Lecture 40: Embryo of Head and Neck Flashcards
What are the two fates of invaginating epiblasts during gastrulation
- Intraembryonic mesoderm (fill space between epiblast and hypoplast)
- Endoderm (replace hypoblast)
(Remaining epiblasts becoming ectoderm)
The presence of ___ induces thickening in the adjacent ectoderm
Notochord
What are the two longitudinal ridges that form in neural plate
neural folds
What structure is between neural folds
Neural groove
What are neural crest cells
Crests of neural folds that grow towards each other and then continue to proliferate and migrate away from neural folds/tube to develop in many regions of the embryo
What drives lateral folding
Growth of somites
What drives craniocaudal folding
Longitudinal growth of the cranial and caudal ends of the neural plate
What separates the pharynx from the oral cavity in development
Craniocauudal folding
What are pharyngeal arches
Parried bulges along the wall of the developing pharynx
What forms the outer surface of the pharyngeal arches
Ectoderm
What forms the middle surface of the pharyngeal arches
Mesenchyme from the paraxial and lateral plate mesoderm
What cells are present in the middle of pharyngeal arches
Neural crest cells
What are the 5 arches
1,2,3,4, 6
The mesoderm of the pharyngeal arches become most of the muscles of the ___
Head
What is responsible for forming the skeleton of head and neck
Neural crest cells
What nerve innervates Arch 1
Trigeminal CN V
What nerve innervates Arch 2
Facial CN VII
What nerve innervates arch 3
Glossopharyngeal CN XI
What nerve innervates arch 4
Cranial laryngeal on vagus CN X
What nerve innervates arch 6
Caudal laryngeal nerve on vagus CN X
What are the two processes that make up the first pharyngeal arch
maxillary and manidbular processes
What is the cartilage of the the 1st arch
Merkel’s cartilage
What two structures derive from merkel’s cartilage
Malleus and incus
Mesenchyme derived from neural crest cells form bones of ___ and ___
Mandible and lower face
Mesoderm derived mesenchyme of the first arch produces the dermis of the ___ and ___ associated with ____ and ____
Face and muscles associated with mandible and ear
What structures does the trigeminal nerve innervates in the first arch
Muscles of mandible (mastication), tensor tympani and tensor veil palatini and the skin of the face
The cartilage of the 2nd arch articulates with what
Merkels cartilage of 1st arch
Cartilage of the second arch becomes what two structures
Hyoid apparatus and the stapes
What are the muscles of the second arch
Stylohyoideus, caudal DI gastric, stapedius, muscles of facial expression
What bones are in the 3 arch
Thyrohoid and basihyoid
What muscle is in 3rd arch
Stylopharyngeus
What cartilages are in 4th arch
Laryngeal
What muscles are in 4th arch
Cricothyroid and pharyngeal
Arch 6 contains what muscles
Intrinsic laryngeal muscles (except cricothyroid)
What structures are between the arches
External: cleft
Internal: pouches
The first pouch and cleft form between what
First and second arch
The cleft becomes ____
External auditory canal
The first pouch becomes what two structures
Tympanic cavity and pharyngotympanic tube
Invagination of the 1st cleft and 1st pouch continue deep until surfaces join at what structure
Tympanic membrane
The tonsils are a derivative of what pouch
Pouch 2
Glands are a derivative of what pouch
Pouch 3
What pouch contributes to C cells of thyroid gland
Pouch 4
The cervical sinus is from what arch
Arch 2
Failure of the cervical sinus to develop results in what in adults
Cervical cysts
Failure of arch 2 to fuse with the distal lateral cervical tissue results in ___ that may connect to cervical cysts
Fistulas
The nasal placode results from thickening of what structure
Ectoderm
What is the stomodeum
Primitive oral cavity
Completion of the secondary palate results in fusion of what two structures
Palatine shelves and nasal septum
Several swellings from the floor of the developing oral pharynx contribute to the development of the ___
Tongue
What two swellings come from the first arch
Lateral lingual and tuberculum impar
copula swelling comes from what arches
2,3,4
The epiglottal swelling comes from what arch
4