Embryology of Facial Development
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Questions and Answers

What forms the lateral boundaries of the stomodeum?

  • Lateral nasal prominences
  • Mandibular prominences
  • Maxillary prominences (correct)
  • Frontal nasal prominence
  • During which period does facial development occur mainly?

  • First trimester
  • Second trimester
  • Fourth to eighth weeks (correct)
  • Third trimester
  • What does the common chin dimple result from?

  • Incomplete fusion of the lateral nasal prominences
  • Incomplete fusion of the mandibular prominences (correct)
  • Incomplete fusion of the frontal nasal prominence
  • Incomplete fusion of the maxillary prominences
  • What signaling regulates the process of movement of the medial nasal prominences toward the median plane?

    <p>Platelet-derived growth factor receptor α-polypeptide (PDGFRA) signaling</p> Signup and view all the answers

    From where do the primordia of the auricles begin to develop by the end of the fifth week?

    <p>Frontal nasal prominence</p> Signup and view all the answers

    Which structure develops from a rod-like thickening in the floor of the nasolacrimal groove?

    <p>Nasolacrimal duct</p> Signup and view all the answers

    How does the nasolacrimal duct form?

    <p>Through apoptosis and canalization</p> Signup and view all the answers

    What happens between the 7th and 10th weeks in relation to the facial prominences?

    <p>The medial nasal prominences merge with the maxillary and lateral nasal prominences</p> Signup and view all the answers

    What is continuous with the rostral portion of the nasal septum formed by the frontal prominence?

    <p>Intermaxillary segment</p> Signup and view all the answers

    What persists to form the frenulum of the upper lip?

    <p>Labiogingival lamina</p> Signup and view all the answers

    What is the main source of connective tissue components in the facial and oral regions?

    <p>Neural crest populations from the mesencephalic and rostral rhombencephalic neural folds</p> Signup and view all the answers

    What gives rise to the optic vesicles that form the eyes?

    <p>Frontal part of the frontonasal prominence</p> Signup and view all the answers

    Which of the following is true about facial development?

    <p>It involves inductive influence of the forebrain, frontonasal ectodermal zone, and developing eye</p> Signup and view all the answers

    What are the derivatives of the first pair of pharyngeal arches?

    <p>Maxillary and mandibular prominences</p> Signup and view all the answers

    Which part of the frontonasal prominence forms the forehead?

    <p>Frontal part</p> Signup and view all the answers

    What is the function of the periodontal ligament?

    <p>It holds the tooth firmly in position and functions as a shock absorber</p> Signup and view all the answers

    Which structure is responsible for the eruption of deciduous or milk teeth?

    <p>The growth of permanent teeth buds</p> Signup and view all the answers

    What is the function of ameloblasts in tooth development?

    <p>They produce long enamel prisms that are deposited over the dentin</p> Signup and view all the answers

    During which stage of tooth development does the tooth take on the appearance of a bell?

    <p>Cap stage</p> Signup and view all the answers

    What is the origin of the mesenchyme that forms the dental papilla?

    <p>Neural crest cells</p> Signup and view all the answers

    When does the eruption of deciduous or milk teeth typically occur?

    <p>6 to 24 months after birth</p> Signup and view all the answers

    What is the function of the dental sheath during tooth development?

    <p>It penetrates into underlying mesenchyme and forms the root of the tooth</p> Signup and view all the answers

    Which cells produce predentin and continuously provide it throughout the life of the tooth?

    <p>Odontoblasts</p> Signup and view all the answers

    What gives rise to a number of dental buds along the upper and lower jaws during tooth development?

    <p>The dental lamina</p> Signup and view all the answers

    During which week does the oronasal membrane rupture, bringing the nasal and oral cavities into communication?

    <p>End of the sixth week</p> Signup and view all the answers

    What is the role of the trigeminal nerves (CN V) in the development of facial muscles?

    <p>Supply muscles of mastication and others in the first pair of arches</p> Signup and view all the answers

    At what age do the maxillary sinuses reach full development?

    <p>Early adulthood</p> Signup and view all the answers

    What contributes to altering the size and shape of the face during infancy and childhood?

    <p>Growth of paranasal sinuses</p> Signup and view all the answers

    What is the critical period for palatogenesis?

    <p>End of the sixth week to beginning of the ninth week</p> Signup and view all the answers

    What forms the anterior and midline aspect of the maxilla?

    <p>Primary palate (median process)</p> Signup and view all the answers

    When do the lateral palatine processes assume a horizontal position above the tongue?

    <p>Eighth week</p> Signup and view all the answers

    What persists in the median plane of the palate between the anterior part of the maxilla and palatine processes?

    <p>Nasopalatine canal</p> Signup and view all the answers

    What develops from proliferation of cells lining them in the nasal cavities?

    <p>Temporary epithelial plugs</p> Signup and view all the answers

    Which pair of sinuses are not present at birth?

    <p>Frontal or sphenoidal sinuses</p> Signup and view all the answers

    The dental lamina forms a C-shaped structure along the length of the upper and lower jaws during tooth development.

    <p>True</p> Signup and view all the answers

    The mesenchyme cells in the dental papilla adjacent to the inner dental layer differentiate into ameloblasts.

    <p>False</p> Signup and view all the answers

    Enamel is first laid down at the neck of the tooth and from there spreads toward the apex.

    <p>False</p> Signup and view all the answers

    The crown is gradually pushed through the overlying tissue layers into the oral cavity as the root lengthens.

    <p>True</p> Signup and view all the answers

    The eruption of deciduous or milk teeth typically occurs 6 to 24 months before birth.

    <p>False</p> Signup and view all the answers

    The buds for permanent teeth form during the third month of development but begin to grow around the first year of postnatal life.

    <p>False</p> Signup and view all the answers

    The mesenchymal cells on the outside of the tooth differentiate into cementoblasts that produce specialized bone called dentin.

    <p>False</p> Signup and view all the answers

    The dental sheath is responsible for the resorption of deciduous teeth as permanent teeth grow.

    <p>False</p> Signup and view all the answers

    The fusion between the nasal septum and palatine processes is completed anteriorly during the 12th week of development.

    <p>False</p> Signup and view all the answers

    The irregular suture visible in the anterior region of the palates of young persons indicates where the embryonic primary and secondary palates fused.

    <p>True</p> Signup and view all the answers

    Study Notes

    Development of the Face

    • Facial development begins in the fourth week, dependent on the inductive influence of the forebrain, frontonasal ectodermal zone, and developing eye
    • Five facial primordia appear as prominences around the stomodeum (mouth): frontonasal, maxillary, mandibular, and paired nasal placodes
    • These prominences are produced mainly by the expansion of neural crest populations originating from the mesencephalic and rostral rhombencephalic neural folds
    • The frontonasal prominence forms the forehead, nasal part, and orbits; maxillary and mandibular prominences form the lateral boundaries and caudal boundary of the stomodeum, respectively

    Development of Palate

    • Palatogenesis begins in the sixth week, involving the primary and secondary palates
    • The primary palate, formed by merging medial nasal prominences, represents the anterior and midline aspect of the maxilla
    • The secondary palate develops from two mesenchymal projections (palatal shelves) extending from the internal aspects of the maxillary prominences
    • Lateral palatine processes assume a horizontal position above the tongue, eventually forming the hard and soft parts of the palate

    Development of Nasal Cavities

    • Nasal placodes (primordia of nasal epithelium) develop on the inferolateral parts of the frontonasal prominence
    • Mesenchyme in the margins of the placodes proliferate, producing horseshoe-shaped elevations, the medial and lateral nasal prominences
    • Nasolacrimal duct develops from a rod-like thickening of ectoderm in the floor of the nasolacrimal groove
    • By the end of the sixth week, the nasal pits have formed, and the nasal cavities are separated from the oral cavity by the oronasal membrane

    Postnatal Development of Paranasal Sinuses

    • Paranasal sinuses, such as maxillary sinuses, begin to develop during late fetal life; others develop after birth
    • Original openings of the diverticula persist as the orifices of the adult sinuses
    • Maxillary sinuses grow slowly until puberty and are not fully developed until early adulthood
    • Frontal and sphenoidal sinuses are not present at birth, but grow rapidly around 2 years of age

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    Development Of The Face PDF

    Description

    This quiz covers the embryological development of facial structures including the chin, lower lip, cheek regions, and nasal cavities. It includes the formation of nasal pits, nasal sacs, and their relationship to the developing forebrain.

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