The Nasal and Oral Cavities Flashcards
What separates the left and right nasal cavities from each other?
from the oral cavity inferiorly?
from the brain superiorly?
Thin, midline septum formed of cartilage and bone
Hard palate (the floor of the nasal cavity)
Bone - cribriform plate (the roof of the nasal cavity)
What lies posterior to the nasal cavity?
The nasopharynx
Also paranasal sinuses
Describe composition of midline nasal septum
Anteriorly- formed of cartilage
Posteriorly- formed of 2 thin plates of bone: superiorly the perpendicular plate of the ethmoid bone, inferiorly the vomer
Describe the lateral wall of the nasal cavity
3 projections of bone (superior, middle, inferior) - conchae or turbinates
Spaces inferior to them are meatuses (superior, middle, inferior)
Air travelling through meatuses is warmed, humidified and filtered
What happens to air as it travels through the meatuses?
It is warmed, humidified and filtered
Describe the anatomy of the cribriform plate
Separates nasal cavity from cranium and brain
Delicate section of bone, perforated with holes
Mucosa in upper part of nasal cavity contain olfactory receptors. The axons of these nerves travel through the perforations to the brain.
Describe blood supply to the nasal cavity
Several arteries, including branches of maxillary artery (a terminal branch of external carotid)
An anastomotic network supplies nasal septum, often site of bleeding in epistaxis
Sensory innervation of nasal cavity?
Branches of the trigeminal nerve (CN V)
Name CN V
Trigeminal nerve
What are the 4 sinuses?
Frontal, ethmoid, sphenoid, maxillary
Where are the frontal sinuses?
Where do they drain?
Anterior part of the frontal bone (forehead ones)
Drains into middle meatus
Where are the ethmoid air cells/sinuses?
Where do they drain?
They are air cells that lie within the ethmoid bone
posterior to frontal sinuses, anterior to sphenoid sinuses
(superior to the nasal cavity and medial to the orbits)
Drains into superior and middle meatus
Where are the sphenoid sinuses?
Where do they drain into?
The sphenoid bone
Most posterior sinus, posterior to ethmoid sinuses
Drain into spheno-ethmoidal recess (above superior turbiculate)
Where are the maxillary sinuses?
Where do they drain into?
The maxillae of the facial skeleton. (pyramidal cheek sinuses)
They lie lateral to the lateral walls of the nasal cavity
Drain into middle meatus - lies superomedially - cant drain fully when head is upright
The nasal cavity receives the nasolacrimal duct. What is it?
It drains the fluid that lubricates the anterior surface of the eye.
Opens into inferior meatus
Why we get a runny nose when we cry
What gives us a runny nose when we cry?
Nasolacrimal duct
How does the nasal cavity communicate with the middle ear?
Eustachian tube - auditory tube - connects middle ear to nasopharynx
Opening seen on lateral wall of nasopharynx surrounded by bulge of tonsillar tissue
What is the middle ear?
Small cavity in the temporal bone
Modified for hearing - 3 tiny bones that transmit sound waves to inner ear
Allows air to pass into middle air for equal air pressure either side of the tympanic membrane (between middle and external ear)
Describe the palate
Anterior - bone - hard palate
Posterior - muscle - soft palate
Palate is the roof of the oral cavity
What forms the hard palate?
Palatine process of maxillae
Horizontal plates of palatine bones
Function of the hard palate?
Prevents food/fluid entering nasal cavity
Tongue pushes up against is in 1st phase of swallowing - forces food/fluid backwards into oropharynx
Tongue pushes up against hard palate to articulate certain sounds
What is a cleft palate?
Palate doesn’t form properly in embryological development.
e.g. don’t develop properly, don’t fuse in midline
Difficulty eating, swallowing and speech if not repaired surgically
Describe the soft palate
Midline conical projection - uvula - hangs from posterior border of soft palate, seen at the back of the mouth
Composed of several muscles - contract during swallowing to elevate the soft palate
Purpose of soft palate
Muscles contract, soft palate elevated, nasopharynx closed off from oral cavity, prevents reflux of food and fluid
What innervates muscles of the soft palate?
Vagus nerve CN X
Epistaxis
Nosebleed
Mostly arise due to trauma, can happen spontaneously
Usually applying pressure stops it, but can be profuse esp on anticoagulants
Bleeding can be cauterised if pressure doesn’t help, or a nasal tampon can be inserted to compress the vessels
Fracture of the nose
Breaking of the nasal bones or septum - blunt trauma
Nose may be deviated to one side
May fracture cribriform plate - must be considered in patients with nasal trauma
Sinusitis
Inflammation or infection of mucosa lining
Problematic if it affects maxillary sinuses as they don’t drain freely.
Inflammation of maxillary sinus may cause pain in the cheek as sensory nerve for the cheek runs in the roof of the sinus
Describe the borders of oral cavity
Superior - hard and soft palate
Inferior - soft tissues and muscles (floor of mouth)
Laterally - cheeks (contain the buccinator muscles)
What is an analgesia?
Drug prescribed for pain
How many teeth in an adult? Maxilla and mandible?
32 teeth
16 in maxilla (upper jaw)
16 in mandible
What are the 4 types of teeth? How many of each in the upper/lower jaw?
Incisors - 4
Canines - 2
Premolars - 4
Molars - 6
What are teeth composed of?
Inner pulp - blood vessels and nerves
Dentin - surrounds the pulp
Enamel - outer, hard coating
What happens in erosion of teeth?
Enamel/dentin can be eroded by bacteria or foodstuffs
Leads to decay, inflammation and infection of pulp
Painful
Infection may spread to the bone - abscess formation
What is the vallecula?
Space between the posterior tongue and epiglottis
Describe the tongue position and appearance
Superiorly - papillae on the surface, some detect taste
Anterior part - lies in oral cavity
Posterior part - the root - extends into oropharynx
What is the muscle composition of the tongue?
Intrinsic muscles - paired bilaterally and fuse in the midline - change the shape of the tongue
Extrinsic muscles - attached to the tongue but originate outside of it (mandible and hyoid bone) - they move the tongue
Which nerve innervates the muscles (motor function) of the tongue?
Hypoglossal nerve CN XII
Describe the sensory innervation of the tongue
Facial nerve VII - taste in the anterior 2 thirds of the tongue
Trigeminal nerve V - general sensation(touch, pain, temp) in anterior 2 thirds
Glossopharyngeal nerve IX - taste and general sensation in posterior third
What vessels supply the oral cavity?
Lingual, maxillary and facial arteries - all branches external carotid artery
Innervation of the oral cavity?
Soft palate - vagus nerve
Tongue - CN V,VII,IX for sensory for motor
Name the 4 tonsils and where they are found
Pharyngeal tonsil - roof and posterior wall of nasopharynx (adenoid)
Tubal tonsil - surrounds opening of auditory tube on lateral wall of nasopharynx
Palatine tonsil - lateral wall of oropharynx, visible when mouth is open
Lingual tonsil - collection of lymphoid tissue in the posterior tongue
What are the 3 pairs of salivary glands in the oral cavity?
What stimulates glandular secretion?
Parotid gland
Submandibular glands
Sublingual glands
Stimulated by parasympathetic
Describe the parotid salivary gland?
Biggest paired salivary gland
Overlies posterior part of mandible
Saliva enters mouth via parotid duct - adjacent to upper 2nd molar tooth
How is parotid gland related to facial nerve?
After exiting skull, facial nerve enters deep surface of parotid gland.
Divides into 5 branches to innervate the muscles of facial expression
What stimulates secretion of parotid gland?
Parasympathetic fibres in glossopharyngeal nerve.
Describe submandibular glands
Smaller than parotid glands
Lie inferior to the body of the mandible, anterior to the angle
Submandibular duct opens into floor of mouth, under tongue
Describe sublingual glands
Lie in the floor of the mouth
Open via several small ducts into floor of the mouth
What stimulates secretion of submandibular and sublingual glands?
Parasympathetic fibres in the facial nerve.
Hypoglossal nerve injury
Injury to left or right results in atrophy and weakness or paralysis of ipsilateral tongue muscles.
Tongue deviates to affected side when patient protrudes their tongue (muscles on unaffected side continue to function)
Nasal and oral cancer
Cancer of nasal cavity or sinuses is rare
Cancer can develop in structures associated with the mouth - oral mucosa, tonsils, tongue, salivary glands
Mouth cancers may present as ulcers, lumps, or patches of discolouration on oral mucosa
Tonsillitis and tonsillectomy
Tonsillitis is inflammation of the tonsils, most commonly palatine - may be due to viral or bacterial
Tonsils become enlarged , red, covered in pus(white spots) - Swallowing is painful
Pharyngeal tonsil - adenoid - common in children - may obstruct the nearby opening of the auditory tube - fluid accumulation in middle ear and hearing impairment
recurrent infection my lead to removal - tonsillectomy
