Corpus: Nasalis muscle

The nasalis muscle is a muscle of facial expression located in the nose, consisting of two parts. It plays a role in controlling the movements of the nostrils.

The nasalis muscle is composed of two parts:

• Transverse part: This part originates from the maxilla, just above and slightly lateral to the incisive fossa. Its fibers run upward and inward, inserting into a thin aponeurosis that spans the nasal bridge. Some fibers also blend into the aponeurosis of the procerus muscle.
• Alar part: This part originates from the incisive fossa of the maxilla, slightly medial and below the origin of the transverse part, at the bony area above the root of the second incisor. The fibers then extend into the cartilage of the nasal wing and to the tip of the nose.

The nasalis muscle is innervated by the buccal branches of the facial nerve (cranial nerve VII).

The transverse part of the nasalis muscle pulls the nasal cartilage towards the maxilla, narrowing the nostrils. The alar part, in contrast, pulls the cartilage of the nostrils laterally, widening the nostrils and aiding in nasal breathing.