embryology

Question 1

what is a brachial fistula

Answer 1

the second pharyngeal arch does not grow over 3rd and 4th arches. anterior to SCM

Question 2

where does the anterior 2/3 of tongue come from and therefore what is its innervation

Answer 2

lateral lingual swelling and tuberculum impor on arch one. sensory- mandibular nerve Vc. special sensory- chordai tympani from facial.

Question 3

where does the posterior 1/3 of tongue come from and therefore what is its innervation

Answer 3

2nd, 3rd and 4th pharyngeal arch. sensory- glossopharyngeal. special sensory- glossopharyngral

Question 4

what is the nerve for motor innervation of tongue and where is the muscles of tongue derived from

Answer 4

occipital somite myoblasts. the hypoglossal nerve

Question 5

where is epiglottis derived from

Answer 5

superior laryngeal nerve and 4th arch

Question 6

where does the thyroid descend from and what keeps it attached as it descends

Answer 6

foramen cecum. the thyroglossal duct

Question 7

where does the thhyroid descend

Answer 7

in front of hyoid and larynx

Question 8

what causes thyroglossal cyst

Answer 8

any point along migratory pathway where the thyroglossal duct persists.