The nasalis muscle is a

sphincter A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. Sphincters are found in many animals. There are over 60 types in the h ...

-like muscle of the

nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passe ...

. It has a transverse part and an alar part. It compresses the

nasal cartilages The nasal cartilages are structures within the nose that provide form and support to the nasal cavity. The nasal cartilages are made up of a flexible material called hyaline cartilage (packed collagen) in the distal portion of the nose. There are fi ...

, and can "flare" the nostrils. Some people can use it to close the nostrils to prevent entry of

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

when underwater. It can be used to test the

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...

(VII), which supplies it.

Structure

The nasalis muscle covers the

of the lower surface of the

. It consists of two parts, ''transverse'' and ''alar'': * The ''transverse part'' (compressor naris muscle) arises from the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

, above and lateral to the

incisive fossa In the human mouth, the incisive foramen (also known as: "''anterior palatine foramen''", or "''nasopalatine foramen''") is the opening of the incisive canals on the hard palate immediately behind the incisor teeth. It gives passage to blood ves ...

. Its fibers proceed upward and medially, expanding into a thin

aponeurosis An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join muscl ...

which is continuous on the bridge of the nose with that of the muscle of the opposite side, and with the aponeurosis of the

procerus muscle The procerus muscle (or pyramidalis nasi) is a small pyramidal slip of muscle deep to the superior orbital nerve, artery and vein. ''Procerus'' is Latin, meaning tall or extended. Structure The procerus muscle arises by tendinous fibers from t ...

. It compresses the nostrils and may completely close them. * The ''alar part'' (

dilator naris muscle The dilator naris muscle (or alae nasi muscle) is a part of the nasalis muscle. It has an anterior and a posterior part. It has origins from the nasal notch of the maxilla and the major alar cartilage, and a single insertion near the margin of th ...

) arises from the

over the lateral incisor and inserts into the

greater alar cartilage The major alar cartilage (greater alar cartilage) (lower lateral cartilage) is a thin, flexible plate, situated immediately below the lateral nasal cartilage, and bent upon itself in such a manner as to form the medial wall and lateral wall of th ...

. Its medial fibres tend to blend with the depressor septi nasi muscle, and has been described as part of that muscle.

Nerve supply

Like all the other muscles of facial expression, the nasalis muscle is supplied by the

(VII).

Function

The nasalis muscle compresses the

. It may also "flare" the nostrils. Some people can use it to close the nostrils to prevent entry of

when underwater.

Clinical significance

Cleft lip and cleft palate

The nasalis muscle is one of the key muscles not formed or inserted correctly with

cleft lip and cleft palate A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The te ...

deformity. The head of the transverse part needs to be identified during

reconstructive surgery Reconstructive surgery is surgery performed to restore normal appearance and function to body parts malformed by a disease or medical condition. Description Reconstructive surgery is a term with training, clinical, and reimbursement implicat ...

so that it can be surgically sutured (connected to) the

nasal septum The nasal septum () separates the left and right airways of the nasal cavity, dividing the two nostrils. It is depressed by the depressor septi nasi muscle. Structure The fleshy external end of the nasal septum is called the columella or co ...

. The origin at the

may also be repositioned for better

symmetry Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definiti ...

Facial nerve testing

Due to it being superficial, the nasalis muscle can be used to test the

. Specifically, it can be used to test the zygomatic branches.

Additional images

File:Sobo 1909 260.png File:Sobo 1909 262.png File:Sobo 1909 264.png File:Sobo 1909 266.png File:Nasalis muscle animation small.gif, Position of nasalis muscle (shown in red). File:Gray157.png, Left maxilla. Outer surface.

References

External links

Interactive diagram at ivy-rose.co.uk
{{Authority control Muscles of the head and neck