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80 Cards in this Set
- Front
- Back
1. Pharyngeal (branchial arches)
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Are composed of mesoderm and neural crest cells.
They are formed by migration of neural crest cells around cores of mesoderm covered externally by ectoderm and internally by endoderm. Each arch has its own cartilaginous, muscular, vascular and nervous components. |
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2. Pharyngeal arch 1
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Forms the Meckel's cartilage which develops:
1. Malleus 2. Incus 3. Maxilla 4. Zygomatic and temporal squamous bones 5. Mandible Forms CN V (V2 and V3), which supply muscles of mastication and mylohyoid, digastric anterior belly, tensor veli palatini, and tensor tympani muscles. |
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3. Pharyngeal arch 2
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Forms the Reichert's cartilage, whch develops:
1. Stapes 2. Styloid process 3. Lesser horn and upper half of the hyoid bone Forms CN XII, which innervates muscles of facial expression and the digastric posterior belly, stylohyoid, and stapedius muscle. |
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4. Pharyngeal arch 3
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Forms the third arch cartilage which forms:
1. Greater horn and lower half of the hyoid bone Forms CN IX, which innervates the stylopharyngeus muscle |
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5. Pharyngeal arch 4
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Forms the fourth arch cartilage, which forms the laryngeal cartilages.
Forms CN X (superior laryngeal branch), which innervates the muscles of the soft palate (except the tensor veli palatini), muscles of the pharynx (except stylopharyngeus), and the cricopharyngeus muscle. |
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6. Pharyngeal arch 6
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Forms the sixth arch cartilage, which forms laryngeal cartilages
Forms CN X (recurrent laryngeal branch), which innervates the intrinsic muscles of the larynx (except cricothyroid), and the upper muscles of the esophagus |
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7. Pharyngeal pouches
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Are evaginations of the foregut endoderm.
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8. Pharyngeal pouch 1
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Forms the epithelium of the auditory tube (pharyngotympanic tube) and the middle ear cavity
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9. Pharyngeal pouch 2
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Forms the epithelium and crypts of the palatine tonsil
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10. Pharyngeal pouch 3
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Forms the inferior parathyroid gland and thymus
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11. Pharyngeal pouch 4
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Forms the superior parathyroid gland and the ultimobranchial (ultimopharyngeal) body
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12. Pharyngeal grooves (or clefts)
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Are four invaginations of the surface ectoderm between adjacent arches
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13. Pharyngeal groove 1
Grooves 2, 3, and 4 |
Gives rise to the epithelium of the external auditory meatus and skin over the tympanic membrane
Other grooves (2, 3, and 4) are obliterated |
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14. Pharyngeal membranes
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Are located at the junction of each pharyngeal groove and pouch
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15. Pharyngeal membrane 1
Membranes 2, 3, and 4 |
Pharyngeal membrane 1 gives rise to the tympanic membrane
Membranes 2, 3, and 4 are obliterated |
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16. Development of the thyroid gland
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1. The gland derives from median endodermal thickenings on the floor of the pharynx and is closely associated w/ the development of the tongue.
2. The thyroid descends from the pharynx to the neck and remains connected to the tongue via a thyroglossal duct. 3. The superior opening of the thyroglossal duct remains open as a small pit on the dorsum of the tongue - This pit is the foramen cecum |
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17. Branchial cysts/fistulas
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Occur when the second pharyngeal arch fails to grow caudally over the third and fourth arches, leaving remnants of the second, third and fourth grooves in contact with the surface by a narrow canal.
Such a defect results in a lateral cervical cyst directly anterior to the SCM muscle below the jaw. Fistulas have openings on the lateral aspect of the neck. |
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18. Branchial vestiges
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Normally, pharyngeal cartilages disappear; remnants of cartilage or bone elements under the skin anterior to the inferior 1/3 of the SCM muscle.
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19. Ectopic thyroid tissue
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The thyroid gland undergoes a migration from the oral cavity to the neck region.
It is common for remnants of thyroid tissue to remain along the course of migration. The parathyroids also undergo a migration and are highly variable in the their location. |
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20. Thyroglossal cysts and sinuses
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Thyroglossal cysts lie in the midline of the neck and are tubular remnants of the thyroglossal duct.
Are usually located close to or just inferior to the body of the hyoid bone. Sometimes they are connected to the outside by a fistulous canal, a thyroglossal fistula (sinus) |
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21. Treacher Collins syndrome
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Is a genetic defect involving the first arch
Characterized by: 1. Malar hypoplasia 2. Mandibular hypoplasia 3. Down-slanting palpebral fissures 4. Lower eyelid colobomas 5. Malformed external ears 6. Faulty dentition |
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22. Pierre Robin sequence
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Also involves the first arch.
Characterized by: 1. Micrognathia (small jaw) 2. Cleft palate 3. Glossoptosis (post. placed tongue) 4. External ear defects |
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23. DiGeorge anomaly
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Involves abnormalities with the heart, parathyroid glands, face, and thymus gland.
Affected individuals will have: 1. Congenital heart disease 2. Unusual facial features 3. Low set ears 4. Jawbone that recedes 5. Wide set eyes 6. Born w/o parathyroid glands |
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24. Goldenhar syndrome
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Includes a number of craniofacial abnormalities that usually involve the maxillary, temporal, and zygomatic bones, which are small and flat.
Defects in: 1. Ear (anotia, microtia) 2. Eye (tumors and dermoids in eyeball) 3. Vertebral (fused and hemivertebrae, spina bifida) 4. Cardiac abnormalities (tetrology of fallot and ventricular septal defects) |
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25. Anterior 2/3's of the tongue
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Develop from one median lingual swelling (tongue bud) and two lateral lingual swellings in the pharyngeal arch 1.
Lateral swellings grow over the median tongue bud and fuse and form the anterior 2/3's of the tongue |
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26. Posterior 1/3 of tongue
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Develops behind the foramen cecum from the copula ( from pharyngeal arch 2) and the hypopharyngeal eminence (from the mesoderm of the pharyngeal arches 3 and 4.
Terminal sulcus marks the division of the anterior 2/3 and posterior 1/3 of tongue. |
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27. Muscles of the tongue
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Most of the tongue muscles are derived from myoblasts athat migrate to the tongue region from occipital somites.
These somites are accompanied by the hypoglossal nerve (CN XII). |
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28. Tongue tie (ankyloglossia)
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The tongue is not freed from the floor of the mouth.
Normally, extensive cell degeneration occurs and the frenulum is the only tissue that anchors the tongue to the floor of the mouth. In the most common form of ankyloglossia, the frenulum extends to the tip of the tongue. |
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29. Development of the cranial base (cartilaginous neurocranium)
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Develops mainly by endochondral ossification
Contains cartilages: 1. Prechordial (mostly up front) 2. Parachordal (around back) 3. Hypophyseal (in center) |
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30. Development of the flat bones of skull (membranous neurocranium)
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Derives from neural crest cells
Formed by intermembranous ossification at the sides and top of the brain (calvaria) Has the significance of six fontanelles at birth |
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31. Development of the facial skeleton (membranous viscerocranium)
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Arises from the first arch (maxillary prominence) and neural crest cells
Forms mainly by intramembranous ossification so not from the cartilage of the first arch. |
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32. Summary of development of skull:
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Cranial base develops mainly from endochondral ossification
Cranial vault and facial skeleton develops mainly by intramembranous ossification Sutures are important sites of growth and allow bones to overlap during birth |
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33. Primary palate
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During the 6th week the primary palate forms from the intermaxillary segment (medial nasal prominences)
Is triangular in shape and forms the premaxillary part of the maxilla and holds the incisor teeth. |
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34. Secondary palate
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Also develops in the 6th week
Formed by fusion of the lateral palatine processes (palatal shelves) that develop from the maxillary prominences to form the hard palate Bone ceases to form in the secondary palate leaving a bone free soft palate and uvula |
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35. Acrania or anencephaly
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No calvaria, failure of cephalic part of neural tube to close.
As a result, the vault of the skull does not form, leaving the malformed brain exposed. Later this tissue degenerates, leaving a mass of necrotic tissue called anencephaly, although the brainstem remains intact. |
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36. Craniosynostosis
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Premature closing of the sutures; results in a skull w/peculiar shapes
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37. Scaphocephaly
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Sagittal suture closes
Skull is long and narrow |
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38. Oxycephaly
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Coronal suture closes
Skull is tall |
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39. Clover leaf skull
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Sagittal, coronal, and lambdoid sutures closed
Only squamous suture is still open between the temporal and parietal bones Skull is trilobate: one frontal protrusion and two postero-lateral protrusions |
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40. Microcephaly
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Cranial vault is smaller than normal. Fontanelles close early and sutures close during the first year.
Since the size of the cranium depends of the growth of the brain, underlying defects is in brain development. Often accompanied by severe mental retardation |
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41. Causes of microcephaly
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Fetal infection by toxoplasmosis may result in cerebral calcification, mental retardation, hydrocephalus, or microcephaly
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42. Causes of exancephaly, anencephaly, or acrania
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Brain develops outside of skull
Exposure to radiation during the early stages of development or hyperthermial by maternal infection or by sauna baths may cause spina bifida and exancephaly. |
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43. Microstomia
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Small mouth due to excessive merging of maxillary and mandibular prominences
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44. Clefts anterior to the incisive foramen (anterior clefts)
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1. Lateral cleft lip
2. Cleft upper jaw 3. Clefts between primary and secondary palates Due to a partial or complete lack of fusion of the maxillary prominence and intermaxillary segment (medial nasal prominence) |
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45. Clefts posterior to the incisive foramen (posterior clefts)
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1. Cleft (secondary palate)
2. Cleft uvula Cleft palate results from a lack of fusion of the palatine shelves; defective development of the secondary palate Cleft palates usually occurs in females and freq occur with other deformities, unlike cleft lip |
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46. Cleft lip
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Involves only the lip and may be bilateral; occurs in various degrees
1/1000; 80% of cases are male |
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47. Median (midline) cleft lip
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Rare; failure of the medial nasal prominences to merge and form intermaxillary segments
Usually accompanied by a deep groove between the right and left sides of the nose. Lost of midline structures may be so extensive that the lateral ventricles fuse (holoprosencephaly). Characteristic of Mohr syndrome |
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48. Oblique facial clefts
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produced by failure of the maxillary prominence to merge with its corresponding lateral nasal prominence.
When this occurs, the nasolacrimal duct is usually exposed to the surface |
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49. Positional plagiocephaly
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Flat head syndrome
Due to assymetric closure from physical deformations (car seat position) The skull becomes twisted |
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50. Development of external ear
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1. Pharyngeal groove 1 forms the external auditory meatus and tympanic membrane
2. Auricular hillocks form the auricle |
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51. Development of the middle ear.
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1. Pharyngeal arch 1 forms the incus, malleus, tensor tympani muscle and trigeminal nerve (CN V)
2. Pharyngeal arch 2 forms the stapes, stapedius muscle and facial nerve (CN VII) 3. Pharyngeal pouch 1 forms the auditory tube and middle ear cavity 4. Pharyngeal membrane 1 forms the tympanic membrane |
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52. Development of the internal ear
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Develops from the otic placodes (thickening of embryonic ectoderm), which invaginates to form the otic pit and otic vesicle (vesicle forms the otic capsule)
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53. Otic vesicle
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Gives rise to the membranous labyrinth and develops:
1. Utriclar portion 2. Saccular portion 3. Vestibular pouch 4. Cochlear pouch |
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54. Utricular portion
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Forms:
1. Utricle 2. Semicircular ducts 3. Vestibular ganglion on CN VIII |
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55. Saccular portion
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Forms:
1. Saccule 2. Cochlear duct 3. Spiral ganglion of CN VIII |
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56. Vestibular pouch
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Forms:
1. Semicircular canals 2. Utricle 3. Endolymphatic duct |
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57. Cochlear pouch
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Forms:
1. Saccule, which forms a diverticulum, that in turn, forms the cochlear duct |
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58. Otic capsule
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Develops from mesenchyme around the otic vesicle and forms:
1. Perilymphatic space (develops into the scala tympani and scala vestibule) 2. The cartilaginous part ossifies to form the bony labyrinth |
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59. Derivation of the tympanic membrane
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Derived from all three germ layers
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60. Minor deformities of the external ear
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The top of the ear should be in the same horizontal level as the corner of the eye.
Common; they are often associated with other anomalies |
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61. Auricular appendages
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Caused by the persistence of extra auricular hillocks
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62. Microtia
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Results from the absence of auricular hillocks and is characterized by the absence of the auricle; this defect is often associated w/other defects
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63. Preauricular pits or sinuses
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Small depression located anterior to the auricle.
Results from the abnormal closure of the first pharyngeal groove. Can become infected |
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64. Atresia of external auditory meatus
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During development of the external ear, there is a plug of cells situated in front of the tympanic membrane
These cells normally regress but if they fail to die, atresia occurs |
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65. Congenital deafness
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Caused by abnormal development of the membranous and bony labyrinths or by malformations of the auditory ossicles and eardrum.
Can be caused by: 1. Genetics 2. Rubella virus 3. Poliomyelitis 4. Erythroblastosis fetalis 5. Diabetes 6. Hypothyroidism 7. Toxoplasmosis |
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66. Development of the eye (neuroectoderm)
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Neuroectoderm from diencephalon evaginates to form the optic vesicle, which invaginates to form the optic cup and optic stalk.
This induces the ectoderm to thicken and form the lens placode. |
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67. Optic cup
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Forms:
1. Retina 2. Iris 3. Ciliary body |
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68. Optic stalk
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Forms the optic nerve
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69. Development of the eye (surface ectoderm)
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Invaginates to form the lens placode which forms the lens and anterior epithelium of the cornea
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70. Development of the eye (mesoderm)
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Forms:
1. Sclera 2. Portions of the cornea 3. Vitreous body 4. Extraocular muscles (from prechordal plate mesoderm or preotic somites) 5. Fibrous and vascular coats |
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71. Development of the eye (neural crest cells)
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Forms:
1. Choriods 2. Sphincter pupillae muscle 3. Dilator pupillae muscle 4. Ciliary muscle |
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72. Development of the eye (hyaloid artery and vein)
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Forms the central artery and vein of the retina
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73. Congenital retinal detachment
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The two layers of the retina (pigmented and neural) are separated by an intraretinal space
Normally, there is some degree of fusion between the two layer but if they fail to fuse during development the defect is congenital Can also be caused by a blow to the eye in which case fluid can accumulate and vision can be impaired |
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74. Coloboma
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This defect involves an improper closing of the choriod fissure resulting in a gap in the iris only (coloboma iridis) or in both the retina and iris.
May occur w/other eye defects or be present as a part of the renal coloboma syndrome (renal defects) |
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75. Persistent iridopupillary membrane
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The iridopupillary membrane may persist instead of being resorbed during the formation of the anterior chamber
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76. Cyclopia and synophthalmia
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Single eye (cyclopia) and fused eyes (synophthalmia) are due to a loss of midline tissue that may occur with an underdevelopment of the forebrain and frontonasal prominence.
Associated with cranial defects such as holoprosencephaly. Commonly occur with a midline proboscis superior to the fused eyes |
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77. Micophtalmia
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Indicated by a small, normal appearing eye or an eye that was arrested at some point during normal development.
May lack a lens |
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78. Anopthalmia
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Congenital absence of an eye or eye tissue.
Can only involve the optic stalk and may involve development of the forebrain which is usually accompanied by severe cranial abnormalities |
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79. Congenital glaucoma (cataracts)
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The lens becomes opaque during intrauterine life and results in an increased intraocular pressure.
Occurs due to a congenital defect in the draining mechanism (the scleral venous sinus) May arise in relation to a rubella infection during pregnancy |
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80. Congenital aphakia and aniridia
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Aphakia (absence of the lens) and aniridia (absence of the iris) are rare anomalies that are due to disturbances in induction and formation of tissues responsible for these structures.
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