Dominic Stone
The tongue is a muscular organ that is formed by a complex arrangement of intrinsic and extrinsic muscles. The extrinsic muscles of the tongue are those that originate from structures outside the tongue and insert into it. There are four pairs of extrinsic muscles: the genioglossus, hyoglossus, styloglossus, and palatoglossus. These muscles are responsible for the movement of the tongue, including protrusion, retraction, depression, and elevation. The styloglossus muscle, for example, is involved in the retraction and elevation of the tongue.
| Characteristics | Values |
|---|---|
| Number of extrinsic tongue muscles | 4 |
| Type of muscles | Paired |
| Origin of muscles | Outside the tongue |
| Attachment of muscles | To osseous structures: hyoid bone, mandible, or styloid process |
| Main function | Altering the position of the tongue |
| Innervation | Hypoglossal nerve (CN XII) |
| Exceptions | Palatoglossus muscle is innervated by the vagus nerve (CN X) |
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What You'll Learn
The tongue is formed by eight paired muscles
The tongue is a muscular organ situated in the oral cavity, and it plays a role in digestion, taste perception, speech, and breathing. The tongue is formed by eight paired muscles, comprising four intrinsic and four extrinsic muscles. The intrinsic muscles are unique in that they have no insertions in bone; instead, they arise and insert within the tongue. On the other hand, the extrinsic muscles attach to osseous structures, namely the hyoid bone, mandible, or styloid process.
The four extrinsic muscles of the tongue are the genioglossus, hyoglossus, styloglossus, and palatoglossus. These muscles are responsible for producing movements that the intrinsic muscles cannot, including protrusion, retraction, retrusion, depression, and elevation of the tongue. The genioglossus muscle, in particular, is associated with the upper respiratory tract airway and plays a role in phoneme expression.
The hyoglossus muscle causes retrusion and depression of the tongue's lateral margin. The palatoglossus muscle, innervated by the vagus nerve, elevates the posterior tongue, closes the oropharyngeal isthmus, and aids in swallowing. It also prevents the spill of saliva from the vestibule into the oropharynx by maintaining the palatoglossal arch.
The tongue's muscles are separated and surrounded by connective tissue structures, including the median septum, paramedian septum, and lateral septum. The median septum gives rise to the transverse muscles, while the paramedian septum separates the inferior longitudinal muscle from the genioglossus muscle. The lateral septum surrounds the inferior longitudinal muscle. The superior longitudinal muscle, located under the mucosa of the tongue's dorsal surface, shortens and widens the tongue, causing it to curl upward.
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Four intrinsic and four extrinsic muscles
The tongue is a muscular organ formed by a complex arrangement of eight paired muscles, comprising four intrinsic and four extrinsic muscles. The intrinsic muscles change the shape of the tongue, while the extrinsic muscles move it in different directions. The tongue is attached via the extrinsic muscles to the hyoid bone, mandible, styloid process, soft palate, and pharynx.
The four extrinsic muscles are the genioglossus, hyoglossus, styloglossus, and palatoglossus. The genioglossus muscle is involved in tongue protrusion and retraction, while the hyoglossus muscle causes tongue retrusion and depression of the tongue's lateral margin. The styloglossus muscle, a thin, paired muscle located on either side of the oropharynx, is responsible for tongue retraction and elevation. The palatoglossus muscle is the only extrinsic muscle of the tongue that is not innervated by the hypoglossal nerve but by the vagus nerve. It elevates the posterior tongue, closes the oropharyngeal isthmus, and aids in swallowing.
The four intrinsic muscles are located within the tongue and have no insertions in bone. They arise and insert within the tongue and are separated from the extrinsic muscles by connective tissue structures, including the median, paramedian, and lateral septum. The superior longitudinal muscle shortens and widens the tongue, causing it to curl upward (dorsiflexion). Conversely, the inferior longitudinal muscle shortens and widens the tongue, curling it downward (ventroflexion). The transverse muscle elongates and narrows the tongue, while the vertical muscle flattens it. These intrinsic muscles work together to produce movements essential for chewing, speech, and swallowing.
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The genioglossus is a paired tongue muscle
The genioglossus muscle originates from the superior mental spine on the posterior surface of the mandible, superior to the attachment of the geniohyoid muscle. The muscle extends in a posterosuperior direction and attaches to the superior surface of the hyoid body and along the length of the ventral tongue from root to apex. The right and left genioglossus muscles are separated by the lingual septum posteriorly but blend with each other anteriorly. The genioglossus muscle is involved in multiple actions: during unilateral contraction, it laterally moves the tongue to the opposite side; during bilateral contraction, it protrudes the tongue and depresses the central portion of the tongue. The left and right genioglossus muscles protrude the tongue (anteriorly, out of the mouth) and deviate it towards the opposite side. When acting together, the muscles protrude the tongue directly forward and depress the center of the tongue at its back.
Contraction of the genioglossus stabilizes and enlarges the portion of the upper airway that is most vulnerable to collapse. The muscle is electrically involved in the generation of maximal sniff nasal inspiratory (with higher values of electromyography) and nasal expiratory pressures. The muscle contributes to the ability to express phonemes. The genioglossus muscle will be negatively affected by the presence of pathologies, both of the oral cavity, and systemic diseases. For example, constant hypoxia (during sleep) can alter muscle metabolism. Type 17 microRNAs (miRNAs-17) help the genioglossus muscle satellite cells repair muscle tissue and maintain an efficient mitochondrial membrane potential.
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The styloglossus is a thin, paired muscle
The styloglossus is located on either side of the oropharynx. It originates from the styloid process of the temporal bone and inserts onto the lateral aspect of the tongue. The function of the styloglossus is to elevate and retract the tongue. It draws up the sides of the tongue to create a trough for swallowing. When both styloglossus muscles contract simultaneously, they aid in retracting the tongue.
The styloglossus is innervated by the hypoglossal nerve (CN XII), which is the case for all muscles of the tongue except the palatoglossus muscle. The palatoglossus muscle is innervated by the vagus nerve (CN X). The styloglossus receives its blood supply from the lingual artery, with contributions from the tonsillar artery.
The tongue is a muscular organ with a complex arrangement of intrinsic and extrinsic muscles. The intrinsic muscles are those that comprise the core of the tongue and are placed within it. They are responsible for changing the shape of the tongue. On the other hand, the extrinsic muscles are outside the tongue but are functionally associated with it, helping it perform its functions. They are attached to osseous structures such as the hyoid bone, mandible, or styloid process.
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The tongue's main functions include taste, chewing, swallowing, speech and clearing the oral cavity
The tongue is a muscular organ formed by a complex arrangement of intrinsic and extrinsic muscles. The extrinsic muscles are generally responsible for moving the tongue in different directions. The styloglossus, a thin, paired extrinsic muscle, is located on either side of the oropharynx and is responsible for the retraction and elevation of the tongue. The tongue is also attached via the extrinsic muscles to the hyoid bone, mandible, styloid process, soft palate, and pharynx.
The tongue's main functions include taste, chewing, swallowing, speech, and clearing the oral cavity.
Taste perception is facilitated by taste buds, which contain taste receptors that interact with chemicals (tastants) to produce taste sensations. Taste buds are found within the various papillae of the tongue and are responsible for our ability to taste food.
The tongue plays a crucial role in chewing and swallowing. When we chew, the tongue works with the cheeks to position food between the teeth for grinding. The tongue then presses the chewed food against the roof of the mouth and moves it towards the throat, initiating the swallowing process. The tongue's movement also stimulates the production of saliva, aiding in the predigestion of food.
Speech is another primary function of the tongue. It works in coordination with the lips and teeth to produce sounds that form words. The tongue's flexibility allows it to make over 30 different movements, enabling us to produce more than 90 words per minute.
Additionally, the tongue contributes to clearing the oral cavity by searching for and removing any remaining bits of food after swallowing. Its sensitivity to touch helps detect even small particles, ensuring a thorough cleaning of the mouth.
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Frequently asked questions
The extrinsic tongue muscles are the muscles that are outside the tongue but are functionally associated with it and help it perform its function. They are also known as the muscles that determine the movement of the tongue.
Yes, there are four pairs of extrinsic tongue muscles: the genioglossus, hyoglossus, styloglossus, and palatoglossus.
The extrinsic tongue muscles produce movements of the tongue that the intrinsic muscles cannot. These include the protrusion, retraction, retrusion, depression, and elevation of the tongue.
The tongue's main functions include taste perception, mastication (chewing), deglutition (swallowing), speech, and clearing the oral cavity.
All the extrinsic tongue muscles are innervated by the hypoglossal nerve (CN XII), except for the palatoglossus muscle, which is supplied by the vagus nerve (CN X).
