Different from that (body) made of the essence of food, more interior, is the Self made of prāṇa. By it the former is filled. It has the form of a person. Prāṇa is its head, vyāna its right wing, apāna its left wing, space is its body, earth its tail and foundation.

This verse presents the second kosha: prāṇamaya-kosha, the sheath made of vital energy. It is subtler than the physical body and animates it from within.

Anyo’ntara ātmā — another Self, more interior. The key word is antara (interior). Each successive kosha is more inward, closer to the core. Tenaiṣa pūrṇaḥ — by it (the prāṇamaya) the former (annamaya) is filled, vitalized. Without prāṇa, the physical body would be a corpse.

The bird structure is now formed by the five prāṇas:

• Prāṇa (head) — the ascending vital force, associated with breathing and the chest region
• Vyāna (right wing) — the energy that circulates throughout the entire body
• Apāna (left wing) — the descending force, associated with elimination
• Ākāśa (body) — the inner space where the prāṇas operate
• Pṛthivī (tail) — earth as foundation

Notably, samāna (digestion) and udāna (ascent) are missing, which are mentioned in other texts. Here the Upaniṣad simplifies to maintain the five-part structure.

The prāṇamaya-kosha is the domain of haṭha-yoga: prāṇāyāma practices work directly with this layer. The yogī learns to perceive and direct these energy flows. But even this is not the final Self — there are still subtler layers to discover.