(j)Ontogeni Respiratory Syst.(Int)

8/10/2019 (j)Ontogeni Respiratory Syst.(Int)

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ONTOGENY OF RESPIRATORY

SYSTEM

Abd. Razak Ratu


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Development of the nose

The root of the nose is formed from the lateral

nasal processes, from which the lateral walls

are also formed.

The anterior openings of the nose bein as

olfactory pits in the frontonasal process

Each olfactory pit is bounded medially by

medial nasal rocess, laterally by the lateral

nasal process, and inferiorly by maxillary

process.


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The olfactory pits

The olfactory pits become deeper and form

well-defined blind sacs, the opening into each

of which is the nostril

The floor of the nose at first is very short and

consists of the medial nasal process and the

anterior part of the maxillaprocess.

The floors of the olfctoy pits rupture so that

the nasal cavities communicate with the

developing mouth


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Development of the mouth

The cavity of the mouth is formed from two

sources: a depression from the exterior,

called the stomodeum, which is line d with

ectoderm, and a part posterior to the

stomodeum, derived from the end of the

foregut and lined with entoderm.

These two parts are separated by thebuccopharyngeal membrane.


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Buccopharyngeal membrane


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DEVELOPMENT OF THE PALATE

In early fetal life, the nasal and mouth cavities

are in in communication, but later they

separated by the development of the palate.

The primary palate, is formed by the medial

nasal process. Posterior to the primary palate ,

the maxillary process on each side sends

medially a hrizontal plate called the palatalprocess.These plates fuse to form secondary

palate and also unite with the primary palate.


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DEVELOPMENT OF THE PALATE

The primary and secondary palates later will

form thehard palate.

Two folds grow posteriorly from the posterior

edge of the platal processes to create the soft

palateand uvula.

The interval between the primary and

secondarypalate is represented in the midline

by the incisive formen.


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DEVELOPMENT OF THE TONGUE

At about the 4th week, a medial swelling

appear in the ventral wall of the floor of the

pharynx called tuberculum impar. Another

sweeling called lateral lingual swelling

(derived from the anterior end of each first

pharyngeal arch) , appear on lateral side of

the tuberculum impar.


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The lateral lingual swellings now enlarge, grow

medially , and fuse with each other and the

tuberculum impar form the anterior 2/3 of

the body of the tongue.

Because they are derived from the 1st

pharyngeal arches, the mucous membrane

will be innervated by the lingual nerve, abranch of the mandibular devision of the fifth

cranial nerve (for common sensation).


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The chorda tympani from the seventh cranial

nerve also supplies this area (taste).

Copula, appear in the floor of the pharynx

behind the tuberculum impar. This copula (

formed from anterior end of second, third,

and forth of the pharyngeal arches) extends

forward on each side of the tuberculumimpar, and become V shaped


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The third arch on each side overgrow the

other arches and extend into the copula,

fusing in the mid line. The copula now

disappear.

The mucous membrane of the posterior third

of the tongue is formed from the 3rd

pharyngeal arches and is innervated by the9th cranial nerve. (common sense and taste).


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The anterior two thirds of the tongue is

separated from the posterior third by a grove

called sulcus terminalis.

The muscles of the tongue are derived from

the occipital myotomes, and innervated by the

12th cranial nerve.


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PHARYNGEAL ARCHES

The pharyngeal arches contribute extensively

to formation of the face, the neck, the nasal

cavities, the mouth, the larynx, and pharynx.

There are six pairs of pharngeal arches,

however, the fifth pharyngeal arch is

disappear.


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THE FIRST ARCH CARTILAGE

The first pharyngel arch (Meckel,scartilage) is

closely related to the developing ear, and

becomes ossified toform two middle ear

bone, the malleus, and the incus.

The intermediate portion become regress, and

forms: the anterior ligamnent of malleus; and

the splenomandibular ligament.


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The 2nd pharyngeal arch

The dorsalend of the 2nd arch cartilage also

closely related to the developing of the ear

and ossifies to form the stapes , styloid

process, and the stylohyoid ligament.

The ventral part ossifies to form: the lesser

cornu and superior part of the body of the

hyoid bone.


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The 3 rd Pharyneal arch cartilage

The third cartilage ossifies to form the greater

cornu and inferior part of the body of the

hyoid bone.

The epiglottis cartilage develops from

mesenchyme in the hypobranchial eminence a

derivative of the third and fourth pharyngeal

arch.


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DEVELOPMENT OF THE LUNGS

A. Longitudinal groove develops in theentodermal lining of the floor of the pharynx,

this groove called the larygo tracheal

groove.

The margins of the groove fuse and form the

laryngotracheal tube = diverticulum

tracheobronchialis

The laryngotracheal tube grows caudally into

the splanchinc mesenchyme and lie anterior

to the esophagus


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The tube divides distally nto the right and left

lung buds.

Cartilage develops in the mesenchyme

surrounding the tube, upper part of the tube

becomes the larynx. Whereas the lower part

becomes the trachea.

Each lung bud consists of an entodermal tube

surrounded by splanchnic mesoderm


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Each lung bud consists of an entodermal tube

surrounded by splanchnic mesoderm, from

this, all the tissues of the corresponding lung

are derived

The lung bud divides in to two main bronchi .

Each main bronchus then divides repeatedly

in a dichotomous manner, until eventuallythe terminal bronchioles and alveoliare

formed.


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PLEURA

Each lung will receive a converting of visceral

pleura derived from the splanchnic

mesoderm.

The parietal pleura will be formed from

somatic mesoderm

The space between the visceral and parietal

pleura called pleural cavity.


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DEVELOPMENT OF THE

DIAPHRAGM

The diaphragm is formed from the following

structures

1. the septum transversum, which forms the

muscle and central tendon

2. the two pleuroperitoneal membranes, which

are largely responsible for the peripheral areas

3. the dorsl mesentery of the esophagus. Inwhich the crura develop.


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DEVELOPMENT OF THE

DIAPHRAGM

The pleuroperitoneal membranes grow

medially from the body wall on each side

until they fuse with the septum transversum

and dorsal mesentery.

During the prosess of fusion, the mesoderm of

the septum transversum extends into the

other parts, forming all muscles of thediaphragm


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CONGENITAL ANOMALY

Esophagotracheal fistula

Labio schisis

Labio palatoschisis


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(j)Ontogeni Respiratory Syst.(Int)

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