The dilator naris muscle (or alae nasi muscle) is a part of the

nasalis muscle The nasalis muscle is a sphincter-like muscle of the Human nose, nose. It has a transverse part and an alar part. It compresses the nasal cartilages, and can "flare" the Nostril, nostrils. It can be used to test the facial nerve (VII), which suppl ...

. It has an anterior and a posterior part. It has origins from the nasal notch of 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 ...

and the major alar cartilage, and a single insertion near the margin of the

nostril 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 controls nostril width, including changes during breathing. Its function can be tested as an analogue for the function of 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 dilator naris muscle is divided into posterior and anterior parts. * The ''dilator naris posterior'' is placed partly beneath the levator labii superioris muscle. It arises from the margin of the nasal notch of the

, and from the minor alar cartilages. It is inserted into the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

near the margin of the

. * The ''dilator naris anterior'' is a delicate

fasciculus ''Fasciculus vesanus'' is an extinct species of stem-group ctenophores known from the Burgess Shale of British Columbia, Canada. It is dated to and belongs to middle Cambrian strata. The species is remarkable for its two sets of long and sho ...

. It originates from the lateral crus of the major alar cartilage, more laterally. It inserts into the margin of the

, the alar groove. It is situated in front of the dilatator naris posterior muscle.

Nerve supply

The dilator naris muscle is supplied by the

(VII).

Function

The dilator naris muscle has a role in widening and narrowing the nostril, along with other muscles. It may prevent the collapse of the nostril during

inhalation Inhalation (or inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...

, particularly in people with narrower nostrils. The respiratory centre of the

brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...

can use the muscle to control nostril width in relation to

breathing Breathing (spiration or ventilation) is the rhythmical process of moving air into ( inhalation) and out of ( exhalation) the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxy ...

. It also moves the tip 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 ...

slightly.

Clinical significance

The function of the dilator naris muscle can be used as an analogue for the activity of the

(VII).

History

The dilator naris muscle may also be known as the alae nasi muscle.

References

External links

* {{Portal bar, Anatomy Muscles of the head and neck Facial muscles Human head and neck