Oral and Nasal Cavity Flashcards
Two parts of the Oral Cavity
- Vestibule
- Oral Cavity Proper
Vestibule
Space between the teeth and the mucosal inner lining of the cheeks and lips
Oral cavity proper
Space contained within the upper and lower dental arches
filled by the tongue
Oral Cavity
- Roof
- Anterior boundary
- Floor and Posterior Walls
Roof:
- maxilla bones
- palatine bones
Anterior boundary: (teeth + front bit of mandible)
- Maxilla
- Mandible with their dental arches
Other boundaries (floor & post walls):
- Made up of soft tissues
- Rami of mandible (post boundary)
Floor of the mouth
Made up of a muscular sling and mucous membrane
Muscles:
- Mylohyoid
- Geniohyoid
- Anterior belly of digastric
Lips - Orbicularis Oris
- Mobile, muscular folds
- Covered externally by skin and internally by mucous membrane
- Transitional zone between the two:
- Vermillion Border:
- Doesn’t contain any glands
- therefore lips need to be licked to be moistened
- Vermillion Border:
N.B. Cheeks have a similar construction, Buccinator muscle in between the two layers
Muscles of facial expression
- Functions in mouth
Buccinator:
- pushes cheek towards teeth during mastication
- ensures food doesn’t fall into vestibule
Lips:
- form a seal preventing food falling out of the mouth during mastication
- form a seal around any vessel pressed against it ensureing liquid enters the mouth and doesn’t drip between the mouth and cup
Closure of hte mouth and sealing of lips - vital to swallowing
Oral cavity
Contents:
- Teeth
- Tongue
- Ducts of Salivary glands
Posteriorly mouth communicates with the Oropharynx
Nerve Supply to the Oral Cavity
- Oral cavity is supplied by a number of cranial nerves
- Mucous membrane of roof: branch of maxillary nerve
- Lateral walls & floor: Luingal branch of the mandibular branch of the Trigeminal
- Muscles in lateral wall: Facial nerve
- Muscles in floor:
- Genohyoid - CN I
- Mylohyoid & Ant belly of digastric - Mandibular branch (nerve to Mylohyoid) of of the Trigeminal
- Teeth:
- Alveolar branches of the Maxillary nerve (upper teeth)
- Mandibular nerve (lower teeth)
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Tongue
- Ant 2/3rds lie in oral cavity
- post 1/3rd lie in oropharynx
Extrinsic muscles: Change position of the tongue
- Palatoglossus
- Styloglossus
- Hyoglossus
- Genioglosus
Intrinsic Muscles: Change the shape of the tongue
- Sup & inf longitudinal muscles
- Vertical and transverse muscle
Nerve supply to the Tongue
All the extrinsic and intrinsic muscles of the tongue are supplied by the:
Hypoglossal nerve CN XII
Apart from Palatoglossus which is supplied by the:
Vagus nerve CN X (via the pharyngeal branch to the pharyngeal plexus
Where do the ducts of the major salivary glands enter the oral cavity?
- Parotid Salivary Gland:
- Near the 2nd upper molar tooth
- Secretion : Serous
- Submandibular Gland:
- Enters Floor of the mouth
- Mixed gland - has both serois and mucous secretions
- Sublingual Gland:
- between 16 to 20 short ducts which open into the floor of the mouth
- Secretes mucus
Minor glands: v. imp in maintaining oral hygiene as continual background level of secretion flushes oral surfaces and helps to control the level of bacteria
Major Artery of the Tongue
Lingual Artery
- originates from the External Carotid Artery adjacent to tip of greater horn of the hyoid bone
- Forms an upward bend then loops downwards to pass under the Hyoglossus muscle
- Supplies:
- Tongue
- sublingual gland
- gingiva
- oral mucosa in the floor of the oral cavity
Venous Drainage of the Tongue
Follows 2 routes:
Posterior lingual veins & deep lingual veins
Posterior Lingual Veins:
- Drain the dorsum and sides of tongue
- join the lingual vein which accompanies the artery
- Near the greater cornu of the Hyoid bone the lingual vein joing the internal jugular vein
Deep Lingual Vein:
- Begins near the tip of the tongue and runs backwards on its interior surface
- Near border of hyoglossus, it joins the Sublingual vein, which runs along the course of the Hypoglossal nerve and joins the Facial Vein
Lymphatic Drainage of the Tongue
Anterior to the Vallate Papillae:
Drained into central and marginal lymph vessels
Posterior 1/3rd:
Drain into posterior lymph vessels
From here they enter a series of nodes the efferent vessels of which drain to nodes surrounding the SCM
