The nasalis muscle is a

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

-like muscle of the

nose A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...

. 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 f ...

, and can "flare" the

nostrils A nostril (or naris , : nares ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbinates, ...

. 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 ta ...

(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 In vertebrates, the maxilla (: maxillae ) 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. The two maxil ...

, 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 vesse ...

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

aponeurosis An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerable ...

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 muscle in the glabella. It is involved in facial expressions such as frowning and those associated with attentional control, and it indirectly helps shield the eyes from bright ligh ...

. 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 Nasal septum, medial wall and later ...

. Its medial fibres tend to blend with the

depressor septi nasi muscle The depressor septi nasi muscle (or depressor alae nasi muscle) is a muscle of the face. It connects the incisive fossa of the maxilla and the orbicularis oris muscle to the nasal septum of the nose. It draws the ala of the nose downwards, re ...

, 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

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 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 Human nose, nasal cavity, dividing the two nostrils. It is Depression (kinesiology), depressed by the depressor septi nasi muscle. Structure The fleshy external end of the nasal s ...

. The origin at the

may also be repositioned for better

symmetry Symmetry () in everyday life refers to a sense of harmonious and beautiful proportion and balance. In mathematics, the term has a more precise definition and is usually used to refer to an object that is Invariant (mathematics), invariant und ...

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

Nasalis.png, Muscles of the head, face, and neck. (Nasalis labeled at center left.) File:Nasalis muscle animation small.gif, Position of nasalis muscle (shown in red).

References

External links

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