Pharyngeal Apparatus: Development and Structure
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Questions and Answers

What is the Pharyngeal Apparatus also known as?

  • Cephalic Apparatus
  • Digestive Tract
  • Mesodermal Masses
  • Branchial System (correct)

    • On which embryonic day does the formation of the Pharyngeal Apparatus start?

  • 25
  • 22 (correct)
  • 20
  • 18

    • What is the function of the Pharyngeal Apparatus in the development of the embryo?

  • Modeling and development of the cephalic end and face (correct)
  • Development of the limbs
  • Formation of the digestive tract
  • Formation of the nervous system

    • What are the four components of the Pharyngeal Apparatus?

    <p>Pharyngeal Arches, Pharyngeal Grooves, Pharyngeal Pouches, Pharyngeal Membranes</p> Signup and view all the answers

    What is the derivative of the 1st Pharyngeal Pouch?

    <p>Auditory tube (eustachian tube) and tympanic cavity</p> Signup and view all the answers

    What is the derivative of the 1st Pharyngeal Arch?

    <p>Maxilla and Zygomatic bone</p> Signup and view all the answers

    What happens to the pharynx and cardiac structures during the expansion of brain and associated structures?

    <p>They expand caudally</p> Signup and view all the answers

    What is the derivative of the dorsal part of the fourth pharyngeal pouch?

    <p>Superior parathyroid gland</p> Signup and view all the answers

    What is formed from the ventral part of the fourth pharyngeal pouch?

    <p>Ultimobranchial body</p> Signup and view all the answers

    What is the function of the pharyngeal grooves?

    <p>To separate the pharyngeal arches externally</p> Signup and view all the answers

    Which of the following cartilages is associated with the mandibular arch?

    <p>Meckel's cartilage</p> Signup and view all the answers

    Which pharyngeal arch is responsible for the formation of the mandible?

    <p>Second pharyngeal arch</p> Signup and view all the answers

    What is the fate of the second to fourth pharyngeal grooves and the cervical sinus?

    <p>They are normally obliterated along with the sinus as the neck</p> Signup and view all the answers

    What is the function of the pharyngeal membranes?

    <p>To form the tympanic membrane</p> Signup and view all the answers

    Which of the following muscles is innervated by the glossopharyngeal nerve?

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

    What is the relationship between the epithelia of the pharyngeal grooves and the pouches?

    <p>They are separated by mesenchyme</p> Signup and view all the answers

    Which of the following arteries is derived from the third pharyngeal arch?

    <p>Internal Carotid artery</p> Signup and view all the answers

    What is the ultimate fate of the cervical sinus?

    <p>It is normally obliterated along with the sinus as the neck</p> Signup and view all the answers

    Which of the following structures is derived from the dorsal part of the third pharyngeal pouch?

    <p>Parathyroid gland</p> Signup and view all the answers

    Which of the following nerves is associated with the fourth pharyngeal arch?

    <p>Superior laryngeal nerve</p> Signup and view all the answers

    Which of the following structures is derived from the ventral part of the fourth pharyngeal pouch?

    <p>Postbranchial body</p> Signup and view all the answers

    Which of the following pharyngeal arches is rudimentary?

    <p>Fifth pharyngeal arch</p> Signup and view all the answers

    What is the origin of the cartilage of the epiglottis?

    <p>Hypopharyngeal eminence</p> Signup and view all the answers

    How many well-defined pairs of pharyngeal pouches are there?

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

    What is the outcome of the expansion of the first pharyngeal pouch?

    <p>Formation of the tympanic membrane</p> Signup and view all the answers

    What is the outcome of the second pharyngeal pouch?

    <p>Development of the palatine tonsil</p> Signup and view all the answers

    What develops from the dorsal part of the third pharyngeal pouch?

    <p>Parathyroid gland</p> Signup and view all the answers

    What develops from the ventral parts of the third pharyngeal pouch?

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

    What is the connection between the tubotympanic recess and the pharynx?

    <p>Pharyngotympanic tube</p> Signup and view all the answers

    How many pharyngeal pouches do develop?

    <p>More than 5</p> Signup and view all the answers

    Study Notes

    Pharyngeal Apparatus

    • Also known as the branchial apparatus, meaning gills
    • Formation starts on embryonic day 22
    • Involved in modeling and development of the cephalic end and face of the embryo
    • Results in a complex form for the pharyngeal segment of the digestive tract

    Components of Pharyngeal Apparatus

    • Four components: Pharyngeal Arches, Pharyngeal Grooves, Pharyngeal Pouches, and Pharyngeal Membranes

    Pharyngeal Arches

    • First pharyngeal arch (mandibular arch): masses of mesoderm covered by ectoderm and lined by endoderm
    • Develops into muscular and skeletal components, as well as aortic arches and nerve networks
    • Separates into two prominences: maxillary and mandibular prominences
    • Aortic Arch: Maxillary Artery
    • 1st Pharyngeal Pouch: Auditory tube (eustachian tube) and tympanic cavity
    • 1st Pharyngeal Groove: External auditory meatus (exterior ear opening)

    Mandibular Arch

    • 2 prominences: Maxillary and Mandibular
    • Maxillary Process: Cranial/Ventral - upper jaw
    • Bone (intramembranous): 1. maxilla, 2. zygomatic bone, 3. squamous part of the temporal bone
    • Mandibular Process: Caudal/Dorsal - lower jaw
    • Cartilages: Meckel's cartilage, Malleus, Incus
    • Bone: Mandible

    Second Pharyngeal Arch (Hyoid Arch)

    • Os hyoid (along with parts of the third and fourth arches)
    • Enlarges and overgrows the third and fourth arches, forming an ectodermal depression - the cervical sinus
    • 2nd Aortic Arch: Hyoid artery, Stapedial artery
    • 2nd Pharyngeal Pouch: Supratonsillar fossa - component of the palatine tonsils

    Third Pharyngeal Arch

    • Greater cornu and the inferior part of the body of the hyoid bone
    • Musculature: stylopharyngeus muscles, innervated by the glossopharyngeal nerve
    • 3rd Aortic Arch: Internal Carotid artery
    • 3rd Pharyngeal Pouch: Dorsal - paired inferior parathyroid, fuses with thyroid gland; Ventral - hollow and elongate, fuses ventro-medially to form the bilobed thymus

    Fourth Pharyngeal Arch

    • Cartilages fuse to form laryngeal cartilages, except for the epiglottis
    • Muscles: cricothyroid, levator palatini, and constrictors of the pharynx, innervated by the superior laryngeal branch of the vagus
    • Intrinsic muscles of the larynx: supplied by the recurrent laryngeal branch of the vagus
    • 4th Aortic Arch: Right Subclavian artery, Aorta
    • 4th Pharyngeal Pouch: Dorsal - forms paired superior parathyroids; Ventral - Postbranchial Body (ultimobranchial body, calcitonin)

    Fifth Pharyngeal Arch

    • Rudimentary (if present) and has no derivatives
    • Cartilage of the epiglottis develops from mesenchyme in the hypopharyngeal eminence, derived from the third and fourth pharyngeal arches

    Pharyngeal Pouches

    • Develop in a craniocaudal sequence between the arches
    • 4 well-defined pairs of pharyngeal pouches; the 5th pair is rudimentary or absent
    • The endoderm of the pouches contacts the ectoderm of the pharyngeal grooves
    • A double-layered pharyngeal membrane separates the pharyngeal pouches from the pharyngeal grooves

    Pharyngeal Grooves

    • Visible on each side during the fourth and fifth weeks
    • Separate the pharyngeal arches externally
    • Only one pair of grooves contributes to postnatal structures; the first pair persists as the external acoustic meatus or ear canals

    Pharyngeal Membranes

    • As floors of the pharyngeal grooves
    • The epithelia of the grooves and pouches approach each other
    • The endoderm of the pouches and the ectoderm of the grooves are soon separated by mesenchyme
    • Only one pair of membranes contributes to the formation of adult structures; the first pharyngeal membrane, along with the intervening layer of mesenchyme, becomes the tympanic membrane

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    Description

    This quiz covers the pharyngeal apparatus, also known as the branchial apparatus, including its formation, components, and developmental anomalies. Learn about its role in modeling the cephalic end and face of the embryo.

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