Natyashastra
सा मातृकेति विज्ञेया तद्योगात्करणं भवेत् । कटी कर्णसमा यत्र कोर्परांसशिरस्तथा ॥ ६०॥
These are known as Mātṛkās, and through their combinations, the Karaṇas arise, where the hip, ears, elbows, shoulders, and head are aligned.
english translation
sA mAtRketi vijJeyA tadyogAtkaraNaM bhavet । kaTI karNasamA yatra korparAMsazirastathA ॥ 60॥
hk transliteration by Sanscript