Embryology - ENT Flashcards
which germ layer gives rise to the musculature of the face and neck?
mesoderm
during which weeks do the pharyngeal arches develop?
weeks 4-5
what does each pharyngeal arch consist of?
core of mesenchyme associated with pharyngeal clefts and pouches
neural crest cells
cranial nerve
artery
true or false: there are 5 pharyngeal arches and the 5th does not develop in humans
true
only arches 1,2,3,4 and 6 exist
which cranial nerve is associated with pharyngeal arch 1?
CN V
which cranial nerve is associated with pharyngeal arch 2?
CN VII
which cranial nerve is associated with pharyngeal arch 3?
CN IX
which cranial nerve is associated with pharyngeal arch 4?
CN X (superior laryngeal branch)
which cranial nerve is associated with pharyngeal arch 6?
CN X (recurrent laryngeal branch)
what skeletal components are associated with pharyngeal arch 1?
maxillary = maxilla, zygoma, temporal bone mandibulary = mandible, meckel's cartilage, incus and malleus
what skeletal components are associated with pharyngeal arch 2?
stapes
styloid process of temporal bone
stylohyoid ligament
lesser horn and upper hyoid
what skeletal components are associated with pharyngeal arch 3?
greater horn and lower hyoid
what skeletal components are associated with pharyngeal arch 4 + 6?
laryngeal cartilages
what muscles are associated with pharyngeal arch 1?
muscles of mastication
mylohyoid
tensor tympani
tensor palatini
what muscles are associated with pharyngeal arch 2?
muscles of facial expression
stapedius
stylohyoid
what muscles are associated with pharyngeal arch 3?
stylopharyngeus
what muscles are associated with pharyngeal arch 4?
cricothyroid
levator palatine
pharyngeal constrictors
what muscles are associated with pharyngeal arch 6?
intrinsic laryngeal muscles
what pharyngeal cleft does the external auditory meatus develop from?
cleft 1
what happens to the 2nd-4th pharyngeal clefts?
they usually disappear, lose contact and form the cervical sinus
what does the 1st pharyngeal pouch develop into?
middle ear cavity
eustachian tube
ultimately the tympanic membrane
what does the 2nd pharyngeal pouch develop into?
palatine tonsil
what does the 3rd pharyngeal pouch develop into?
inferior parathyroid gland
thymus
what does the 4th pharyngeal pouch develop into?
superior parathyroid gland
ultimobranchial body
what are otic placodes?
thickening of the ectoderm at the back of the embryo
what are otic vesicles?
endocytosed otic placode that gives rise to the inner ear
what three regions develop as part of the otic vesicle?
endolymphatic duct sac
utricular portion
saccular portion
list the five facial swellings present from week 4
frontonasal prominence
2 x maxillary prominences
2 x mandibular prominences
what is the stomodeum?
site of the future mouth
list the nasal swellings that develop on the frontonasal prominence in week 5
2 x medial nasal swellings
2 x lateral nasal swellings
what grows in the groove between the eye and the lateral nasal swelling?
nasolacrimal duct
what nasal features develop from the frontonasal prominence?
bridge
bony septum
what nasal features develop from the medial nasal prominence?
crest and tip of nose
what nasal features develop from the lateral nasal prominences?
alae (side of nostrils)
what does the primary palate form from?
intermaxillary segment
formed by the fusion of two medial nasal prominences
what does the labial portion of the intermaxillary segment give rise to?
philtrum of upper lip
what does the upper jaw component of the intermaxillary segment give rise to?
carries four incisors
what does the secondary palate form from?
palatine shelves that grow downwards from maxillary prominences
is cleft palate more common in females or males?
females
failure of fusion of secondary palate
is cleft lip more common in females or males?
males
failure of fusion of primary palate
