test 7 Flashcards
when does prenatal development begin
how is it divided
- begins at the start of pregnancy and continues until the birth of the child
- 9 months of gestation divided into 3 trimesters
what periods make up each trimester
first trimester: preimplantation period AND embryonic period
second and third trimester: fetal period
define primordium
earliest indication of a tissue or an organ during prenatal development
developmental disturbances can include ________ which are evident at ______
most occur during both ____ and _____
Such malformations occur in _____ cases
One of leading causes of _____
developmental disturbances can include CONGENITAL MALFORMATIONS which are evident at BIRTH
most occur during both PREIMPLANTATION PERIOD and EMBRYONIC PERIOD
Such malformations occur in 3/100 cases
One of leading causes of INFANT DEATH
what causes malfomation
- genetic factors (chromosome abnormalities)
- environmental agents/factors
what are teratogens
environmental agents and factors including infections, drugs, chemicals, and radiation
examples of teratogens
drugs: ethanol (alcohol), tetracycline, lithium, methotrexate, warfarin, thalidomide, androgens, progesterone
chemicals: methymercury, polychlorinated biphenyls
infections: rubella virus, syphilis spirochete, herpes simplex, human immunodeficiency
radiation: high levels of ionizing radiation
pregnant women and dental xrays`
diagnostic levels of radiation should be avoided but have not been directly linked to congenital malformations
if xrays are needed, wear proper lead gear and minimize exposure
PREIMPLANTATION PERIOD
______ week after conception
______ meets ______ during fertilization
Union of ovum and sperm forms a _______
During fertilization, the final stages of ______ occur in the _____
FIRST week after conception
OVUM meets SPERM during fertilization
Union of ovum and sperm forms a FERTILZIED EGG (ZYGOTE)
During fertilization, the final stages of MEIOSIS occur in the OVUM
PREIMPLANTATION PERIOD
The result of this process is joining of ovum’s _______ with those of the sperm
Joining of chromosomes from both biological parents forms a new individual with “_________” chromosomes
To allow this formation of a new individual, the sperm and ovum, when joined, have proper number of chromosomes (from diploid number of ___)
If both these cells carried the full complement of chromosomes:
- Fertilization would result in a zygote with ___ the proper number
- Result is severe ________ and/or _____
The result of this process is joining of ovum’s CHROMOSOMES with those of the sperm
Joining of chromosomes from both biological parents forms a new individual with “SHUFFLING” chromosomes
To allow this formation of a new individual, the sperm and ovum, when joined, have proper number of chromosomes (from diploid number of 46)
If both these cells carried the full complement of chromosomes:
- Fertilization would result in a zygote with 2 TIMES the proper number
- Result is severe MALFORMATINS and/or PRENATAL DEATH
KARYOTYPE
The _______ of a person’s chromosomes is done by ______ arrangement of the pairs in a karyotype, with the sex known by the presence of either having ___ chromosomes for females or ___ for males
The PHTOGRAPHIC ANALYSIS of a person’s chromosomes is done by ORDERLY arrangement of the pairs in a karyotype, with the sex known by the presence of either having XX chromosomes for females or XY for males
PREIMPLANTATION PERIOD
After fertilization:
Zygote undergoes _______ (individual cell division or _____)
Ongoing process of ______ and secretion of
fluid by the cells
Zygote becomes a vesicle known as a _________
After fertilization:
Zygote undergoes MITOSIS (individual cell division or CLEAVAGE)
Ongoing process of MITOSIS and secretion of
fluid by the cells
Zygote becomes a vesicle known as a BLASTOCYST
what are the hourly/daily stages of growth of a zygote
zygote: 12-24 hours
2 cells: 30hours
4 cells: 40-50 hours
8 cells: 60 hours
16 cells: 4 days
blastocyst: 5 days
implantation 6 days
PREIMPLANTATION PERIOD
describe implantation in 3 steps
- blastocyst approaches endometrium
- trophoblasts invade endometrium
- endometrial tissue grows over the blastocyst to complete implantation
what developmental disturbances can occur during the PREIMPLANTATION PERIOD
down syndrome (trisomy 21)
DOWN SYNDROME
Disturbances in ______ (during fertilization)
Major congenital malformations result from
_______ abnormality
___% of cases
Example: Down syndrome (_______), where _____ chromosome number 21 is present after meiotic division
Disturbances in MEIOSIS (during fertilization)
Major congenital malformations result from
CHROMOSOMAL abnormality
10% of cases
Example: Down syndrome (TRISOMY 21), where EXTRA chromosome number 21 is present after meiotic division
what are the physical differences in patients with down syndrome (6)
- epicanthic folds
- flat, broad face
- widely spaced eyes
- oblique eyelid fissures
- flat bridged nose
- furrowed lower lip
CLINICAL CONSIDERATIONS FOR PATIENTS WITH DOWN SYNDROME
Eruption patterns ______ and may occur in an
______ order; Delay may be as long as _____
Patient may have altered ____; not enough
______ to chew some foods
High rate of _______
- Other irregularities: (7)
Eruption patterns DELAYED and may occur in an UNUSUAL order; Delay may be as long as 2-3 YEARS
Patient may have altered DIET; not enough
TEETH to chew some foods
High rate of MISSING TEETH (primary and permanent)
Other irregularities:
1. microdontia/malformed teeth
2. underdeveloped midface/jaw
3. severe crowding for those who have all their permanent teeth
4. small/conical roots (more likely to have perio disease)
5. tongue may protrude/ macroglossia
6. narrow palatal arch/high palatal vault
7. less space for tongue, affects speech and mastication
what is the second period in prenatal development
when does it occur
EMBRYONIC PERIOD
beginning of the second week to the end of the eighth week
EMBRYONIC PERIOD
Certain _______ processes or spatial and
temporal events called _____ occur during
this period
Physiological processes that facilitate _______
Certain PHYSIOLOGICAL processes or spatial and temporal events called PATTERNING occur during this period
Physiological processes that facilitate FURTHER DEVELOPMENT
induction
proliferation
differentiation
morphogenesis
maturation
induction: action of one group of cells on another that leads to the establishment of the developmental pathway in the responding tissue
proliferation: controlled by cellular growth and accumulation of byproducts
differentiation: change in identical embryonic cells to become distinct structurally and functionally
morphogenesis: development of specific tissue structure or differing form due to embryonic cell migration and inductive interactions
maturation: attainment of adult function and size due to proliferation, differentiation, and morphogenesis
EMBRYONIC PERIOD
describe induction (4)
- first physiological process
- action of one group of cells on another (responding tissue)
- establishment of the developmental pathway
- “game plan”
EMBRYONIC PERIOD
Describe proliferation (3)
- after/follows induction
- dramatic process of controlled levels of cellular growth
- present during most prenatal development
EMBRYONIC PERIOD
what are the two types of growth during proliferation
interstitial: occurs from deep WITHIN a tissue or organ
appositional: tissue enlarges its size by the ADDITION OF NEW LAYERS on the OUTSIDE of a structure (increases thickness)
EMBRYONIC PERIOD
describe differentiation (3)
- change occurring in genetically identical embryonic cells which later become distinct functionally and structurally
- occurs at various rates in the embryo
- many parts of the embryo are affected: cells, tissue types, organs, and systems
EMBRYONIC PERIOD (SECOND WEEK)
Implanted blastocyst grows by:
1) Increased _______ of the embryonic cells
2) _______ also occurring
3) Resulting in cellular _______
Every ridge, bump, and recess now indicate these increased levels of ________
Increased number of embryonic cells = creates
the embryonic cell layers (________) within the _______
Implanted blastocyst grows by:
1) Increased PROLIFERATION of the embryonic cells
2) DIFFERENTIATION also occurring
3) Resulting in cellular MORPHOGENESIS
Every ridge, bump, and recess now indicate these increased levels of CELLULAR DIFFERENTIATION
Increased number of embryonic cells = creates
the embryonic cell layers (GERM LAYERS) within the BLASTOCYST
what are the germ layers
ectoderm, mesoderm, endoderm, neural crest cells
*neural crest cells are not present in the embryonic disc until later in the 3rd week
ECTODERM
- origin
- morphology
- future structures
- epiblast layer
- columnar cells
- epidermis, sensory epithelium of eyes, ears, nose, mammary and cutaneous glands
MESODERM
- origin
- morphology
- future structures
- migrating cells from the epiblast layer
- varies
- dermis, muscle, bone, lymphatics, blood cells, bone marrow, cartilage, reproductive organs
ENDODERM
- origin
- morphology
- future structures
- hypoblast layer
- cuboidal
- respiratory and digestive system linings, liver and pancreatic cells
NEURAL CREST CELLS
- origin
- morphology
- future structures
- migrating neuroectoderm
- varies
- components of the nervous system, pigment cells, connective tissue proper, cartilage, bone, certain dental tissues
SECOND WEEK
the bilaminar embryonic disc is developed from what
how does it appear
what are the layers
developed from the blastocyst
appears as a flattened circular plate of bilayered cells
Superior layer/epiblast layer: made of high columnar cells
inferior layer/hypoblast layer: made of small cuboidal cells
SECOND WEEK
____ and developing _____ circulation
Permit selective exchange of soluble ________ substances between ________ and _______
Includes: (4)
PLACENTA and developing UMBILICAL circulation
Permit selective exchange of soluble BLOODBORNE substances between PREGNENT WOMEN and DEVELOPING EMBRYO
Includes OXYGEN, CARBON DIOXIDE, AND NUTRITIONAL/HORMONAL SUBSTANCES
EMBRYONIC PERIOD (THIRD WEEK)
at the beginning of the third week:
______ forms within the _______
PRIMITIVE STREAK forms within the BILAMINAR EMBYONIC DISC
THIRD WEEK
Embryonic connective tissue comes from _____ cell layers
Become _____ cells
Mesenchymal cells have potential to ______ and _______ into diverse types of _________
Forming cells (such as ________)
Embryonic connective tissue comes from MIGRATORY cell layers
Become MESENCHYME cells
Mesenchymal cells have potential to PROLIFERATE and DIFFERENTIATE into diverse types of CONNECTIVE TISSUE
Forming cells (such as FIBROBLASTS, CHONDROBLASTS, AND OSTEOBLASTS)
Mesenchyme: (mesenchymal connective tissue) is an example of _______ connective tissue, a type of _______ connective tissue, which is derived from _______ embryonic (or _____) layers and located _______ the embryo.
Mesenchyme: (mesenchymal connective tissue) is an example of RETICULAR connective tissue, a type of LOOSE connective tissue, which is derived from ALL THREE embryonic (or GERM) layers and located WITHIN the embryo.
THIRD WEEK
Some of this tissue begins to create a new embryonic cell layer= ______
With three layers present, the bilaminar disc has become thickened into a _______ embryonic disc
Some of this tissue begins to create a new embryonic cell layer= MESODERM
With three layers present, the bilaminar disc has become thickened into a TRILAMINAR embryonic disc
zygote > blastocyst > _______
GASTRULA
THIRD WEEK
after the formation of the trilaminar disc, it now has:
cephalic end and caudal end
what is the cephalic end (3)
- head end
- contains oropharyngeal membrane
- consists of only ectoderm and endoderm
THIRD WEEK
During the later part of the third week, the ______ begins to develop in the embryo
Many steps occur during this week to form the beginnings of the ______ and _______
During the later part of the third week, the CENTRAL NERVOUS SYSTME begins to develop in the embryo
Many steps occur during this week to form the beginnings of the SPINAL CORD and BRAIN
THIRD WEEK
Specialized group of cells differentiates from the _____ and is now considered _______
These cells are localized to _____ of the embryo
Neural plate:
Plate undergoes further _______ and ______
It deepens and folds ____, forming the ______
Specialized group of cells differentiates from the ECTODERM and is now considered NEUROECTODERM
These cells are localized to NEURAL PLATE of the embryo
Neural plate: central band of cells that extend from cephalic end to caudal end
Plate undergoes further GROWTH and THICKENING
It deepens and folds INWARD forming the NEURAL GROOVE
THIRD WEEK
near the end of the third week, the _______ deepens further and is surrounded by _____
further growth of the _______ occurs
______ is formed through _____ of the most ____ part of the structure
near the end of the third week, the NEURAL GROOVE deepens further and is surrounded by NEURAL FOLDS
further growth of the NEUROECTODERM occurs
NEURAL TUBE is formed through FUSION of the most SUPERIOR part of the structure
describe the development of the central nervous system in 3 steps
- neuroectoderm forms from the ectoderm and is located at the neural plate
- the neural plate thickens to form the neural groove and is surrounded by neural folds
- folds meet and fuse, forming a neural tube
THIRD WEEK
by the end of the third week, the ______ additionally differentiates and begins to ____ on each side of the tube into ____ paired ______ segments of mesoderm, forming the _______
by the end of the third week, the MESODERM additionally differentiates and begins to DIVIDE on each side of the tube into 38 paired CUBOIDAL segments of mesoderm, forming the SOMITES
EMBRYONIC PERIOD (FOURTH WEEK)
Disc undergoes _______
- Establishing an ____
- Places forming tissue types into their proper _____
Producing a somewhat ______ embryo
Folding results from extensive ______ of the _____ and _______ of basic tissue types
Initially occurs mainly at ______ end (where ____ will form)
Tissue grows beyond the __________ to overhang the developing ______
Disc undergoes EMBRYONIC FOLDING
- Establishing an AXIS
- Places forming tissue types into their proper POSITIONS
Producing a somewhat TUBULAR embryo
Folding results from extensive PROLIFERATION of the ECTODERM and DIFFERENTIATION of basic tissue types
Initially occurs mainly at CEPHALIC end (where BRAIN will form)
Tissue grows beyond the OROPHARYNGEAL MEMBRANE to overhang the developing HEART
FOURTH WEEK
Folding due to increased growth occurs not only at the cephalic end but also at the _____ end and at the sides of the embryo ________
Folding at both positions of the embryonic cell layers take on a more _______ placement for the further development of the embryo
Folding due to increased growth occurs not only at the cephalic end but also at the CAUDAL end and at the sides of the embryo SIMULTANEOUSLY
Folding at both positions of the embryonic cell layers take on a more RECOGNIZABLE placement for the further development of the embryo
what happens AFTER folding of the disc (4)
- endoderm lies inside the ectoderm
- mesoderm fills the area between the two layers
- creates a hollow tube lined by endoderm from the cephalic to caudal end of the embryo
- this tube is the future digestive tract and is separated into the foregut, midgut, and hindgut
FOLDING OF THE EMBRYO
________ disc has folded into the embryo as a result of extensive growth of the _______
______ is thus inside the ectoderm
________ filling in the areas between these two tissue types (Developing _____,______, AND____)
TRILAMINAR disc has folded into the embryo as a result of extensive growth of the ECTODERM
ENDODERM is thus inside the ectoderm
MESODERM filling in the areas between these two tissue types (Developing BRAIN, HEART, AND DIGESTIVE TRACT)
DEVELOPMENT OF THE PHARYNX
anterior part of tube =
posterior parts (2) of tube =
anterior part = foregut (forms the primitive pharynx)
posterior parts = midgut and hindgut (form the rest of the mature pharynx and remainder of the digestive tract)
During development of the digestive tract, ____ pairs of pharyngeal pouches will form on the _____ lining the pharynx
During development of the digestive tract, FOUR pairs of pharyngeal pouches will form on the LATERAL WALLS lining the pharynx
FOURTH WEEK
finally during the fourth week, the _______ begin to develop: (5)
finally during the fourth week, the FACE AND NECK begin to develop: PRIMITIVE EYES, EARS, NOSE, ORAL CAVITY, AND JAW AREAS
what is the most critical period of prenatal development and why
what can occur
the EMBRYONIC period because the beginnings of all essential external and internal structures are formed during this period
developmental disturbances occurring during this period may give rise to major congenital malformations of the embryo
what developmental disturbances can occur during the EMBRYONIC PERIOD
- ectodermal dysplasia: abnormal development of one or more structures from the ectoderm
- partial or complete anodontia: absent teeth, teeth that are present have disturbances
- treacher collins syndrome: failure of migration of neural crest cells to the facial region in the embryo
- syphilis: produces Hutchinson’s incisors, mulberry molars, blindness, deafness, and facial paralysis
what is the clinical appearance of treacher collins syndrome
- failure of full facial development
- downward slanting eyes
- micrognathia (small jaw)
- hearing loss
- underdeveloped zygomatic bone
- drooping of lateral lower eyelids
- malformed or absent ears
bacterial spirochete of syphilis is an example of what
infective teratogen
FETAL PERIOD
- when does it start
- what is the time frame
- what occurs
- what processes are involved
- after the embryonic period
- beginning of the nineth week (third month) until the nineth month
- maturation of existing structures; embryo becomes a fetus
- the physiological process of MATURATION of the individual tissue types and organs. As well as proliferation, differentiation, and morphogenesis
what developmental disturbance can occur during the FETAL stage, describe it
TETRACYCLINE STAIN
- systemic tetracycline antibiotic therapy of the pregnant female can act as a teratogenic drug during the fetal period
- can result in tetracycline stains within the child’s primary teeth that are developing during this time
when does facial development occur (what period)
what layers are involved in facial development
rapid growth of _____
embryo does what
embryonic period
all 3: ectoderm, mesoderm, and endoderm
rapid growth of the BRAIN
embryo bulges over the OROPHARYNGEAL MEMBRANE and developing heart
Most of the facial tissues develop by _____ of swellings or tissue on the _____ surface of the embryo.
A _______ is initially located between these adjacent swellings due to _____, ______, and ______
Most of the facial tissues develop by FUSION of swellings or tissue on the SAME surface of the embryo.
A CLEFT OR FURROW is initially located between these adjacent swellings due to PROLIFERATION, DIFFERENTIATION, and MORPHOGENESIS
STOMODEUM AND ORAL CAVITY FORMATION
The primitive mouth is now the ______
- Initially appeared as a shallow depression in the embryonic surface ______ at the _____ end before the _____ week
At this time, the stomodeum is limited in depth by the __________
- The membrane separates the stomodeum from ________
The primitive pharynx is the _____ part of the _____, the beginning of the future digestive tract
The primitive mouth is now the STOMODEUM
- Initially appeared as a shallow depression in the embryonic surface ECTODERM at the CEPHALIC end before the FOURTH week
At this time, the stomodeum is limited in depth by the OROPHARYNGEAL MEMBRANE
- The membrane separates the stomodeum from the PRIMITIVE PHARYNX
The primitive pharynx is the CRANIAL part of the FOREGUT, the beginning of the future digestive tract
formation of the stomodeum and oral cavity in 3 steps
- disintegration of the oropharyngeal membrane which enlarges the stomodeum of the embryo
- allows access between the primitive mouth and the primitive pharynx
- mandibular processes fuse, forming the mandibular arch inferior to the enlarged stomodeum
MANDIBULAR ARCH AND LOEWR FACE FORMATION
forms after formation of the ______
Two bulges of tissue appear inferior to the _______, they are the ________
these paired mandibular processes then fuse at the ________ to form the ______
the mandibular arch is the future ________
forms after formation of the STOMODEUM
Two bulges of tissue appear INFERIOR to the PRIMITIVE MOUTH, they are the MANDIBULAR PROCESSES
these paired mandibular processes then fuse at the MIDLINE to form the MANDIBULAR ARCH
the mandibular arch is the future MANDIBLE
MANDIBULAR ARCH AND LOWER FACE FORMATION
Interesting fact: midline on mature bony mandible is the _________. Indicating where the mandible is formed by _____ of right and left ________
In the future, the mandibular arch directly gives rise to: (3)
Interesting fact: midline on mature bony mandible is the MANDIBULAR SYMPHYSIS. Indicating where the mandible is formed by FUSION of right and left MANDIBULAR PROCESSES
In the future, the mandibular arch directly gives rise to:
- lower face
- lower lip
- mandibular teeth
FRONTONASAL PROCESS AND UPPER FACE FORMATION
During this _____ week, the frontonasal process also forms as a _____ of tissue in the ______ facial area
This process is at the most ____ end of the embryo and is the ________ of the _______.
During this FOURTH week, the frontonasal process also forms as a BULGE of tissue in the UPPER facial area
This process is at the most CEPHALIC end of the embryo and is the CRANIAL BOUNDARY of the STOMEDEUM.
PLACODE DEVELOPMENT
what are placodes
where are they located
gives an example
placodes: specialized, thickened ECTODERM found at the location of developing special sense organs
located on the outer surface of the embryo
EXAMPLE: 2 lens placodes that are initially located fish like on each side of the frontonasal process
NOSE AND PARANASAL SINUS FORMATION
During the _____ week
_________ on the frontonasal process undergoes growth
Placodes become ________ forming a depression in the center of each placode, the _____
________ are two crescent‑shaped swellings located between the ______
_________ are the outer part crescent-shaped swellings of the _________
During the FOURTH week
NASAL PLACODES on the frontonasal process undergoes growth
Placodes become SUBMERGED forming a depression in the center of each placode, the NASAL PITS
MEDIAL NASAL PROCESSES are two crescent‑shaped swellings located BETWEEN the NASAL PITS
LATERAL NASAL PROCESSES are the outer part crescent-shaped swellings of the NASAL PITS
DEVELOPMENT OF THE INTERMAXILLARY SEGMENT
The development of the intermaxillary segment from the fused _________ on the inside of the __________
The development of the intermaxillary segment from the fused MEDIAL NASAL PROCESSES on the inside of the STOMODEUM
MAXILLARY PROCESS AND MIDFACE FORMATION
Maxillary process derived from ________ and forms from increased growth of the ________ on each side of the ________
Each maxillary process will grow _____ and _______ around the stomodeum
Upper lip is formed when each maxillary process ______ with each _________ on both sides of the _________
Maxillary process derived from ADJACENT SWELLINGS and forms from increased growth of the MANDIBULAR ARCH on each side of the STOMODEUM
Each maxillary process will grow SUPERIORLY and ANTERIORLY around the stomodeum
Upper lip is formed when each maxillary process FUSES with each MEDIAL NASAL PROCESS on both sides of the STOMODEUM
the maxillary process contributes to the ________, and the two medial nasal processes contribute to the _________
the maxillary process contributes to the SIDES OF THE UPPER LIP, and the two medial nasal processes contribute to the PHILTRUM (frontonasal process)
what is cleft lip
- failure of fusion of the maxillary process with the medial nasal process
- varying degrees of disfigurement and disability
- may be hereditary or associated with environmental factors
- more common/severe in males
- more common as unilateral (left side)
- complicates nursing/feeding/suckling of a child, as well as speech development and appearance, and can increase oronasal infection levels
what are commissural lip pits
- epithelium lined blind tracts located at the labial commissure
- may be shallow or several mm deep
- congenital lip pits may be observed near the midline of the vermillion border
- no treatment
what gives rise to the primitive pharynx, what will it form
The FOREGUT gives rise to the primitive pharynx, which will form the OROPHARYNX
DEVELOPMENT OF BRANCHIAL ARCHES
Occurs during ______ week
Stacked _________ swellings of tissue appear _____ to the stomodeum
These are the branchial arches:
_________ being the first branchial arch
Others numbered in _______ sequence
____ pairs of U‑shaped bars with a core of _______ tissue
Occurs during FOURTH week
Stacked BILATERAL swellings of tissue appear INFERIOR to the stomodeum
These are the branchial arches:
MANDIBULAR ARCH being the first branchial arch
Others numbered in CRANIOCAUDAL sequence
SIX pairs of U‑shaped bars with a core of MESENCHYME tissue
DEVELOPMENT OF BRANCHIAL ARCHES
what does each paired branchial arch have
Each paired branchial arch has ITS OWN developing cartilage, nerve, vascular, and muscular components within each mesodermal core
PHARYNGEAL POUCHES AND DERIVATIVE STRUCTURES
what are the future tissues of the first pouches
second pouches
third and fourth pouches
first: tympanic membrane, tympanic cavity, mastoid antrum, auditory tube
second: crypts and lymphatic nodules of the palatine tonsils
third and fourth: parathyroid and thymus glands
PALATAL DEVELOPMENT
5-6 week:
6-12 week:
12 week:
fifth to sixth week
PRIMARY PALATE: intermaxillary segment from fused medial nasal processes
sixth to twelfth week
SECONDARY PALATE: fused palatal shelves from maxillary processes
twelfth week
FINAL PALATE: fusion of all 3 processes
PRIMARY PALATE FORMATION
During the ______ week of prenatal development, still within the ______ period, the ________ forms
During the FIFTH week of prenatal development, still within the EMBRYONIC period, the INTERMAXILLARY SEGMENT forms
DEVELOPMENT OF INTERMAXILLARY SEGMENT
The development of the intermaxillary segment from the fused __________ on the inside of the _______
The development of the intermaxillary segment from the fused MEDIAL NASAL PROCESSES on the inside of the STOMEDEUM
PRIMARY PALATE FORMATION
The intermaxillary segment also gives rise to the ______
At this time, the primary palate serves only as a ________ between the developing ________ and _______
The intermaxillary segment also gives rise to the PRIMARY PALATE/ PRIMITIVE PALATE
At this time, the primary palate serves only as a PARTIAL SEPARATION between the developing ORAL CAVITY PROPER and NASAL CAVITY
SECONDARY PALATE FORMATION
During the ______ week of prenatal development, within the _______ period, the bilateral _________ give rise to two ______ (or lateral palatine processes).
These shelves grow _______ and deep on the inside of the _______ in a ________ direction, along both sides of the developing _____
Tongue is forming on the floor of the _____
Tongue ______ begin to function
Tongue ______ and moves out of the way of these developing _______
During the SIXTH week of prenatal development, within the EMBRYONIC period, the bilateral MAXILLARY PROCESSES give rise to two PALATAL SHELVES (or lateral palatine processes).
These shelves grow INFERIORLY and deep on the inside of the STOMODEUM in a VERTICAL direction, along both sides of the developing TONGUE
Tongue is forming on the floor of the PHARYNX
Tongue MUSCLES begin to function
Tongue CONTRACTS and moves out of the way of these developing PALATAL SHELVES
SECONDARY PALATE FORMATION (CONT.)
Palatal shelves move into a _____ position (______ to developing tongue)
Two palatal shelves ____ and move _____ toward each other
Meeting and joining, fusing to form the _____ palate
The secondary palate will give rise to the _________, which contains canines and posterior teeth, posterior to the ________
what two structures indicate the line of fusion of the palatal shelved
Palatal shelves move into a HORIZONTAL position (SUPERIOR to developing tongue)
Two palatal shelves ELONGATE and move MEDIALLY toward each other
Meeting and joining, fusing to form the SECONDARY palate
The secondary palate will give rise to the POSTERIOR TWO THIRDS OF THE HARD PALATE, which contains canines and posterior teeth, posterior to the INCISIVE FORAMEN
The median palatine raphe on the mucosa and the median palatine suture on the bone
COMPLETION OF THE PALATE
Posterior part of the ________ meets the ______
Gradually they fuse together in an __________ direction
Posterior part of the PRIMARY PALATE meets the SECONDARY PALATE
Gradually they fuse together in an ANTERIOR TO POSTERIOR direction
What is cleft palate
- failure of fusion of the palatal shelves with the primary palate and/or with each other
- varying degrees of disability
- occurs in 1/2500 cases
NASAL CAVITY AND SEPTUM DEVELOPMENT
The nasal cavity forms in the same time frame as the _____, from the ______ week of prenatal development.
It will serve as part of the _________
Future________ is also developing when the palate is forming
The nasal cavity forms in the same time frame as the PALATE, from the 5TH-12TH week of prenatal development.
It will serve as part of the RESPIRATORY SYSTEM
Future NASAL SEPTUM is also developing when the palate is forming
NASAL CAVITY AND SEPTUM DEVELOPMENT
The tissues that form the nasal septum will grow _______ and _____ to the _______ and superior to the ______
The ______ nasal septum then fuses with the horizontally oriented ________ after it has formed
The tissues that form the nasal septum will grow INFERIORLY and DEEP to the MEDIAL NASAL PROCESSES and superior to the STOMODEUM
The VERTICAL nasal septum then fuses with the horizontally oriented FINAL PALATE after it has formed
clinical consideration for the nasal cavity and associated tissues; describe a deviated septum
- occurs when the thin wall that makes up the nasal septum inside the nose is displaced to one side
- nasal septum separates the right and left nasal cavities and ideally is situated in the center of the nose to equally separate the two sides
TONGUE DEVELOPMENT
The tongue develops during the _____ week of prenatal development
It develops from __________ located _____ on the floor of the primitive pharynx, formed by the _______ branchial arches
The tongue develops during the 4TH-8TH week of prenatal development
It develops from INDEPENDENT SWELLINGS located INTERNALLY on the floor of the primitive pharynx, formed by the FIRST FOUR branchial arches
DEVELOPEMENT OF THE TONGUE
4-8 week
body:
base:
8th week
completed tongue:
4-8 week
body: tuberculum impar and lateral lingual swellings appear
base: copula overgrowing second branchial arches
8th week
completed tongue: merging of anterior swellings of the body and copula of the base
DEVELOPMENTAL DISTURBANCE OF THE TONGUE: ankyloglossia
- tongue tied
- short lingual frenum that extends to tongue apex
