Natyashastra
इत्यादि लोकभावार्था ग्रीवाभङ्गैरनेकधा । ग्रीवाकर्माणि सर्वाणि शिरः कर्मानुगानि हि ॥१७७॥
Thus, the various gestures of the neck, representing different emotional states, are explained. All neck gestures follow the movements of the head.
english translation
ityAdi lokabhAvArthA grIvAbhaGgairanekadhA । grIvAkarmANi sarvANi ziraH karmAnugAni hi ॥177॥
hk transliteration by Sanscript