Transcript No. 9

No. 9
1. Introduction of the Respiratory
System
2. The nose
3. The pharynx
4. The larynx
Chapter 3 The
Respiratory System
Introduction
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In order for the cells of the body to carry
on their metabolic activities under aerobic
conditions, they require a constant supply
of oxygen and an efficient means of
removing the carbon dioxide that their
activities produce. Oxygen is supplied and
carbon dioxide is removed by the
respiratory system, with the assistance of
the circulatory system.
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The respiratory system also makes
vocalization possible. We are able to speak,
sing, and laugh by varying the tension of
the vocal folds as exhaled air passes over
them.
The exchange of oxygen and carbon
dioxide between the air and the blood
occurs in the lungs. In order to reach the
exchange sites in the lungs, the air must
flow through a series of conducting
passageways that branch from one
another much like the branches of a tree.
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Inclusion of the respiratory system:
The respiratory system includes the
respiratory tract and lungs.
The respiratory tract consists of the
nose, pharynx, larynx, trachea and
principal bronchi.
From the clinical point of views, the upper
respiratory tract is that above the larynx,
and the trachea, principal bronchi with
their branches belong to the lower
respiratory tract.
The right and left lungs are the essential
respiratory organs.
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Function of respiratory system:
The primary function of the
respiratory system is to supply the
body with oxygen and to get rid of
excess carbon dioxide resulting from
cell metabolism.
Section 1 The Nose
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The nose is not only the first part of
respiratory tract but also an organ of
smell and phonation, it includes
external nose, nasal cavity and
paranasal sinuses.
Ⅰ. The External Nose
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It consists of bones and cartilages
covered with skin.
It has a root, a back, an apex of
nose, two alae nasi and two nares.
Ⅱ. The Nasal Cavity
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It is divided into right and left halves
by the nasal septum. The right and
left nasal cavities open in front
through nares and communicate with
the pharynx behind through the
choanae.
Each nasal cavity may be divided
into nasal vestibule and proper nasal
cavity.
Ⅰ) The Nasal Vestibule
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The anterior portion of the nasal
cavity is called the nasal vestibule
which is just inside the alae nasi and
posteriorly limited by the limen nasi.
The nasal vestibule is surrounded by
cartilage and lined by skin.
Ⅱ) The Proper Nasal Cavity
Constitution and morphology of the proper
nasal cavity:
Each cavity has a roof, a floor, a medial
wall and a lateral wall.
① The roof is formed by the nasal bone,
cribriform plate of the ethmoid bone.
② The floor is formed by the upper
surface of the hard palate in front (2/3)
and the soft palate behind (1/3).
③ The medial wall is the nasal septum.
④ The lateral wall, which are irregular, are
formed by: the superior and middle conchae
of the ethmoid bone, the separate inferior
concha bones.
Beneath the shelves formed by the conchae are
recesses called the superior, middle, and
inferior meatuses.
Sphenoethmoidal recess: above and behind
the superior nasal concha there is the
sphenoethmoidal recess.
The inferior nasal meatus receives the
termination of the nasolacrimal duct.
The middle and superior meatuses and
sphenoethmoidal recess receive the openings of
paranasal sinuses.
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The nasal mucous membrane:
It divided into two regions:
Olfactory region: The olfactory receptors
lie in the mucous membrane lining the
upper portion of the nasal cavity where is
called the olfactory region.
Respiratory region: The rest of medial
and lateral nasal wall covered by a thick
glandular and vascular mucous membrane
constitute the respiratory region.
Ⅲ. The Paranasal Sinuses
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In the bones around the nasal cavity there are
some air spaces called paranasal sinuses, they
are:
the frontal sinus,
maxillary sinus,
ethmoidal sinus,
sphenoidal sinus.
All these sinuses communicate with the nasal
cavity and are lined by mucous membrane which
is continuous with that of the nasal cavity. So the
infection of nasal cavity may spread to the
paranasal sinuses, resulting in sinusitis.
Table 1: The paranasal sinuses
Name
Location
Opening(s)
Frontal Sinuses
In the frontal bone
The middle nasal
meatuses
Maxillary
Sinuses
In the bodies of the
maxilla
The middle nasal
meatuses
Ethmoidal
Sinuses
Within the ethmoid
bone
Anterior group:
Middle group:
Posterior group:
The middle nasal
meatuses
The middle nasal
meatuses
The superior nasal
meatuses
Sphenoidal
Sinuses
Within the body
sphenoid bone
Sphenoethmoidal
recesses
Section 2 The Pharynx
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The pharynx is the common channel
for both alimentary system and
respiratory system, the food and air
pathways cross each other in
pharynx.
Section 3 The Larynx
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The larynx is a part of respiratory
passage as well as the organ of phonation.
It lies in the neck region in front of the
fourth, fifth and sixth cervical vertebrae.
The larynx consists of a framework of
cartilages that are connected together by
ligaments, membranes and joints. It also
has a number of small muscles which
move the cartilages.
The larynx is lined with mucous
membrane which is continuous with that
of pharynx above and that of trachea
below.
Ⅰ. The Laryngeal Cartilages
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The larynx is formed by nine
cartilages—three unpaired and three
paired.
These cartilages are held together,
and attached to the hyoid bone
above and the trachea below, by
ligaments and muscles.
Ⅰ) The Thyroid Cartilage
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It is the largest of the unpaired
cartilages. It is formed by the
midline junction of two broad plates
anteriorly, producing the laryngeal
prominence. The plates remain
separated posteriorly, which leaves a
wide opening in the laryngopharynx.
Ⅱ) The Cricoid Cartilage
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Just below the thyroid cartilage is the
ring-shaped cricoid cartilage. It is
composed of a lamina of cricoid
cartilage behind, a narrow arch of
cricoid cartilage in front.
Ⅲ) The Arytenoid Cartilages
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Each arytenoid cartilages is shaped
like a small pyramid and rests on the
superior-posterior border of the
cricoid cartilage. They articulate with
the superoposterior border of the
cricoid cartilage.
The base sends a vocal process
forward for attachment of the vocal
ligament and a muscular process
laterally for muscular attachment.
Ⅳ) The Epiglottic Cartilage
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The epiglottic cartilage is the leafshaped epiglottic cartilage. This
cartilage covered by mucous
membrane and forms the epiglottis.
The epiglottis is attached by its
narrow end to the inner surface of
the anterior region of the thyroid
cartilage; its free upper portion
projects like a flap behind the base
of the tongue.
Ⅱ. The Laryngeal Joints
Ⅰ) The Cricothyroid Joint
Composition:
 Inferior cornu of the thyroid cartilage,
 The larteral surface of cricoid
cartilage.
Movements:
 It allows rotation of thyroid cartilage
around the coronal axis, so that the
length and the tenseness of the vocal
fold can be changed.
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Ⅱ) The Cricoarytenoid Joint
Composition:
The lamina of cricoid cartilage,
The base of the arytenoid cartilage.
Movements:
When the arytenoids cartilage glide
and rotate on the cricoid, apposition
and abduction of vocal folds occur.
Ⅲ. The Laryngeal Ligaments and
Membranes
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Ⅰ) The Thyrohyoid Membrane
Ⅱ) The Conus Elasticus
It extends upward from the cricoid
cartilage to the arytenoid cartilages and
the posterior surface of the thyroid
cartilage.
Its superior border is free and forms the
vocal ligament which extends from the
posterior surface of thyroid to the vocal
process of arytenoid cartilage.
Ⅲ) The Quadrangular Membranes
Ⅳ. The Muscles of Larynx
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They are skeletal muscle.
They serve to open and close the
glottis and regulate the tension of
the vocal fold.
Ⅴ. The Laryngeal Cavity
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Ⅰ) Morphology of lateral wall of the laryngeal
cavity:
1. Vestibular folds and vocal folds:
The mucous membrane near the entrance to the
larynx forms two pairs of horizontal folds that
extend on each side from the thyroid cartilages to
the arytenoid cartilages.
The upper pair of folds are called the ventricular
folds (false vocal cords). The lower pair are the
vocal folds (true vocal cords).
The vestibular folds extend anteroposteriorly on
either side of the larynx and enclose between
them a slit, the rima vestibuli.
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The vocal folds are two folds of mucous
membrane which are closely bound to the
underlying vocal ligament.
The slit between the two vocal folds through
which air enters the larynx is the fissure of
glottis.
The glottis consists of the vocal folds and the slit
between them.
Air passing through the glottis causes the vocal
folds to vibrate and produce a sound. The
frequency of the vibrations, and therefore the
pitch of the sound produced, depends upon the
tension of the vocal folds.
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Division of the laryngeal cavity:
The laryngeal cavity is divided into three parts:
The laryngeal vestibule extends from the
aperture of larynx to the vestibular folds
The intermedial cavity of larynx, the
narrowest portion between the level of rima
vestibuli and the fissure of glottis. The ventricles
of larynx are the lateral expansions of the
laryngeal cavity between the vestibular and the
vocal folds.
The Infraglottic cavity lies below the vocal folds
and extending downward to the lower border of
the cricoid cartilage.