FinalEmbryo Flashcards by Patrick Robbins

2 Sections of 1st Pharyngeal Arch

Maxillary and mandibular prominences

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Stomodeum

Primitive oral cavity derived from ectoderm kind of in maxillary prominence of 1st pharyngeal arch

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Cranial Neural Crest Cells Action

Systematically populate areas forming face and pharyngeal arches

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6 Derivatives of Neural Crest Cells

Connective tissue/bones of face and skull
Cranial n.s
Sympathetic ganglia
Cells of thyroid gland
Odontoblasts
Dermis in face/neck

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4 Components of Each Pharyngeal Arch

1) Mesenchymal core derived from mesoderm and neural crest
2) an artery
3) a cranial nerve
4) Specific muscular & skeletal contributions to head and neck

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Primitive Aorta Branches Development

In the pharyngeal arch mesenchyme b/w pouches of the pharynx

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4.2 Cranial Nerve Pharyngeal Arch Origins

1st arch: V
2nd arch: VII
3rd arch: IX
4th and 6th arches: X (& cranial parts of spinal accessory XI)

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Arch Cartilages

Participate in bone formation in head/neck

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3 Derivations from Maxillary Process of 1st Arch

Maxilla, zygomatic process, part of temporal bone

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4 Derivations from Mandibular Process of 1st Arch

Meckel’s cartilage gives rise to intra-membranous mandibular bone, incus, and malleus

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6 Derivations from 2nd Pharyngeal Arch

Reichart’s cartilage gives rise to stapes, styloid process, stylohyoid ligament, and lesser horn/upper body of hyoid bone

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3rd Arch 2 Derivations

Lower body and greater horn of hyoid bone

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4th/6th arch Derivations

Laryngeal cartilages

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Difference b/w Pharyngeal Clefts and Pouches

Clefts invaginating in from outside, pouches invaginating out from inside

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4 Derivations of Pharyngeal Pouches/Arches

Tympanic cavity
Palatine tonsils
Thymus
Endocrine glands

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4 Migrating Pharyngeal Structures

Thyroid, thymus, parathyroids, and ultimobranchial bodies

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Parathyroid gland migration

Glands from 3rd pouch migrate past those from 4th pouch to become the inferior parathyroid glands

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Foramen cecum

Where thyroid migrates from

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Cervical cysts/fistulas (2)

Originate from embryonic clefts and reflect original positioning of branchial clefts

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2 Remnants/Complications of Thyroid Migration

Thyroglossal cysts - can be anywhere, 50% near hyoid though

Aberrant thyroid tissue - can remain anywhere, subject to same diseases as main body

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Tongue Formation

Consecutive regions develop front to back from tissues associated w/ 1st through 4th arches, explaining the V, VII, IX, X sensory pattern

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5 Prominences of Face Development

Frontonasal
2-3. Medial and lateral nasal
Maxillary
Mandibular

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Primary Palate Formation (action and 4 derivations)

Midline fusion of median nasal prominences (intermaxillary segment) contributes to philtrum of upper lip, upper jaw and 4 incisors, and primary palatal triangle

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Secondary Palate Formation Process (3)

1) Palatine shelves initially grow downward on either side of tongue
2) Tongue moves down and palatal shelves reach a horizontal position above it (w/out any fusion). Nasal septum grows down from above
3) Palatal shelves fuse with each other, primary septum, and nasal septum

Anterior Clefts

Result from failed fusion of maxillary prominences with lateral or medial nasal prominences

Posterior Clefts

From failure of palatine shelves to fuse

Anterior and Posterior Cleft Exclusivity

None, can occur together

Facial Cleft Path

Follow track of nasolacrimal duct

Midline Cleft

Relatively rare and associated w/ mental retardation and brain abnormalities

Most Dangerous Time for Birth Defects

3-8 weeks as organ systems developing

4 Factors Used to Assess Growth Rate via US

CR length, biparietal diameter of skull, abdominal circumference, and femur length

Normal Size Range at Delivery

2500-4000 g (6-9 lbs) and CRL of 51 cm (20 inches)

Amniocentesis

Chromosomal test done withdrawing 20-30 mL of amniotic fluid and thus only done after 14 weeks gestation

Intrauterine Growth Restriction (IUGR) (3)

Infants who do not obtain optimal intrauterine growth, are pathologically small, and are at risk for poor outcomes

Small for Gestation Age (SGA) (2)

Below 10th percentile for their gestational age. May have IUGR or may just be small/healthy, need to distinguish so as to not subject to IUGR protocol

Rubella

Viral teratogen now controlled by vaccine

Cytomegalovirus

Serious problematic viral teratogen w/ asymptomatic mothers and ill/defect/dying infants

Toxoplasmosis

Viral teratogen w/ brain defects that present immediately or later

Ionizing Radiation

Physical teratogen that can cause almost any defect depending on dose/stage of development

Thalidomide 2 Modern Uses

Immunomodulatory agent for AIDS and cancer

Thalidomide Teratogenic Effects (4)

Limb and heart defects Intellectual disability GI/Uro defects

FASD

Fetal alcohol spectrum disorder, incorporates entire range of alcohol-related disorders w/ FAS being most severe

FAS 3 Effects

Structural defects Growth deficiency Intellectual deficiency

Alcohol-related Neurodevelopmental Disorder (ARND)

Region of FASD spectrum involving CNS that doesn't meet criteria for FAS

Diethyl Stilbesterol (DES)

Endocrine teratogen - Synthetic estrogen used to prevent abortion, shown with reproductive organ malformation more severe in females

Modern Environmental Estrogens Exposures/Effects

Industrial chemicals/pesticides and affect sexual development, both anatomical and behavioral

Spinal Bifida

Neural tube defect failure of vertebral/spinal cord fusion, ranging from mild asymptomatic failure of sacral fusion to complete splaying of spinal cord

Failure of Cranial Neural Tube Closure

Leads to anencephaly w/ failure of both brain/cranium to develop

Folic Acid

Reduces occurrence of NTDs by 50-70%

5 Circulation Changes at Birth

Closure of umbilical arteries, umbilical vein, ductus venosus, ductus arteriosus, and foramen ovale

Apgar Score 5 Criteria

``` Appearance Pulse Grimace Activity Respiration ```

Apgar Score Times

Taken on 1st and 5th minute and later on if necessary

Apgar Apperance

Skin color/complexion - blue to no blue (0-2)

Apgar Pulse

Pulse rate, below 60 to over 100 (0-2)

Apgar Grimace

Reflex irratibility, no response to stimulation to sneeze/cough/pull away after stimulation (0-2)

Apgar Activity

Muscle tone - none to active movement (0-2)

Apgar Respiration

Breathing - absent to strong (0-2)

Apgar Grading Scale

<3 - critically low 4-6 - fairly low 7+ - generally normal

Apgar Interpretations

Critically low after 10/15/20 minutes may show increase risk of long-term neurological damage or cerebral palsy, but it doesn't necessarily make long-term predictions on child's health