respiratory anatomy

1. Development of Nose,
Paranasal sinus and Pharynx

2. • Overview of pharyngeal apparatus
• Overview of facial development
• Development of the nose
– Nasal cavity
– External nose
• Development of paranasal sinus
• Development of pharynx
Outline

3. • Consists of
– pharyngeal arches
– pharyngeal pouches
– pharyngeal grooves(clefts)
– pharyngeal membranes
• These embryonic
structures contribute to the
formation of the face and
neck.
Overview of Pharyngeal apparatus

5. A
B
Primitive pharynx (as seen in coronal
section). A. Before the formation of
pharyngeal arches. B. After the
formation of pharyngeal arches.

10. Structures Derived from Pharyngeal Arch Components

12. • Develop from the frontonasal prominence & 1st pharyngeal
arches that were surrounding the stomodeum
• Stomodeum is surrounded by
1. Frontonasal prominence (process) cranially
2. Right & left maxillary prominence(process) cranially & laterally
3. Right & left mandibular prominence caudally & laterally
Development of the face: overview

14. 1. Maxillary prominence
– develop from upper division of 1st pharyngeal arch
– Grow medially and fuse with mandible, lateral nasal process and
intermaxillary segment
– Form cheek and upper jaw
2. Mandibular process
– Grow medially and fuse with each other at the midline
– Form the lower jaw and check
Cont…

15. 3. Frontonasal prominence
– Formed by mesenchymal proliferation
– Two nasal placodes (buds) develop on either side of the frontonasal
process.
– Each nasal placode becomes invaginated to form a nasal pit.
– The edges of each nasal pit form med- and lat-nasal folds.
– The nasal pits become deeper forming the nasal cavities which will
later open into the pharynx posteriorly
– Each lat-nasal fold will form the ala of the nose.
– The medial nasal fold grow fast than the lateral one and fuse
medially to form intermaxillary segment
Cont…

18. Intermaxillary segment
• has the 3 component
– Labial
– Upper jaw
– Palatal components
Cont…

19. • Labial component gives rise to the philtrum of the upper lip
• Upper jaw component gives rise to the median part of upper
jaw carrying the 4 incisors teeth
• Palatal component gives rise to the primary palate
Cont…

20. Development of the palate
• Develops as
1. Primary palate
2. Secondary palate
• Primary palate develops from the intermaxillary segment

21. Secondary palate
• Develop from the right and left palatine shelves that develop
from inferolateral aspects of maxillary prominences & grow
inferomedially
• Palatine shelves fuse with each other, primary palate and
nasal septum that grow from the inner aspects of frontonasal
prominence
• Soft palate with uvula develop as two folds growing out
from the posterior end of the secondary palate
Cont…

22. Development of definitive palate. Note derivation of its various parts
from different sources. Figure in the inset (on the left side) shows
separation of nasal cavities from each other and from the oral cavity.

24. Nasal cavity
• Oronasal membrane which initially separate nasal sac
from oral cavity & pharynx ruptures during the 7th wk to
form the primitive choana
• When secondary palate is formed the nasal cavity & oral
cavity are separated
• When completely developed nasal cavities will have the
following boundaries
– Roof from lateral nasal processes
– Lateral wall by lateral nasal processes & contribution from
maxillary prominences
Development of the Nose

25. Sagital section. A & B. 6wk, C 7 wk & D 9wk embryo
showing the development of nasal cavity

26. • The choncha develop by projections from inner aspects of the lateral
walls
• Medial wall(nasal septum) develops from the frontonasal prominence
as direct downward growth, as well as through the medial nasal
processes
• Floor develop from medial nasal processes and anterior part of the
maxillary processes
• The nares (olfactory pit) develop from medial nasal
processes(medially) lateral nasal processes(laterally) and maxillary
processes(inferiorly)
Cont…

28. • External nose develop from
– Frontonasal prominence which gives the bridge
– Merged medial nasal prominence gives crest & tip
– Lateral nasal prominences gives the sides (alae)
Cont…

29. • Ectodermal invaginations
along the nasolacrimal
groove, b/n maxillary &
lateral nasal prominences,
make a solid cord in the
mesenchyme
• Extends from medial angle of
developing orbit to nasal
cavity
• Later the cord is canalized,
and upper end expand to form
lacrimal sac, while the lower
end opens into the inferior
meatus
Development of nasolacrimal duct

30. • Develop as invaginations of the nasal cavity into
surrounding bones
• By late fetal period only maxillary and a few anterior &
posterior ethmoidal air cells are developed
• Later postnatally,
– Frontal sinuses develop from the 2 most anterior ethmoidal sinuses
– Sphenoidal sinuses develop from the 2 most posterior ethmoidal
sinuses
– Reach maximum size by puberty
Development of the paranasal sinus

31. • is derivative of the foregut from the pharyngeal
primordium
Development of pharynx