Session 5: The Nasal and Oral Cavities Flashcards
What are the left and right nasal cavities separated from?
The left and right nasal cavities are separated from:
● each other by a thin midline septum, formed of cartilage and bone. When the head is bisected, the septum is seen on one half only.
● the oral cavity inferiorly by the hard palate (the floor of the nasal cavity)
● the brain superiorly by bone (the roof of the nasal cavity)
What is the nasal cavity composed of?
The midline nasal septum is formed of cartilage anteriorly and two thin plates of bone posteriorly. The perpendicular plate of the ethmoid bone forms the superior part of the posterior septum, and the vomer forms the inferior part of the posterior septum.
What is the nasal cavity separated from?
The nasal cavity is separated from the cranium and the brain by the cribriform plate.
What are the vessels and nerves of the nasal cavity
The nasal cavity is supplied by several arteries, including branches of the maxillary artery, which is a terminal branch of the external carotid artery. An anastomotic network formed supplies the nasal septum and is often the site of bleeding in a nosebleed (epistaxis). The sensory innervation of the nose is via branches of the trigeminal nerve (CN V).
What are the paranasal sinuses?
The paranasal sinuses are cavities within the skull bones and are named according to the bones within which they are located.
Which sinuses are clearly seen?
The frontal sinus and sphenoid sinus are usually clearly seen in the bisected head. The maxillary sinuses lie lateral to the lateral walls of the nasal cavity.
What do the paranasal sinuses communicate with?
The paranasal sinuses communicate with the nasal cavity via small ducts / channels.
● The frontal sinus drains into the middle meatus.
● The sphenoid sinus drains into the spheno-ethmoidal recess.
● The ethmoid air cells drain into the superior and middle meatuses.
● The maxillary sinus drains into the middle meatus – the opening into the middle meatus lies superomedially, therefore it cannot drain feely when the head is upright
What does the nasal cavity also receive?
The nasal cavity also receives the nasolacrimal duct which drains the fluid (‘tears’) that lubricate the anterior surface of the eye. The duct opens into the inferior meatus. When we cry, we get a runny nose because excess fluid runs down the nasolacrimal duct.
What does the nasal cavity communicate with?
The nasal cavity also communicates with the middle ear.
- auditory tube
- Middle ear
What does the palate do?
separates the nasal cavities from the oral cavity
- composed anteriorly of bone – the hard palate
- posteriorly of muscle – the soft palate
The palate forms the roof of the oral cavity.
Why is the hard palate important?
The hard palate is functionally important because:
● it prevents food or fluid entering the nasal cavity.
● we push our tongue up against the hard palate during the first phase of swallowing, which forces food and fluid backwards into the oropharynx.
● we push our tongue up against the hard palate to articulate certain sounds.
What is the soft palate?
The soft palate lies posterior to the hard palate.
- the uvula - ‘hangs’ from the posterior border of the soft palate and can be seen at the back of the mouth
What is epistaxis?
Nosebleeds
most commonly arise due to trauma, but they also occur spontaneously
- stopped by applying pressure
- bleeding can be profuse - taking anticoagulants (‘blood thinners’).
- the bleeding vessels can be cauterised, or a nasal tampon can be inserted into the nostril which compresses the blood vessels inside the nose
What is the fracture of the nose?
The nasal bones or septum may be broken by blunt trauma. The nose may be deviated to one side as a result. Traumatic blows to the nose may fracture the cribriform plate and this must be considered in patients with nasal trauma.
What is sinusitis?
This is inflammation or infection of the mucosa lining the paranasal sinuses. It is painful.
What is a cleft palate?
Cleft palate
Development of the palate is complex. If the bones of the hard palate do not develop properly or do not fuse in the midline, a cleft remains that allows communication between the nasal and oral cavities. A cleft palate is surgically repaired
What are the boundaries of the oral cavity?
The oral cavity is bounded:
● superiorly by the hard and soft palate (mouth roof)
● inferiorly by soft tissues and muscles (mouth floor)
● laterally by the cheeks (contain the buccinator muscle).
- continuous posteriorly with oropharynx.
What must you know about the teeth and gums?
The basics are:
● Adults have 32 teeth – 16 embedded in the maxilla (upper jaw) and 16 embedded in the mandible (lower jaw).
● In the upper and lower jaws there are four incisors, two canines, four premolars and six
molars.
What causes enamel or dentin to be eroded?
Enamel and dentin can be eroded by bacteria or foodstuffs (e.g. sugar and acids). This can lead to decay, inflammation, and infection of the pulp, which is painful. Infection may spread to the bone, leading to abscess formation
What is the tongue like?
It bears papillae on its superior surface, some of which detect taste (‘taste buds’). The anterior part of the tongue lies in the oral cavity, and the posterior part (the root) extends into the oropharynx.
What muscles are in the tongue?
The tongue is composed of intrinsic and extrinsic muscles The muscles are innervated by the hypoglossal nerve (CN XII).
● Intrinsic muscles lie within the tongue.
- paired bilaterally, fuse in the midline.
- change the shape of the tongue.
● Extrinsic muscles attached to the tongue
- originate from outside it (from the mandible and hyoid bone).
- move the tongue.
What is the tongue innervated by?
The sensory innervation of the tongue is via three cranial nerves:
● Taste in the anterior two thirds of the tongue is served by the facial nerve (CN VII).
● General sensation (touch, pain, temperature) in the anterior two thirds is served by the trigeminal nerve (CN V).
● Taste and general sensation in the posterior third are served by the glossopharyngeal nerve (CN IX).
What are the vessels and nerves of the oral cavity?
The oral cavity is supplied by the lingual, maxillary, and facial arteries, which are branches of the external carotid artery.
● Innervation of the oral cavity is complex. The muscles of the soft palate are innervated by the vagus nerve. The tongue is innervated by four cranial nerves (CNs V, VII, IX and XII) as described above
Where are tonsils found?
Tonsillar tissue is found in several locations in the nasal and oral cavities:
● The pharyngeal tonsil lies in the roof and posterior wall of the nasopharynx
(sometimes called the ‘adenoid’).
● The tubal tonsil surrounds the opening of the auditory tube on the lateral wall of the
nasopharynx.
● The palatine tonsil lies on the lateral wall of the oropharynx. Usually referred to as ‘the
tonsils’, they are visible on either side of the oropharynx when the mouth is open.
● The lingual tonsil is a collection of lymphoid tissue in the posterior tongue.
How many salivary glands are there?
Three pairs of salivary glands secrete saliva into the oral cavity: the parotid, submandibular and sublingual salivary glands. Glandular secretion is stimulated by parasympathetic fibres. In the practical session we will look for the parotid and submandibular glands
What is the parotid gland like?
The parotid gland is the largest of the three paired salivary glands and overlies the posterior part of the mandible. Saliva empties into the mouth via the parotid duct, which opens adjacent to the upper second molar tooth.
What are the submandibular and sublingual glands like?
Submandibular and Sublingual Glands
The submandibular glands are smaller than the parotid glands. They lie inferior to the body of the mandible, just anterior to the angle. The submandibular duct opens into the floor of the mouth, under the tongue. Secretion of saliva is stimulated by parasympathetic fibres in the facial nerve. The sublingual glands lie in the floor of the mouth. They open via several small ducts into the floor of the mouth. Secretion is stimulated by parasympathetic fibres in the facial nerve
What is a hypoglossal nerve injury?
Hypoglossal nerve injury
Injury to the left or right hypoglossal nerve results in atrophy (wasting) and weakness or paralysis of the ipsilateral tongue muscles. Because the muscles on the unaffected side continue to function, the tongue deviates to the affected (injured) side when the patient protrudes their tongue.
What is nasal and oral cancer like?
Nasal and oral cancer
Cancer of the nasal cavity or sinuses is rare. Cancer can develop in structures associated with the mouth, including the oral mucosa, tonsils, tongue, and salivary glands. Mouth cancers may present as ulcers, lumps, or patches of discolouration on the oral mucosa.
What is tonsillitis and tonsillectomy like?
Tonsillitis and tonsillectomy
Tonsillitis is inflammation of the tonsils - the palatine tonsils are commonly affected. The cause may be a viral or bacterial infection. The tonsils become enlarged, red and may be covered in pus which appears as white spots on the surface of the tonsils. Swallowing is very painful. Inflammation and enlargement of the pharyngeal tonsil (adenoid) is common in children. Enlargement may obstruct the nearby opening of the auditory tube, which can result in fluid accumulation in the middle ear and hearing impairment. Recurrent infection of the tonsils may be managed by tonsillectomy - surgical removal of the tonsils
What is the pathology of the parotid gland?
Pathology of the parotid gland
Disease of the parotid gland (e.g. tumour), trauma or surgery on the gland risks injury to the facial nerve and its branches. Injury to the nerve may result in paralysis of some or all the ipsilateral facial muscles. Mumps is a viral infection that causes painful inflammation and swelling of the parotid gland.
What does the nasal cavity communicate with?
The nasal cavity communicates with the nasopharynx posteriorly. The nasal cavity also communicates with the paranasal sinuses, which are cavities within the skull bones.
What do the nasal cavity form?
The left and right nasal cavities form the first part of the respiratory tract.
What is the lateral wall of the nasal cavity composed of?
The lateral wall of the nasal cavity bears three projections of bone, the superior, middle, and inferior conchae (Latin = shell), or turbinates.
● The spaces inferior to them are the meatuses: the superior meatus lies inferior to the superior concha; the middle meatus lies inferior to the middle concha and the inferior meatus lies inferior to the inferior concha.
● As inspired air travels through the meatuses it is warmed, humidified, and filtered
