Facial expressions has a huge part of body language readign and non-verbal communication, that is why facial muscles has an important part on our world.

Facial muscles

Facial expressions are vital to social communication between humans. They are caused by the movement of facial muscles that connect to the skin and fascia in the face.

These facial muscles move the skin, creating lines and folds and causing the movement of facial features, such as the mouth and eyebrows.

These muscles develop from the second pharyngeal arch in the embryo. The temporalis, masseter, and internal and external pterygoid muscles, which are mainly used for chewing, have a minor effect on expression as well. These facial muscles develop from the first pharyngeal arch.

Neuronal pathways



There are two brain pathways associated with facial expression; the first is voluntary expression.

Voluntary expression travels from theprimary motor cortex through the pyramidal tract, specifically the corticobulbar projections.

The cortex is associated with display rules in emotion, which are social precepts that influence and modify expressions. Cortically related expressions are made consciously.

The second type of expression is emotional.

These expressions originate from the extrapyramidal motor system, which involves subcortical nuclei. For this reason, genuine emotions are not associated with the cortex and are often displayed unconsciously.

This is demonstrated in infants before the age of two; they display distress, disgust, interest, anger, contempt, surprise, and fear.

Infants’ displays of these emotions indicate that they are not cortically related. Similarly, blind children also display emotions, proving that they are subconscious rather than learned.

Other subcortical facial expressions include the “knit brow” during concentration, raised eyebrows when listening attentively, and short “punctuation” expressions to add emphasis during speech.

People do not consciously realize that they are producing these expressions.



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