The verse meticulously describes the three principal nāḍī channels—Iḍā, Piṅgalā, and Suṣumnā—as reservoirs for prāṇa, the vital force. These aren’t simply conduits for breath, but rather complex systems through which prāṇa flows, influencing the entire psychophysical constitution. The phrase “of great extension” indicates a significant energetic capacity within each nāḍī; Iḍā, residing on the left, Piṅgalā on the right, and Suṣumnā, the central channel, representing the most expansive. The statement that prāṇa “always resides” within them highlights the inherent stability and grounding provided by these channels, essential for the sustained practice of āsana and prāṇāyāma. This echoes the later systematization of these channels in the haṭha yoga system, where mastery of movement and breath is predicated on understanding and directing the flow of prāṇa through these three primary nāḍīs.