Development of pharyngeal
apparatus and palate
Dr. Abdul Waheed Ansari
Chairperson &Prof. Anatomy,
Learning outcomes for this developmental
• What are the components of pharyngeal
• 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
• Explain the congenital forms of pharyngeal
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.
On approximately day 20 of development
• The first arch develops, followed by the second and the
• 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
• The ectodermally lined depressions between the
pharyngeal arches are called pharyngeal grooves.
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-
• While the fourth aortic arch artery is forming, the
arteries of the first and second arches are breaking up
• 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.
Endoderm lines the internal surfaces of
the pharyngeal arches.
• The endodermally lined depressions
between the pharyngeal arches are called
• 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.
The embryonic composition of
• 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
• 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.
Pharyngeal pouches are endodermal
• They protrude between the two succeeding arches from
• 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
• 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.
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.
Origin of the pharyngeal arch musculature
1st pharyngeal arches Mm. masseter, temporalis,
Mandibular nerve from the
(HN V 3)
2nd pharyngeal arches Mimic musculature:
Mm. Stylohyoideus, digastricus
(venter posterior) and stapedius
3rd pharyngeal arches M. stylopharyngeus N. glossopharyngeus (HN IX)
4th pharyngeal arches Almost the entire pharynx and
N. vagus and accessory
(HN X and XI)
5th pharyngeal arches and
M. sternocleidomastoideus and
Development of palate
• The face develops from 5 prominences, frontonasal, right
and left maxillary and right and left mandibular
• 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
Development of upper lip
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 outgrowth from the
medially inside and
when tongue is growing
from below the two
halves of palatine
shelves fuse together in
Fusion of palatine shelves forming palate.
The four maxillary incisor teeth develop in pre-maxilla
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
• The other one third will have only a cleft
Cleft hard and soft palate due to non fusion of palatine processes
with each other
Cleft lip due to non fusion of frontonasal
and maxillary processes
The congenital forms of pharyngeal
• 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
• Axial CT scan showing a right
branchial cleft cyst
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.
Mandibulofacial Dysostosis (Treacher
This malformation due to
disturbed development of
neural crest cells,
malformation of mandible
and external ear.
Hypoplasia of first arch