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34 Cards in this Set

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