Verse 5.18.2

तस्य ह वा एतस्यात्मनो वैश्वानरस्य मूर्धैव सुतेजाश्चक्षुर्विश्वरूपः प्राणः पृथग्वर्त्मात्मा संदेहो बहुलो बस्तिरेव रयिः पृथिव्येव पादावुर एव वेदिर्लोमानि बर्हिर्हृदयं गार्हपत्यो मनोऽन्वाहार्यपचन आस्यमाहवनीयः ॥ ५.१८.२ ॥
॥ इति अष्टादशः खण्डः ॥

tasya ha vā etasyātmano vaiśvānarasya mūrdhaiva sutejāścakṣurviśvarūpaḥ prāṇaḥ pṛthagvartmātmā saṃdeho bahulo bastireva rayiḥ pṛthivyeva pādāvura eva vedirlomāni barhirhṛdayaṃ gārhapatyo mano'nvāhāryapacana āsyamāhavanīyaḥ || 5.18.2 ||
|| iti aṣṭādaśaḥ khaṇḍaḥ ||

2. Suteja [i.e., ‘the bright and beautiful’—heaven] is the head of this Vaiśvānara Self; Viśvarūpa [‘having many forms’—the sun] is the eye; Pṛthagvartmā [‘one who changes direction’—air] is the prāṇa; Bahula [‘pervasive’—space] is the middle part; Rayi [‘wealth’—water] is the bladder; the earth [Pratiṣṭhā—‘the support’] is the feet; the sacrificial altar is the chest; the kuśa grass is the hair on the chest; the Gārhapatya fire is the heart; the Anvāhāryapacana [i.e., the Dakṣiṇāgni] fire is the mind; and the Āhavanīya fire is the mouth.

Word-for-word explanation:

Tasya etasya ha vai vaiśvānarasya ātmanaḥ, of this Vaiśvānara Ātman; sutejāḥ eva mūrdhā, heaven is the head; viśvarūpaḥ cakṣuḥ, the sun is the eye; pṛthakvartmātmā prāṇaḥ, air is prāṇa; bahulaḥ sandehaḥ, the sky is the middle part of the body; rayiḥ bastiḥ eva, water is the bladder; pṛthivī eva pādau, the earth is the feet; vediḥ, the sacrificial altar; ura eva, is the chest; barhiḥ lomāni, the kuśa grass [used in the sacrifice] is the hair [on the chest]; gārhapatyaḥ hṛdayam, the Gārhapatya fire is the heart; anvāhāryapacana manaḥ, the Anvāhāryapacana fire [i.e., the Dakṣiṇāgni fire] is the mind; āhavanīyaḥ āsyam, the Āhavanīya fire is the mouth. Iti aṣṭādaśaḥ khaṇḍaḥ, here ends the eighteenth section.

Commentary:

The implication is that none of these taken separately can be the Vaiśvānara Self. It is only a part of it.