Nasalis muscle

The nasalis (a.k.a. the compressor naris) is the principal muscle of the nose and is a muscle of facial expression. It consists of two distinct parts — transverse and alar — which act together to compress or dilate the nostrils, thereby regulating nasal airflow.

1. Transverse Part (Compressor Part)

• Origin: From the maxilla, above and lateral to the incisive fossa.

• Course and Insertion: The fibres pass upward and medially, expanding into a thin aponeurosis that crosses the bridge of the nose. This aponeurosis blends with:

  • The contralateral nasalis muscle on the opposite side, and

  • The aponeurosis of the procerus muscle.

• Action: Compresses the nasal aperture, narrowing the nostrils.

2. Alar Part (Dilator Part)

• Origin: From the maxilla, near the lateral incisor region.

• Insertion: Attaches to the greater alar cartilage of the nose.

• Action: Draws the ala of the nose downward and laterally, helping to flare (dilate) the nostrils.

Innervation

• Facial nerve (cranial nerve VII) — via the buccal branch.

Blood Supply

• Facial artery (a branch of the external carotid artery).

Actions (Summary)

• Compressor (transverse) part: Narrows the nasal aperture.

• Alar part: Flares or dilates the nostrils. Together, these actions facilitate expression, respiration, and subtle nasal movements important in facial communication.