Embryology Exam 3

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  1. Pharyngeal Arch I
    • Mandibular Arch
    • Nerve: CN V, Mandibular and Maxillary
    • Muscles: Mastication, mylohyoid, anterior digastric, tensor palatine, tensor tympani
    • Skeleton: Premaxilla, maxilla, temporal zygomatic, mandible, malleus, incus
  2. Pharyngeal Arch II
    • Nerve: CN VII Facial
    • Muscles: Facial expression, post. digastric, stylohyoid, stapedius
    • Bones: Stapes, styloid process, part of hyoid
  3. Pharyngeal Arch III
    • Nerve: CN IX
    • Muscles: Stylopharyngeus
    • Bones: Part of hyoid bone
  4. Pharyngeal Arch IV-VI
    • Nerve: CN X, superior laryngeal (IV), recurrent laryngeal (VI)
    • Muscles: Cricothyroid, levator palatine, pharyngeal constrictors, intrinsic muscles of larynx
    • Bones: Laryngeal cartilages (IV is thyroid cartilage, VI is cricoid cartilage)
  5. Treacher-Collins Syndrome
    • Auto-dom mutation on Chr. 5
    • Affects all Arch I structures
    • Downward slanting eyes, small lower jaw, malformed or missing ears
  6. DiGeorge Syndrome
    • Affects Arches I & II
    • Affects Pouches I, II, III, IV, V
    • CATCH-22 (22 chromosome)
    • C- Cardiac Defects
    • A- Abnormal facies
    • T- Thymic aplasia
    • C- Cleft Palate
    • H- Hypoparathyroidism
  7. Hemifacial Microsomia
    • Also called Goldenhar Syndrome (Oculo-Auriculo-vertebral syndrome)
    • Not heritable
    • 1st and 2nd arch defect
    • maxillary, temporal and zygomatic bones small
    • small mandible
    • anotia
    • microtia
    • tetrology of fallot
  8. Pharyngeal Clefts
    • Cleft I - external auditory meatus
    • Cleft II, III, IV - form cervical sinus (degenerates)
    • Persistent sinus can form a cist, or a fistula if it has an external opening
  9. Thyroid Gland
    • Starts at base of tongue and migrates inferior to laryngeal prominence
    • Thyroid forms as a part of a blind pouch, the thyroglossal duct, may persist as pyramidal lobe of the thyroid
    • Remnant is the foramen cecum of tongue
    • C-cells come from the 4th pharyngeal pouch
  10. Parathyroid migration
    Migrates to posterior surface of thyroid, inferior pair is III pouch, superior pair is IV pouch
  11. Ultimobranchial body
    Arises from 4th pouch, incorporates into thyroid gland as parafollicular cells (C) cells
  12. Thymus
    • Migrates from 3rd left and right pouch to anterior mediastinum
    • Ectopic Thymus: often misdiagnosed as tumor or cyst
  13. Pouch I
    • Tympanic cavity (middle ear cavity)
    • Auditory tube
  14. Pouch II
    • Palatine tonsils
    • Tonsillar fossa
  15. Pouch III
    Inferior parathyroid, thymus
  16. Pouch IV
    Superior parathyroid glands, parafollicular cells (ultimobranchial body) of thyroid
  17. Thyroglossal Cysts
    • May lie anywhere in midline along migratory path of thyroid
    • Most common is inferior to hyoid bone
    • Treatment with antibiotics
  18. Tongue
    • Develops from 2 lateral and 1 medial swelling (tuberculum impar)- Arch I
    • Second swelling (copula) forms from Arches II-IV
    • Third swelling forms from posterior IVth arch
    • Lateral swellings grow and form anterior 2/3rds of tongue, CN V innervation
    • Posterior 1/3 of tongue formed from arches II-IV receives sensory innervation from CN IX to arch III
  19. Ankyloglossia
    Short frenulum of tongue
  20. Bifid Tongue
    Lateral lingual swellings fail to fuse
  21. Macroglossia
    Big ass tongue
  22. Origin of bones in skull
    • Frontal: Neural Crest
    • Parietal: Paraxial mesoderm
    • Laryngeals: Lateral plate mesoderm
  23. Placodes
    Thickenings of neural crest-like cells that remain in surface of ectoderm to form neuroepithelium.
  24. Formation of Nose
    • 1. Nasal placode forms elevated nasal prominence
    • 2. Nasal pit forms in the center of prominence
    • 3. Line drawn through pit creates medial and lateral regions
    • 4. Nasolacrimal groove forms between maxillary and nasal prominence (gives rise to nasolacrimal duct and lacrimal sac)
    • 5. Right and left medial nasal prominence fuses to form upper lip
  25. Frontonasal Prominence
    Forms forehead and bridge of nose
  26. Maxillary Prominence
    Forms cheeks and lateral portion of upper lip
  27. Medial Nasal Prominence
    Forms philtrum of upper lip, crest and tip of nose
  28. Lateral nasal prominence
    Forms Alae of nose
  29. Mandibular Prominence
    Forms lower lip
  30. Dermatomes of Face
    • All trigeminal nerve
    • V1 (Ophthalmic) - Scalp, upper eyelid, conjunctiva and cornea of eye, bridge of nose
    • V2 (maxillary) - lower eyelid, cheeks, upper lip and alae of nose
    • V3 (mandibular) - lower lip and lower jaw
  31. Nasal Cavity formation
    • 1.  Nasal pit invaginates to form nasal cavity, stomodeum forms oral cavity, oronasal membrane separates cavities
    • 2.  Oronasal membrane disappears, medial nasal prominence forms primary palate
    • 3.  Maxillary prominence grows to form secondary palate
    • 4.  Neural crest cells form nasal placode
  32. Primary Palate Formation
    Forms from medial ingrowth of nasal prominences
  33. Formation of secondary palate
    • Two palatine shelves grow from maxillary prominences
    • Initially lateral to tongue and project obliquely downward
    • Secondary palate important for baby sucking
    • Tongue moves downward and palatine shelves project horizontally and meet at midline to form secondary palate
    • Incisive foramen is the midline landmark for junction of primary and secondary palates
    • Nasal septum grows inferiorly to contact superior surface of secondary palate
  34. Facial Clefts
    • Anterior Defects: anterior to incisive foramen
    • Posterior Defects: posterior to incisive foramen
    • Median cleft of lower lip: mandibular prominences don't fuse
    • Median cleft of upper lip: left and right medial nasal prominences fail to fuse
    • Complete unilateral cleft of upper lip and unilateral cleft of primary palate: failure of maxillary and medial nasal prominences to fuse
    • Bilateral cleft of secondary palate: failure of left and right palatine shelves to fuse
    • Bilateral oblique facial cleft with complete bilateral cleft lip and exposed nasolacrimal duct: failure of maxillary prominences to fuse to medial and lateral nasal prominences
  35. Macrostomia
    Mouth extends far laterally, failure of maxillary and mandibular prominences to fuse
  36. Microstomia
    Small mouth, excessive fusion of maxillary and mandibular prominences
  37. Dental Formula
    I2 C2 P2 M3
  38. Developing tooth
    • -Oral ectoderm invaginates to form dental lamina which develops into cup shaped structure
    • -Ectomesenchyme condenses adjacent to ectoderm
    • -Enameloblasts secrete enamel
    • -Odontoblasts secrete dentin
    • -kid tooth forms first, permanent tooth froms from a bud in the dental lamina
    • -dental lamina will degenerate
  39. Inner enamel epithelium forms:
    Enameloblasts: enamel
  40. Ectomesenchyme forms:
    Odontoblasts (dentin) and Pulp
  41. Apical Foramen of Tooth
    -Opening of root of tooth where nerves and blood vessels enter pulp
  42. Cementum
    Mesenchymal cells in contact with dentin of tooth differentiate to cementoblasts which secrete cementum, anchored in bony sockets called alveoli.
  43. Peridontal ligament
    • Layer of connective tissue attaches cementum to alveolar bone
    • Sharpey's fibers attach the periodontal ligament to both cementum and alveolar bone
    • When tooth erupts, ameloblasts undergo apoptosis leaving the enamel exposed to the exterior
    • Periodontal ligament anchors tooth to underlying bonem allows tooth to move a little bit, to flow and change position
  44. Febrile diseases (fever) on tooth causes:
    hypocalcification of enamel
  45. Effect of tetracycline on tooth
    leads to brown bands of enamel in teeth
  46. Excess fluoride effect on tooth
    fluorosis results in mottled enamel in children
  47. TORCH
    • Toxoplasmosis
    • Rubella
    • CMV
    • Herpes
  48. Isotretinoin Birth effects
    CNS malformations, microtia, cardiac defects, thymic hypoplasia
  49. Tobacco
    Reduced fetal growth, polycythemia
  50. Cocaine
    Vascular disruptive events, cerebral infarction, urogenital anomalies, limb reduction defects
  51. Valproic Acid
    Midface hypoplasia, spina bifida, cardiac defects
  52. Neonatology
    Sick newborns
  53. Perinatology
    Pregnant women and their fetuses
  54. Gestational Age
    number of weeks of a pregnancy from the first day of the mother's last menstrual period to the date of birth
  55. Prematurity
    Birth before 37 weeks gestation
  56. Postmaturity
    Birth after 42 weeks gestation
  57. Neonate
    Infant between 0-28 days of birth
  58. Alpha-fetoprotein Risks
    • High - Neural Tube defects, multiple gestations
    • Low - Trisomies 18/21 and intrauterine growth restriction
  59. Triple Marker
    • AFP (alpha fetoprotein)
    • Unconjugated estriol
    • Beta HCG
  60. Trisomy 21 Triple Marker
    Low AFP, Low unconjugated estriol, high HCG
  61. Trisomy 18 Triple Marker
    Low AFP, low unconjugated estriol, low HCG
  62. Development of the Eye
    • Lens placode invaginates to form lens vesicle
    • Optic cup forms around lens vesicle, forming retinal fissure
    • Lens is initially hollow, but fills in later
  63. Optic Stalk Differentiation
    Become ganglion cells of the retina
  64. Fate of Hyaloid Artery and Vein
    • Become the retinal artery/vein
    • Retinal fissure begins to close, trapping the hyaloid vessels
    • Axons of the ganglion cells surround central artery and vein, forming optic nerve
    • As optic stalk matures, distal portions of hyaloid vessels degenerate, but proximal portions persist as central artery and vein of retina
  65. Colobomas
    • Missing structures of the eye: iris, retina, choroid, or optic nerve
    • Occurs if a fissure doesn't close properly
    • If the retinal/choroid fissure persists, a cleft in the iris forms called a coloboma iridis.

    Can be linked to Renal Disease (Renal coloboma syndrome thorugh mutation in PAX2)
  66. Scleral Venous Sinus
    Ciliary processes produce aqueous humor that flows from posterior chamber of the eye to anterior chamber, drains into scleral venous sinus (chamber of schlemm).  Blockage results in Glaucoma
  67. Glaucoma
    • Pressure the eye
    • 1. Closed angle: angle between cornea and iris becomes too narrow
    • 2. Open angle: canal of schlemm blocked so you don't get drainage
  68. Development of chambers of eye
    Mesenchyme surrounding eye produces most of remaining structures
  69. Iridopupillary membrane
    • Forms from mesenchyme posterior to the anterior chamber
    • Degenerates to form opening of the pupil
    • Persistant iridopupillary membrane
  70. Cornea
    • Avascular, outer cornea is simple squamous non-keratinized epithelium
    • Epithelium of cornea forms from surface ectoderm
    • Dense CT of cornea forms from mesenchyme anterior to anterior chamber
  71. Clouding of eyeball
    • Corneal: Results from congenital glaucoma due to abnormal formation of scleral venous sinus, rubella infection, or mutation in CYP1B1
    • Lens: can be caused by rubella, radiation, congenital galactosemia
  72. Synopthalmia/Cyclopia
    • Fusion of eyes due to underdeveloped frontonasal prominence
    • Associated with holoprosencephaly
    • Can be caused by maternal diabetes, alcohol
  73. Retina Germ Layer
    Outer and inner layer of optic up (neuroectoderm)
  74. Iris and Ciliary body (lining) Germ Layer
    Outer and inner layer of optic cup (neuroectoderm)
  75. Iris and ciliary body (stroma), dilator and constrictor muscles Germ Layer
  76. Choroid Germ Layer
  77. Sclera Germ Layer
  78. Lens Germ Layer
    Surface Ectoderm
  79. Cornea (anterior epithelium) Germ Layer
    Surface Ectoderm
  80. Cornea (dense CT) Germ Layer
  81. Vitreous Body Germ Layer
  82. Eyelids Germ Layer
    Surface ectoderm with core of mesenchyme
  83. Inner Ear Germ Layer
    Surface Ectoderm (otic placode)
  84. Membranous Labyrinth
    • Filled with endolymph
    • Inside temporal bone
    • Inside Bony labyrinth
    • Formed from otic placode
    • Mesenchyme surrounding the labyrinth will vacuolize to form scala vestibuli and scala tympani
  85. Bony Labyrinth
    • Filled with perilymph
    • Surrounds membranous labyrinth
  86. Otic Placode
    • Invaginates to form otic vesicle
    • Superior portion of vesicle: utricle and endolymphatic duct (cochlea)
    • Inferior portion of vesicle: saccule
    • Otic vesicle gives rise to organ of corti, basilar membrane and vestibular membrane
  87. Function of Saccule
    Linear acceleration, gravity, tilt of head
  88. Function of Utricle
    Linear acceleration, gravity, tilt of head
  89. Function of semicircular canals
    • Angular acceleration
    • Form by flattening 3 parts of utricle, eventually the walls undergo apoptosis forming 3 circular canals
  90. Function of cochlea
  91. Cochlea Development
    Curving growth of narrow process of saccule
  92. Organ of Corti
    • Ep. Cells of cochlear duct form 2 ridges separated by groove.
    • Outer Ridge: forms row of inner hair cells and 3-4 layers of outer hair cells (tips of hair cells embedded in tectorial membrane)
    • Impulses travel by cranial nerve VIII
  93. Perilymph Drainage
    Drains into subarachnoid space
  94. Endolymph drainage
    Drains into endolymphatic duct, which drains into venous sinuses of cranial dura
  95. Decidua
    • Functional layer of endometrium that is shed during birth
    • Consists of: Basalis, capsularis, and parietalis
  96. Two parts of Placenta
    • 1. Chorionic Frondiosum (fetal part from chorion)
    • 2. Decidua Basalis (maternal part from endometrium)
  97. Can't cross placenta
    Bacteria, Heparin, IgS, IgM
  98. Breech position
    umbilicus wrapped around abdomen, head in wrong orientation
  99. Placenta Previa
    Covers internal os
  100. Placenta Accreta
    Placenta grows up to myometrium
  101. Placenta Increta
    Placenta grows into myometrium
  102. Placenta Percreta
    Placenta grows into perimetrium
  103. Placenta Abruptio
    Placenta separates from uterine wall
  104. Functions of Amniotic Fluid
    • Lung development
    • Fluid and electrolyte homeostasis
    • Shock absorber
    • Barrier to infection
    • Maintains temperature
  105. Amniotic fluid circulation
    Before 11 weeks, swalled by fetus and wastes pass from fetus by skin, respiration or GI tract

    After 11 weeks, fetus excretes urine into amniotic fluid
  106. Hydrops Fetalis
    • Excessive fluid due to imbalance/hemolysis of fetal red blood cells by maternal antibodies
    • Distends abdomen due to accumulation of ascites in peritoneal cavity
  107. Polyhydroamnios/Oligohydroamnios
    • Polyhydroamnios: Excess fluid in sac
    • Oligo: too little amniotic fluid
  108. Amniotic band syndrome
    • Fetus is entangled with strands of amniotic bands that are fibrous and string-like
    • It is a disruption
  109. Fetus Papyraceus
    Growth of one twin compresses a second mummified twin against the uterus
  110. Twin Transfusion Syndrome
    Monochorionic/diamniotic - arterial blood from one twin shunted to other twin
  111. Parturition
    Fetal hypothalamus secretes corticotropic releasing hormone, stimulating release of cortisol from fetal adrenal cortex, increases estrogen production, which releases prostaglandins and oxytocin that increase intensity of contraction of uterine smooth muscle.
Card Set
Embryology Exam 3
How babies are born, son.
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