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Oral cavity: want to learn more about it?

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Oral cavity

They don’t say for nothing ‘health comes first, and it enters through the mouth’. When we say ‘mouth’ we mean the oral cavity; a space in the lower part of the head that functions as the entrance to the digestive system.

The content of the oral cavity determines its function. It houses the structures necessary for mastication and speech, which include the teeth, the tongue and associated structures such as the salivary glands. Most of the oral cavity functions are related to the tongue, especially the tongue’s muscular and sensory abilities. That’s why this page on the anatomy of the mouth will focus on tongue anatomy.

Key facts about the oral cavity
Definition The first part of the digestive system that contains the structures necessary for mastication and speech; teeth, tongue and salivary glands.
Tongue A muscular organ in the oral cavity that enables taste sensation, chewing, swallowing and speaking.
Muscles of the tongue
Intrinsic: Superior longitudinal, inferior longitudinal, transverse and vertical muscles
Extrinsic: Genioglossus, hyoglossus, styloglossus and palatoglossus muscles
Innervation of the tongue
Motor: All muscles are innervated by hypoglossal nerve (CN XII), except for palatoglossus which is supplied by vagus nerve (CN X).
Sensory: 
- General and taste sensation from the posterior third: glossopharyngeal nerve (CN IX);
- General sensation from the anterior two-thirds: lingual nerve (branch of the mandibular nerve - V3);
- Taste sensation from the posterior two-thirds: facial nerve (CN VII)

Oral cavity

The oral cavity is situated anteriorly on the face, under the nasal cavities. It is bounded by a roof, a floor and lateral walls. Anteriorly it opens to the face through the oral fissure, while posteriorly the oral cavity communicates with the oropharynx through a narrow passage called the oropharyngeal isthmus (also termed the isthmus of the fauces). The oropharyngeal isthmus is surrounded by the soft palate and palatoglossal arches.

A number of bones contribute to the framework of the oral cavity; these are the paired maxillae, palatine and temporal bones, as well as the unpaired mandible, sphenoid and hyoid bones.

The cavity is separated into anterior and posterior parts by the dental arches (or teeth): the anterior oral vestibule sits anteriorly to the teeth and behind the lips, whilst the oral cavity proper describes the area behind the teeth.

The inside of the oral cavity is constantly lubricated by salivary glands which also participate in food digestion by secreting enzymes that start the digestion of carbohydrates. These glands are the parotid, submandibular and sublingual glands.

Learn more details about the oral cavity and test your knowledge about it using the following study units:

Tongue anatomy

The tongue is the central part of the oral cavity. It’s a muscular organ whose base is attached to the floor of the oral cavity, whilst its apex is free and mobile. 

The tongue is predominantly muscle. There are 8 in total; 4 intrinsic muscles and 4 extrinsic. For more on these muscles, see the tongue muscles section below. Besides the muscles, the other important feature of the tongue is its mucosa. The dorsal tongue mucosa is covered with lingual papillae which function as the sensory receptors for taste. There are four types: filiform, fungiform, vallatae and foliate papillae. The papillae have different shapes upon which they are named. Can you guess what a fungiform papillae looks like? Like a fungus, exactly! 

All the papillae act as taste receptors except for the filiform, which have a purely mechanical role. You may wonder what that mechanical role is. Well, filiform papillae are present on the tongue of every vertebrate species and are quite prominent in cats. So basically, they are very sharp and serve for the cleaning of fur. Luckily for us, soap was invented in 2800 BC so we don’t have to lick our skin in order to get clean. This is why our filiform papillae have shrunk and became less prominent.

Tongue muscles

Tongue mobility and strength are important for the processes of speech and mastication. These abilities are determined by the tongue muscles. Muscles that make up the inside of the tongue are called the intrinsic muscles of the tongue. They are responsible for many of the tongue’s functions; such as talking, mastication and any other action that requires the tongue to move. These muscles control movements such as twirling, curling, flattening and broadening of the tongue.

Stressed out about memorizing the tongue muscles? Simplify your learning and cement the information efficiently using Kenhub's muscle anatomy and reference charts!

Muscles that are located outside the tongue and only attach to it in specific regions are called the extrinsic muscles of the tongue. These assist the tongue and support it in more complex actions such as protrusion and retraction.

The 4 intrinsic muscles of the tongue are: the superior longitudinal, inferior longitudinal, transverse and vertical muscles.

Key facts about the intrinsic muscles of the tongue
Superior longitudinal
Origin - submucosa of posterior tongue, lingual septum
Insertion - apex/anterolateral margins of tongue
Innervation - hypoglossal nerve (CN XII)
Action - retracts and broadens tongue, elevates apex of tongue
Inferior longitudinal Origin - root of tongue, body of hyoid bone
Insertion - apex of tongue
Innervation - hypoglossal nerve (CN XII)
Action - retracts and broadens tongue, lowers apex of tongue
Transverse muscle Origin - lingual septum
Insertion - lateral margin of tongue
Innervation - hypoglossal nerve (CN XII)
Action - narrows and elongates tongue
Vertical muscle Origin - root of tongue, genioglossus muscle
Insertion - lingual aponeurosis
Innervation - hypoglossal nerve (CN XII)
Action - broadens and elongates tongue

The 4 extrinsic muscles of the tongue are: the genioglossus, hyoglossus, styloglossus and palatoglossus muscles. 

Key facts about the extrinsic muscles of the tongue
Genioglossus Origin - Superior mental spine of mandible
Insertion - entire length of dorsum of tongue, lingual aponeurosis, body of hyoid bone
Innervation - hypoglossal nerve (CN XII)
Action - depresses and protrudes tongue (bilateral contraction); deviates tongue contralaterally (unilateral contraction)
Hyoglossus Origin - body and greater horn of hyoid bone
Insertion - inferior/ventral parts of lateral tongue
Innervation - hypoglossal nerve (CN XII)
Action - depresses and retracts tongue
Styloglossus Origin - anterolateral aspect of styloid process (of temporal bone), stylomandibular ligament
Insertion - blends with inferior longitudinal muscle (longitudinal part); blends with hyoglossus muscle (oblique part)
Innervation - hypoglossal nerve (CN XII)
Action - retracts and elevates lateral aspects of tongue
Palatoglossus Origin - palatine aponeurosis of soft palate
Insertion - lateral margins of tongue, blends with intrinsic muscles of tongue
Innervation - vagus nerve (CN X) (via branches of pharyngeal plexus)
Action - elevates root of tongue, constricts isthmus of fauces

Learn everything about the structure and muscles of the tongue muscles using the study units given below.

Tongue innervation

The sensory and motor functions of the tongue are enabled by cranial nerves. All of the tongue muscles are innervated by the hypoglossal nerve (CN XII), except for the palatoglossus muscle which is supplied by the vagus nerve (CN X).

Sensory innervation is carried by several nerves: 

Besides rich innervation, the tongue has an extensive blood supply that comes from the lingual artery, a branch of the external carotid artery.

Learn everything about the innervation and vascularization of the tongue with this study unit:

Oral cavity: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

Illustrations:

  • Oral cavity (anterior view) - Paul Kim
  • Structure of the tongue - Begoña Rodriguez
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