EYEBROW KNIT
The eyebrows pull together and down, creating a vertical crease between them — the muscle responsible is the glabella.
Concentration, confusion, displeasure, or anger.
Read the rest of the face to distinguish. Glabella plus tight lips and squinted eyes is anger. Glabella plus a slight head tilt is confusion. Glabella with a soft mouth is concentration. Long-term habitual frowners develop a permanent vertical line here.
Reading-glasses pose, where the brow knits to focus on close print.
