Pharyngeal Apparatus, Face And Neck Flashcards
What is the pharyngeal apparatus
Pharyngeal arches, pharyngeal pouches, pharyngeal grooves, and pharyngeal membranes
They contribute to the formation of the neck and face
The pharyngeal arches benign to develop early in the _ week as the _ migrate into the future head and neck regions
4th
NCC
Initially, what does each pharyngeal arch consist of
Core or mesenchyme. And is covered externally by ectoderm and internally by endoderm
The first pair of arches, the primordium of the ____, appears as surface elevations __ to the developing pharynx
Jaws
Lateral
Other arches soon appear as obliquely disposed, rounded ridges on each side of the future _ and _ regions
Head neck
By the end of the fourth week, _ pairs of arches are visible externally
4
The fifth and sixth arches are ___- and are not visible on the surface of the embryo
Rudimentary
The arches are separate from each other by the __ ___
Pharyngeal grooves
The pharyngeal arches support the lateral walls of the primordial pharynx, which is derived from the cranial part of the ___
Foregut
The ___ initially appears as a slight depression of the surface actoderm
Stomodeum
The stomodeum is separated from the cavity of the primordial pharynx by a bilaminar (NIJM jun7 2018 2155 assessing drug information in children) -the ____ ___-composed of fused ectoderm and endoderm
Oropharyngeal membrane
The oropharyngeal membrane ruptures at _ days
26
What happens when the oropharyngeal membrane ruptures
Brings the primordial pharynx and foregut into communication with the amniotic cavity
What do the arches contribute to
Formation of face, nasal cavities, mouth, larynx, pharynx, and neck
The first arch develops two arches. What are they
Smaller maxillary prominence
Larger mandibular prominence
The second arch makes a major contribution to the ___ bone
Hyoid
A typical arch has what components
Arch artery
Cartilaginous rod
Muscular component
Nerve
An arch artery (aortic arch artery) that arises from the __ ___ of the primordial heart and courses around the primordial ___ to enter the dorsal ___
Truncus arteriosus
Pharynx
Aorta
What does the cartilaginous rod form
Skeleton of the arch
What is the muscular component for
Primordium of the msucles of the head and neck
Pharyngeal arch nerve?
Supplies the mucosa and muscles derived from each arch
The dorsal end of the first pharyngeal arch cartilage becomes ossified to form what
Malleus
Incus
The middle section of the cartilage regresses, but its perichondrium forms what
Anterior ligament of the malleus
Sphenomandibular ligament
Ventral parts of the first pharyngeal arch cartilage form what
Horseshoe shaped primordium of the mandible
Each half mandible forms lateral to and in close association with its ___
Cartilage
The cartilage disappears as the mandible develops around it by __ __-
Intramembranous ossification
First arch nerve
Trigeminal cn5
First arch muscles
Mastication
Mylohyoid , anterior belly of digastric, tensor tympani, tensor veli palatini
1st arch skeletal structures
Malleus
Incus
Second arch nerve
Facial cn7
Second arch muscles
Fascial expression
Stapedius
Stylohyoid
Posterior belly of digastric
Second arch skeletal structures
Stapes(portion)
Styloid process
Lesser cornua of hyoid bone
1st arch ligaments
Anterior ligament of malleus
Sphenomandibular ligament
2nd arch ligaments
Stylohyoid
Third arch nerve
Glossopharyngeal cn9
Third arch muscle
Stylopharyngeus
Third arch skeletal
Greater cornua of hyoid bone
Fourth arch and sixth arch nerve
Superior laryngeal branch of vagus and recurrent laryngeal branch of vagus
Fourth and sixth arch muscles
Cricothyroid Elevator veli Palatini Constrictors of pharynx Intrinsic muscles of the larynx Striated msucles of esophagus
Fourth and sixth arches skeletal
Thyroid cartilage Cricoid cartilage Arytenoid cartilage Cornicualte cartilage Cuneiform cartilage
The fifth pharyngeal arch ____
Regresses
The cartilaginous components of the 4th and 6th arches fuse to form what
Cartilages of the larynx
The dorsal Nd of the second arch cartilage contributes to the _____ and _____
Stapes
Styloid process
The part of the cartilage between the styloid process and the hyoid bone ___. What does its perichondrium form
Regresses
Stylohyoid ligament
The ventral end of the second arch cartilage ossifies to form what
Lesser Cornu of the hyoid bone
The third arch cartilage ossifies to form what
Greater Cornu of the hyoid bone
The fourth and sixth arch cartilages fuse to form the ___ cartilages, except which one
Laryngeal
Epiglottis
The epiglottis and thyroid cartilages develop from _____
NCC
The cricoid cartilage develops from ___
Mesoderm
The mscular components of the arches form various msucles in the head and neck
Ok
Musculature of the first arch forms what
Muscles of mastication
Each arch is supplied by its own cranial nerve
Ok
The special ___ ____ (brachial) components of the cranial nerves supply muscles derived from the pharyngeal arches
Special visceral efferent
Because the mesenchyme from the pharyngeal arches contribute to the dermis and mucous membranes of the head and neck, these areas are supplied with the ___ ___ __ nerves
Special visceral afferent
The facial skin is supplied by the _ CN
5
However, only the caudal two branches of cn 5 supply derivatives of the first pharyngeal arch. What are they
Maxillary and mandibular
Cnv is the principal ___ nerve of the head and neck and is the motor nerve for what
Sensory
Muscles of mastication
Cnv sensory branches innervated what
Face, teeth, mucous membranes of the nasal cavities, palate, mouth, and tongue
The seventh cranial nerve supplies what arch
2
The 9th Cn supplies what arch
3
The 10 CN supplies what arch
4 6
The superior laryngeal branch of the vagus supples wat
4th arch
The recurrent laryngeal branch supplies the _ arch
6
The nerves of the second to sixth pharyngeal arches innervated the mucous membranes of what
Tongue, pharynx, and larynx
The primordial pharynx widens cranially where it joins the stomodeum and narrows caudally where it joins the ___
Esophagus
The endoderm of the pharynx lines the internal aspects of the pharyngeal arches and passes into the __ ___
Pharyngeal pouches
The pairs of pouches develop in a craniocaudal sequence between the arches
For example the first pair of pouches lies between the 1st and 2nd pharyngeal arches
Four pairs of pouches are well defined. What about the 5th
Absent or rudimentary
The endoderm of the pouches contacts the ectoderm of the pharyngeal ___
Grooves
The endodermal pouches and ectoderm of grooves form what
Double layered pharyngeal membranes
Expression of the __ gene in the pharyngeal pouches is essential for the formation of pharyngeal arches and pouches
TBx2
The first pharyngeal pouch gives rise to the ___ ___
Tubotympanic recess
The first pharyngeal membrane contributes to the formation of the ___ ____
Tympanic membrane
The cavity of the tubotympanic recess gives rise to the __ ___ and ___ ___
Tympanic cavity
Mastoid antrum
The connection of the tubotympanic rescues with the pharynx forms the __ ___
Pharyngotympanic tube
The second pharyngeal pouch is largely obliterated as the __ ___ develops
Palatine
A part of the second pouch remains as the __ ___
Tonsillar sinus
The endoderm of the second pouch proliferates and grows into the underlying ___
Mesenchyme
The central parts of these buds break down, forming __ ___
Tonsillar crypts (pit-like depression)
The pouch endoderm forms the surface epithelium and the lining of the crypts
Ok
Lymphoid infiltration occurs approximately in the _ month while germinal centers are not apparent until the __ period
Seventh
Neonatal
The third pharyngeal pouch expands and develops a solid, bulbar, ___ part and a hollow, elongate __ part
Dorsal
Ventral
The connection between the pouch and pharynx is reduced to a narrow duct that soon ___
Degenerates
By the _ week of development , the epithelium of each bulbar dorsal part begins to differentiate into an ___ ___ ___
6th
Inferior parathyroid gland
The epithelium of the elongated ventral parts of the third pair of pouches proliferates, ___ their cavities
Obliterating
These parts come together in the median plane to form the ___ (3rd pouches)
Thymus
The primordia of the thymus and parathyroid glands lose their connections with the pharynx
Later the inferior parathyroid glands separate from the thymus and lie on the dorsal surface of the thyroid glans, whereas the thymus descends into the superior mediastinum
The mesenchyme surrounding the thymic primordium is derived from __
NCC
The dorsal part of each 4th pouch develops into a __ ___ __ which lies on the dorsal surface of the thyroid gland
Superior parathyroid gland
The parathyroid glands derived fromt he third pouches descend with the thymus and are carried to a more inferior position than the parathyroid glands that are derived from the fourth __
Pouches
The elongated ventral part of each fourth pouch develops into the __ __, which fuses with the thyroid glans, giving rise to the __ ___ or the thyroid gland
Ultimopharyngeal body
Parafollicular cells
The parafollicular cells produce ___, a hormone involved int he regulation of calcium
Calcitonin
Parafollicular (c cells) differentiate from ___ that migrate from the pharyngeal arches into the fourth pair of pharyngeal pouches
NCC
If The fifth pharyngeal pouches develop, it is __ and becomes part of the _ pouches
Rudimentary
4th
The head and neck regions of the embryo exhibit four grooves on each side during the 4th and 5th weeks.
These grooves separate the pharyngeal arches externally
Only one pair of grooves contributes to structures. Which one
The first
The first pair of pharyngeal grooves persist as the __ __ ___
External acoustic meatus
The other grooves lie in a slit like depression-the __ __- and are usually obliterated with it as the neck develops
Cervical sinus
Birth defects of the _ pharyngeal groove are the most common of groove defects
2
Where are small auricular sinuses and cysts
Usually in triangular area of skin anterior to the auricle of the external ear, or around auricle or in its lobule
Although some auricular sinuses and cysts are remnants of the _ pharyngeal groove, others represent what
1st
Ectodermal folds sequestered during formation of the auricle from the auricular hillocks
Cervical branchial sinus
Uncommon
Open externally on side of neck
What causes cervical branchial sinus
Failure of the second pharyngeal go=rove and cervicalsinue to obliterate
Where does the cervical branchial sinus open
Along anterior border of the sternocleidomastoid muscle in the inferior third of hte neck
External cervical sinuses
Detected during infancy bc of discharge of mucous
These lateral cervical sinuses are bilateral _% of the time and are commonly associated with __ ___
10
Auricular sinuses
Internal cervical sinuses
Open into the pharynx and are rare
What causes internal cervical sinus
Persistence of the proximal part of the second pharyngeal pouch so they usually open into the tonsillar sinus or near the palatopharyngeal arch
-normally this pouch disappears as the palatine tonsil develops its -its normal remnant is the tonsillar sinus
Cervical branchial fistula
Abnormal canal that opens internally into the tonsillar sinus and externally on the side of the neck
What causes hte rare cervical branchial fistula
Persistence of parts of the second pharyngeal groove and pouch
In cervical fistula, the fistula ascends from its opening in the neck, through the subcuntaneous tissue and platysma muscle to reach the __ ___
Tonsillar sinus
Cervical cysts
The third and fourth pharyngeal arches are buries in the cervical sinus. Remnants of parts of the cervical sinus, the second groove, or both may persist and form a spherical of elongated. Cyst
Cervical cysts often do not become apparent until late childhood or early adulthood, when they produce a slowly enlarging, painless ___ in the ___
Swelling neck
Cervical cysts enlarge why
Accumulation of fluid and cellular debris derived from desquamation of their epithelial linings
Cervical vestiges
Normally the pharyngeal cartilages disappear, except for parts that form ligaments or bones. However here cartilaginous or body remnants of the pharyngeal arch cartilages appear under the skin on the side of the neck..
Where are cervical vestiges normally found
Anterior to the inferior third of their sternocleidomastoid muscle
First pharyngeal arch syndrome
Abnormal development of 1st p arch results in congenital anomalies of eyes, ears, mandible, and palate
What causes 1st pharyngeal arch syndrome
Insufficient migration of neural crest cells into the first arch during the 4th week
What are he two main clinical manifestations of 1st p arch syndrome
Treacher collnis
Pierre robin sequence
Treacher Collins syndrome (mandibulofacial dysostosis) caused by what gene
AD defect in TCOF1
What does an AD mutation in TCOF1 cause
Underdevelopment of the zygomatic bones of the face -malar hypoplasia
Characteristic features of treacher Collins
Down slanting palpebral fissures, birth defects of the lower eyelids , deformed external ears, and sometimes defects of the middle and internal ears
Pierre robin sequence
Hypoplasia of the mandible, cleft palate, and defects of eye and ear
Many causes of Pierre Robin Sequence are ___. However some have a genetic basis
Sporadic
In robin morphogenetic complex, the proposed initiating defect is a small mandible, which results in what
Posterior displacement of the tongue and obstruction to full closure of the palatine process, resulting in bilateral cleft palate
Pharyngeal membranes form where the epithelial of the grooves and pouches approach each other. The membranes appear in the floors of the ___ during the _ week
Grooves
4
Only one pair of membranes contributes to the formation of adult structures
1st
What does the 1st pharyngeal membrane become
Tympanic membrane
What is the first endocrine gland to develop
Thyroid
When does the thyroid gland begin to form
24 days
Where does the thyroid gland begin to develop
Median endodermal thickening in the floor of the primordial pharynx
The endodermal thickening soon forms a small outpouching- the __ ___
Thyroid primordium
As the embryo and tongue grow, the developing thyroid gland descends int he neck, passing __ to the developing hyoid one and the laryngeal cartilages
Ventral
For a short time the developing thyroid is connected to the tongue by the __ __
Thyroglossal duct
As a result of rapid cell proliferation, the lumen of the thyroid diverticulum soon obliterates and divides into the __ and __ lobes, which are connected by the __ ___ of the thyroid gland
Right left
Thyroid isthmus
DiGeorge syndrome
No thymus or parathyroid glands
Charactization of DiGeorge
Congenital hypoparathyroidism , increased susceptibility to infections, palate abnormalities, micrognathia, low set notches ears, nasal clefts, cardiac abnormalities
When does digeorge syndrome occur
Third and fourth pharyngeal pouches do not differentiate into the thymus and parathyroid glands
Why get facial birth defects with digeorge
Abnormal development of the first pharyngeal arch components during formation of the face and ears
Digeorge syndrome commonly involves a microdeletion (____region), mutation of the ___, ___ and ____ genes, and ____ defects
22q11.2
HIRA, UFDIL TBx1
NCC
Incidence of digeorge
1/2000-4000
Ectopic parathyroid glands
Anywhere near or in the thyroid or thymus
Superior are most constant in positions han inferior
Occassiionally an inferior parathyroid chains does not descend and remains near the bifurcation of the __ ___ ___. In other cases it may accompany the __ in the thorax
Common carotid artery
Thymus
Abnormal number of parathyroid glands :supernumerary
From division of the primordia of the original glands
Absence of a parathyroid gland
Failure of one of the primordia to differentiate or from atrophy of a gland early in development
By _ weeks the thyroid gland has assumed its definitive shap and position
7
By 7 weeks, the thyroglossal duct has ___ and ___
Degenerates disappeared
The proximal opening of the thyroglossal duct persists as a small pit-what is it called and where is it?
Foramen cecum in the dorsum of the tongue
What is a pyramidal lobe of the thyroid
Extends superiorly from the isthmus in 50% of people. May be attached to the hyoid bone by fibrous Titus, smooth muscle or both
A remnant of the thyroglossal duct may persist and form a __ in the tongue or in the anterior part of the neck, usually just inferior to the hyoid bone
Cyst
How does the swelling from a thyroglossal duct cyst present
Painless, progressively enlarging, movable median mass
Does a thyroglossal duct cyst contain thyroid tissue
It may
What happens if a thyroglossal duct cyst becomes infected
Perforation of the skin occurs , forming a thyroglossal duct sinus that usually opens in the median plane of the neck, anterior to the laryngeal cartilages
___, an ectopic thyroid gland is located along the normal route of its descent from the tongue
Infrequently
90% of ectopic thyroid gland are represented by ___ thyroid glandular tissue
Lingual
Incomplete descent of the thyroid gland results in a ___ thyroid gland that appears high in the neck, at or just inferior to the hyoid bone
Sublingual
In 70% of cases, an ectopic sublingual thyroid gland is the __ thyroid tissue present
Only
Why is it clinically important to differentiate an ectopic thyroid gland from a thyroglossal duct or cyst or from acesssory thyroid tissue
Prevent inadvertent surgical removal of the thyroid gland bc this may be the only thyroid tissue present …could leave a person permanently dependent on thyroid medication!
During the 11th week, __ begins to appear in the thyroid follicles;thereafter, __ concentration and the synthesis of thyroid hormones can be demonstrated
Colloid
Iodine
By 20 weeks, the levels of fetal thyroid stimulating hormone and thyroxine begin to increasing, reaching adult levels by __ weeks
35
Near the end of the fourth week, a median triangular elevation appears int he floor of the primordial pharynx, just rostral to the foramen cecum. What is it
The median lingual swelling(tongue bud)-the first indication of tongue development
Spin after the tongue bud appears, two oval ___ ___ ___(_) develop on each side of the median tongue swelling
Lateral lingual swellings (distal tongue buds)
The three lingual swellings result fromt he proliferation of mesenchyme in the ___ parts of the first pair of pharyngeal arches
Ventromedial
The lateral lingual swellings rapidly increase in size, merge with each other, and overgrow the __ ___ __
Median tongue swellings
The merged lateral tongue swellings form tha __ __ __ of the tongue
Anterior two thirds
The plane of fusion of the lateral tongue swellings is indicated superficially by the midline groove of the tongue and internally by the fibrous __ ___
Lingual septum
The median lingual swelling forms no recognizable part of the adult tongue
Ok
Formation of the posterior third of the tongue
Two elevations that develop caudal to the foramen cecum
The __ forms by fusion of the ventromedial parts of the second pair of pharyngeal arches
Copula
The __ ___ develops caudal to the copula from mesenchyme in the ventromedial parts of the third and fourth pairs of pharyngeal arches
Hypopharyngeal eminence
Congenital lingual cysts
Derived from remnants of the thyroglossal duct
Presentation of congenital lingual cyst
Enlarge and produce pharyngeal pain, dysphagia or both
Congenital lingual fistula
Persistence of the lingual parts of thyroglossal duct open through the foramen cecum into the oral cavity
As the tongue develops, the __ is gradually overgrown by the hypopharyngeal eminence and disappears
Copula
As a result , the pharyngeal part of the tongue develops from the rostral part of the __ ___
Hypopharyngeal eminence
The line of fusion of the anterior and posterior parts of tongue is the V shaped groove-the __ __
Terminal sulcus
Cranial __ migrate into the developing tongue and give rise to its CT and vasculature
NCC
Most of the tongue msucles are derived from ___ that migrate from the __ __
Myoblasts
Occipital somites
The __ nerve accompanies the myoblasts as they develop
Hypoglossal
The molecular mechanisms involved into e development of the tongue include myogenic regulating factors, the paired box genes __ and ___ as well as ___, ___ and ____
Pax3 Pax7
TGFB FGF SHH
Ankyloglossia
Lingual frenulum normally connects the inferior surface of the tongue to the floor of the mouth
1/300
No clinicasignificance
Short frenulum usually stretches with time making surgical correction of the anomaly unnecessary
Lingual papillae appear at the end of the _ week
8
The gallate and foliage papillae appear first , close to the terminal branches of the ___ nerve
Glossopharyngeal
The fungiform papillae appear later, near where
The terminations of the chorda tympani branch of the facial nerve
The long and numerous papillae are called __ ___ because of the thread like shape
Filiform papillae
The filiform papillae contain what
Afferent nerve endings and are sensitive to touch
Taste buds develop during weeks _ to __ by inductive interaction between the __ cells of the tongue and invading gustatory nerve cells from the ___ __, ___ and __ nerves
11 13
Chorda tympani, glossopharyngeal, vagus
Facial responses on taste bud can be induced by bitter tasting substances at _ to _ weeks, indicating that reflex pathways between taste buds and facial muscles are established at this stage
26-28
The sensory supply to the mucosa of almost the entire anterior tongue is from the lingual branch of the mandibular division of the _ nerve
Trigeminal
What supplies taste buds of anterior 2/3, except the vallate papillae
Facial chorda tympani
Bc the second arch component, the copula, is overgrown by the third arch, the facial nerve does not supply any of the tongue mucosa, except for what
Taste buds in the anterior tongue
The vallate papillae int he anterior tongue are innervated by what
Glossopharyngeal nerve 3rd arch
The posterior third f the tongue is innervated by the __ nerve
Glossopharyngeal.
The superior laryngeal branch of the vagus supplies what
Small area of the tongue anterior to the epiglottis
Al muscles of the tongue are supplied by the __ nerve , except for which one
Hypoglossal
Palatoglossus
What supplies the palatoglossus
Pharyngeal plexus by fibers arising from the vagus nerve
During the 6th and 7th weeks, the salivary glands begin as solid __ buds from the endoderm of the primordial oral cavity
Epithelial
The salivary epithelial buds undergo branching morphogenetic and grow into the underlying ___
Mesenchyme
The CT in the salivary glands is derived from __
Ncc
All parenchyma tissue of salivary glands arises by proliferation of the oral ___
Epithelium
The __ glands are the first o appear in the _ week
Parotid
6
The parotid glands develop from buds that arise from the oral ectodermal lining near the angles of the ___
Stomodeum
The parotid buds grow towards the __, branching to form solid cords with rounded ends
Ears
Later, the cords canalize and become ducts by _ weeks
10
The rounded ends of the cords differentiate into ___
Acini
Parotid secretions begin at __ weeks
18
Parotid: the capsule of CT develops from the surrounding mesenchyme
Ok
The submandibular glands appear late in the _ week
6
The submandibular glands develop from endodermal buds int he floor of the ___
Stomodeum
Submandibular: solid cellular processes grow __, lateral tot he developing tongue
Posteriorly
Submandibular: acini begin to form at _ weeks and secretory activity begins at _ weeks
12 16
Growth of the submandibular glands continues after birth, with the formation of __ ___
Mucous acini
Submandibular: lateral to the developing tongue, a linear groove forms that soon closes over to form the ___ ___
Submandibular duct
The sublingual glands appear in the _ week, approximately two weeks after the other salivary glands
8
The sublingual glands develop from multiple endodermal epithelial buds in the __ __
Paralingual sulcus
The sublingual buds branch and canalize to form _ to _ ducts that open independently into the floor of the mouth
10-12
The facial primordium appear around the __ early in the fourth week
Stomodeum
Facial development depends on the inductive influence of three organizing areas
Forebrain (establishes a gradient of SHH factor)
Frontonasal ectoderm
Developing eye
The five facial primordia that appear as prominences aroudnthe stomodeum
A frontonasal prominence
Paired maxillary prominences
Paired mandibular prominences
The maxillary and mandibular prominences are derivatives of the __pair of pharyngeal arches
1st
The prominences are produced by mesenchyme derived from the ___ that migrate into the arches during the 4th week of development
Ncc
These cells are the major sources of CT components, including cartilage, bone and ligaments in the __ and __ regions
Facial
Oral
The frontonasal prominence surrounds the ventrolateral part of the forebrain, which gives rise to the __ __ that form the __
Optic vesicles
Eyes
The frontal part of the FNP forms the forehead; the nasal part of the frontonasal prominence forms the rostral boundary of the stomodeum and nose
Ok
The maxillary prominences form the _ boundaries of the stomodeum and the mandibular prominences constitute the __ boundary of the stomodeum
Lateral
Caudal
The lower jaw and the lower lip are the __ parts of the face to form
First
The lower jaw and lip result from merging of the medial ends of the __ ___
Mandibular prominences
What is a chin dimple
Incomplete fusion of the prominences
By the end of the fourth week, bilateral oval thickening of the surface ectoderm-__ __- have developed in the inferolateral parts of the FNP
Nasal placodes
Initially the nasal placodes are ___, but later, they are stretched to produce a flat ____ in each placode
Convex depression
The mesenchyme in the margins of the placodes proliferates, producing horseshoe shaped elevations-the medial and lateral ___ __
Nasal prominences
As a result of the nasal prominences, the nasal placodes lie in depressions-__ ___
Nasal pits
The nasal pits are the primordia of the anterior ___ and ___ ___
Nares
Nasal cavities
Proliferation of mesenchyme int he maxillary prominences causes them to enlarge and grow medially toward each other and the ___ ___
Nasal prominences
The medial migration of the maxillary prominences moves the medial nasal prominences toward the median plan and each other. What is this process regulated by
Transcription factor PDGFRa signalling
Each lateral nasal prominence is separated fromt he axillary prominence by a cleft called ___ ___
Nasolacrimal groove
By the end of the fifth week, six ___ ___-primordia of ___ form around the _ pharyngeal groove, the primordia of the external acoustic meatus
Auricle hillocks
Auricles
1st
Initially, the external ears are positioned in the _ region; however, as the mandible develops, they ascend to the side of the head at the level of the eyes
Neck
By the end of the sixth week, each maxillary prominence has begun to merge with the lateral nasal prominence along the line of the nasolacrimal groove. What does this establish
Continuity between the side of the nose, formed by the lateral nasal prominence, and the cheek region, formed by the maxillary prominence
The nasolacrimal duct develops from a rod-like thickening of ectoderm in the floor of the __ ___
Nasolacrimal groove
The nasolacrimal duct gives rise to a solid epithelial cord that separates fromt he ectoderm and sinks into the mesenchyme
Latera as a result of apoptosis, this cord canalize to form the nasolacrimal duct
The rcranila end of this duct expands to form the lacrimal sac
In the late fetal period, the nasolacrimal duct drains into the inferior meatus in the lateral wall of the nasal cavity. The duct usually becomes completely patent after birth
Between weeks 7 and 10 the MNP merge with each other and with the m__ and ___ nasal prominences , resulting in disintegration of their contacting surface epithelial
Maxillary lateral
This causes intermingling of the underlying mesenchyme,.
Merging of the medial nasal and maxillary prominences results in continuity of the upper jaw and lip and separation of the nasal pits from the stomodeum
As the medial nasal prominences merge, they for an ___ ___
Intermaxillary segment
What does the intermaxillary segment give rise to
Median part (philtrum) of upper lip
Per axillary part of the maxilla and its associated gingiva (gum)
Primary palate
The lateral parts of the upper lip , most of the maxilla, and the secondary palate form from the ___ __
Maxillary prominences
The maxillary prominences merge laterally with the ___ ____
Mandibular prominences
Recent studies indicate that the lower part of the medial nasal prominences appear to have become deeply positioned and covered by medial extensions of the maxillary prominences to form the ___
Philtrum
The primordial lips and cheeks are invaded by ___ from the second pair of pharyngeal arches, which differentiate into the __ ___
Myoblasts
Facial muscles
The myoblasts from the first pair of arches differentiate into muscles of ___
Mastication
The smallness of the face prenatally results from the following
Rudimentary upper and lower jaws
No erupted deciduous teeth
Small size of nasal cavities and maxillary sinuses
As the face develops , the nasal placodes become ____, forming nasal pits
Depressed
Proliferation of thesurrounding mesenchyme forms the medial and lateral ___ ___ and results in deepening of the nasal pits and formation of primordial nasal sacs
Nasal prominences
Each nasal sac grows ____, ventral to the developing forebrain
Dorsally
At first, the nasal sacs are separated fromt he oral cavity by the ___ ___
Oronasal membrane
The oronasal membrane ruptures by the end of the _ week, bringing the nasal and oral cavities into communication
6
Proliferating epithelial cells fills the anterior lumen of the nasal cavity by _ to _ weeks
7 8
This epithelial plug undergoes apoptosis and by the 17th week, the nasal passage are reopened becoming the nasal vestibule
Ok
The regions of continuity between the nasal and oral cavities are the ___ ___, which lie posterior to the primary palate
Primordial choanae
After the secondary palate develops, the choanae are located at the junction of the nasal cavity and pharynx
Ok
While these changes are occurring, the superior, middle and inferior __ ___ develop as elevations of the lateral walls of the nasal cavities
Nasal conchae
Concurrently, the ectodermal epithelium in the roof of each nasal cavity becomesspecialized to form the ___ ___
Olfactory epithelium
Som epithelial cells differentiate into olfactory receptor cells. The axons grow into the __ __ of the brain
Olfactory bulbs
Some Paranasal sinuses, such as ___ ___, begin to develop during late fetal like; remainder of them develop after birth
Maxillary sinuses
The Paranasal sinuses form outgrowths (diverticula) of the walla of the nasal cavities, becoming pneumatic(air filled) extensions of the nasal cavities in the adjacent bones
Ok
The original openings of the diverticula persist as the ___ of the adult sinuses
Orifices
Most of the Paranasal sinuses are rudimentary or absent in ___
Neonates
The maxillary sinuses are __ at birth
Small
The maxillary sinuses grow slowly until puberty and are not fully developed until all of the permanent teeth have erupted in early adulthood
Ok
No frontal or sphenoid sinuses are present at birth.
Ok
The ethmoid cells are small before ) years and they do not begin to grow rapidly until 6 to 8 years
2
At 2 year, the most anterior ethmoid cells grow into the frontal bone, forming a ___ sinus on each side
Frontal
Usually, the frontal sinuses are visible on radiographs by _ years
7
The two most anterior ethmoid cells grow into he frontal bone at approximately _ years, forming a frontal sinus on each side
2
The two most posterior ethmoid cells grow into the sphenoid bone at approximately _ years of age, forming two sphenoidal sinuses
2
Growth of the Paranasal sinuses is important in altering the size and shape of the face during infancy and childhood and in adding resonance to the voice during ___
Adolescence
The palate develops from two primordia
The primary palate and secondary palate
Palatogenesis begins int he _ week and is complete in the _
6 12
Multiple molecular pathways, including __ and ___ are involved
Wnt PRICKLE1
Ther critical period of pathogenesis is from the end of the __ week until the beginning of the __
6 9
Early int he 6th week the primary palate (median palatine process) begins to develop from the deep part of the ___ segment of the ___
Intermaxillary
Maxilla
Initially, the intermaxillary segment is a wedge-shaped mass of ___ between the internal surfaces of the maxillary prominences of the developing maxilla
Mesenchyme
The primary palate forms the ___ part of the maxilla
Premaxillary
The premaxillary part of the maxilla representes only a small part of the adult __ ___ . What part
Hard palate
The part anterior to the incisive fossa
The secondary palate is the primordium of the hard and soft parts of the palate
Ok
It begins to develop early int he 6th week from two mesenchyme projections that extend fromt he internal aspects of the ___ ___
Maxillary prominences
Initially these structures-__ ___ ___-project inferomedially on each side of the tongue
Lateral palatine processes
As the jaw develops, they pull the tongue away from this root, and , as a result is brought __ in the mouth
Lower
During the 7th and 8th weeks, the lateral palatine processes elongate and ascend to the horizontal position _ to the tongue
Superior
The release of ___ __ in the palatine process mesenchyme helps with this elevation
Hyaluronic acid
Gradually, the processes approach each other and fuse int he ___ plane
Median
They also fuse with the __ __ and the posterior part of the __ ___
Nasal septum
Primary palate
Elevation of the palatine processes to the horizontal position is believed to be caused by an intrinsic force that is generated by the hydration of ___ ___ in the mesenchymal cells within the palatine process
Hyaluronic acid
The medial epithelial seam at the edges of the palatine shelves breaks down, allowing for the fusion of the __ __
Palatine shelves
The nasal septum develops in a __ growth pattern from internal parts of the merged medial nasal prominences
Downward
The fusion between the nasal septum and palatine processes begins anteriorly during the _ week and is completed by the _ week, superior to the primordium of the hard palate
9 12
Bone gradually develops by intramembranous ossification in the __ palate, forming the ___ part of the maxilla, which lodges the incisor teeth
Primary
Premaxillary
Concurrently, bone extends from the maxilla and palatine bones into the lateral palatine processes to form the ___ __
Hard palate
The posterior parts of these processes do not become ossified; they extend posteriorly beyond the nasal septum and fuse to form the ___ __, including its conical projection, the ___
Soft palate
Uvula
The median palatine raphe indicates the line of fusion of the __ palatine process
Lateral
A small __ __ persists int he median plane of the palate, between the premaxillary part of the maxilla and the palatine processes of the maxilla
Nasopalatine canal
The nasopalatine canal is represented in the adult hard palate by the __ __-
Incisive fossa
An irregular suture runs from the incisive fossa to the alveolar process of the maxilla, between the lateral incisor and the canine teeth on each side, indicating where the embryonic primary and secondary palates fused
Ok
Clefts of the upper lip and palate are ___
Common
Anterior cleft
Cleft lip with or without cleft of the alveolar part of the maxilla
Complete cleft anomaly :anterior cleft
Cleft extends through the lip and the alveolar part of the maxilla to the incisive fossa, separating the anterior and posterior parts of the palate
Anterior cleft results from what
Defiency of mesenchyme I int he maxillary prominences and the median palatine process
Posterior cleft
Defects include clefts of the secondary, or posterior, palate that extend through the soft and hard regions of the palate to the incisive fossa, separating the anterior and posterior parts of the palate
What causes posterior cleft
Defective development of the secondary palate and result from growth distortions in the lateral palatine processes that, in turn, prevent the medial migration and fusion of these processes
Clefts of the upper lip
With or without cleft palate, occur in approximately 1/1000 births; however their frequency varies widely and 60% to 80% of those affected are males
Clefts involving the upper lip vary in severity from small notches in the __ border of the lip to larger clefts that extend into the floor of the nostril and through the alveolar part of the maxilla
Vermilion
Clefts involving the upper lip can be unilateral or bilateral
No
Unilateral cleft lip results from what
Failure of the maxillary prominence on the affected side to untie with the merged medial nasal prominences. The tissues in the floor of the persistence groove break down. As a result the lip i divided into medial and lateral parts. Sometimes a bridge of tissue, a simonart band, joins the parts of the incomplete cleft lip
Bilateral cleft lip results from what
Failure of the mesenchymal masses int he maxillary prominences to meet and unite with the merged medial nasal prominences . Where there is a complete bilateral cleft of the lip and alveolar part of the maxilla, the intermaxillary segment hangs free and projects anteriorly. These defects are especially deforming because of the loss of continuity of the orbicularis oris muscle, which closes the mouth and purse the lips
What causes the rare median cleft lip upper lip
From partial or complete failure of the medial nasal prominences to merge and forms he intermaxillary segment.
What causes median cleft lip of lower lip (also rare)
Failure of the mandibular prominences to merge completely.
The landmark for distinguishing anterior from posterior cleft anomalies is the ___ ___
Incisive fossa
Cleft palate occurs in how many births . More in boys or girls
1/2500
Girls
Cleft uvula
Only involves the uvula , giving it a fish tail appearance
A palate can also go through the soft and hard regions of the palate
Ok
In severe cases associated with cleft lip, the cleft in the palate extends through the __ part of the maxilla and lips on both sides
Alveolar
What causes clefts of the anterior palate
Failure of the lateral palatine processes to meet and fuse with the primary palate
What causes clefts of the posterior palate
Results from failure of the lateral palatine processes to meet and fuse with each other and with the nasal septum
What causes clefts of the anterior and posterior parts of the palate
Result from failure of the lateral palatine processes to meet and fuse with the primary palate with each other, and with the nasal septum
Most cleft of the lip and palate result from ___ ___
Multiple factors
What drugs can give cleft palate
Anticonvulsant
A sibling of a child with a cleft palate has an elevated risk of having a __ _-
Cleft palate
A cleft of the lip and the alveolar process of the maxilla that continues through the palate is usually transmitted through the __ _-___ ___
Male sex linked gene
Other clefts are features of chromosomal syndromes, such as __ __
Trisomy 13
Oblique facial clefts
Often bilateral and extend fromt he upper lip to the medial margin of the orbit. When this occurs, the nasolacrimal ducts are open grooves.
What causes oblique facial clefts
Failure of the maxillary prominences to merge with the lateral and medial nasal prominences
Lateral or transverse facial clefts
Run from the mouth toward the ear
Bilateral clefts result in macrostomia. What is that
Large mouth
