Also known as the compressor naris, the nasalis muscle is located within the nose. It works like a sphincter, or ring-like muscle. The muscle works as its alternative name suggests: to compress nasal cartilage. Also, it depresses the tip of the nose while it elevates the nostril's corners. Typically, this flexing and retracting within the nose is commonly referred to as nostril flaring.
The muscle originates in the maxilla (upper jaw) part of the skull and inserts into the nasal bone. The nasalis muscle is comprised of two regions: the transverse and the alar. The transverse section arises from the maxilla and covers the bridge of the nose. The alar is attached to the greater alar (nostril) cartilage, which is situated between the tissue of the nostril and the lateral cartilage.
The buccal branch of the facial nerve serves the nasalis muscle and many other muscles within the face.