The document discusses the development of the pharyngeal arches, pouches, and clefts in humans. It notes that there are 6 pharyngeal arches which give rise to important structures like bones, muscles, blood vessels and nerves. The 4 pharyngeal pouches form structures such as the tonsils, thymus gland, and parathyroid glands. The pharyngeal clefts normally disappear but remnants can lead to congenital anomalies like branchial cysts or fistulas. In summary, the document outlines the embryonic development of the pharyngeal system and some associated congenital defects.

1. Bones of the Pelvic Girdle
And Lower Extremity

2. Introduction
After folding, the 2ry yolk sac inside the
embryo gives rise to : Foregut -Midgut –
hindgut.
The foregut is divided into :
a. Cranial part : extends from oral
membrane to the laryngo-tracheal groove.
It gives rise to :
 Part of mouth cavity
 Salivary glands
 Pharyngeal apparatus
 Respiratory system
b. Caudal part :
Begins distal to the
laryngotracheal groove.
It gives rise to: esophagus-stomach- part of duodenum-
liver-biliary system –pancreas.

3. Prof. Mohamed. A. Autifi

4. These arches appear in the 4th
and 5th weeks of development.
There are 6 pharyngeal
arches which are separated
from each other:
• Externally by 4 pharyngeal
clefts.
• Internally by 5 pharyngeal
pouches.
PHARYNGEAL APPARATUS (BRANCHIAL APPARATUS)
Pharyngeal or Branchial Arches.

5. DEVELOPMENT OF THE FACE
FORMATION OF 5 PROMIENCES AROUND THE STOMODEUM
1. The 1st pharyngeal arch develops 2 prominences:
A-Maxillary prominences can be distinguished lateral to the stomodeum.
B-Mandibular prominences can be distinguished caudal to the stomodeum.
2. The frontonasal prominence, formed by proliferation of mesenchyme ventral
to the brain vesicles. It constitutes the upper border of the stomodeum.
3. So the stomodeum becomes surrounded by 5 prominences:
• Frontonasal prominence lies cranially.
• 2 maxillary prominences lie on each side and cranially.
• 2 mandibular prominences lie caudally.
A-Maxillary prominences
B-Mandibular prominences
The frontonasal prominence

6. Fate of the frontonasal process
 The lateral nasal folds form the alae of the
nose.
 The nasal pits get deeper and they form the
primitive nasal cavities.
 The medain nasal fold forms:
1. Forehaed
2. Middle of the nose and nasal septum
3. Filtrum of the upper lip
4. Premaxilla
5. Frontal and nasal bones
Forehaed
Middle of the nose and
nasal septum
Bilateral ectodermal thickenings above the lateral angle
of stomodeum form the nasal placodes.
By the 5th weak, the nasal placodes are invaginated to
form the nasal pits, thus the nasal placodes are divided into medial and lateral
nasal folds (promeninces).
The two medial nasal folds fuse to form median nasal fold.
I. Frontonasal process

7. The medial nasal swellings
enlarge, grow medially and
merge with each other in
the midline to form the
intermaxillary segment
Human embryo: 7 weeks

8. Intermaxillary Segment
Gives rise to the:
 Philtrum of lip
 Premaxillary part of
the maxilla, that
bears the upper 4
incisors and the
associated gums
 Primary palate
(region of hard palate
just posterior to the
upper incisors)

9. II. Maxillary processes
 The maxillary process develops as mesodermal proliferation from the
1st pharyngeal arch.
 It grows ventrally and medially, compressing the medial nasal folds
towards the middle line and converting them into one median nasal fold.
 The maxillary processes are separated from the lateral nasal folds by
the nasolacrimal groove.
 The lower part of the groove will form the nasolacrimal duct while its
upper part will form the lacrimal sac.

10. II. Maxillary processes
 A palatine shelf arises from the
medial aspects of each maxillary
process.
 Both shelves are approximated
towards each other and fuse
together and with the premaxilla
forming the hard and soft palate.
Thus the nasal cavity becomes
separated from the oral cavity.
1. Cheeks
2. Upper lip except the filtrum
3. Palate except the premaxilla
Fate of maxillary processes

11. The primary palate represents only a small
part lying anterior to the incisive fossa, of
the adult hard palate
Hard palate
Primary
palate
Soft palate
Secondary
palate
The palate develops from two primordia:
• The Primary palate
• The Secondary palate
The Primary Palate
 Begins to develop:
 From the deep part of
the intermaxillary
segment, as median
palatine process
 Lies behind the
premaxillary part of the
maxilla
 Fuses with the
developing secondary
palate

12. The Secondary Palate
 Is the primordia of hard
and soft palate
posterior to the incisive
fossa
 Begins to develop:
 Early in the 6th week
 From the internal
aspect of the
maxillary processes,
as lateral palatine
process

13. III. The mandibular processes
 Develop from the mesenchyme of the 1st
pharyngeal arch.
 Fate :
1. Lower jaw
2. Lower lip
3. Floor of the mouth

14. Mouth:
Primitive oral cavity:develops
from:
a) An ectodermal depression
between frontonasal prominence
and the first pharyngeal arch:
b) An endormal part: is the
cranial end of the pharynx.
Lips & gingivae:
They develop as a linear ectodermal
thickenings
around the stomodeum  labiogingival laminae.
They grow into mesenchyme,
then degenerate
forming labiogingival grooves separating lips
from gingivae.
A small area of laminae persists in median plane
forming frenulum of the lip.

15. Submandibular gland: Appear late in 6th week, from an endodermal bud in floor of
stomodeum (alveolo- lingual groove).
Develops in same way as parotid gland.
Sublingual gland: appear in 8th week, from multiple endodermal buds in the alveolo-lingual
groove.
Salivary glands:
Appear as epithelial buds from oral
cavity.
Parotid gland: The first to appear,
early in 6th week, from oral
ectoderm, near angle of stomodeum.
It forms a tube, extends into cheek’s
mesoderm.
Its Proximal part forming the
parotid duct;
Its distal end breaks to form the
glandular alveoli.
Capsule & connective septae develop from surrounding mesoderm.
 The duct opening is carried to open inside the cheek.

16. Congenital anomalies
1. Anomalies of the mouth :
 Microstomia : small mouth opening
reduction in the size of the oral aperture that is severe
enough to compromise cosmesis, nutrition, and quality of life
 Macrostomia : large mouth opening
 Agnathia : absence lower jaw
 Micrognathia : small lower jaw
 Anodontia : absence of the teeth
2. Anomalies of the nose :
 Stenosis of nostrils
 Deviation of the nasal septum Macrostomia
Microstomia and single nostril

17. Facial clefts
Failure of the embryonic facial
prominences to fuse properly
 May be unilateral or bilateral
 May involve:
 Lips only: Cleft lip
 Palate only: Cleft palate
 Lip & palate: Cleft lip & palate
 Region of nasolacrimal
groove: Facial clefts
Lead to
difficulty in
breathing
feeding
sucking
swallowing
&
speech

18.  Median cleft lip: results from
failure of the medial nasal
prominences to merge and form
the intermaxillary segments
 Unilateral cleft lip: result from
failure of the maxillary
prominence to merge with the
medial nasal prominence on the
affected side
 Bilateral cleft lip: results due to
failure of maxillary prominences
to meet and unite with the medial
nasal prominences on both sides
Median Cleft lip
Unilateral cleft lip
Bilateral cleft lip

19. 2. Oblique facial cleft: results
from failure of the maxillary
prominence to fuse with the
lateral nasal prominence
3. Cleft palate leaves the nasal
and oral cavities connected &
results in nursing problem for
the new born
May be:
 Anterior/posterior to incisive
foramen
 Unilateral/bilateral
 Isolated/associated with cleft
lips
Cleft lip, cleft jaw &
cleft palate
Oblique facial cleft

20. Cleft lip coupled with clefts of the anterior
palate or entire palate.

21. • Gnathochisis- failure of central fusion of
mandibular prominences
• Micrognathia-underdevelopment of lower jaw,
incorrect positioning of ear.
• Agnathia- total lack of development of lower jaw
& incorrect positioning of ear.

22. Prof. Mohamed. A. Autifi

23. Development of Tongue
A. The mucous membrane
 Anterior 23:(lingual of mandibular Chorda
tympani ) arises from 3 swelling derived
from the ventral parts of both 1st
pharyngeal arches as follows:
• 2 lateral lingual swellings and
• 1 median swelling “tuberculum impar”
 Posteror 13:Glossopharyngeal nerve
developed from the upper half of
hypobranchial eminince”
 The post.13 fuses with the ant.23 along
a v-shaped sulcus terminalis.
B. The muscles of the tongue
 Derived from the occipital myotomes that
migrate to the developing tongue taking with
it their nerve supply (hypoglossal nerve)
 Some of the tongue muscles are
differentiated in situ.

24. Prof. Mohamed. A. Autifi

25. Congenital Anomalies:
1. Ankyloglossia (tongue-tie):
Frenulum of tongue extends to its
tip. Prevents movements & hinders
proper speech
2. Microglossia: small sized of tongue
3. Macroglossia: Large tongue, due to
lymphangioma or muscular
hypertrophy

26. Congenital Anomalies:
4. Cleft tongue: Incomplete fusion of
lingual swellings ➪ median
groove/cleft, does not extend to
tongue tip
5. Bifid tongue: Cleft extends to tip
6. Congenital cysts & fistulae:
Remnants of thyroglossal duct
7. Lingual thyroid tongue

27. Development of Pharyngeal arches

28. Prof. Mohamed. A. Autifi
Arch Skeletal
Derivatives
Muscular
Derivatives
Vascular
Element
Nereve
First arch
(mandibular
arch)
Consists of
maxillary
process
and
mandibular
process
Maxillary process
gives rise to:
1. Maxilla
2. Zygomatic
bone
3. Squamous part
of temporal
bone
Mandibular
process
differentiates
into :
1. Malleus
2. Incus
3. Anterior
ligament of
malleus
4. Spheno-
mandibular
ligament
5. Mandible
1.Muscles of
Mastication
2.Tensor
palati
3.Tensor
tympani
4. Mylohoid
5. Anterior
belly of
digastric
1. Maxillary
artery
Mandibular
nerve (V)

29. Prof. Mohamed. A. Autifi
Arch Skeletal
Derivatives
Muscular
Derivatives
Vascular Element Nereve
Second arch
(Hyoid arch)
Reichert’s
cartilage:
Differentiates
into:
1. Stapes
2. Styloid
process
3. Stylohyoid
ligament
4. Lesser horn
of the hyoid
bone
5. Upper part
of body of
hyoid bone
1. Muscles of
the scalp
and face
2. Platysma
3. Stylohyoid
4. Stapedius
5. Posterior
belly of
digastric
Stapedial
artery
(carotico-
tympanic br.
of ICA)
Facial nerve
(VII)

30. Arch Skeletal
derivatives
Muscular
derivatives
Vascular
Element
Nereve
Third arch 1. Greater horn of
hyoid bone
2. Lower part of
body of hyoid bone
Stylopharyngeus 1. I.C.A
2. C.C.A
Glossopharyngeal
nerve (IX)
Fourth arch Thyroid cartilage Cricothyroid 1. Arch of aorta
on left side
2. Subclavian A
on right side
Superior laryngeal
nerve (X)
Sixth arch Rest of Cartilages
of the larynx
except
epiglottis:
-Cricoid,
-Arytenoid,
-Corniculate
and
-Cuneiform.
NB. The epiglottis
develops from
mesenchyme in
hypobrancheal
eminence
1. Other intrensic
muscles of larynx
2. Constrector
muscles of pharynx
except
Stylopharyngeus
3. Muscles of
palate except
tensor palati
1. Pulmonary A
on each sides
2. Ductus
arteriosus
on left side
Recurrent
laryngeal nerve
(X)

31. Development of Pharyngeal pouches and clefts

32. First pouch
It gives rise to
tubotympanic recess
which forms:
1.Tympanic cavity
2.Auditory tube.
(pharyngotympanic
tube or Eustachian
tube)
Pharyngeal pouches

33. Second pouch
Gives rise to palatine tonsils
-Early in 3rd month, its lining
epithelium proliferates ➪ solid
tonsillar buds which grow into
underlying mesoderm.
-Their central cells
degenerate➪ hollow tonsillar
crypts.
-Crypts & surrounding
mesoderm ➪ palatine tonsils.
-Lymphatic tissue infiltrates its
mesoderm during 3-5 Month
-Tonsillar capsule formed by
condensed mesoderm.
-Remnants of pouch ➪
intratonsillar cleft

34. Third pouch
Gives rise to:
-inferior parathyroid glands.
-thymus gland.
At 6th week, they lose connection to
pharyngeal wall.
-Thymus gland migrates caudally &
medially, pulling the parathyroid. The two
thymic rudiments descend into
thorax. Gland is large at time of birth, ➚
up to 2nd year, little ➚ until 7th year,
rapid growth to 11th year,
then ➘ to adult weight (12-15 gm)
-Inferior parathyroid glands descends
to lower pole of thyroid gland

35. Fourth pouch
It gives rise to:
1.Superior parathyroid
glands.
It migrates with the thyroid
gland.
2. Ultimo-branchial
body.
It incorporates into the
thyroid gland.
It gives parafollicular or C
cells of thyroid gland

36. PHARYNGEAL GROOVES
(CLEFTS):
In the 5th week: 4 clefts seen.
The first cleft gives:
external auditory meatus.
The epithelium of the bottom
forms outer layer of eardrum
NB. Active growth of 2nd arch
mesoderm overlaps 3rd & 4th
arches.
Temporarily, clefts ➪ectodermal
cavity, cervical sinus, which
disappears later.

37. Development of Pharyngeal pouches and clefts

38. Congenital anomalies
Lateral cervical cysts and fistulas
(Branchial cyst & Branchial fistula)

39. 1. Branchial Cyst: Sinus persists as cyst along ant border
of sternomastoid muscle.
If ruptures ➪ branchial sinus
2. Branchial Sinus:
a) External: Cyst opens outside, usually anterior to
sternomastoid.
b) Internal: Cyst opens
into pharynx,usually
in the tonsillar region.
3. Cervical Fistula:
Sinus opens externally
& internally, connects
pharynx with outside.
Congenital anomalies