Procerus muscle

The Procerus is a small pyramidal slip of muscle deep to the superior orbital nerve, artery and vein.

Origin and insertion
It arises by tendinous fibers from the fascia covering the lower part of the nasal bone and upper part of the lateral nasal cartilage.

It is inserted into the skin over the lower part of the forehead between the two eyebrows, its fibers decussating with those of the Frontalis.

Function
It helps to pull that part of the skin between the eyebrows downwards, which assists in flaring the nostrils.

It can also contribute to an expression of anger.