Prenatal Development Quiz
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Questions and Answers

What is the process called that leads to the formation of the neural tube?

  • Neural induction
  • Neural differentiation
  • Neural migration
  • Neurulation (correct)

    • Which structure closes first during the neural tube development?

  • Neural crest
  • Neural plate
  • Anterior neuropore (correct)
  • Posterior neuropore

    • What happens to the neural tube after its formation?

  • It retains communication with the amniotic cavity initially. (correct)
  • It loses all connections to the amniotic cavity.
  • It immediately forms the laryngeal structures.
  • It remains connected to the external environment indefinitely.

    • What is formed by the cells at the margin of the neural plate during invagination?

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

    What does the closure of the anterior and posterior neuropores signify?

    <p>The completion of neural tube formation.</p> Signup and view all the answers

    What type of transition do neural crest cells undergo as they migrate into the mesoderm?

    <p>Epithelial-to-mesenchymal transition</p> Signup and view all the answers

    Which structures are developed from the neural crest cells?

    <p>Melanocytes and Schwann cells</p> Signup and view all the answers

    What major development occurs at the end of the 4th week regarding the respiratory system?

    <p>The respiratory system arises from the laryngotracheal pouch.</p> Signup and view all the answers

    How long are vocal folds at birth, according to the provided information?

    <p>4 mm</p> Signup and view all the answers

    What structure is formed from the splanchnic mesenchyme of the 4th and 6th arches?

    <p>Arytenoid cartilages</p> Signup and view all the answers

    During which week does the trachea separate from the esophagus?

    <p>Week 4</p> Signup and view all the answers

    What significant change occurs in vocal fold length during puberty?

    <p>Length increases significantly for males compared to females.</p> Signup and view all the answers

    Which of the following structures represents part of the hyoid arch?

    <p>Part of the hyoid bone</p> Signup and view all the answers

    Which layer of the vocal fold cover is responsible for lubrication through hydration?

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

    What are the two zones of the basement membrane zone (BMZ)?

    <p>Lamina lucida and lamina densa</p> Signup and view all the answers

    What primarily composes the intermediate layer of the lamina propria?

    <p>Elastic fibers</p> Signup and view all the answers

    What term is used to refer to the superficial layer of the lamina propria?

    <p>Reinke's space</p> Signup and view all the answers

    Which function does the basement membrane zone (BMZ) primarily provide?

    <p>Physical support to the epithelium</p> Signup and view all the answers

    What type of fibers mainly constitute the deep layer of the lamina propria?

    <p>Collagenous fibers</p> Signup and view all the answers

    Which component is essential for the vibratory function of the superficial layer?

    <p>Extracellular matrices</p> Signup and view all the answers

    What is the primary role of the fibers in the superficial layer of the lamina propria?

    <p>Provide structural support</p> Signup and view all the answers

    What is the primary function of elastin in the vocal fold tissues?

    <p>Contributes to tissue elasticity</p> Signup and view all the answers

    What significant change occurs to the vocal folds between the ages of 10 and 16 years?

    <p>All three layers of lamina propria develop</p> Signup and view all the answers

    At what age is laryngeal cartilage growth typically complete?

    <p>20 years</p> Signup and view all the answers

    Which structural change in the vocal folds is associated with aging?

    <p>Stiffening due to collagen increase</p> Signup and view all the answers

    What causes presbyphonia in older adults?

    <p>Lower respiration efficiency</p> Signup and view all the answers

    Which of the following contributes to vocal fatigue as a person ages?

    <p>Decreased muscle mass in thyroarytenoid</p> Signup and view all the answers

    Which vocal characteristic is commonly observed in older adults?

    <p>Increased breathiness</p> Signup and view all the answers

    What is likely to decline after the age of 60 regarding laryngeal nerves?

    <p>Action potential efficacy</p> Signup and view all the answers

    How does the fundamental frequency of adult males change with age?

    <p>Increases from around 130 Hz to 140 Hz</p> Signup and view all the answers

    What is the relationship between respiration and phonation as individuals age?

    <p>Weaker respiration leads to weaker phonation</p> Signup and view all the answers

    What happens to the mass and length of vocal folds around puberty?

    <p>They increase significantly</p> Signup and view all the answers

    What vocal change is typically associated with aging and affects the harmonic-to-noise ratio?

    <p>Increased harmonic-to-noise ratio</p> Signup and view all the answers

    What structural change occurs in laryngeal cartilage as individuals reach their late 60s?

    <p>Laryngeal cartilage fully ossifies</p> Signup and view all the answers

    What happens to the SLP, ILP, and DLP layers of the vocal folds in infants compared to adults?

    <p>Infants have 50% adult elastin and collagen</p> Signup and view all the answers

    Study Notes

    Prenatal Development

    • Neurulation: Formation of the neural tube from the neural plate.
      • Neural plate develops a neural groove bounded by neural folds.
      • Neural folds fuse, transforming the groove into the neural tube.
    • Neural Tube Closure: The neural tube initially connects to the amniotic cavity through the anterior and posterior neuropores.
      • The anterior neuropore closes first, followed by the posterior neuropore.
      • Neural tube closure is complete within 28 days.
    • Neural Crest Formation: During neural plate invagination, cells at the plate's margins form the neural crest, a strip of ectodermal cells between the neural tube and the covering ectoderm.
      • Neural crest cells undergo epithelial-to-mesenchymal transition and migrate into the underlying mesoderm.
      • These cells differentiate into various structures, including posterior root ganglia, sensory ganglia of cranial nerves, autonomic ganglia, melanocytes, cells of the suprarenal medulla, and Schwann cells.

    Pharyngeal Arches

    • Week 4: Neural crest cells migrate from the neural plate margins, forming structures in the head and neck, including the pharyngeal arch system.
    • Pharyngeal Arches and Phonation:
      • The hyoid arch (2nd arch) forms part of the hyoid bone.
      • The 3rd arch forms the rest of the hyoid bone.
      • The 4th and 6th arches contribute to the pharyngeal, recurrent, and superior laryngeal nerves of the vagus nerve (X). They also form extrinsic and intrinsic laryngeal muscles, and the thyroid, corniculate, cuneiform, and arytenoid cartilages.

    Laryngeal Development

    • Week 4:
      • The laryngotracheal diverticulum develops from the pharyngeal tube.
      • It forms the respiratory bud, which ultimately develops into the lungs.
      • The respiratory tree communicates with the pharyngeal tube through the laryngeal inlet, which becomes the aditus to the larynx.
      • Splanchnic mesenchyme in the 4th and 6th arches develops into the cartilages.
      • The arytenoids develop as swellings.
      • Other structures, like the glottis, laryngeal ventricles, vocal folds, epiglottis, and ventricular folds, also form.
    • Week 4-8:
      • The trachea separates from the esophagus as bronchial buds emerge.
      • The tracheoesophageal tube develops, including the larynx, trachea, bronchi, and lungs.
    • Birth and Growth:
      • Vocal fold length at birth is approximately 4 mm, growing to 12-15 mm in teens.
      • Significant changes occur during puberty, leading to sexual dimorphism in vocal fold size.
        • Adult males: 17.5 to 25 mm.
        • Adult females: 12.5 to 17.5 mm.

    Vocal Fold Histology

    • Five Layers of Vocal Folds:
      1. Cover:
        • Includes the epithelium, basal lamina, and superficial layer of the lamina propria.
        • Epithelium: Stratified squamous non-keratinized epithelium covers the free edge of the vocal fold’s vibratory portion.
          • Microridges and microvilli aid in lubrication and mucous retention.
        • Basal lamina: Acts as a supportive structure for the epithelium.
        • Superficial layer of the lamina propria (SLP): Loose fibrous components and extracellular matrices, also known as Reinke’s space.
          • SLP is highly involved in vocal fold vibration.
          • Primary extracellular matrices in the SLP include reticular, collagenous, and elastic fibers, as well as glycoproteins and glycosaminoglycans.
      2. Transition:
        • Includes the intermediate and deep layers of the lamina propria.
        • Intermediate layer (ILP): Primarily elastic fibers
        • Deep layer (DLP): Primarily collagenous fibers
        • The ILP and DLP comprise the vocal ligament.
          • The transition layer provides structural support and adhesion between the cover (mucosa) and the body (thyroarytenoid muscle).
      3. Body:
        • Comprised of the thyroarytenoid muscle.
        • This muscle is often described as being divided into the vocalis muscle (or thyrovocalis) and the thyromuscularis, depending on the source.

    Vocal Fold Changes from Birth to Puberty

    • SLP: Differentiates into three layers by age 7-10.
    • By 10-16 years: All three layers become adult-like.
    • The development of the lamina propria is crucial for voice quality, contributing to differences between child and adult voices.

    Elastin and Collagen Changes

    • Elastin: Provides elasticity.
    • Collagen: Provides structure and support, reducing injury.
    • Developmental Changes:
      • Adults:
        • SLP lacks collagen and elastin.
        • ILP has elastin but little collagen.
        • DLP is primarily collagen with little elastin.
      • Infants: Have approximately 50% of adult elastin and collagen levels. - Distribution of these components progresses with development.
      • Older adults: Experience a loss of elastin but maintain or increase collagen levels.

    Cartilage Changes During Development

    • At birth: The larynx is approximately 33% of its adult size.
      • Cartilage continues to grow until adulthood.
      • Cartilage stiffens with age.
    • Puberty:
      • Growth of the thyroid and cartilage.
        • The male thyroid cartilage is about twice the weight of the female cartilage.
        • The prominent thyroid angle (Adam’s apple) develops.
    • Cartilage growth is complete at 20 years of age.

    Hyoid and Laryngeal Descent During Development

    • Hyoid:
      • Ossification of the hyoid begins shortly after birth.
      • At birth, the hyoid is at the level of the C2/C3 vertebrae, and the larynx is at the C3/C4 level.
      • By the age of 2, the larynx and hyoid reach their adult positions (C3/C6 and C4, respectively).
    • Torso growth: The vocal tract lengthens with torso growth, increasing resonatory volume, including the subglottal space.

    Fundamental Frequency Changes

    • Development:
      • Neonates have the highest f0, which gradually decreases towards puberty.
      • Sexual dimorphism is strongly present at puberty, as vocal fold mass and length increase.
    • Aging:
      • Adult male f0 is around 130 Hz at 20 years old, and then rises to around 140 Hz at 80.
      • Female f0 is around 190 Hz at 20, and remains relatively steady into older age.

    Aging Effects on Phonation

    • Presbyphonia: The phonatory characteristics of a geriatric vocal mechanism.
    • Prebylarynx: The aging laryngeal structures.
    • Aging effects on phonation closely mirror changes in respiration.
      • Respiratory decline begins in the 20s, and phonation follows a similar trajectory.

    Vocal Effects of Presbyphonia

    • Hoarseness.
    • Low vocal intensity.
    • Increased breathiness.
    • Vocal fatigue.
    • Reduced vocal harmonics.

    Supportive Tissue Changes with Age

    • Decreasing elastin and increasing collagen in the lamina propria (SLP, ILP, DLP).
    • Results in:
      • Vocal fold stiffness and reduced elasticity.
      • Increased vocal fatigue and hoarseness.
      • Reduced f0 range.
      • Thinner and more fragile vocal ligament.

    Muscle Changes with Aging

    • Sarcopenia: Muscle atrophy.
      • Muscle fibers are lost, and existing fibers become thinner and smaller.
      • The thyroarytenoid muscle is particularly susceptible, especially after 60 years old.
      • Weakened thyrovocalis leads to breathy phonation and inefficient respiratory use.
      • Loss of elastin can cause bowing of the vocal folds.
      • Laryngeal descent into the pharynx is increased due to weak supraglottal muscles.

    Cartilage and Nerve Changes with Aging

    • Cartilage:
      • Laryngeal cartilage ossifies with age, with the exception of the epiglottis.
      • Ossification begins around 18 years and is complete around 70 years.
    • Nerves:
      • Laryngeal nerves are vulnerable to aging.
      • Action potential decline occurs after 60 years old.
        • This can result in:
          • Inadequate adduction, f0 change, breathiness, and increased vocal jitter.
          • Reduced sensitivity, making the larynx more susceptible to foreign body entry.

    Other Acoustic Parameters and Aging

    • Vocal jitter: Increases with age due to greater phonation variability.
    • Vocal intensity: Weaker phonation as we age.
    • Vocal range Decreases as we age.
    • Harmonic-to-Noise ratio: Increases with age.

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    Description

    Test your knowledge on the essential stages of prenatal development, including neurulation, neural tube closure, and neural crest formation. This quiz covers key concepts and processes that are crucial in understanding embryonic development. Dive in to see how well you know the formation and functions of the neural structures!

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