Face and Neck Development Flashcards
The face and its associated tissue begin to form during the ___ of prenatal development
fourth week within the embryonic period
Facial development will be completed in the
twelfth week within the fetal period
During the ____ week when the face and associated tissues are forming, the rapidly growing brain of the embryo
fourth through the 12th; bulges over the oropharyngeal membrane and developing heart
The area of the future face is squeezed between
the developing brain and heart with the formation of the three embryonic layers and resultant embryonic folding
____embryonic layers are involved in facial development
the ectoderm, mesoderm, and endoderm ( All three)
Facial development includes formation of:
- the primitive mouth
- mandibular arch
- maxillary process
- frontonasal process
- nose
Facial development depends on the five major facial processes (or prominences) that form during the fourth week and surround the primitive mouth of the embryo:
- one frontonasal process
- paired maxillary processes
- paired mandibular processes
The development of the associated oral structures is occurring at the same time as
facial development
Most of the facial structures develop by the fusion of
swellings (tissues) on the same surface of the embryo
Most of the facial structures develop by the fusion of swellings (tissues) on the same surface of the embryo. ___ is initially located between these adjacent swellings
A cleft (or furrow)
In some cases,____ maybe left on the facial surface, showing where the fusion of the swellings took place.
a slight groove or line
with most facial fusion, these furrows left from fusion of swellings on the same surface or the embryo are usually eliminated as the
underlying mesenchyme migrates into the furrow making the embryonic facial surface smooth
fusion of swellings (tissues) on the same surface of the embryo process differs from that of the neural tube, upper lip, and palatal fusion, which is the
fusion of two separate structures from two different surfaces
Upper lip and palatal fusion involves the fusion of
swellings or tissue from different surfaces of the embryo, such as that which occurs with the fusion of the neural tube
At the beginning of the__ week, the primitive mouth has become the
fourth; stomodeum
The stomodeum initially appeared as a
shallow depression in the embryonic surface ectoderm at the cephalic end before the fourth week
Initially, The stomodeum is limited in depth by
the oropharyngeal membrane (which developed during the third week)
The oropharyngeal membrane also separates the stomedeum from the
primitive pharynx
The primitive pharynx is the____ of the foregut which is the____ of the future digestive tract
cranial part; beginning
In the___ week, the oropharyngeal membrane
latter part of the fourth; disintegrates. With this disintegration, the primitive mouth is increased in depth and enlarges in width across the surface of the midface
Within the_____ week, two bulges of tissue appear inferior to the primitive mouth:
fourth; the two mandibular processes
the two mandibular processes consist of
a core of mesenchyme formed in part by NCCs that migrated to the facial region.
the two mandibular processes Is Covered ___
externally by ectoderm and internally by
endoderm
The paired mandibular processes fuse at the midline to form
The mandioular arch
The mandibular arch then extends as a band of tissue inferior to the stomodeum and between the developing brain and heart.____ indicates where the mandible is formed by fusion of right and left mandibular processes.
The mandibular symphysis
In future development, the developing mandibular arch directly gives rise to
the lower face, including the lower lip The mandibular arch will also give rise to the mandibular teeth and associated tissue
During the__ week, the frontonasal processes forms as a
fourth; bulge of tissue at the most cephalic end of the embryo
In future development, the frontonasal process gives rise to the upper face, which includes:
- The forehead
- Bridge of the nose
- Primary palate
- Nasal septum
- All structures associated with the medial nasal processes
Placodes
rounded areas of specialized thickened ectoderm found at the location of developing special sense organs
The facial area of the embryo has two lens placodes, which are initially located on
each side of the frontonasal process
The facial area of the embryo has two lens placodes, which are initially located on each side of the frontonasal process. Later in development, these lens placodes
migrate medially from their lateral positions and form the future eyes and associated tissue
Two otic placodes are even more laterally and posteriorly placed and form pits that create
the future internal ear and the associated tissue
The Two otic placodes appear to rise to their mature position as a result of
their relative growth
Two nasal placodes form in the
anterior part of the frontonasal process just superior to the stomodeum during the fourth week
There are also orally placed dental placodes from which the ___ are produced
tooth germs
During the____ week, the tissue around the nasal placodes on the frontonasal process undergoes growth. This starts the development of the
fourth; nasal region and the nose
During the___ week, the tissue around the nasal placodes on the frontonasal process undergoes growth. This starts the development of the nasal region and the nose. The placodes become submerged, forming a depression in the center of each placode called the
fourth; nasal pits (or olfactory pits)
Deepening of the nasal pits during growth of the nasal placodes produces a
nasal sac that grows internally toward the developing brain
The middle part of the tissue growing around the nasal placodes appears as
two crescent-shaped swellings located between the nasal pits - the medial nasal processes
The paired medial nasal processes fuse internally during week ___and grow inferiorly on the inside of the stomodeum, forming the
Five; intermaxillary segment (or premaxillary segment) by the end of the seventh week of prenatal
On the outer part of the nasal pits are two other crescent-shaped swellings, (lateral)
the lateral nasal processes
The lateral nasal processes form the
alae of the nose
The fusion of___ forms the nares
the lateral nasal, maxillary, and medial nasal processes
During the___ week, the upper lip is formed when
sixth; each maxillary process fuses with each medial nasal process on both sides of the stomodeum
Fusion of the maxillary processes to form the upper lip is similar to the fusion of
the neural tube and palate. It takes place between two processes on different surfaces on each side of the face
Fusion of the maxillary processes is completed
___
during the end of the seventh week of prenatal development
The maxillary processes on each side of the developing face partially fuse with the mandibular arch on each side to create
each labial commissure, with the mandibular arch already forming the lower lip
In upper lip formation, Maxillary processes contribute to the____ and the two medial nasal processes contribute to
sides of the upper lip; the midline philtrum
Failure of fusion of the maxillary process with the medial nasal process can result in
cleft lip, with varying degrees of disfigurement and disability in the upper lip
Two main types of cleft lip deformities:
- Unilateral cleft
- Bilateral cleft
Cleft lip occurs in about ___cases
1 in 1000 (about 1%)
Cleft lip May be isolated or associated with other developmental abnormalities, such as
cleft palate
cleft lip is More common and more severe in
men
Cleft lip is More commonly
unilateral and on the left side
Cleft lip Can complicate
nursing and feeding of the child as well as appearance and it may increase oronasal infection levels
Cleft lip treatment
It is treated by oral and plastic surgery, with dental intervention; however, speech and hearing therapy may also be needed
The development of the neck parallels
the development of the face
The development of the neck Begins during
the fourth week of prenatal development within the embryonic period and Completed during the fetal period
The neck and its associated tissue develop from the
primitive pharynx and the branchial (or pharyngeal) apparatus
The endoderm of the pharynx lines
the internal parts of the branchial (or pharyngeal) arches and passes into balloon-like areas of the pharyngeal pouches
The endoderm of the pharynx does not line
the oral cavity proper or nasal cavity
The oral cavity proper and nasal cavity are both lined by
ectoderm as a result of embryonic folding
The foregut is originally derived from the ____ embryonic cell layer
endoderm
The primitive pharynx widens ____and narrows
___
cranially where it joins the primitive mouth or later, the stomodeum; caudally as it joins the esophagus
The caudal part of the primitive pharynx forms
the esophagus which leads to the stomach
A ventral outgrowth of the primitive pharynx forms the
laryngopharynx, larynx, and trachea and ends in the superior part of the developing lungs. The developing thyroid gland is also an anterior outpouching or evagination from the ventral wall of the pharynx
Branchial Apparatus:
Also called the pharyngeal apparatus. Consists of the arches, grooves and membranes, as well as pouches
During the___ week of prenatal development, stacked bilateral swellings of tissue appear inferior to the stomodeum
And include the mandibular arch. These are the
fourth; pharyngeal or branchial arches
The mandibular arch is the first pharyngeal arch and The others are numbered in
craniocaudal sequence
The pharyngeal or branchial arches consist of
six pairs of U-shaped bars of which the central core consists of mesenchyme derived from mesoderm invaded by NCCs, now referred to as ectomesenchyme. Mesenchyme condenses to form a bar of cartilage in each
The pharyngeal or branchial arches are located
bilaterally
The pharyngeal or branchial arches are Oriented in an
anterior-posterior direction on the embryo, bending to surround and support the lateral walls of the developing pharynx
The fifth branchial arch or pharyngeal arch is
often absent or it is included within the fourth branchial arch or pharyngeal arch
Each paired pharyngeal or branchial arch has its own
developing cartilage, nerve, vascular, and muscular components
The first two pairs of arches develop
to the greatest extent of all the arches and
are also the only ones specifically named
The first branchial arch or pharyngeal arch, which is also known as the mandibular arch and its associated tissue includes___ cartilage
Meckel
Meckel cartilage
a hyaline cartilage that forms in the lower jaw of vertebrate embryos; plays a key role in the development of the jaw and middle ear
Forming within the second branchial arch or pharyngeal arch, which is also known as the___, is ______
hyoid arch; cartilage similar to that of the mandibular arch, Reichert cartilage
Reichert cartilage
a cartilaginous structure in the second pharyngeal arch of an embryo that develops into several parts of the head and neck like the Styloid process, stylohyoid ligament, lesser horns of hyoid bone, stapes, facial canal
The third branchial arch or pharyngeal arch has an unnamed cartilage associated with it
This cartilage will be responsible for the
formation of parts of the hyoid bone
Both the fourth branchial arch or pharyngeal arch and the sixth branchial arch or pharyngeal arch also have unnamed cartilage associated with them. These arches
fuse and participate in the formation of most of the laryngeal cartilages.
The mesoderm of the 3rd,4th and 6th pharyngeal arches is associated with the muscles of the
larynx and pharynx
Pharyngeal arches are innervated by the
ninth and tenth cranial nerves
Each pharyngeal or branchial arch is associated with a particular cranial nerve:For the first arch it is the
trigeminal or fifth cranial nerve
Each pharyngeal or branchial arch is associated with a particular cranial nerve: For the second arch it is the
facial or seventh cranial nerve
Each pharyngeal or branchial arch is associated with a particular cranial nerve: For the third arch it is the
glossopharyngeal or ninth cranial nerve
Each pharyngeal or branchial arch is associated with a particular cranial nerve: For the fourth and sixth arches it is the
vagus or tenth cranial nerve.
the oral cavity and the anterior two-thirds of the tongue formed from the first pharyngeal arch come to be supplied by the ___nerves
trigeminal
The maxillary nerve of the trigeminal supplies the structures formed ________the more caudal regions are supplied by the__
in association with the maxillary process such as the nasal cavity and palate; mandibular nerve of the trigeminal , the nerves of the mandibular processes
The posterior one-third of the tongue and oropharynx receive their nerve supply from the
glossopharyngeal nerves
the interior of the larynx with the laryngopharynx are supplied by the
vagus nerves
Between neighboring pharyngeal arches,___ are noted on each side of the embryo
external grooves. These are the pharyngeal grooves or branchial grooves
Only the first groove, located between the first and second arches at approximately the same level as the first pharyngeal pouches, gives rise to a
definitive mature structure of the head and neck. The first groove forms the external auditory meatus
Only the first groove, located between the first and second arches at approximately the same level as the first pharyngeal pouches, gives rise to a definitive mature structure of the head and neck. The first groove forms the external auditory meatus. At the same time, four well-defined pairs of pharyngeal pouches develop as
endodermal evaginations from the lateral walls lining the pharynx
The pharyngeal pouches develop as
balloon-like structures in a craniocaudal sequence between the arches
The first pharyngeal pouches form between
the first and second branchial or pharyngeal arches
The first pharyngeal pouches become the
auditory (pharyngotympanic) tubes
The palatine tonsils are derived from the
lining of the second pharyngeal pouches and also from the pharyngeal walls
The parathyroid glands and thymus gland are derived from the
lining of the third and fourth pharyngeal pouches
The face and neck of a human embryo develop between
the third and eighth weeks of gestation
The face and neck of a human embryo develop between the third and eighth weeks of gestation, with the following key events occurring at different stages:
Week 4: The primordia of the face appear, and the pharyngeal apparatus, which includes the pharyngeal arches, grooves, and pouches, first appears
Week 5: The first pharyngeal arches split into the maxillary and mandibular prominences
Week 6: The face is fully developed, and the palate begins to develop
Week 10: The fetus’s face takes on a more human profile
Week 12: The baby’s fingernails form, and the palate development is completed, separating the nasal and oral cavities
The face develops from the fusion of five mesenchymal swellings:
the frontonasal prominence, two maxillary processes, and two mandibular processes
Failure of these prominences to fuse can result in facial abnormalities
the frontonasal prominence, two maxillary processes, and two mandibular processes
