Verse 3.5

पायूपस्थेऽपानं चक्शुःश्रोत्रे मुखनासिकाभ्यां प्राणः स्वयं प्रातिष्टते मध्ये तु समानः । एष ह्येतद्धुतमन्नं समं नयति तस्मादेताः सप्तार्चिषो भवन्ति ॥ ५ ॥

pāyūpasthe'pānaṃ cakśuḥśrotre mukhanāsikābhyāṃ prāṇaḥ svayaṃ prātiṣṭate madhye tu samānaḥ । eṣa hyetaddhutamannaṃ samaṃ nayati tasmādetāḥ saptārciṣo bhavanti || 5 ||

5. The apana stays in the two lower apertures. Prana stays in the eye, ear, speech and nose. In the middle is samana. He distributes the food supplied equally; so, these seven flames arise.

Shankara’s Commentary:

Com.—Of its division now; the apana, an aspect of the chief Prana, stays in the two lower apertures expelling urine and faeces, etc.; so in the eye and the ear and going out from the mouth and the nose, Prana, occupying himself the place of the sovereign, stays. In the middle, i.e., between prana and apana, i.e., in the navel, samana (so called, because he distributes food and drink saman, i.e., equally). As this distributes equally, the food and drink thrown into the fire of the body, these seven flames go out from the fire in the stomach fed by food and drink, and reaching the region of the heart through the apertures in the head. The drift is that the objects of seeing, hearing, etc., are enlightened through the prana.