Visuddhimagga XIV-50

Sasambhāraghānabilassa anto ajapadasaṇṭhāne padese ghānaṃ yathāvuttappakārupakārupatthambhanānupālanaparivāraṃ ghānaviññāṇādīnaṃ yathārahaṃ vatthudvārabhāvaṃ sādhayamānaṃ tiṭṭhati.

「鼻（根）」──在全体的鼻孔之内那如山羊足的形状的地方，它的资助、支持、保护、随从，已如前述，它恰好是鼻识等处的所依和门。

Ñ(XIV,50): 3. The nose [sensitivity] is to be found inside the [feature of the] nose-hole with its accessories in the place shaped like a goat's hoof. It has assistance, consolidation and maintenance in the way aforesaid; and it duly serves both as physical basis and as door for nose-consciousness, and the rest.