Thorax
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Thorax is the superier
part of the trunk
between the neck and
adomen.
It extends below the
neck to the
diaphragm.
It contains the
primary organs of
respiratory and
cardiovascular system
Thoracic Skeleton

The thoracic skeleton
forms the
osteocartilaginous
thoracic cage, which
protects the thoracic
viscera and some
abdominal organs.
Thoracic Skeleton

The thoracic skeleton
includes the thoracic
cage formed by the
horizontal bars
formed by ribs and
costal cartilages
supported by the
vertical
sternum,anterierly
and thoracic
vertebrae,posterierly
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A typical human rib
cage consists of 24
ribs, the sternum,
costal cartilages, and
the 12 thoracic
vertebrae.
All ribs are attached in
the back to the
thoracic vertebrae.
Thoracic ribs
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The upper seven are true ribs,
are attached in the front to the
sternum by means of costal
cartilage. Due to their elasticity
they allow movement when
inhaling and exhaling.
The 8th, 9th, and 10th ribs are
called false ribs, and join with
the costal cartilages of the ribs
above.
The 11th and 12th ribs are
known as floating ribs, as they
do not have any anterior
connection to the sternum.
The spaces between the ribs
are known as intercostal
spaces; they contain the
intercostal muscles, nerves,
and arteries.
Sternum
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1.
2.
3.
The sternum is the
flat,elongated bone
that forms the middle
of the anterior part of
thoracic cage.
The sternum consists
of
Manubrium,
Body,
Xiphoid process
Mediastinum
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The thoracic cavity is
divided into three
major spaces.
The central/median
compartment called
mediastinum houses
the conducting
structures(esophagus,
trachea,major blood
vessels and most
importantly heart).

The two lateral
compartments
contains the
lungs
Nasal cavity
The lateral wall of the
nasal cavity is mainly
made up by the maxilla,
and the conchae on the
wall
 The floor of the nasal
cavity, which forms the
roof of the mouth, is
made up by the bones
of the hard palate.
 The nasal cavity is
divided in two by nasal
septum.

Nasal Cavity
The air passing through the nasal cavity is
 warmed or cooled to within 1 degree of body
temperature.
 humidified, and dust and other particulate matter
is removed by vibrissae, short, thick hairs,
present in the vestibule.
The cilia of the respiratory epithelium move the
particulate matter towards the pharynx where it
passes into the esophagus and is digested in the
stomach.
Pharynx

The pharynx (plural:
pharynges) is the part
of the neck and throat
situated immediately
posterior to (behind)
the mouth and nasal
cavity
Pharynx
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The pharynx is part of
the digestive system
and respiratory
system
food and air pass
through the pharynx,
a flap of connective
tissue called the
epiglottis closes over
the trachea when food
is swallowed to
prevent choking or
aspiration.
Pharynx
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The human pharynx is
conventionally divided
into three sections:
Nasopharynx
Oropharynx
Laryngopharynx
Nasopharynx
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The nasopharynx region
extends between the
internal nares and the soft
palate and lies superior to
the oral cavity.
The Eustachian tubes, or
auditory tubes(equalizing
the air pressure in the
middle ear to that of the
atmosphere. This is
needed for proper
conduction of sound),
which connect the middle
ear to the pharynx, open
into the nasopharynx.
Oropharynx
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The oropharynx lies
behind the oral cavity.
the lateral wall is
made up of the tonsil,
the superior wall
consists of the inferior
surface of the soft
palate and the uvula.
Laryngopharynx
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It lies inferior to the
upright epiglottis and it
is continuous with the
respiratory tract
anterierly and digestive
pathways,posterierly.
During swallowing,
food has the "right of
way", and air passage
temporarily stops.
epiglottis closes over
the trachea when food
is swallowed
larynx
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The larynx ("voice
box“), is involved in
protection of the
trachea and sound
production.
The laryngeal skeleton
consists of nine
cartilages: three
single (thyroid,
cricoid, and epiglottic)
and three paired
(arytenoid,
corniculate, and
cuneiform).
Nerve supply of Larynx
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Superier and inferior laryngeal brances of vaus
nerve(CN X).
Superier laryngeal nerve divides into
int(supplies sensory and autonomic) and
ext(motor) laryngeal nerve
Inferier laryngeal nerve is the primary motor
nerve
Trachea
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The trachea (windpipe), is
a fibrocartilagenous tube
that connects to the
pharynx/larynx, to the
lungs.
It has mucosal goblet cells
which produce mucus. This
mucus lines the cells of the
trachea to trap inhaled
foreign particles which the
cilia then waft upwards
towards their larynx and
then the pharynx where it
can either be swallowed
into the stomach or
expelled as phlegm.
Trachea
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Trachea is supported by incomplete cartilaginous
rings(keeping the trachea patent), that occupies a
median position in the neck.
The posterior gap in tracheal rings is spanned by
involuntary trachealis muscle,smooth muscle
connecting the ends of the cartilages.
The esophagus is right behind the trachea, so the
smooth muscle of trachea can accommodate
according to the esophagus.
The brachiocephalic trunk is related to the right
side of the trachea in the root of the neck.
So any deviation of the trachea from
midline,apparent superficially or radiographically, is
the sign of any pathological process.
Trachea
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Trachea bifrucates at
the level of sternal
angle into primary
bronchus, one to each
lung to enter the lung
at the hila
The right main
bronchus is
wider,shorter and
runs more vertically
than left
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Within the lungs the bronchi
branch in a constant fashion.
Each main bronchus divides
into lobar bronchi(secondary
bronchi) 2 on left and 3 on
right.
Lobar bronchus
several
segmental bronchi
segmental bronchi
after
30-35 generation of branches
end in terminal bronchioles.
Terminal bronchioles
respiratory bronchiole
alveolar ducts
alveolar
sacs , which are lined by
alveoli
Lungs
Their principal function
is to transport oxygen
from the atmosphere
into the bloodstream,
and to release carbon
dioxide from the
bloodstream into the
atmosphere.
 This exchange of gases
is accomplished in the
mosaic of specialized
cells that form millions
of tiny, exceptionally
thin-walled air sacs
called alveoli,that are
sorrounded by the
pulmonary capillaries
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pleura
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The pleura is a serous
membrane which form a
two-layered, membrane
structure.
The outer parietal pleura is
attached to the chest wall.
The inner visceral pleura
covers the lungs
The thin space between the
two pleural layers is known
as the pleural cavity; it
normally contains a small
amount of pleural fluid
The parietal pleura is highly
sensitive to pain while the
visceral pleura is not, due to
its lack of sensory
innervation.
Bronchopulmonary Segments

Right lung is divided
into superier,middle
and inferior lobes

Left lung is divided
into superior and
inferior lobe
•These lobes are inturn divided into 10
bronchopulmonary segments, each of which are
seperated anatomically from each other by a
connective tissue layer.
•each segment is indepently supplied by a
segmental bronchi and a tertiary branch of
pulmonary artery.
Alveoli
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Pulmonary alveolus is
the basic structural
unit of gas exchange
in the lung.
In both lungs by 8 yrs
of age we have 300
million alveoli
Blood supply

The lungs have a double blood supply, the
pulmonary circulation for gas exchange with the
alveoli and the bronchial circulation to supply the
parenchyma (tissue) of the lung itself.
Mediastinum
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The thoracic cavity is
divided into three
major spaces.
The central/median
compartment called
mediastinum houses
the conducting
structures(including
pericardium,heart and
roots of its great
vessels
Pericardium
There are two layers to
the pericardial sac:
1. the fibrous
pericardium and
2. the serous
pericardium.
 The serous
pericardium, in turn,
is divided into two
layers, the parietal
pericardium and
visceral pericardium
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In between the
parietal and visceral
pericardial layers
there is a potential
space called the
pericardial cavity.
It normally contains
thin film of
fluid,pericardial fluid
that enables the heart
to move and beat in a
frictionless
environment

The inferior wall of the
fibrous pericardium is
firmly attached and
partically blended with
central tendon of
diaphragam. The
heart is well tethered
in place inside the
fibrous sac
Heart
The wall of each heart chamber consists of
1. Endocardium:thin internal layer of endothelium
2. Myocardium: thick, middle layer composed of
cardiac muscle
3. Epicardium:thin external layer fromed by the
visceral layer of serous pericardium
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The heart has four
chambers:
Right and left atria
Right and left
Ventricles
Three borders of the
heart:
 right border made up
of the right atrium
 inferior border made
up of right atrium,
right ventricle and left
ventricle
 left border made up of
the left ventricle
Surfaces of the heart
Anterior sterno-costal
surface, formed mainly
by R. ventricle
 Diaphragmatic or inferior
surface is formed mainly
by L. ventricle and partly
by R. ventricle.
 Right pulmonary surface
is formed by R. atrium
 Left pumonary surface is
formed by L. ventricle
which forms the cardiac
impression of the left
lung
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Apex of the heart
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Is the infero-lateral
part of left ventricle
Lies beneath the 5th
intercostal space in
adults,
approxiamately 9 cm
from median plane
Is where the sounds
of mitral valve
closure(apex beat) are
maximal
Atrium
Right Atrium
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The superior vena
cava opens at the
level of R. 3rd costal
carilage and inferior
vena cava at 5th costal
cartilage.
The right atrium
opens into the R.
ventricle thru Tri
cuspid valve
Left Atrium
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The pairs of right and
left pulmonary veins
enter the posterior
aspect of atrium.
The left atrium opens
into L. ventricle thru
Bicuspid or mitral
valve.
Auricles
The auricles are think ear-like conical
muscular pouch which projects from the
atria, increasing the capacity of atria
 Each atria has an auricle on the superior
surface
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Ventricles
Right ventricle
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Receives the
deoxygenated blood
from the atium
And thru R. and L.
pulmonary arteries
pumps blood to the
lungs
Left ventricle
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Receives the
oxygenated blood
from the atium
And thru Aorta pumps
blood to the systemic
circulation
Papillary muscles
Papillary muscles are
nothing but the conical
muscular projections
from the myocardium of
the heart
 They support,
strenghthen and
responsible for the
opening and closure of
the cuspid valves.
 They area attached to the
cuspid valves thru
tendinous cords called
chordae tendinae

Conducting systemof the heart

Conducting
system of the
heart consists of
the cardiac
muscle cells, SA
and AV nodes,
purkinje fibres
and Bundle of
His.
Nodal tissues

Sinuatrial node(SA)
is located antero-laterally
just deep to epicardium at
the jucnction of SVC and
R.atrium.
 It is the pacemaker of the
heart,initiating and
regulating the impulses for
contraction.
 It is a small collection of
nodal tissue and specialized
cardiac muscle fibres.
 It could be stimulated or
inhibited by the sympathetic
or parasympathetic division
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Atrio-Ventricular
Node(AV)
Smaller collection of
nodal tissue than SA
node.
Located in the
posteroinferior region
of the interatrial
septum.
Bundle of His, Purkinje firbes
AV bundle- the AV
node passes the
signal from atrium to
the ventricles thru AV
bundle,which is the
only bridge between
the atrial and
ventricular
myocardium.
 Av bundle divides into
R. and L. bundles.
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These bundles
proceed on each side
and then ramify into
subendocardial
branches(purkinje
fibres)
These purkinje fibres
on both side stimulate
the IVS, papillary
muscles and
respective ventricles.
Nerve supply to the heart

The sympathetic
fibers arise from
segments T2-T4 of
the spinal cord

The vagus provides
the parasympathetic
control to the heart
Nerve supply to the heart
The cardiac plexus,
the nerve network
consisting of both
sympathetic and
parasympathetic
nerves is located
primarily in the level
of bifurcation of
trachea.
 This supplies the
nodal tissues,
conducting system
and coronary vessels
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Sympathetic or
adrenergic stimulation
causes increased
heart rate; impulse
conduction; also
increases the blood
flow through the
coronary vessels.
Parasympathetic
stimulation slows the
heart rate,reduces the
force of contraction
Vasculature of the heart
Endocardium receive O2 and nutrients by
diffusion or microvasculature directly from
the chambers of the heart.
 The R. and L. coronary artery the direct
and the first branches of aorta, arising
from R. & L. aortic sinus supplies both
atria and ventricles.

R. Coronary artery
RCA supplies
1. SA node thru sinuatrial nodal branch
2. Right border of the heart thru R.marginal
branch
3. AV node thru atrioventricular nodal
branch
It supplies R. atrium, most of R. ventricle.
L. Coronary artery

LCA
L. marginal artery
ant. Interventricular branch

L. marginal artery
circumflex branch of
L. coronary artery
ant. Interventricular branch
lateral diagonal branch
L. Coronary artery
Left border thru L. Marginal artery
 Most of L.ventricle and part of R.ventricle
and apex thru ant. Interventricular branch
It supplies
 L.atrium ,
 most of L.ventricle
 Part of R.ventricle
 Most of interventricular system
 Apex of the heart

Posterier interventricular artery is given
out by the RCA(66%) in the Right
dominant coronary arterial system.
 Post & ant interventricular artery
anastomosis at the posterior aspect.

Aorta
The ascending
aorta,which is intrapericardial begins at
aortic orifice and gives
out coronary arteries
The arch of aorta
which is the continuation of
ascending aorta begins at the
the 2nd R.sternocostal joint at
the level of sternal angle
 It gives out brachiocephalic
trunk,left common carotid
artery and L. subclavian
artery.
 The brachiocephalic trunk first
and largest branch of arch of
aorta gives out R.common
carotid artery and R.subclavian
artery

Thoracic aorta
Thoracic aorta,which is a continuation of
arch of the aorta extends between the
levels of T5-T12 verterbrae.
 They give out posterior intercostal
arteries, subcostal, some phrenic arteries
and visceral branches (eg.,esophaus,
bronchial for bronchus and visceral
pleura)
