Śāṅkhāyana (Kauṣītaki) Āraṇyaka 2.3

2.3

ŚĀ 2,3
athaitaṃ graivaṃ śaṃsati | tā vai tisra ṛco bhavanti | trīṇi vā āsāṃ grīvāṇāṃ parvāṇi bhavanti | tānyevaitābhiḥ saṃdadhāti | uṣṇig uttamā | so 'yaṃ skandho vidalo 'vyūḷhaḥ (laḥ) ||

ŚĀ 2.3
Then he recites this neck hymn. It consists of three verses. Three indeed are the joints of this neck. He unites them with these [verses]. The last is an Uṣṇih. That is this collarbone, split, not disjointed.