Mouth Structures: Components and Function

• General characteristics of mouth structures include the mouth itself (components and function) and the dentition.

Mouth (Components and Function)

• The oral cavity or buccal cavity is part of the buccal region, which is located in the face's lower area.
• Together with the tongue, teeth, gums, hard and soft palate, jugal mucosa, and salivary glands is responsible for the first step of food digestion.
• The mouth's anterolateral limits include the lips, cheeks, and jowls.
• The dorsal limit of the mouth is the palatine vault, soft palate, and pharynx.
• The ventral limit is the tongue and floor of the mouth.
• The mouth's posterior limit is the entrance to the oropharynx or isthmus of the fauces
• The bone structure comprises the mandible, the maxilla, and the palatine bone.
• Alveolar ridges of the maxilla and the mandible, along with the teeth, divide the oral cavity into two parts: the buccal vestibule and the oral cavity.

Vestibulo Buccal

• It is the space between the inner surface of the lips and cheeks and the outer surface of the teeth and gums.
• The muscles include the orbicularis oris, buccinator, risorius, levator labii superioris, levator labii superioris alaeque nasi, depressor labii inferioris, and levator anguli oris muscles.
• It connects with the oral cavity through the interdental spaces and the retromolar space

Oral Cavity

• This space is demarcated from the inner surface of the teeth to the oropharynx.
• Its superior limit is the hard and soft palate.
• Its posterior limit ends in communication with the oropharynx, through the base of the tongue and isthmus of the fauces, which is constituted by 4 pillars (2 on each side, anterior and posterior).
• The palatine tonsils are located between these pillars.
• The tongue completely occupies the mouth when closed.

Adjacent Structures for the Buccal Cavity

Tongue

• The tongue is a muscular organ that occupies the oral cavity and part of the oral portion of the pharynx.
• Its main functions are speech, mastication, swallowing, and the sense of taste.
• There are 2 sides to the tongue: the upper and lower surface
• The upper surface contains the gustatory papillae and contains the "V" lingual through the caliciform or circumvallate papillae and lymphoid follicles.
• The interior surface or ventral surface has a mucous membrane called the lingual frenulum, which connects the tongue to the floor of the mouth, allowing mobility.
• The portions of the tongue include: the base, which fixes it to the mandible and hyoid bone, the body (largest part of the tongue), and the apex, which its the anterior third.

Gustatory Papillae

• There are four types of gustatory papillae that has a specific shape and location:
  • Filiform papillae: are the most common and abundant, located over the entire surface of the tongue in parallel series obliquely from the median sulcus of the tongue to the edges. They are conical or cylindrical shapes with thermal and tactile function, meaning, thanks to them, texture and temperature are assessed
  • Fungiform papillae: are located on the apex and the sides of the tongue as well as in front of the V-shaped lingual. They are very visible because of their reddish color, which is a result of their irrigation by blood vessels
  • Caliciform or circumvallate papillae: are the least numerous but largest and most important as they are located in the posterior part of the tongue to form the V lingual.
  • Foliate papillae: are transverse folds located on the posterolateral and lateral sides of the tongue with taste receptors.

Senses of Taste

• Major senses of taste include:
  • Sweet, accepted as one of the most enjoyable tastes. The fungiform papillae are primarily responsible for detecting this flavor.
  • Bitter is seen as an unpleasant flavor. The caliciform papillae are responsible for identifying this flavor.
  • Acid, also identified as sour. The foliate papillae primarily detect this flavor.
  • Salty, which is primarily detected by the foliate papillae
  • Umami, its name means, "pleasant, tasty." This flavor is detected in the center of the tongue.

Muscles of the Tongue

• The tongue has intrinsic and extrinsic muscles.
  • The Intrinsic muscles include: the superior and inferior longitudinal muscles, the vertical muscle, and the transverse muscle.
  • Extrinsic muscles include: the genioglossus, hyoglossus, styloglossus, and palatoglossus.

Irrigation and Innervation of the Tongue

• The lingual artery supplies blood to the tongue while the dorsal lingual veins and the sublingual vein supply blood to drain the tongue.
• The posterior third is innervated by the lingual branch of the glossopharyngeal nerve (IX cranial pair) for general sensitivity, taste, and the circumvallate papillae.
• The anterior two-thirds are innervated by the lingual nerve (branch of the mandibular nerve) in order to have general sensitivity while the sensation of the gustatorys by the chorda tympani (branch of the facial nerve).

Teeth

• Teeth aid digestion through mastication, phonation, and provide support to facial structures
• Adult teeth are 32 divided into 8 incisors, 4 ​​canines, 8 premolars, and 12 molars
• Incisors have the function of cutting, canines of tearing, premolars of tearing and grinding, and molars of grinding.

Anatomy of a Tooth

• Parts of the tooth consist of the crown, neck, root, pulp chamber, root canal, and dental cement.
• The clinical crown is the tooth's visible portion.
• The neck or cervical area is the portion that connects the crown and root (at the cementoenamel junction).
• The root's number can vary and attaches to the dental alveolus via periodontium.
• The pulp chamber houses nerves, blood vessels and connective tissue
• The root canal allows passage of the vessels and nerves from and to the pulpal chamber.
• Dental cement is a mineralized structure similar to bone that coats the tooth's root, protecting it and providing a site for attachment to anchor the periodontal ligament of the tooth to alveolar bone
• Teeth receive blood from the superior and inferior alveolar arteries, branches of the maxillary artery, and are drained by the alveolar veins, which follow the exact same path.
• Innervation occurs through the superior and inferior alveolar nerves, which originate from the maxillary and mandibular divisions of the trigeminal nerve (V cranial pair).

Gums or Gingiva

• Gingiva are fibrous tissue covered by mucosa attached to the neck of the teeth and the alveolar area of the mandible and maxilla.
• The part adjacent to the oral cavity is called palatal gingiva (superior) or lingual gingiva (inferior), while the part adjacent to the lips and cheeks is called vestibular or buccal gingiva.
• Innervation and vascularization is the same as for the teeth.

Types of Gums (Gingiva)

• Types include:
  • Marginal or free gingiva (mobile)
  • Attached or inserted gingiva
  • Interdental encia.

Marginal or Free Gums (Gingiva)

• Gingiva, which measures around 1.5 mm in width wraps around the tooth's neck
• It is neither directly connected to hard tissue nor forms the exterior wall of the gingival sulcus.
• The union epithelium forms a special epithelium structure in the fundus that keeps the gums around the tooth that it envelops in a collar shape.

Attached or Inserted Gingiva

It covers the alveolar bone of the maxilla and the mandible.

• Its height usually measures at 4-5 mm
• It cannot be removed without harming the structure.

Interdental Gingiva or Dental Papilla.

• A triangular portion of gum tissue is located between two adjacent teeth.
• It is also known as dental papilla
• Many authors classify it as a portion of the marginal gingiva.

Col

• Connects the vestibular interdental gingiva to the palatal or lingual interdental gingiva.

Histology involves three main parts:

• Oral epithelium that covers the gingiva that orients towards vestibular face.
• Sulcus epithelium that is continuous with the oral epithelium and covers the gingival sulcus
• Union epithelium, which linings the dentoepitelial junction.

Palate

• Part of the limits of the oral cavity that correspond to the roof of the mouth

• It separates the oral cavity from the nasal cavity and collaborates in mastication, swallowing, and speech processes.

• It is divided into two parts:

  • The hard and soft palate
  • The Hard Palate forms the front two-thirds of the palate and contains transverse folds

• The soft palate is a fold of soft, mobile tissue attached to the posteriorborder of the hard palate, with a boundary between the oral cavity and the oropharynx.

• The structure contains muscular tissue, aponeurosis, neural structures and mucous forming glands.

• The muscles of the uvula include the tensor veli palatini, levator veli palatini, palatopharyngeus, and palatoglossus muscles.