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34 Cards in this Set
- Front
- Back
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on which pharyngeal arch do 3 swellings form early in tongue development?
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first arch
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what forms the three lingual swellings?
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mesenchyme proliferation on the first laryngeal arch.
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which lingual swelling(s) over grows the other(s)? what do they form?
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the lateral swellings overgrow the medial swelling to form the anterior 2/3 of the tongue.
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the mucosa of the tongue receives general sensory innervation by which CN?
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CN V
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what forms the posterior tongue?
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hypopharyngeal eminence in the 3rd and 4th pharyngeal arches.
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what happens to the second arch?
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it gets overgrown by the third and fourth arches, but it contributes its innervation to special sensory (taste)
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what marks the fusion of the hypopharyngeal eminence and the lateral lingual swellings?
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terminal sulcus
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which arches do the posterior 1/3 of tongue and epiglottis arise from? what innervates those arches?
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arise from the 3rd and 4th arches, respectively. The 3rd arch is innervated by the glossopharyngeal nerve (IX) and the fourth arch is innervated by the vagus nerve (X)
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what are the tongue muscles derived from? what innervates those things? what is the one exception?
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derived from myoblasts that migrate from (CN XII innervated) occipital myotomes. exception is the palatoglossus
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ankyloglossia?
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tongue is not freed form the floor of the mouth
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what does the thyroid gland form from?
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thyroid diverticulum: an outpocketing of the ventral pharynx between the 1st and 2nd arches.
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what connects the tongue to the developing thyroid?
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the foramen cecum (on the tongue) leads to the thyroglossal duct
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what happens to the thyroglossal duct?
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it degenerates, and the tissue at its caudal end turns into thyroid follicular cells
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thyroglossal cyst
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remnant of the thyroid's descent (can be anywhere along that pathway).
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what are pharyngeal pouches?
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lateral endodermal outpocketings b/w pharyngeal arches.
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how many pharyngeal pouches are there?
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4
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**development of the thyroid?
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1. thyroid diverticulum between 1st and 2nd arches.
2. foramen cecum leads to thyroglossal duct. 3. duct descends. 4. duct degenerates and leaves a mass caudally that develops into thyroid follicular cells |
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what is the name of the first pharyngeal pouch?
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tubotympanic recess
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what do the distal and proximal portions of the tubotympanic recess become?
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1. Distal: primitive tympanic cavity and part of tympanic membrane
2. Proximal: forms the auditory tube |
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what arises from the second pharyngeal pouches?
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palatine tonsils
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what is the remnant in adults of the second pharyngeal pouch?
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tonsillar fossa
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what is special about the third and fourth pouches?
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each has two wings: dorsal and ventral.
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what does the dorsal region of 3rd pharyngeal pouch form?
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inferior parathyroid gland
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what does the ventral region of 3rd pharyngeal pouch form?
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thymus
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what does the dorsal region of the 4th pharyngeal pouch form?
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superior parathyroid gland
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what does the ventral region of the 4th pharyngeal pouch form?
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ultimobranchial body, which becomes the parafollicular (C cells) of the thyroid gland
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what does the 1st pharyngeal groove form through invagination?
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external acoustic meatus
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what happens to the other pharyngeal grooves (other than 1st)?
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they are overgrown by the 2nd arch
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how does the lateral cervical sinus form?
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the 2nd arch encloses the 3rd and 4th pharyngeal grooves
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what eventually happens to the lateral cervical sinus?
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it is obliterated
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**lateral cervical cyst?
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result of abnormal closure and obliteration of lateral cervical sinus.
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cervical fistulae?
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may be present with lateral cervical cyst. opening can be internal and/or external
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**which pharyngeal arches contribute significantly to the tongue?
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1, 3, and 4
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**what three things do the pharyngeal clefts (grooves) develop into?
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thymus, parathyroid, and ultimobranchial bodies.
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