The nasalis is a paired facial muscle located in the nose region and is the largest of the nasal muscles. It covers both the dorsum and ala of the nose. This muscle plays a key role in controlling the width of the nostrils and is involved in facial expressions and respiratory movements. Each nasalis muscle is situated on either side of the midline.

The nasalis consists of two parts: the transverse part and the alar part. These portions differ in their origin, insertion, and function.

The transverse part (also known as transverse nasalis or compressor naris) is larger than the alar portion. It appears triangular-shaped and covers the dorsum of the nose. This part is responsible for compressing the nostrils and narrowing the nasal aperture. It also merges with the procerus at the bridge of the nose.
The alar part (also called alar nasalis or dilator naris) is smaller and covers the ala of the nose. It functions to draw the nostrils laterally, resulting in the widening of the nasal aperture.

The activity of both parts becomes especially noticeable during deep breaths or strong emotional expressions such as anger or intense concentration, when nasal movements are more pronounced.

The nasalis is innervated by the buccal branches of the facial nerve (CN VII) and receives arterial blood supply primarily from branches of the facial artery. Venous drainage happens via the facial vein.

Transverse part (transverse nasalis)

The transverse nasalis is the largest portion of the nasalis muscle. It compresses the nostrils by pulling the ala of the nose medially toward the nasal septum. Therefore, this muscle is also known as the compressor naris, and it plays a role in narrowing the nasal aperture, particularly during breathing.

Origin and insertion of transverse nasalis

Origin: maxilla, superolateral to the incisive fossa.

Insertion: aponeurosis crossing the dorsum of the nose, blending with fibers from the contralateral transverse nasalis.

Action: compresses and closes the nostrils. It helps reduce the size of the nasal aperture.

Innervation: buccal branches of the facial nerve (CN VII).

Arterial blood supply: lateral nasal branches of the facial artery, with possible contributions from the infraorbital artery of the maxillary artery.

Venous drainage: external nasal veins draining into the facial vein.

Alar part (alar nasalis)

The alar portion of the nasalis muscle is involved in flaring the nostrils. It originates from the maxilla and inserts into the major alar cartilage of the nose, helping to dilate the nasal aperture during breathing. This muscle is also known as the dilator naris.

Origin: maxilla superior to the lateral incisor tooth.

Insertion: lateral crus of the major alar cartilage and the overlying skin.

Action: dilates the nostrils and prevents collapse during breathing.

Innervation: buccal branches of the facial nerve (CN VII).

Arterial blood supply: superior labial artery and lateral nasal branches of the facial artery, and nasal septal branches of the superior labial artery.

Venous drainage: external nasal veins draining into the facial vein.

Unlock with Premium

Nasalis