Oral Cavity Flashcards
Structure of oral cavity
Roof: hard and soft palates
Floor: mainly soft tissues, including tongues
Lateral wall: cheeks
The cavity is separated into:
- oral vestibule: anteriorly to teeth but behind lips
- oral cavity proper: area behind teeth
Anteriorly is opening of oral cavity (oral fissure) created by lips and posteriorly is oropharynx
Structure of tongue
Is predominately muscle (4 intrinsic and 4 extrinsic)
Dorsal tongue is covered by lingual papillae 4 types
- fungiform
- foliate
- vallatae
- filiform
The terminal sulcus divides the tongue into an anterior 2/3 (oral) and posterior 1/3 (pharyngeal)
Extrinsic muscles of the tongue
Extrinsic muscles alter position while intrinsic alter shape.
Palatoglossus: origin from palatine aponeurosis to insert in tongue. Elevate root of tongue. Innervated by vagus nerve
Styloglossus: from styloid process to tongue. Retracts and elevates tongue. Innervated by Hypoglossal.
Hyoglossus: from hyoid bone to tongue. Depresses and retracts tongue. Innervated by hypoglossal
Genioglossus: from chin to tongue. Depresses or protrudes tongue. Innervated vis hypoglossal
Structure of hard palate
Anterior 3/4 is formed palatine process of maxilla and posterior 1/4 by horizontal process of palatine bones and overlying mucosa
Anterior to palatine rugae is incisive papilla which overlies incisive canals
Structure of soft palate
Muscular continuation of hard palate that acts to close the oropharyngeal isthmus or separate the oro- and naso-pharynx
Palate muscles motor control
Via vagus nerve except for tensor veli palatini which is supplied by mandibular nerve CN V3
Palate blood supply
Greater palatine supplies the hard palate
Lesser palatine supplies the soft palate
Nerve supply to tongue
Motor: hypoglossal except for palatoglossus which is by vagus
General sensory to anterior 2/3 of tongue: lingual nerve
Taste sensation to anterior 2/3 of tongue: facial nerve via chorda tympani
General and taste sensation to poster 1/3 of tongue: Glossopharyngeal
Blood supply and venous drainage of tongue
Lingual artery
Deep lingual and dorsal lingual veins drain the tongue to IJV
Structure of pharynx
Tube of fibrous and muscular tissue lies posterior to
- nasal cavity (nasopharynx)
- oral cavity (oropharynx)
- larynx (laryngopharynx)
Function of tonsils
Lymphoid tissue found in several places forming Waldeyers ring
- pharyngeal tonsils
- tubal tonsils
- palatine tonsils
- lingual tonsils
Protection ring to fight infections
Pharyngeal elevators
Descend from skull to fan out into the inner surface of the pharynx
Salpinogopharyngeus
- extends from Eustechian tube to lateral wall of pharynx. Elevates the pharynx and larynx. Innervation by vagus
Palatopharyngeus
- part of the soft palate and posterior part of the pharynx. Elevates the pharynx and larynx. Draws the soft palate downwards. Supplied by vagus.
Stylopharyngeus
- originates from styloid process and inserts into the pharynx
- elevates the pharynx and larynx during swallowing
- supplied by Glossopharyngeal
Pharynx Innervation
Motor and sensory Via pharyngeal plexus and receives branches of CN IX and X
Sensory also from Glossopharyngeal
Parasympathetic secretomotor Innervation by CN X and pterygopalatine ganglion CN VII via CN V2
Gag reflex Innervation
Afferent CN IX and efferent CN X
major salivary glands
Parotid
Submandibular
Sublingual
Submandibular gland
Function: contribute to production of saliva to lubricate oral cavity and aid in chemical digestion of food.
Found along mandible between mylohyoid and hyoglossus
Submandibular duct supply is by submental arteries and drainage by sub mental veins
Blood supply via ECA via facial and lingual arteries
Sublingual gland
Lies in floor of mouth between the mandible and hyoglossus lateral to submandibular duct. Sits in sublingual fossa.
Sublingual ducts drain into the oral cavity
Blood supply via submental and sublingual arteries and drainage via submental veins
Sublingual and Submandibular gland secretomotor Innervation
Parasympathetic Innervation
- preganglionic parasympathetic fibres travel to submandibular ganglion from the chorda tympani and via the lingual nerve
- post ganglionic parasympathetic fibres then travel in the lingual nerve to the sublingual gland OR travel directly to the sublingual and submandibular glands
Sympathetic Innervation
- derived from the superior cervical ganglia and nerve plexus of ECA
Minor salivary glands
Buccal
Palatine
Lingual
Labial
These glands are susceptible to mucoceles (swelling due to blockage of associated ducts)
Secretomotor Innervation on minor salivary glands (above oral fissure)
Parasympathetic Innervation (secretomotor to produce saliva)
- Preganglionic parasympathetic fibres travel to pterygopalatine ganglion in the greater petrosal nerve (CN VII nervus intermedius)
- post ganglionic fibres travel to the palate via the palatine nerves
Secretomotor Innervation to minor salivary glands (below oral fissure)
Parasympathetic Innervation fibres travel to submandibular ganglion from the chorda tympani and via the lingual nerve
Post ganglionic parasympathetic fibres then travel in the lingual nerve (CN V3) to the glands or travel directly to the glands (not in a nerve)
Pathologies of minor salivary ducts/glands
Mumps
- viral infection in children
- painful swellings over salivary glands
Salivary stones (sialothiasis)
- present with pain, swelling and lack of salivation
- most common in submandibular ducts
Excessive salivation
- occurs prior to vomiting
- or related to other disease processes
