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Development of pharyngeal
apparatus and palate
By
Dr. Abdul Waheed Ansari
Chairperson &Prof. Anatomy,
RAKCODS. RAKMHSU.
12...
Learning outcomes for this developmental
topic
• What are the components of pharyngeal
apparatus?
• Enlist the derivatives...
The pharyngeal apparatus are the bronchial apparatus
developing at the cranial end of embryo during 4th &5th
week of embry...
On approximately day 20 of development
• The first arch develops, followed by the second and the
third.
• By the time that...
Components of a pharyngeal arch
• Each arch has its own artery, nerve, cartilage rod
“skeleton”, and a group of muscle cel...
Nerves and muscles of pharyngeal arches
Pharyngeal arch Cranial nerve Muscles
12/18/2014 6
1st Trigeminal (V) Muscles of m...
Endoderm lines the internal surfaces of
the pharyngeal arches.
• The endodermally lined depressions
between the pharyngeal...
12/18/2014 8
The embryonic composition of
pharyngeal arch
• The core is made up of mesenchyme covered
externally by ectoderm and intern...
12/18/2014 10
Pharyngeal pouches are endodermal
• They protrude between the two succeeding arches from
inside.
• The first pouch is betw...
12/18/2014 12
The derivative of first pharyngeal cleft
• It forms the external acoustic meatus.
• The membrane so farmed between the cle...
External ear development
12/18/2014 14
12/18/2014 15
Origin of the pharyngeal arch musculature
1st pharyngeal arches Mm. masseter, temporalis,
pterygoideus (12)
Mandibular ner...
Development of palate
• The face develops from 5 prominences, frontonasal, right
and left maxillary and right and left man...
Development of upper lip
12/18/2014 18
Philtrum= medial nasal processes
Lateral part of upper lip= maxillary processes
The palate development
• Primary palate is
formed fusion of
medial nasal processes.
• The secondary palate is
the outgrowt...
Fusion of palatine shelves forming palate.
The four maxillary incisor teeth develop in pre-maxilla
12/18/2014 20
Incidences of cleft palate
• Roughly 1 out of every 900 children are born
with a cleft palate.
• About 70% of these childr...
Cleft hard and soft palate due to non fusion of palatine processes
with each other
12/18/2014 22
Cleft lip due to non fusion of frontonasal
and maxillary processes
12/18/2014 23
The congenital forms of pharyngeal
apparatus
• The cervical cyst and fistulas are
congenital malformation when the
2nd pha...
Thyroglossal duct cysts
• Are remnants of the
embryonic thyroglossal duct
that may occur anywhere
from the base of the ton...
Mandibulofacial Dysostosis (Treacher
Collins Syndrome)
12/18/2014 26
This malformation due to
disturbed development of
neu...
References
• http://quizlet.com/16788403/
embryology-pharyngeal-
apparatus-flash-cards/
• http://quizlet.com/6930680/gr
os...
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Development of pharyngeal apparatus and palate

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Development of pharyngeal apparatus and palate

  1. 1. Development of pharyngeal apparatus and palate By Dr. Abdul Waheed Ansari Chairperson &Prof. Anatomy, RAKCODS. RAKMHSU. 12/18/2014 1
  2. 2. Learning outcomes for this developmental topic • What are the components of pharyngeal apparatus? • Enlist the derivatives of all pharyngeal arches • Mention the derivatives of pharyngeal pouches • What are the derivatives of pharyngeal clefts? • Name the developmental sequences of hard and soft palate • Explain the congenital forms of pharyngeal apparatus 12/18/2014 2
  3. 3. The pharyngeal apparatus are the bronchial apparatus developing at the cranial end of embryo during 4th &5th week of embryogenesis • The result of the pharyngeal apparatus are the development of face, neck, organs like tongue, tonsil, thyroid, parathyroid, thymus, middle ear, muscles of face, muscles of mastication, laryngeal and pharyngeal muscles. • The pharyngeal arches are bilateral/paired swellings that surround the foregut of the embryo from day 20 to day 35 of development . • These arches are numbered 1,2,3,4, and 6. 12/18/2014 3
  4. 4. On approximately day 20 of development • The first arch develops, followed by the second and the third. • By the time that arches 4 and 6 develop, the first two arches are no longer distinctly visible externally. • The cellular elements of the pharyngeal apparatus are formed by cells that are derived from ectoderm, endoderm, mesoderm and neural crest cells. • Ectoderm lines the external surfaces of the pharyngeal arches. • The ectodermally lined depressions between the pharyngeal arches are called pharyngeal grooves. 12/18/2014 4
  5. 5. Components of a pharyngeal arch • Each arch has its own artery, nerve, cartilage rod “skeleton”, and a group of muscle cells. • The first structure to develop in each arch is the aortic (pharyngeal) arch artery. • The arteries, like the arches, develop in a rostro- caudal sequence. • While the fourth aortic arch artery is forming, the arteries of the first and second arches are breaking up and disappear. • The third arch artery becomes part of the common carotid, the fourth arch artery becomes the arch of the aorta, and the sixth becomes the pulmonary artery. 12/18/2014 5
  6. 6. Nerves and muscles of pharyngeal arches Pharyngeal arch Cranial nerve Muscles 12/18/2014 6 1st Trigeminal (V) Muscles of mastication 2nd Facial (VII) Muscles of facial expression 3rd Glossopharyngeal (VIII) Stylopharyngeus 4th 6th Vagus (X) External laryngeal nerve Recurrent laryngeal nerve Laryngeal musculature Pharyngeal constrictors
  7. 7. Endoderm lines the internal surfaces of the pharyngeal arches. • The endodermally lined depressions between the pharyngeal arches are called pharyngeal pouches. • They will form endocrine glands, tonsillar crypts and thymus. • The tongue is formed by the endoderm of the floor of mouth by 2 lateral lingual swellings, median lingual swelling, cupola of His and hypobranchial eminence. 12/18/2014 7
  8. 8. 12/18/2014 8
  9. 9. The embryonic composition of pharyngeal arch • The core is made up of mesenchyme covered externally by ectoderm and internally by endoderm. • The first pharyngeal arch separates into two prominences, the maxillary and mandibular prominences. • The maxillary prominence gives rise to the maxilla, zygomatic bone, and a portion of the vomer bone. • The mandibular prominence forms the mandible and the squamous temporal bone. • The second pharyngeal arch (hyoid arch) contributes, along with parts of the third and fourth arches, to the formation of the hyoid bone. • The cartilages of larynx develops from 6th arch. 12/18/2014 9
  10. 10. 12/18/2014 10
  11. 11. Pharyngeal pouches are endodermal • They protrude between the two succeeding arches from inside. • The first pouch is between first and second arch. It give rise to middle ear cavity and auditory tube. • The second pouch will form the tonsillar crypts. • The third pouch develops into inferior parathyroid glands and thymus. • The fourth pouch will form the superior parathyroid glands. • The distal pharyngeal complex will form ultimo bronchial body- the parafollicular cells/”C” cells of thyroid gland. • The thyroid gland perse arises from a diverticulum from the floor of oral cavity, thyroglossal duct. This duct descends inferiorly and settle down in neck. 12/18/2014 11
  12. 12. 12/18/2014 12
  13. 13. The derivative of first pharyngeal cleft • It forms the external acoustic meatus. • The membrane so farmed between the cleft and pouch remains as tympanic membrane. • There are very little elements of mesoderm between first cleft and pouch. • The remaining pharyngeal cleft closes down. If they persists, they form cervical cyst or sinus. • The external ear is formed around the brim of first and second arches externally, by six ear hillocks, which later forms the external pinna. 12/18/2014 13
  14. 14. External ear development 12/18/2014 14
  15. 15. 12/18/2014 15
  16. 16. Origin of the pharyngeal arch musculature 1st pharyngeal arches Mm. masseter, temporalis, pterygoideus (12) Mandibular nerve from the trigeminal nerve (HN V 3) 2nd pharyngeal arches Mimic musculature: Mm. Stylohyoideus, digastricus (venter posterior) and stapedius Facial nerve (HN VII) 3rd pharyngeal arches M. stylopharyngeus N. glossopharyngeus (HN IX) 4th pharyngeal arches Almost the entire pharynx and larynx musculature N. vagus and accessory (HN X and XI) 5th pharyngeal arches and cervical somites M. sternocleidomastoideus and trapezius N. accessory (HN XI) 12/18/2014 16
  17. 17. Development of palate • The face develops from 5 prominences, frontonasal, right and left maxillary and right and left mandibular prominences. • The maxillary prominences sends out a horizontal shelves, the palatine shelves from inside. This later fuses in the mid line separating the nasal cavity from the oral cavity. • The posterior 1/3rd of palate is soft and the palatine muscles contribute to its formation. Failure of closure of palatine shelves in the midline can give rise to cleft palate or cleft lip. • A bifid uvula is a minor degree of non-fusion of two palatine shelves. 12/18/2014 17
  18. 18. Development of upper lip 12/18/2014 18 Philtrum= medial nasal processes Lateral part of upper lip= maxillary processes
  19. 19. The palate development • Primary palate is formed fusion of medial nasal processes. • The secondary palate is the outgrowth from the maxillary prominences medially inside and when tongue is growing from below the two halves of palatine shelves fuse together in the midline. 12/18/2014 19
  20. 20. Fusion of palatine shelves forming palate. The four maxillary incisor teeth develop in pre-maxilla 12/18/2014 20
  21. 21. Incidences of cleft palate • Roughly 1 out of every 900 children are born with a cleft palate. • About 70% of these children will also have a cleft lip. • The other one third will have only a cleft palate. 12/18/2014 21
  22. 22. Cleft hard and soft palate due to non fusion of palatine processes with each other 12/18/2014 22
  23. 23. Cleft lip due to non fusion of frontonasal and maxillary processes 12/18/2014 23
  24. 24. The congenital forms of pharyngeal apparatus • The cervical cyst and fistulas are congenital malformation when the 2nd pharyngeal arch fails to grow caudally over the 3rd and 4th arches. • They usually occur in carotid triangle. • Axial CT scan showing a right branchial cleft cyst 12/18/2014 24
  25. 25. Thyroglossal duct cysts • Are remnants of the embryonic thyroglossal duct that may occur anywhere from the base of the tongue to the thyroid gland. • The majority, however, are found at the level of the thyrohyoid membrane, under the deep cervical fascia. • They are midline or just off the midline, and move up and down upon swallowing. 12/18/2014 25
  26. 26. Mandibulofacial Dysostosis (Treacher Collins Syndrome) 12/18/2014 26 This malformation due to disturbed development of neural crest cells, malformation of mandible and external ear. Hypoplasia of first arch elements.
  27. 27. References • http://quizlet.com/16788403/ embryology-pharyngeal- apparatus-flash-cards/ • http://quizlet.com/6930680/gr oss-anatomy-development-of- the-pharyngeal-apparatus-the- head-and-neck-flash-cards • http://www.columbia.edu/itc/ hs/medical/humandev/2004/C hapt9-PharyngealArches.pdf • http://www.ghorayeb.com/Br anchialCleft.html • http://www.youtube.com/wat ch?v=r18fexJ-UnE • http://www.youtube.com/wat ch?v=rlA6ncGwwAU • https://web.duke.edu/anatom y/embryology/craniofacial/cra niofacial.html • https://syllabus.med.unc.edu/ courseware/embryo_images/u nit- hednk/hednk_htms/hednk033 .htm 12/18/2014 27

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