H&N 3 Flashcards
What is the stomadaeum?
the site of the future mouth which is the first evidence of face development and is a depression in the ectoderm on ventral aspect of head
How do facial clefts and cleft lips occur?
failure of fusion of the paired mandibular prominences and laterally paired maxillary prominences consisting of mesenchyme and a covering of ectoderm
what does the frontonasal prominence go on to form?
forehead, bridge of nose, upper eyelids, centre of upper lip
what do the maxillary prominences go on to form?
middle 1/3 of face, upper jaw, most of lip and sides of nose
what do the mandibular prominences go on to form?
lower 1/3 of face, lower jaw and lip
what is the first evidence of nose formation?
appearance of nasal placodes- bilateral ectodermal thickenings on ventrolateral aspect of frontonasal prominence
formation of nasal pits?
inagination of nasal placodes to form deep pits
entrance of each pit= future nostril
what is the oronasal memebrane?
thin layer of cells separating the stomodaeum from the deepening nasal pits dorsally
what prominences are involved in palate development?
maxiallry and medial nasal
how does cleft palate occur?
failure of 1 or both palatal shelves which grom for each maxillary prominence to reach midline or fuse with its opposite number
what does the temporal fossa comprise?
the temporalis muscle and its neurovascular supply
what does the infratemporal fossa contain?
medial and lateral pterygoid muscles, inferior part of temporalis muscle, mandibular nerve (division of trigeminal), inferior alveolar nerve, lignual, buccal nerves, maxillary artery, pterygoid venous plexus, otic ganglion (where glossopharyngeal nerve supplying salivary glands synapses), and chorda tympani- branch of facial nerve
where does the infratemporal fossa lie?
beneath base of skull, between pharynx and ramus of mandible
what is the mandibular foramen?
superior opening of the mandibular canal on the medial aspect of the ramus of the mandible, which also forms the lateral wall of the infratemporal fossa
what passes through the mandibular foramen?
inferior alveolar nerve and vessels
what happens if anasesthetic is injected around the mandibular foramen?
anaesthetise all mandibular teeth on that side- inferior alveolar nerve block
what nerve is vulnerable to injury when traumatic dislocation of TMJ?
auriculotemporal nerve- branch of mandibular division of trigeminal nerve
what is the inferior alveolar nerve a branch of?
the mandibular division (mandibular nerbe) of the trigeminal nerve
gives rise to the mental nerve- supplies skin and mucous membrane of lower lip
what drives the development of the face?
expansion of cranial neural tube
appearance of complex tissue system assoc. with cranial gut tube and outflow of developing heart
development of sense organs and need to separate resp. from GI tract
what is a placode?
thickened plate of ectoderm from which a sense organ develops- lens(eye), otic(ear), nasal (nose)
number of pharyngeal cleft characterising 5wk embryo?
4
what do neural crest cells contribute to the development of?
head and neck structures
CVS
melanocytes
chromaffin cells
where do neural crest cells arise?
lateral border of the neuroectoderm along edges of neural folds
displaced and enter mesoderm, then migrate
how do neural crest cells contribute to development of CVS?
contribute to conotruncal endocardial cushions which separate outflow tract of heart into pulmonary and aortic channels, and regulation of secondary heart field
what prominences contribute to the formation of the face?
frontonasal
maxillary
mandibular
medial and lateral nasal
structures formed by lateral nasal prominences?
alae of nose
structures formed by maxillary prominences?
cheeks, lateral portion of upper lip
why might the palatine shelves fail to fuse?
smallness of shelves
failure of shelves to elevate
inhibition of fusion process itself
failure of tongue to drop from between shelves because of micrognathia- jaw undersized
what is formed by the 2 merged medial nasal prominences?
intermaxillary segment
components of intermaxillary segement from medial nasal prominences?
labial part: philtrum
upper jaw: 4 incisors
palate: primary
importance of mandible initially being very small and then enlarging?
mandible grows large enough to allow tongue to drop, and so allow fusion of palatal shelves- if problem with this, can cause cleft palate
how do the ears come to lie in line with the eyes?
growth of mandible allows ears to ascend
how does maxillary prominence grow?
population by neural crest cells