Nasalis (Transverse Part)
Facial Expression · Head & Neck
The transverse part of nasalis, also called the compressor naris, is the portion of the nasalis muscle that narrows the nasal aperture. It arises from the maxilla over the alveolar eminence of the canine tooth and its fibres run upward and medially to meet an aponeurosis over the dorsum of the nose that is continuous with the muscle of the opposite side. When it contracts it compresses the nasal aperture, pressing the ala toward the septum. As a muscle of facial expression it is supplied by the facial nerve (CN VII) through its buccal branch. It works in opposition to the alar part of nasalis, which dilates the nostril, so together the two parts of nasalis regulate the size of the nasal opening.
Origin, Insertion, Action & Nerve
Origin
Maxilla, over the alveolar eminence of the canine tooth
Insertion
Aponeurosis over the dorsum of the nose, continuous with the opposite side
Action
Compresses the nasal aperture (nostril)
Nerve
Buccal branch of facial nerve (CN VII)
Attachments explained
The Nasalis (Transverse Part) is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Maxilla, over the alveolar eminence of the canine tooth
Insertion
Aponeurosis over the dorsum of the nose, continuous with the opposite side
Action & function
When the Nasalis (Transverse Part) contracts, it produces the following movement: Compresses the nasal aperture (nostril).
As part of the Facial Expression group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Nasalis (Transverse Part) receives its nerve supply from the Buccal branch of facial nerve (CN VII).
Because a muscle can only contract when its nerve is intact, injury to the Buccal branch of facial nerve can weaken or paralyse the Nasalis (Transverse Part), impairing the movements it normally produces (compresses the nasal aperture (nostril)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Nasalis (Transverse Part) (the OIANS method)
Study nasalis as a two-part muscle and let the alternative name of this part, the compressor naris, tell you its action: it compresses, or narrows, the nasal aperture. Note that its fibres arch up from the maxilla over the canine and join a shared aponeurosis across the nasal dorsum, which is why contraction of both sides squeezes the nose. Compare it directly with the alar part, its antagonist.
Because the two parts of nasalis have opposite actions but the same nerve, focus your memory on the contrast: the transverse part narrows the nostril while the alar part flares it, and both are supplied by the facial nerve (CN VII) via the buccal branch. Anchoring the pair as a compressor-versus-dilator team keeps their functions and shared innervation clear.
Frequently asked questions
Where is the Nasalis (Transverse Part) located?
The Nasalis (Transverse Part) is a muscle of the Facial Expression group, located in the Head & Neck.
What is the origin of the Nasalis (Transverse Part)?
Maxilla, over the alveolar eminence of the canine tooth
What is the insertion of the Nasalis (Transverse Part)?
Aponeurosis over the dorsum of the nose, continuous with the opposite side
What movements does the Nasalis (Transverse Part) produce?
Compresses the nasal aperture (nostril)
What nerve supplies the Nasalis (Transverse Part)?
Buccal branch of facial nerve (CN VII)
Is the Nasalis (Transverse Part) free to study in OIANS?
The Nasalis (Transverse Part) is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
Study the Nasalis (Transverse Part)
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