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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 hu ...
-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 passes t ...
. 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 when underwater. It can be used to test the facial nerve (VII), which supplies it.


Structure

The nasalis muscle covers 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 ...
of the lower surface 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 t ...
. 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. The 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 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. 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 t ...
) 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. The t ...
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 t ...
. 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 facial nerve (VII).


Function

The nasalis muscle 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 ...
. It may also "flare" the nostrils. Some people can use it to close the nostrils to prevent entry of water 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 t ...
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
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 ...
may also be repositioned for better symmetry.


Facial nerve testing

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