈夫三八而真牙生
三八腎氣平均，筋骨勁強，故真牙生而長極 — Suwen 1
5
The sign of the extreme 故真牙生而長極
真牙既生，則身量長極
故真牙生而長極 — Suwen 1
6
Why the kidney 腎氣平均
腎主骨，齒為骨之餘，故腎氣平而真牙生
三七腎氣平均 — Suwen 1

Occurrences in the classics

Passages where the term does real work, with the original, pinyin and English on the same line.

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1 passages
素問·上古天真論 Suwen 1 · 上古天真論 Read in context →
歧伯曰：女子七歲，腎氣盛，齒更髮長。二七而天癸至，任脉通，太衝脉盛，月事以時下，故有子。三七腎氣平均，故真牙生而長極。四七筋骨堅，髮長極，身體盛壯。五七陽明脉衰，面始焦，髮始墮。六七三陽脉衰於上。面皆焦。髮始白。七七任脉虛，太衝脉衰少，天癸竭，地道不通，故形壞而無子也。 歧伯曰：女子七岁，肾气盛，齿更发长。二七而天癸至，任脉通，太冲脉盛，月事以时下，故有子。三七肾气平均，故真牙生而长极。四七筋骨坚，发长极，身体盛壮。五七阳明脉衰，面始焦，发始堕。六七三阳脉衰于上。面皆焦。发始白。七七任脉虚，太冲脉衰少，天癸竭，地道不通，故形坏而无子也。
Qí Bó yuē: nǚ zǐ qī suì, shèn qì shèng, chǐ gēng fà zhǎng. èr qī ér tiān guǐ zhì, rèn mài tōng, tài chōng mài shèng, yuè shì yǐ shí xià, gù yǒu zǐ. sān qī shèn qì píng jūn, gù zhēn yá shēng ér cháng jí. sì qī jīn gǔ jiān, fà cháng jí, shēn tǐ shèng zhuàng. wǔ qī yáng míng mài shuāi, miàn shǐ jiāo, fà shǐ duò. liù qī sān yáng mài shuāi yú shàng. miàn jiē jiāo. fà shǐ bái. qī qī rèn mài xū, tài chōng mài shuāi shǎo, tiān guǐ jié, dì dào bù tōng, gù xíng huài ér wú zǐ yě.
Qi Bo said: at seven a girl’s kidney qi is full — the teeth change and the hair grows. At fourteen the heavenly water arrives, the conception vessel opens, the great surge vessel is full, and the menses come down in season, so she can bear children. At twenty-one the kidney qi is even and balanced, so the wisdom teeth come and growth reaches its extreme. At twenty-eight the sinews and bones are firm, the hair has grown to its utmost, and the body is at its fullest strength. At thirty-five the yangming vessel declines, the face begins to sear and the hair begins to fall. At forty-two the three yang vessels decline in the upper part; the face is entirely seared and the hair begins to whiten. At forty-nine the conception vessel is empty, the great surge vessel is decayed and scant, the heavenly water is exhausted and the way of the earth is blocked, so the body is broken down and she can have no children.
**「真牙」本篇2見，女子三七、丈夫三八各一**；**「長極」之長讀 cháng，與上文「髮長」之 zhǎng 本篇二讀**；**「任脉」之脉，底本不从肉**；**「月事以時下」與下文「地道不通」首尾相應**

Compounds built on this term

長極
cháng jí
growth's extreme
本篇3見；真牙生而長極
齒更
chǐ gēng
the changing of the teeth
本篇2見
腎氣
shèn qì
kidney qi
本篇7見；主骨而生齒
筋骨
jīn gǔ
sinews and bones
本篇4見

How it has been translated

Every rendering below is a decision about which reader is being addressed. There is no neutral option.

This siteThe wisdom teeththe received English name, and the chapter is about the age at which they come
Literalthe true teethexact to the graph, and it keeps the sense that they are the ones that finish the mouth
Transliterationzhen yaright about the referent, and it tells an English reader nothing

Entry status

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2026-10-08

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