Apāna (resides) in the organs of excretion and generation. Prāṇa itself establishes itself in the eye, ear, mouth and nose. In the middle is samāna. It distributes equally the offered food; from it arise these seven flames.

This verse details the anatomical locations of three of the five main prāṇas.

Pāyūpasthe apānam — apāna resides in the organs of excretion (pāyu) and generation (upastha). Its function is descending and eliminative: it controls defecation, urination, menstruation, ejaculation, childbirth. Everything that must exit the body is under its jurisdiction.

Cakṣuḥśrotre mukhanāsikābhyāṃ prāṇaḥ — prāṇa establishes itself in the eye, ear, mouth and nose. The sense organs and respiration are its domain. Prāṇa is the force that receives: air, sound, vision, taste, smell enter through its gates.

Svayaṃ prātiṣṭhate — it establishes itself. Svayam emphasizes that prāṇa, the principal, chooses its own residence in the centers of vital reception.

Madhye tu samānaḥ — in the middle is samāna. Samāna resides in the navel region, between prāṇa (above) and apāna (below). It is the digestive fire, the intermediary.

Hutam annaṃ samaṃ nayati — it distributes equally the offered food. Huta (offered) suggests that eating is a sacrificial act: we offer food to the inner fire. Sama (equal, equitable) gives samāna its name: it distributes nutrients in a balanced way to all parts of the body.

Saptārciṣaḥ — the seven flames. These are the seven dhātus (tissues): plasma, blood, muscle, fat, bone, marrow, reproductive fluid. Samāna nourishes all of them through the digestive fire (jaṭharāgni).

This subtle anatomy is essential for understanding haṭha-yoga and āyurveda.