04 development of the face and neck -...
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Development of the Face Development of the neck
04 Development of the Face and Neck
+Development of the face
The fourth week ~ the twelfth week of prenatal development
Between developing brain and heart
All three embryonic layers are involved in facial development
Five facial processes
Single frontonasal process
Paired maxillary process
Paired mandibular process
Overview of facial development
stomodeum
Developing brain
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Table 4-1 Branchial Arches and Derivative Structures
First arches(mandibular)
Trigenimal nerve, muscles of mastication, mylohyoid and anterior belly of digastric, tensor tympani, tensor veli palatine muscles
Malleus and incus of middle ear, including anterior ligament of the malleus, sphenomandibularligament, and parts of sphenoid bone
Second arches(hyoid)
Facial nerve, stapedius muscle, muscles of facial expression, posterior belly of the digastric muscle, stylohyoid muscle
Stapes and parts of malleus and incus of middle ear, stylohyoidligament, styloid process of the temporal bone, lesser cornu of hyoid bone, upper portion of body of hyoid bone
Third arches Glossopharyngeal nerve, stylopharyngeal muscle
Greater cornu of hyoid bone, lower portion of body of hyoid bone
Fourth throughSixth arches
Superior laryngeal branch and recurrent laryngeal branch of vagusnerve, levator veli palatine muscles, pharyngeal constrictors, intrinsic muscles of the laynx
Laryngeal cartilage
+Development of the face
Facial processes are centers of growth for the face
Upper face : from frontonasal process
Middle face : from maxillary process
Lower face : from mandibular process
Growth pattern of the face
upper face – rapid
middle and lower face – slow
Overview of facial development
+Development of the face
Fusion
fusion of tissue on the same surface of the embryoe.g.) Most of the facial structures
fusion of tissue on the different surface of the embryoe.g.) Palate
Overview of facial development
+Development of the face
Stomodeum (stomatodeum)
a shallow depression in the embryonic surface ectoderm before fourth week
Oropharyngeal membrane separates the stomodeum from the primitive pharynx
Primitive pharynx (The cranial part of foregut, the beginning of the future digestive tract)
FIRST event during fourth week
Disintegration of the oropharyngeal membrane
Stomodeum will form the oral cavity
lined by oral epithelium
Stomodeum and oral cavity formation
Embryo at third to fourth weeks of development.
+Development of the faceMandibular arch and lower face formation
During fourth week, two bulges of tissue appear inferior to stomodeum two mandibular processes
These paired mandibular processes are formed in part by neural crest cells that migrated to the facial region, covered externally by ectoderm and internally by endoderm.
Paired mandibular processes BOTH fuse at midline to form the mandibular arch mandibular arch, first branchial arch
Meckel’s cartilage forms within each side of mandibular arch, IMPORTANT in alveolar bone development
Directly forms lower face, including lower lip.: mandible, mandibular teeth, associated tissues, tongue
+Development of the face
During fourth week, frontonasal process is a bulge of tissue in upper facial area.
Frontonasal process will form upper face, which includes forehead, bridge of nose, primary palate, nasal septum.
Frontonasal process and upper face formation
+Development of the face
<Placode development>
Rounded areas of specialized, thickened ectoderm
Lens placodes: future eyes and associated tissues
otic placodes: future internal ear and associated tissues
Nasal placodes: form nasal (olfactory) pits, which develop into nasal cavities.
Frontonasal process and upper face formation
+Development of the face
<Nose and paranasal sinus formation>During the fourth week, the tissue around the nasal placodes
undergoes growth.
Nasal pits: Placodes become submerged, forming depression in center of each
Nasal pits develop into nasal cavities.medial nasal process
: the middle portion of the nose from root to apex, center portion of upper lip, philtrum region
lateral nasal processes: alae
premaxillary segment: maxillary incisor teeth and associated tissues, primary palate, nasal septum
Frontonasal process and upper face formation
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+Development of the face
During fourth week, the maxillary processes be formed from increased growth of mandibular arch.
These paired maxillary processes are formed in part by neural crest cells that migrated to the facial region, covered externally by ectoderm and internally by endoderm.
Maxillary process will form the midface: Includes sides of upper lip, cheeks, secondary palate posterior portion of maxilla with maxillary canines and posteriors,
associated tissues Zygomatic bones and temporal bones
Maxillary process and midface formation
+Development of the face
< Upper and lower lip formation>
Upper lip: each maxillary process (sides)+ each medial nasal process(middle)
Lower lip: mandibular process
Maxillary process and midface formation
intermaxillarysegment
** Developmental disturbances of the lips and associated tissue• Cleft lip
+Development of the neck
The fourth week of prenatal development ~ fetal period
Develop from the primitive pharynx and the branchial apparatus
+Development of the NeckPrimitive pharynx formation
Derived from the anterior part of the foregut and will form the primitive pharynx, the future oropharynx
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+Development of the Neck
Branchial apparatus branchial arches, branchial grooves and membranes, pharyngeal
pouches
Branchial apparatus formation
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ARCH
GROOVE or CLEFT
POUCH
MEMBRANE
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The fourth week of prenatal development Stacked bilateral swellings of tissue First branchial arch(mandibular arch ) ~ fourth
mandibular arch Six pairs of U-shaped barsMesenchyme formed by neural crest cells, ectoderm,
and endoderm Fifth branchial arch is often so rudimentary Important structures of the face and neckHas its own developing cartilage, nerve, vascular,
and muscular components FIRST branchial arch(mandibular arch) are involved
in the formation of middle and lower face
Branchial arch formation
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Lower four pairs arches are involved in the formation of the structure of the neck.
Second branchial arch (=Hyoid arch)Reichert’s cartilage
: a middle ear bone, a process of the temporal bone, parts of the hyoid bone
Mesoderm of the hyoid arch: facial muscle, middle ear muscle, suprahyoidmuscle
Facial nerve
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Third branchial arch Parts of the hyoid bonePharyngeal muscleGlossopharyngeal nerve
Fourth and sixth branchial archMost of the laryngeal cartilageVagus nerve (+Glossopharyngeal nerve)
Table 4-2 Branchial Arches and Derivative Structures
First arches(mandibular)
Trigeminal nerve, muscles of mastication, mylohyoid and anterior belly of digastric, tensor tympani, tensor veli palatine muscles
Malleus and incus of middle ear, including anterior ligament of the malleus, sphenomandibularligament, and parts of sphenoid bone
Second arches(hyoid)
Facial nerve, stapedius muscle, muscles of facial expression, posterior belly of the digastric muscle, stylohyoid muscle
Stapes and parts of malleus and incus of middle ear, stylohyoidligament, styloid process of the temporal bone, lesser cornu of hyoid bone, upper portion of body of hyoid bone
Third arches Glossopharyngeal nerve, stylopharyngeal muscle
Greater cornu of hyoid bone, lower portion of body of hyoid bone
Fourth throughSixth arches
Superior laryngeal branch and recurrent laryngeal branch of vagusnerve, levator veli palatine muscles, pharyngeal constrictors, intrinsic muscles of the laynx
Laryngeal cartilage
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External grooves, between neighboring branchial arches
FIRST branchial groove Is located between the first and second branchial archesA mature structure of the head and neck First branchial membrane
: tympanic membrane First branchial groove
: external auditory meatus By the end of the seventh week,
: Hyoid arch enlarges and overlaps the third, fourth, and sixth arches and cover them.: the last for branchial grooves are obliterated neck formation
Branchial groove and membrane formation
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Four well-defined pairs of pharyngeal pouches
Endodermal evaginations form the lateral walls lining the pharynx
Many structures of the face and neck.
Pharyngeal pouch formation
Table 4-3 Pharyngeal Pouches and Derivative Structures
First pouches Tympanic membrane (with first branchial groove), tympanic cavity, mastoid antrum, auditory tube
Second pouches Crypts and lymphatic nodules of the palatine tonsils
Third and fourth pouches Parathyroid and thymus gland
** Developmental disturbances of the branchial apparatus• Cervical cysts or Cervical sinuses