What is tooth development an example of?
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Epithelial–mesenchymal interaction.
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What is tooth development an example of?
Epithelial–mesenchymal interaction.
What is the origin of the mesenchyme involved in tooth development?
Neural crest.
What causes differentiation to the bud stage in tooth development?
The epithelium.
What is the name of the organizer region in tooth development?
Enamel knot.
What factors does the enamel knot express during the cap stage?
SHH, FGF4, and BMP2 and 4.
What lies on a thick layer of dentine in tooth structure?
Ameloblasts.
What are the three pairs of constrictors in the pharynx?
Superior, middle, and inferior constrictors.
What is the conical projection that hangs from the middle of the inferior border of the mouth and pharynx?
The uvula.
What is a cleft palate?
A congenital defect caused by non-fusion of the right and left palatal processes.
How are the fibres of the three constrictors arranged?
The inferior overlaps middle which in turn overlaps the superior.
What are the two curved folds of mucous membrane extending laterally and downwards from each side of the base of the uvula?
The palatoglossal arch (anterior pillar of fauces) and the palatopharyngeal arch (posterior pillar of fauces).
What are the actions of the Tensor veli palatini muscle?
Tightens the soft palate and opens the auditory tube to equalize air pressure between the middle ear and the nasopharynx.
What are the types of congenital cleft palate?
Bilateral complete, Unilateral complete, Partial midline, Cleft of soft palate, Bifid uvula.
What is the anterior border of the tonsil related to?
The palatoglossal arch with its muscle.
Where does the superior constrictor muscle reach posteriorly?
The base of the skull.
What muscle does the palatoglossal arch contain?
Palatoglossus muscle.
Where does the Levator veli palatini muscle originate and insert?
Originates from the inferior aspect of the auditory tube and adjoining part of the inferior surface of petrous temporal bone, and inserts into the upper surface of the palatine aponeurosis.
What are the components of each cheek?
Skin, superficial fascia, buccinator, submucosa, and mucous membrane.
How is the premaxilla or primitive palate formed?
By the fusion of medial nasal folds, which are folds of frontonasal process.
What is the posterior border of the tonsil related to?
The palatopharyngeal arch with its muscle.
What closes the gap between the base of the skull and the upper edge of the superior constrictor?
The pharyngobasilar fascia.
What is the function of the oral cavity?
It is used for the ingestion of food and fluids.
What muscle does the palatopharyngeal arch contain?
Palatopharyngeus muscle.
What forms the fibrous basis of the palate?
The palatine aponeurosis.
What are the actions of the Musculus uvulae muscle?
Pulls up the uvula.
What is the function of the pharynx?
To transmit air and food, and it is a common passage for both air and food.
What is the buccal pad of fat and in which age group is it best developed?
It lies on the buccinator and is best developed in infants.
What is the upper pole of the tonsil related to?
The soft palate.
From which pharyngeal arches do the pharyngeal constrictor muscles develop?
IV and VI pharyngeal arches.
What structures form the roof of the oral cavity?
The hard and the soft palates.
What is the function of the palatoglossal arch?
It forms the lateral boundary of the oropharyngeal isthmus or isthmus of fauces.
What are the boundaries of the pharynx?
Superiorly: Base of the skull, including the posterior part of the body of the sphenoid and the basilar part of the occipital bone. Inferiorly: The pharynx is continuous with the oesophagus at the level of the sixth cervical vertebra, corresponding to the lower border of the cricoid cartilage. Posteriorly: The pharynx glides freely on the prevertebral fascia which separates it from the cervical vertebral bodies. Anteriorly: It communicates with the nasal cavity, the oral cavity and the larynx.
Which nerve supplies all muscles of the soft palate except the tensor veli palatini?
Pharyngeal plexus derived from the cranial part of the accessory nerve through the vagus.
What is the function of the Palatoglossus muscle?
Pulls up the root of the tongue, approximates the palatoglossal arches, and closes the oropharyngeal isthmus.
What structures bound the oral cavity proper anterolaterally?
Teeth, gums, and alveolar arches of the jaws.
What are the dimensions of the pharynx?
Length: About 12 cm, Width: Upper part is widest (3.5 cm) and non-collapsible.
What is the lower pole of the tonsil related to?
The tongue.
How many teeth does an adult oral cavity contain?
32 teeth.
What is the function of the palatopharyngeal arch?
It forms the posterior boundary of the tonsillar fossa and merges inferiorly with the lateral wall of the pharynx.
What are the nerve supplies to the tonsil?
Glossopharyngeal and lesser palatine nerves.
What are the parts of the pharynx?
What are the actions of the Palatopharyngeus muscle?
Pulls up the wall of the pharynx and shortens it during swallowing.
What is the function of Passavant’s muscle?
To raise a ridge called the Passavant’s ridge on the posterior wall of the nasopharynx.
What forms the roof of the oral cavity proper?
Hard palate and soft palate.
What is the plica triangularis?
A triangular vestigial fold of mucous membrane covering the anteroinferior part of the tonsil.
What are the divisions of the oral cavity?
The vestibule and the oral cavity proper.
What is the soft palate?
A fold of mucous membrane containing various parts.
What is the method usually used for tonsillectomy?
Guillotine method.
What are the components of Waldeyer’s lymphatic ring?
The right and left palatine tonsils, nasopharyngeal tonsil, tubal tonsils, and lingual tonsil.
What is the role of the palatopharyngeus muscle when the soft palate is elevated?
It forms a sphincter internal to the superior constrictor, closing the pharyngeal isthmus between the nasopharynx and the oropharynx.
What is the oropharyngeal isthmus and what structures bound it?
It is the communication between the oral cavity and the pharynx, bounded by the soft palate, tongue, and palatoglossal arches.
What is the intratonsillar cleft?
The largest crypt of the tonsil, present in its upper part, representing the internal opening of the second pharyngeal pouch.
Where is the palatine tonsil located?
In the tonsillar sinus or fossa between the palatoglossal and palatopharyngeal arches.
What is the vestibule of the mouth bounded by externally and internally?
Externally by the lips and cheeks, and internally by the teeth and gums.
What is the function of the palatopharyngeal sphincter?
It clasps the inlet of the larynx.
What is the origin of lymphocytes in the tonsil?
Mesodermal in origin.
What problems can be caused by hypertrophy of the nasopharyngeal tonsil or adenoids?
Obstruction of the posterior nasal aperture, interference with nasal respiration and speech, leading to mouth breathing.
What is the function of the hard palate?
To form a partition between the nasal and oral cavities.
Where is the epithelium of the soft palate derived from?
From the ectoderm of the maxillary process.
What are the features of the sublingual region in the oral cavity?
Frenulum of the tongue, sublingual papilla, sublingual fold, and sublingual gland.
What is the main arterial supply of the tonsil?
Tonsillar branch of facial artery.
What are the characteristics of the medial surface of the palatine tonsil?
Covered by stratified squamous epithelium with 12 to 15 crypts, including the intratonsillar cleft.
What is the function of the frenula of the lips?
To form median folds that pass from the lips to the gums.
What is Passavant’s muscle and where is it located?
It is formed by some fibers of the sphincter inner to the superior constrictor at the level of the hard palate.
What are odontoblasts?
They are tall columnar cells capable of replacing dentine at any time in life.
Where does the tonsil develop from?
Endoderm of ventral part of the second pharyngeal pouch.
What problems can be caused by hypertrophy of the tubal tonsil?
It may occlude the auditory or pharyngotympanic tube, leading to middle ear problems.
What forms the anterior two-thirds of the hard palate?
The palatine processes of the maxillae.
Which nerve carries taste sensations from the oral surface to the nucleus of the tractus solitarius?
The lesser palatine nerves through the greater petrosal nerve to the geniculate ganglion of the facial nerve.
Where do the lymphatics from the anterior part of the floor of the mouth drain?
To the submental nodes.
Where do the lymphatics from the tonsil pass to?
Jugulodigastric node.
Where do the lymphatics of the upper gums pass to?
The submandibular nodes.
How is the lateral surface of the palatine tonsil covered?
By a sheet of fascia which forms the hemicapsule of the tonsil.
What structures compose each lip?
Skin, superficial fascia, the orbicularis oris muscle, submucosa, and mucous membrane.
What role does the soft palate play in swallowing?
It separates the oropharynx from the nasopharynx by locking Passavant’s ridge during the second stage of swallowing, preventing food from entering the nose.
What is the structure of the palatine tonsil?
It is not differentiated into cortex and medulla.
What is the composition of the soft palate?
The soft palate is composed of muscles and mucous membrane.
What forms the posterior one-third of the hard palate?
The horizontal plates of the palatine bones.
What supports the posterior wall of the pharynx in the head and neck region?
Mainly the fourth and fifth cervical vertebrae, and partly the third and sixth vertebrae.
What are the two parts of each gum?
Free part and attached part.
What is Ludwig’s angina?
Cellulitis of the floor of the mouth, causing swelling below the chin and within the mouth.
What keeps the tonsil in place during swallowing?
Firm attachment to the side of the tongue (suspensory ligament of tonsil).
Where do the lymphatics of the central part of the lower lip drain to?
To the submental nodes.
How does the soft palate modify the quality of voice?
By varying the degree of closure of the pharyngeal isthmus, it can modify the quality of voice and correctly pronounce various consonants.
What is the arterial supply of the palatine tonsil?
Arterial supply of the palatine tonsil.
What arteries supply the hard palate?
Greater palatine branch of maxillary artery.
What forms the posterior wall of the pharynx in the head and neck region?
The superior, middle, and inferior constrictors of the pharynx.
How many times are the teeth replaced in man?
Only once (diphyodont).
What is the composition of dentine?
It is a calcified material containing spiral tubules radiating from the pulp cavity.
Which artery enters the tonsil by piercing the superior constrictor?
The tonsillar artery.
What is the function of the soft palate during sneezing and coughing?
It appropriately divides and directs air through the nasal and oral cavities during sneezing, and directs air and sputum into the mouth during coughing.
What is the histology of the palatine tonsil?
Covered with stratified squamous nonkeratinised epithelium, which dips into the underlying tissue to form the crypts.
What is the function of the soft palate?
To separate the nasopharynx from the oropharynx.
What is the depression called on each side of the inlet of the larynx in the head and neck region?
Piriform fossa.
What are the first set of teeth known as?
Milk or deciduous teeth.
What is the composition of enamel?
It is made up of crystalline prisms lying roughly at right angles to the surface of the tooth.
What may be injured during removal of the tonsil or tonsillectomy?
The palatine vein or external palatine or paratonsillar vein.
What are the arterial blood supplies to the soft palate?
Greater palatine branch of maxillary artery, ascending palatine branch of facial artery, and palatine branch of ascending pharyngeal artery.
Where is the palatine tonsil situated?
At the oropharyngeal isthmus.
What are the two surfaces of the soft palate?
Anterior and posterior.
What is the common dental abnormality seen in rickets?
Irregular dentition with notched upper permanent incisors.
What is bounded medially by the aryepiglottic fold and laterally by the thyroid cartilage and the thyrohyoid membrane in the head and neck region?
The piriform fossa.
How many permanent teeth are there in man?
What is the function of the periodontal membrane (ligament)?
It holds the root of the tooth in its socket and acts as a periosteum to both the cementum and the bony socket.
What forms the bed of the tonsil from within outwards?
Pharyngobasilar fascia, superior constrictor and palatopharyngeus muscles, buccopharyngeal fascia, styloglossus, and the glossopharyngeal nerve.
Where do the veins of the soft palate pass to?
They pass to the pterygoid and tonsillar plexuses of veins.
What is the superior border of the soft palate attached to?
The posterior border of the hard palate.
What is the term for the third molar teeth?
Wisdom teeth.
What lies beneath the mucosa of the piriform fossa in the head and neck region?
The internal laryngeal nerve.
What are the three parts of a tooth?
Crown, root, and neck.
How are the shapes of teeth adapted to their function?
The incisors are cutting teeth, canines are holding and tearing teeth, premolars are bicuspid teeth, and molars are grinding teeth.
What is the function of the palatine tonsil?
To form a passage for air and food (respiratory function).
Where do the lymphatics of the soft palate drain into?
They drain into the upper deep cervical and retropharyngeal lymph nodes.
At what age do the wisdom teeth usually erupt?
Between 18 and 20 years.
What may damage the internal laryngeal nerve in the head and neck region?
Removal of foreign bodies from the piriform fossa.
What is the structure of the pulp in a tooth?
Loose fibrous tissue containing vessels, nerves, and lymphatics.
What is the eruption time for the first molar in deciduous teeth?
12–16 months.
What can cause impacted wisdom teeth?
Less space for eruption.
What are the five layers that compose the wall of the pharynx?
Mucosa, submucosa, pharyngobasilar fascia, muscular coat, and buccopharyngeal fascia.
What are the nerve supplies for the upper gums on the labial side?
Posterior, middle, and anterior superior alveolar nerves (V2).
What is the shedding time for the lateral incisor in deciduous teeth?
7–8 years.
How can the time of eruption of teeth help in assessing a person's age?
It can be used to estimate the person's age.
What is the fibrous sheet internal to the pharyngeal muscles in the head and neck region?
Pharyngobasilar fascia or pharyngeal aponeurosis.
What is the usual time of eruption for the second molar in permanent teeth?
13–14 years.
Why are the upper canine teeth called 'eye teeth'?
They have long roots which reach up to the medial angle of the eye.
What does the muscular coat of the pharynx consist of in the head and neck region?
An outer circular layer made up of the three constrictors (superior, middle, and inferior) and an inner longitudinal layer made up of the stylopharyngeus, the salpingopharyngeus, and the palatopharyngeus muscles.
What is the blood supply for both upper and lower teeth?
Supplied by branches of the maxillary artery.
What complications can arise from infection of the upper canine teeth roots?
Infection may spread in the facial vein and lead to thrombosis of the cavernous sinus.
What covers the outer surface of the constrictors of the pharynx and extends forwards across the pterygomandibular raphe to cover the buccinator in the head and neck region?
Buccopharyngeal fascia.
What is the nerve supply for the upper teeth?
Supplied by the posterior superior alveolar, middle superior alveolar, and the anterior superior alveolar nerves (maxillary nerve).
How is anaesthetic injected for the upper teeth?
Separate injections on both the buccal and palatal surfaces of the maxillary process just distal to the tooth.
What is the first stage of development of deciduous teeth?
Formation of C-shaped dental lamina by the 6th week of development.
What is the second stage of development of deciduous teeth?
Development of 10 centres of proliferation from dental lamina, forming dental buds.
What is the third stage of development of deciduous teeth?
Formation of the enamel organ from the deeper enlarged parts of the tooth bud, known as the cap stage.
What is the fourth stage of development of deciduous teeth?
Invagination of the enamel organ by mesenchyme of dental papilla, forming the bell stage.
How is the root of the tooth formed?
By laying down layers of dentine, narrowing the pulp space to a canal for the passage of nerve and blood vessels.
What forms the enamel of the tooth?
Ectoderm.
What cells form dentine, dental pulp, cementum, and periodontal ligament?
Neural crest cells.
