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38 Cards in this Set
- Front
- Back
State the components of the pharyngeal arches |
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Importance of neural crest cells and development |
we have skeletal and cartillagenous coimponents derived from these, they have to migrate from the neural folds to their location and there is potential for this to go wrong. |
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What is treacher collins syndrome and its characterisitcs |
Lack of neural crest cells in the pharyngeal areas leading to a host of problems. Affected due to 1st pharyngeal arch where mandible is derived from
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how does treacher collins affect mandible |
mandibular condyle severly effected, abnormal TMJ - Retrognathia - results in a bird like appearance |
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What causes treacher collins |
genetic condition affecting the TOCF1 gene, which encodes the treacle protien thats expressed in neural folds as neural crest cells. NCCs are forming and migrating - mutations in TOCF1 associated with increased apoptosis of neural crest precursors and decreased proliferation of NCC's |
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What is digeorge anomaly |
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cause of digeorge anomaly |
deletion on chromosome 22 leads to imparied neural crest cell migration. |
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Where does the face develop from and when |
develops from 5 prominences that appear in week 4, 2 maxillary, 2 mandibular and one frontonasal prominence. the prominences are dervied from neural crest cells and surround the stomodeum |
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what happens during week 5 of facial development what do the prominences do what is formed |
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medial nasal prominences fuse to form what |
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secondary palate is derived from what |
maxillary prominences |
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Explain how the palate forms |
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Cleft lip and palate. different types |
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severity of celft lip palate |
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Complications of cleft lip palate |
varies in severity, caused by failure of palatine shelves to fuse, complications include feeding and speech. |
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Causes of celft lip palate |
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Pierre robin sequence |
often seen in treacher colins, micrognatihia results in posterio displacement of tongue (glossoptosis) and prevents lowering of tongue. |
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hypodontia causes |
affects secondary dentition, failure of permanent tooth buds to form from the dental lamina |
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hyperdontia causes |
hyperproliferation of dental lamina resulting in scond permanent tooth bud , less common and associated with other cranial malformations. |
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State what the Notochord, paraxial , intermediate and lateral plate mesoderm go on to form |
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What are neural crest cells derived from |
derived from neuroectoderm, as neural folds elevate and fuse cells at lateral edge sperate from the neural tube, neural crest cells. they migrate laterally and ventrally dispersing widely and differentiating into a variety of structures throghout the body sometimes referred to as the 4th germ layer. |
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when do pharyngeal arches appear and how to they look when viewed |
appear in week 4, there are 5 arches, form in a craniocaudal cuccession, seperated by pharyngeal clefts and internal pharyngeal pouches . evolved from gill arches of fish therfore somtimes called branchial arches, give rise to many structures of the head and neck. |
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skeltal derivatives of 1st arch are |
2 parts mandibular and maxillary, Direct ossification of mesenchyme- maxillae, zygomatic, squamous portion of temporal bone and mandible. - from maxillary cartillage- alisphenoid and incus. from meckels cartillage- malleus. |
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musculature derivatives from 1st pharyngeal arch- and whats its nerve and artery |
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skeletal derivatives of second arch |
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musculature derivates of 2nd arch innervation and artery |
innervated by facial nerve artery is stapedial artery (foetal) |
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what is persistent stapedial artery |
occurs 1-2 in 10,000 usually asymptomatic, usually regresses as its foetal but if remains it can pulse next to eardrum causing noise. |
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Derivatives of 3rd arch |
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derivates of 4th and 6th arch |
1.skeletal - laryngeal cartillages,
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endoderma nd pharyngeal arches contribute to the mucous membrane and glands of the |
tongue, 1st arch- anterior 2/3 2nd arch - part of copula 3rd arch - mucosa of most posterior 1/3 tongue 4th arch - small apart of psterior tongue and epiglottis |
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what is ankyloglossia- |
failure of regression of attachement of ventral surface of the tongue to the floor of the mouth. leading to ankyloglossia |
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what else contributes to structures of the head and neck |
4 pharyngeal clefts, 4 pharyngeal pouches in lateral wall of pharynx. |
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only which cleft contributes to defintive structures |
only 1st pharyngeal cleft contributes to definitive structures. 1st cleft - external auditory meatus and part of tympanic membrane -------------------3 pharyngeal clefts are obliterated by expanding 2nd arch which fuses caudally with epicardial cartillage. |
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what are cervical (branchial) cysts |
swelling present on lateral surface of the neck that are remnants of the 2nd , 3rd and 4th clefts. |
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derivatives of the pharyngeal pouches |
1st pouch - tympanic cavity and auditory tube 2nd pouch - palatine tonsil 3rd- inferior parathyroid gland and thymus 4th - superior parathyroid gland and ultimobranchial body |
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thyroid gland first appears here |
in week 4 as an endoderm proliferation in the foramen caecum |
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how does the thyroid gland migrate |
it migrates into the neck along the thyroglossal duct, joined by the ultimobranchial body derived from the 4th pharyngeal pouch - c cells. - foramen caecum persists in adult and thyroglossal duct degnerates. |
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what is a thryoglossal cyst |
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