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 nose. It has a transverse part and an alar part. It compresses the nasal cartilages, and can "flare" the nostrils. Some people can use it to close the nostrils to prevent entry of water when un ...

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

and the

major 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 t ...

, and a single insertion near the margin of the

nostril A nostril (or naris , plural ''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 turbi ...

. 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 tas ...

(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 The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle of the human body used in facial expression. It is a broad sheet, the origin of which exten ...

. It arises from the margin of the nasal notch of the

, and from the

minor alar cartilage In human anatomy the part of the nose which forms the lateral wall is curved to correspond with the ala of the nose; it is oval and flattened, narrow behind, where it is connected with the frontal process of the maxilla by a tough fibrous membrane ...

s. 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 cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

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 short ...

. It originates from the lateral crus of the

, 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 The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal r ...

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 cont ...

can use the muscle to control nostril width in relation to

breathing Breathing (or ventilation) is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cellular ...

. It also moves the tip 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 passes th ...

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