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Questions and Answers
What is the primary contribution to the development of the pharyngeal part of the tongue?
What is the primary contribution to the development of the pharyngeal part of the tongue?
Which nerve is responsible for general sensation in the mucosa of the anterior two-thirds of the tongue?
Which nerve is responsible for general sensation in the mucosa of the anterior two-thirds of the tongue?
What anatomical feature indicates the line of fusion between the oral and pharyngeal parts of the tongue?
What anatomical feature indicates the line of fusion between the oral and pharyngeal parts of the tongue?
Which of the following nerves provides special sensation for taste appreciation in the anterior two-thirds of the tongue?
Which of the following nerves provides special sensation for taste appreciation in the anterior two-thirds of the tongue?
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From which embryonic component does the mucosa of the posterior one-third of the tongue derive?
From which embryonic component does the mucosa of the posterior one-third of the tongue derive?
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What is the role of the copula in the development of the definitive adult tongue?
What is the role of the copula in the development of the definitive adult tongue?
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Which arch is primarily involved in the development of the oral part of the tongue?
Which arch is primarily involved in the development of the oral part of the tongue?
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What type of sensation do the vallate papillae specifically provide?
What type of sensation do the vallate papillae specifically provide?
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What is the first indication of tongue development?
What is the first indication of tongue development?
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Which embryonic structures contribute to the oral part of the tongue?
Which embryonic structures contribute to the oral part of the tongue?
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What is the role of the lateral lingual swellings in tongue development?
What is the role of the lateral lingual swellings in tongue development?
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The pharyngeal part of the tongue is indicated by which structures?
The pharyngeal part of the tongue is indicated by which structures?
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What embryonic origin is responsible for the development of the anterior two-thirds of the tongue?
What embryonic origin is responsible for the development of the anterior two-thirds of the tongue?
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Which condition is classified as a congenital anomaly associated with the tongue?
Which condition is classified as a congenital anomaly associated with the tongue?
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What embryological basis is associated with an ectopic thyroid gland?
What embryological basis is associated with an ectopic thyroid gland?
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At what point during development do the lateral lingual swellings begin to merge?
At what point during development do the lateral lingual swellings begin to merge?
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What does the foramen cecum indicate in the development of the thyroid gland?
What does the foramen cecum indicate in the development of the thyroid gland?
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Which structure connects the thyroid gland to the tongue during its migration?
Which structure connects the thyroid gland to the tongue during its migration?
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When does the thyroglossal duct typically break down in thyroid development?
When does the thyroglossal duct typically break down in thyroid development?
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At what week does the thyroid gland reach its final position?
At what week does the thyroid gland reach its final position?
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What embryonic layer contributes to the formation of the thyroid gland?
What embryonic layer contributes to the formation of the thyroid gland?
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What may persist after the breakdown of the thyroglossal duct?
What may persist after the breakdown of the thyroglossal duct?
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In which anatomical location does the thyroid gland ultimately settle?
In which anatomical location does the thyroid gland ultimately settle?
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What is the primary hormone secreted by parafollicular cells in the thyroid gland?
What is the primary hormone secreted by parafollicular cells in the thyroid gland?
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Where are ectopic thyroid glands commonly located?
Where are ectopic thyroid glands commonly located?
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Which cells originate from neural crest cells within the ultimopharyngeal body?
Which cells originate from neural crest cells within the ultimopharyngeal body?
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What does the presence of a lingual thyroid indicate?
What does the presence of a lingual thyroid indicate?
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Which embryological structure is responsible for the development of the thyroid gland?
Which embryological structure is responsible for the development of the thyroid gland?
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What significance does the thyroglossal duct have in thyroid development?
What significance does the thyroglossal duct have in thyroid development?
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What role does calcitonin play in the body?
What role does calcitonin play in the body?
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In adults, where is the thyroid gland typically located?
In adults, where is the thyroid gland typically located?
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Which nerve supplies all muscles of the tongue except for the palatoglossus?
Which nerve supplies all muscles of the tongue except for the palatoglossus?
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At which stage of development does the thyroid primordium first appear?
At which stage of development does the thyroid primordium first appear?
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What is the origin of the palatoglossus muscle?
What is the origin of the palatoglossus muscle?
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What structure is formed at the apex of the foramen cecum during thyroid development?
What structure is formed at the apex of the foramen cecum during thyroid development?
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What is the significance of a primordium in developmental biology?
What is the significance of a primordium in developmental biology?
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Which of the following nerves carries motor innervation to the muscles of the tongue?
Which of the following nerves carries motor innervation to the muscles of the tongue?
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Which structure is located posteriorly, near the vallecula, in the development of the tongue?
Which structure is located posteriorly, near the vallecula, in the development of the tongue?
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Study Notes
Development of the Tongue
- The tongue develops from three swellings:
- One median swelling (Tuberculum Impar)
- Two lateral lingual swellings
- These swellings originate from the first pharyngeal arch in the floor of the pharynx.
- The anterior two-thirds (oral part) of the tongue is formed by the lateral lingual swellings merging together.
- The posterior one-third (pharyngeal part) of the tongue develops from pharyngeal arches two, three, and four.
- The line of fusion between the oral and pharyngeal parts of the tongue is indicated by the terminal sulcus.
Nerve Supply of the Tongue
- The tongue's nerve supply reflects its developmental origins:
- The anterior two-thirds of the tongue:
- General sensation (pain, temperature): Lingual nerve (mandibular branch of the trigeminal nerve, CN V3)
- Special sensation (taste): Chorda tympani (Facial nerve, CN VII) except for the vallate papillae.
- The posterior one-third of the tongue:
- General sensation (pain, temperature) and taste: Glossopharyngeal nerve (CN IX), including the vallate papillae.
- The posterior-most part near the vallecula:
- General sensation (pain, temperature): Superior laryngeal nerve (Vagus nerve, CN X).
- The anterior two-thirds of the tongue:
- All muscles of the tongue are supplied by the hypoglossal nerve (XII) except for the palatoglossus, which is supplied by the pharyngeal plexus from the vagus nerve.
Muscles of the Tongue
- All muscles of the tongue are formed by mesoderm derived from myoblasts migrating from occipital somites.
Development of the Thyroid Gland
- The thyroid gland is the first endocrine gland to develop.
- It appears as a solid mass of endodermal proliferating at the apex of the foramen cecum on the developing tongue during the fourth week.
- The thyroid primordium descends in front of the pharyngeal gut as a bilobed thyroid diverticulum.
- The thyroglossal duct connects the thyroid to the tongue during the fifth week and breaks down.
- The site of the thyroglossal duct is indicated by the foramen cecum in the adult.
- The thyroid gland descends in front of the hyoid bone and laryngeal cartilages.
Embryological Basis of Ectopic Thyroid Gland
- Ectopic thyroid glands can be located along the normal descent route from the tongue.
- The most common type is lingual thyroid glandular tissue.
- Sublingual thyroid gland is a less common type, located in the neck at or just inferior to the hyoid bone.
Histogenesis of the Thyroid Gland
- Neural crest cells within the ultimopharyngeal body (pharyngeal pouch 4, ultimobranchial body) disperse throughout the thyroid gland and differentiate into parafollicular cells (C cells).
- These parafollicular cells secrete calcitonin, a hormone involved in regulating calcium levels in the blood.
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Description
Explore the fascinating development of the tongue, beginning from its three swellings and the anatomical fusion between its parts. This quiz also examines the nerve supply associated with each section of the tongue, detailing the specific nerves involved in sensations and taste.
