Craniofacial development Flashcards
Each Pharyngeal arch has
Muscle
Cartilaginous rod- initiates formation of skeletal elements
Cranial nerve
Aortic arch artery
Mesenchymal core
Mesoderm- giver rise to musculature
Neuro crest cells- migrate into the pharyngeal arches to contribute to cartilage/bone and connective tissue
derived mainly from arches 1&2
Face
Derived from arches 3&4
Neck components
Arch 1
Muscle- mastication meckel's cartilage malleus and incus mandible CN V3
Arch 2
muscle- facial expression reichert's cartilage stapes and temporal bone styloid process hyoid bone CN VII
Arch 3
Muscle- stylopharyngeus
hyoid
CN IX
Arch 4&6
muscle- pharynx constrictors
laryngeal cartilages
CNX and recurrent fibers
Symptoms results from defects in growth of the 1st and 2nd pharyngeal arches
leads to - dysplasia/hypoplasia/aplasia of the musculoskeletal derivatives of these arches
Treacher collins syndrom
mutation in TCOF1 gene
Malformation of 1st arch structures- mandible most severely affected
difficulties breathing and eating
Pierre Robin sequence
Triad- micrognathia/cleft palate/glossoptosis(posteriorly placed tongue)
The only cleft that contributes to the definitive structure of the embryo
Dorsal region of the 1st cleft- gives rise to the external auditory meatus
Cervical sinus cavity
occurs from proliferation of the 2nd arch causing it to overlap with the 3rd and 4th
Results when the 2nd arch fails to completely cover the 3rd and 4th
Crachial fistula
forms tympanic cavity and auditory tube
1st pouch
forms palatine tonsils
2nd pouch
forms interior parathyroid gland and thymus
3rd pouch
forms superior parathyroid gland and ultimo brachial body
4th pouch- source of C cells for thyroid
Ectopic thyroid gland
Thyroglossal cyst- often impinge on the lumen of the pharynx and impede swallowing
Development of the tongue
develops from the ventral surface of all four pharyngeal arches
forms the anterior 2/3rds of the tongue
tuberculum impar- appear on the ventral surface of the 1st arch
forms the posterior 1/3rd and root of the tongue
Hypopharyngeal eminence
-derived from the 2nd/3rd/4th arches
Results when the tongue is not completely freed from the floor of the mouth
Ankylogossia
Forms the anterior portion of the hard palate
Primary palate
Forms via fusion of palatine shelves to give rise to the posterior hard palate and soft palate
Secondary palate
Nasolacrimal groove
invaginates to form
- nasolacrimal duct
- lacrimal sac
Results from failed fusion of the maxillary and medial nasal prominences
Cleft lip
Results from failure of palatine shovels to fuse with one another and/or the primary palate
Cleft palate
Palatine shelves failing to fuse with the primary palate
Anterior/primary palate
Failure of the palatine shelves to fuse with each other and with the nasal septum
Posterior/secondary palate
Ondotoblasts
produce dentin
Ameloblasts
Produce enamel
Results from defects in enamel secretion or mineralization
Amelogenesis imperfecta
Vit A deficiency or measles can cause enamel defects
