Week 1 Oral Facial Development and Abnormalities Flashcards
what are the 3 stages of human development and how long are each
proliferation period (0-3 weeks)
embryonic period (3-8 weeks)
fetal development period (9 weeks to term)
what happens in the proliferation period
-fertilization of ovum yields zygote
-mitotic cleavage of zygote forms blastomeres
-more than 32 blastomeres becomes a morula
-keeps dividing then is referred to as a blastocyst
-then travels down uterus and attaches to wall and is called an embryoblast
-inner cell mass of the embryoblast becomes bilaminar embryonic disc
-outer cell mass becomes the cytotrophoblast and syntrophoblast
what is a cyst
any mass that is lined with a cells and is hollow inside
when does implantation of the embryoblast in the uterine wall begin and complet
begins at day 4 and is complete at day 10
what layers are precursors to the placenta
cytotrophoblast and syntrophoblast
what are the layers of the bilaminar embryonic disc
epiblast and hypoblast
what makes up the epiblast layer
ectoderm and mesoderm
what makes up the hypoblast layer
endoderm
what are the structures associated with the bilaminar embryonic disc
epiblast layer
hypoblast layer
amniotic cavity
blastocyst cavity
syntrophoblasts
cytotrophoblasts
what forms Heuser’s membrane
enlargement of the amniotic cavity and migration of cells out of the hypoblast
what does Heusers membrane form
the internal lining of the blastocyst cavity now called the yolk sac
what are the cell layers in the proliferation period
epiblast, embryonic mesoderm, hypoblast
what are the embryonic cavities in the proliferation period
amniotic
yolk sac
chorionic
during the 3rd week of development, the bilaminar embryonic disc is characterized by the formation of what
-primitive streak
-notochord
-neural tube
what are the three distinct emrbyonic germ layers during the 3rd week of development
ectoderm, mesoderm, and endoderm
what does the ectoderm develop from
the epiblast layer
what does the endoderm develop from
hypoblast layer
what are the 3 features of the primitive streak
pit, node, and groove
what does the primitive node turn into
notochordal process -> notochord
how do pre-notochordal cells form the notochord
the cells invaginate within the primitive node and migrate towards the cephalad until they reach the prechordal plate. they then detach themselves from the ectodermal layer to line within the mesoderm forming the notochord
what does the notochord do
- functions as a primitive skeletal support of the embryo around which the axial skeleton later forms
- induces formation of somites, the precursor of the vertebral column, ribs, associated back muscles and the overlying dermis
what layer does the notochord form from
the ectoderm
what are the different parts of mesoderm
-paraxial mesoderm
-intermediate mesoderm
-lateral plate mesoderm
what are the 2 parts of the lateral plate mesoderm
visceral and parietal
what does the paraxial mesoderm form
somites
what does the intermediate mesoderm form
urogenital system
what does each part of the lateral plate mesoderm form
-parietal- mesothelial membranes that cover the peritoneal, pleural and pericardial cavities
- visceral- forms the thin serous membranes that cover individual organs
what are the derivatives of the ectoderm
-epidermic, hair and nails
-epithelium of the oral and nasal cavities and paranasal sinues
-salivary and endocrine glands
-nervous system
-tooth enamel
what are the derivatives of the endoderm
GI tract epithelium and associated glands
what happens when the neural tube does not form correctly
developmental defects in the brain and spinal cord
what are other names for neural crest cells
ectomesenchyme and neuroectoderm
what arches are seen during the embryonic period
branchial/pharyngeal arches
what does the 1st brachial groove form
external auditory canal
what does the 1st brachial pouch form
eustachian tube
what does the 2nd branchial pouch form
palatine tonsils
what does the 3rd brachial pouch form
inferior parathryoids/thymus
what does the 4th brachial pouch form
superior parathyroids/ultimobranchial body
what happens to the proportion of the head to the rest of the body from 3-9 months
the head stays the same size and the body growa
what are the processes in the development in the face
- mandibular process
- maxillary process
-lateral nasal process - median nasal process
what defective fusion results in cleft lip
medial nasal process with the maxillary process
when does the fusion of the medial nasal process and the maxillary process occur
5-6 weeks of gestation
what defective fusion results in cleft palate
the palatine shelves
when does fusion of the palatine shelves occur
8th-12th week of gestation
what is the incidence rate of combine cleft lip and palate, isolated cleft palate and isolated cleft lip
combined- 45%
isolated cleft palate- 30%
isolated cleft lip - 25%
what is the incidence of cleft palate alone
1 in 2,500
what substances are known to be involved in congenital malformation
-radiation
-chemicals
-drugs such as ethanol, tetracycline, dilantin, lithium, warfarin, methotrexate, androgens, progesterone, retinoic acid
where does the nasopalatine duct cysts occur
at line of fusion between palatine shelves and primary palate
what is the relation between clefts and arches
clefts are on inside, arches are on outside
why would a lateral cervical cyst/branchial fistula form
2nd bronchial archoesnt get resorbed and remains forming a cyst
what arches does the tongue develop from
1st-4th branchial arches
what is the intermediate structure and the adult structure of the 1st branchial arch
intermediate- median tongue and foramen cecum and lateral lingual swellings
adult- overgrown by lateral lingual swellings, origin of the thyroid ectoderm, anterior 2/3 of the tongue
what is the intermediate and adult structure of the second branchial arch
intermediate- copula/tuberculum impar
adult- overgorwn by the hypobranchial eminence
what is the intermediate and adult structure of the third branchial arch
intermediate- hypobranchial eminence
adult- posterior 1/3 of the tongue
what is the intermediate and adult structure of the fourth branchial arch
intermediate- minor contributions to the hypobranchial eminence
adult- none
what is the innervation and tongue structure of the first arch
innervation- trigeminal
tongue structure- sensory to the anterior 2/3
what is the innervation and tongue structure of the second arch
inneravtion- facial
tongue structure- special sensory to anterior 2/3 via the chorda tympani branch
what is the innervation and tongue structure of the third arch
innervation- glossopharyngeal
tongue structure- sensory to the posterior 1/3
what is the innervation and tongue structure of the fourth arch
innervation- vegas
tongue structure- sensory tot he extreme posterior 1/3 via the superior laryngeal branch
what is the innervation and tongue structure of the sixth arch
innervation: hypoglossal
tongue structure: motor to all tongue muscles
what is a thyroglossal duct cyst and where is it located
failure of thyroglossal duct to involute located in midline of the neck
what cartilage does each brachial arch form
1- Meckel’s cartilage - forms mandibe, maleus, incus
2- Reichart’s cartilage- forms stapes, styloid process, stylohyoid ligament, lesser horn of hyoid
3- greater horn of hyoid
4- thyroid cartilage
What causes median rhomboid glossitis
Result of a final infection
What does the neural tube become? Notochord?
Neural tube- brain and spinal cord
Notochord- vertebral column
What are derivatives of cranial neural crest cells
Odontoblasts, pharyngeal arch cartilages, connective tissue surrounding eye, dermis and hypodermics of face and neck, some cranial nerve ganglia
What are derivatives of spinal neural crest cells
Preaortic ganglia, adrenal medulla, dorsal root ganglia
What are lateral lingual swellings precursors for
Anterior tongue
What are hypobranchial eminence precursors for
Posterior tongue
