Co Mahaaraahulovaadasutta, no 10.

Relevant sutta passage:

(ka.n.nacchidda.m naasacchidda.m mukhadvaara.m), yena ca
asitapiitakhaayitasaayita.m ajjhoharati, yattha ca
asitapiitakhaayitasaayita.m
santi.t.thati, yena ca asitapiitakhaayitasaayita.m adhobhaaga.m nikkhamati..

and whereby (one) swallows what is tasted, chewed, drunk and eaten, and
where (food) being tasted, chewed, drunk and eaten remains, and whereby
(food) being tasted, chewed, drunk and eaten passes out of the body lower
down.


Commentary:

yena caati yena chiddena.

As to the words ³and that by which² , this means: by which cavity.

ajjhoharatiiti anto paveseti,

As to the words, ³he swallows², this means, he makes it go inside.

jivhaabandhanato hi yaava udarapa.talaa manussaana.m vidatthicatura"ngula.m
chidda.t.thaana.m hoti.

From the base of the tongue as far as the mucous membrane of the intestines
of humans there is a hollow tract of one cube and four fingers length.

ta.m sandhaayeta.m vutta.m.

Now, this is said in this connection.

yattha caati yasmi.m okaase.

As to the words, ³And where², this means: at whichever occasion.

santi.t.thatiiti pati.t.thaati.

As to the expression, it remains, this means: it is established.

manussaana~nhi mahanta.m pa.taparissaavanamatta~nca udarapa.tala.m naama
hoti.

Here the intestines have been referred to which are like a large filter for
humans.

ta.m sandhaayeta.m vutta.m.

Now, this is said in this connection.

adhobhaaga.m nikkhamatiiti yena he.t.thaa nikkhamati.

As to the words , it comes out at the lower part, this means: where it comes
out underneath.

dvatti.msahatthamatta.m ekaviisatiyaa .thaanesu va"nka.m anta.m naama hoti.

Here, the intestines have been referred to that are thirtytwo cubits (a
cubit being half a yard) in length and coiled in twentyone places.

ta.m sandhaayeta.m vutta.m.
Now, this is said in this connection.

ya.m vaa pana~n~nampiiti

As to the words, or whatever else,

iminaa sukhumasukhuma.m cammama.msaadiantaragata~nceva lomakuupabhaavena ca
.thita.m aakaasa.m dasseti.

this means: here he explains the cavity between the very fine inner skin
and flesh and so on, which are porous and are fastened by ligaments.

sesametthaapi pathaviidhaatuaadiisu vuttanayeneva veditabba.m.

Here, what is left should be understood as what is said with reference to
the element of earth and so on.

*****

Note: see also Visuddhimagga VIII, 118-120, for the intestines, etc.

Nina.