Oral Cavity and Floor of the Mouth Anatomy

• The oral cavity, or la cavite buccale, has limits:
  • In the front and on the sides it is bordered by the gingivo-dental arches.
  • The vault of the palate is above.
  • Below is the floor of the mouth.
  • To the rear the oral cavity communicates with the pharynx by the isthmus of the throat.
    • This is circumscribed by the soft palate at the top.
    • The anterior pillars are on the sides.
    • The base of the tongue is at the bottom.

Floor of the Mouth

• The floor of the mouth, or le plancher de la bouche, is divided into two levels by the mylohyoid muscles.
• The upper level contains a central region, the tongue, or la langue.
• The upper level also contains two lateral sublingual regions.
• The lower level contains a central suprahyoid region.
• The lower level also contains two lateral submandibular or lateral suprahyoid regions.

The Tongue

• The tongue is irregularly ovoid and occupies the middle part of the floor of the mouth.
• The tongue is divided into two parts:
  • A free and horizontal anterior two thirds.
  • A fixed and vertical posterior one third.
• The free part of presents two sides, two edges, and a summit.
• The fixed part gives one side.

Dorsal Side of the Free Part of the Tongue

• You can note the lingual V, and foramen cecum.
• Note also the median groove.
• Note also the taste buds.
• The type of mucous membrane is also of note.

Ventral Side of the Free Part of the Tongue

• The type of mucous membrane is of note.
• Note the ranine veins.
• The welts and frenum are also of note.
• Also note the sublingual eminences and the sublingual caruncle.

Edges of the Free Part of the Tongue

• The lateral edges of the tongue are thick in the back, thinning towards the front.
• Foliate papillae are at the posterior end.

Fixed Part of the Tongue

• Also called the pharyngeal part, it is vertical and faces the pharynx.
• Its upper surface has a slightly adherent, bumpy mucous membrane(amygdale linguale).
• Posteriorly, it connects to the epiglottis by 3 glosso-epiglottic folds, one median and two lateral, which define two glosso-epiglottic pits called les vallicules.

The Tongue’s Skeleton

• The tongue has a osteo-fibrous skeletal frame, characterized by:
  • The hyoid bone.
  • Two fibrous membranes, the hyoglossal membrane and the lingual septum.

Muscles of the Tongue

• There are 17 muscles of the tongue (8 pairs and 1 unpaired)
• The muscles are of 2 types:
  • extrinsic
  • intrinsic
• The tongue's muscles include:
  • Genioglossus (paired)
    • (geni-superior apophysis/tongue)
  • Hyoglossus (paired)
    • (body of the hyoid bone/tongue)
  • Styloglossus (paired)
    • (styloid apophysis/tongue)
  • Palatoglossus (paired)
    • (soft palate/tongue)
  • Amygdaloglossus (paired)
    • (tonsil/tongue)
  • Pharyngoglossus (paired)
    • (pharynx/tongue)
  • Transverse (paired)
    • (lingual septum/tongue)
  • Inferior lingual (paired)
    • (tongue/tongue)
  • Superior lingual (unpaired)
    • (tongue/tongue)

Mucous Membrane of the Tongue

• The lingual mucosa consists of a stratified epithelium and a thick, dense connective tissue called fascia linguæ.
• Muscle fibers that attach to the lingual mucosa are inserted on the fascia linguæ.

Innervation of the Tongue

• Motor nerves come from the great hypoglossal nerves (mainly) and vagus (for the palatoglossus).
• Sensory nerves come from the lingual nerves (in front of the lingual V), glossopharyngeal nerves (lingual V and the mucous membrane in the back of the V) and the pneumogastric nerves (the vallicules and glosso-epiglottic folds).

Gustatory Innervation

• Gustatory innervation is provided by:
  • The cord of the tympanum:
    • Originates from the VII nerve
    • Accompanies the lingual nerve in its path to the tip and edges of the tongue (salty and acid)
  • The glossopharyngeal nerve (IX):
    • For the lingual V and the posterior part of the epiglottis (bitter)
  • The pneumogastric nerve (X):
    • For the vallicules and glosso-epiglottic folds.

Sublingual Region

• The sublingual region is the lateral region of the upper level of the floor of the mouth.
• The limits of the sublingual region are:
  • External sublingual fossa of the mandible
  • Inferior mylo-hyoid muscle
  • Superior mucous membrane
  • Internal genio-glossus and genio-hyoid muscles

Contents of the Sublingual Region

• The sublingual gland with its ducts (Walter's complex), the main one being the Rivinius canal.
• An extension of the submandibular gland and its canal (Wharton).
• The lingual nerve.
• The major hypoglossal nerve.
• The lingual vessels.

Suprahyoid Region

• The suprahyoid region is characterized by 3 regions:
  • One median.
  • Two lateral.

The Suprahyoid Median Region

• From superficial to deep:
  • The skin and adipose tissue.
  • Superficial cervical aponeurosis.
  • The anterior belly of the digastric.
  • The mylo-hyoid.
• The submental ganglia are between the muscular planes.

Digastric Muscle

• The digastric muscle is a paired muscle of the upper part of the neck, under the mandible.
• It’s named this way because it consists of 2 bundles or bellies joined by a tendinous bundle.
• It inserts into the digastric groove on the mastoid process of the temporal bone.
• It also inserts into the digastric fossa located below the geni apophysis.
• The anterior belly is innervated by a collateral of the mandibular nerve (mylo-hyoid nerve).
• The posterior belly is innovated by a collateral of the facial nerve.
• Its role enables the tongue to make a postero-inferior movement during swallowing.
• It lowers the mandible.

Suprahyoid Lateral Region

• From superficial to depth:
  • Skin and adipose tissue.
  • Superficial cervical aponeurosis.
  • A lodge (the submandibular lodge).

Contents of the Submandibular Lodge

• The submandibular gland.
• A prolongation of this gland encroaches with its canal (Wharton) on the sublingual region.
• The facial artery in its deep part giving off branches to the submandibular gland and the submental and ascending palatine arteries.
• The facial vein.
• The submandibular ganglia.
• The vessels and nerves of the mylo-hyoid muscle.
• Two triangles within this region can be identified.
  • The triangle of Béclard is formed by:
    • The hyoglossus muscle (posterior border).
    • The digastric muscle (posterior belly).
    • The hyoid bone (greater horn).
    • The lingual artery and vein and the greater hypoglossal nerve pass through this triangle.
  • The triangle of Pirogoff is formed by:
    • The mylohyoid muscle.
    • The digastric muscle (intermediate tendon).
    • The greater hypoglossal nerve.