Thoracic region

1. Anatomy of thorax
• By:- Don. Siyum Alebachew
5/3/2022
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2.  A plane extending from the
sternal angle to the
intervertebral disc between
vertebrae T4 and T5 divide the
mediastinum into:
 Superior mediastinum
 Inferior mediastinum
 The inferior mediastinum
further divided by the
pericardial sac into
 Anterior mediastinum
 Middle mediastinum
 Posterior
mediastinum
Divisions of the mediastinum
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3. Anterior mediastinum
 The area anterior to the
pericardial sac and posterior to
the body of the sternum
Posterior mediastinum
 The region posterior to the
pericardial sac and the
diaphragm and anterior to the
bodies of the vertebrae
Middle mediastinum
 The area in the middle, which
includes the pericardial sac and
its contents
Subdivisions of the inferior
mediastinum
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4. The superior
mediastinum
• Is the upper part of the mediastinum
bounded by:
 Anteriorly – manubrium sterni
 Posteriorly – upper four thoracic vertebrae
 Superiorly – thoracic inlet
 Inferiorly – plane extending from the
sternal angle to the intervertebral disc
between vertebrae T4 and T5
Contents - Three groups
1- Anterior part (behind the sternum)
 Muscles - origin of sternohyoid & sternothyroid mm
venacava and
 Gland - thymus gland
 Veins - right & left brachiocephallic veins, superior
left sup.intercostal vein
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5. Superior mediastinum …
2. Middle
part
• Arch of aorta & its three
branches – brachiocephalic a, left
common carotid a & left subclavian
a
• Nerves – phrenic & vagi nerves
3. Posterior part (prevertebral)
• Tubes – trachea & esophagus
• Nerve – left recurrent laryngeal
nerve b/n trachea & esophagus
• Lymph nodes & vessel –
paratracheal & tracheobronchial
lymph nodes and thoracic duct
• Muscle – longus colli Don. Siyum
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6. Thymu
s
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Is the most anterior component, posterior
to the manubrium of the sternum
The upper extent of the thymus can reach
into the neck as high as the thyroid gland
A lower portion typically extends
into the anterior mediastinum over
the pericardial sac
The costomediastinal recesses are
on either side
It is a bilobed structure
Large in children, begins to atrophy
after puberty
Mainly fat in the adult with small
islets of active thymic cells scattered

7. Thymus …
Arterial
supply
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 From the internal thoracic
arteries
Venous drainage
 Into left brachiocephalic
vein and possibly into
internal thoracic veins
Lymphatic drainage
 Returns to the following
locations:
 Along the internal thoracic
arteries (parasternal)
 At the tracheal bifurcation
(tracheobronchial)

8. Vein
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Consists of
 Left and right
brachiocephalic vein
 Left superior
intercostal vein
 Arch of the azygos vein
 Superior vena cava

9. Left brachiocephalic vein
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Formation - by left internal
jugular and left subclavian veins
• Posterior to the left
sternoclavicular joint
Course - passes anterior to the
branches of the aortic arch
Termination - joins the right
brachiocephalic vein and form the superior vena cava
Tributaries
 The vertebral, first left posterior intercostal vein, left superior
intercostal vein, inferior thyroid, and internal thoracic veins
 It may also receive thymic and pericardial veins

10. Right brachiocephalic vein
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Formation - by of the right internal jugular and right subclavian veins
• Posterior to the right sterno clavicular joint
Course - passes down vertically, both vagus and phrenic nerves
descend posterior to the brachiocephalic veins bilaterally
Termination - joins the left brachiocephalic vein to form the
superior vena cava
Tributaries
 The vertebral vein
 The 1st right posterior
intercostal vein
 Internal thoracic veins
 Thymic veins

11. Formation
• by 2nd, 3rd and the 4th
posterior intercostal veins
Course
• Over the left side of aortic
arch
🗸 Lateral to the left vagus nerve and medial to the left phrenic nerve
Termination - enters into the left brachiocephalic vein
Tributaries
− the 2nd, 3rd and 4th posterior intercostal veins
− Usually the left bronchial veins
− Sometimes the left pericardiacophrenic vein
Left superior intercostal vein
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12. Superior vena cava
Formation
 by the union of the two
brachiocephalic veins
• At the 1st right intercostal
space close to the right
sternal border
Course
 Descend down vertically
 right phrenic n. runs along with it
Termination
 enters the right atrium at the
3rd right costal cartilage level
Tributaries  the two brachiocephalic veins and the azygos vein
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13. Arch of the azygos
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Formation - arising from the
posterior aspect of IVC
 forms a collateral pathway
between the SVC and IVC
Course - ascends on the right side
of the vertebral column and
arches over the right bronchus
Termination - enters the
posterior aspect of superior vena
cava
 at the sternal angel level
Tributaries- posterior intercostal veins
(directly or via hemiazygoses), mediastinal,
esophageal, and bronchial veins

14. Neuro vascular
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1) Aortic arch and its branches
• Brachiocephalic artery
• Left common carotid artery
• Left subclavian artery
2) Nerves:- include
• Left and right vagus nerves
• Left and right phrenic nerves
& cardiac plexus

15. Beginning - the aortic arch
begins at the level of T4/5
or sternal angle behind the
right margin of the
sternum
 A continuation of
ascending aorta
Course - extending as high
as the midlevel of the
manubrium of sternum
Termination - it becomes
the descending aorta to
the left of the T4/5
Aortic arch
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16. Aortic arch …
• The inferior aspect of the
aortic arch contains the
ligamentum arteriosum,
vestige of the ductus
arteriosus
 The ductus arteriosus
shunted blood from the
pulmonary system in
prenatal life
 With expansion of the
lungs and a decrease in
resistance in the
pulmonary arterial system
postnatally, it closes
 The ligamentum arteriosum is intimately associated
with the course of the left recuM
rr
en
e
gi
n
stu
t.D
laryngeal nerve
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17. Branches of arch
of aorta
• The branches arise from the superior
aspect of the aortic arch. They are;
 Brachiocephalic trunk
 Left common carotid
 Left subclavian arteries
🗸 They are crossed anteriorly by
the left brachiocephalic vein
Brachiocephalic trunk
• The 1st & largest of the three branches
• Arises posterior to the manubrium
• Divided into right common carotid and right subclavian arteries
posterior to the right sternoclavicular joint
 The arteries mainly supply the right side of the head and neck and
the right upper limb, respectively
 The thyroid ima artery, occassionally arise from this trunk
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18. Left common
carotid artery
 It arises immediately to the left
and slightly posterior to the
brachiocephalic trunk
 It then ascends through the
superior mediastinum along the
left side of the trachea
 Courses into the head in the
carotid sheath and supplies
the left side of the head and
neck
Left subclavian artery
 Arches over the apex of the left lung
posterior to rib I.
 Enters the axilla over rib I behind the left
subclavian vein
Branches of the arch of aorta …
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19.  They orginate from the
Medulla oblongata as 10th CN
 They descend in the neck
 In the carotid sheath post. to
the common carotid arteries
and internal jagular veins
 Enter the thoracic inlet
posterior to the medial end of
rib 1. Here, they pass
 Anterior to the arteries
 Posterior to veins
 Then, the 2 vagi run posterior to the roots of the lung giving out
branches to the cardiac and pulmonary plexuses.
Vagus
nerves
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20. Left recurrent
laryngeal nerve
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• Branches from the left vagus
• Passes below the ligamentum
arteriosum and the arch of the aorta
• Ascends between the trachea and the
esophagus into the root of the neck
Right recurrent laryngeal nerve?
• Arises from the right vagus anterior to
the right subclavian artery
• Courses around the artery
• Ascends in the neck
🗸Both recurrent nerves provide
vagal innervation to the trachea
and esophagus before
innervating the larynx

21. Arise from anterior rami of C3,4, 5
Enter the thoracic inlet posterior
to the medial end of the clavicle.
Hereafter,
The left phrenic nerve passes
medially & crosses anterior to the
left vagus
The right phrenic nerve lies
lateral to the sup. vena cava
• They descend anterior to the
root of the lungs, between the
lateral wall of the fibrous
pericardium and the mediastinal
pleura
 The right phrenic nerve pierces the diaphragm with the inferior vena cava
 The left phrenic nerve pierces the diaphragm at the margin of the fibrous
pericardial attachment to the central tendon
Phrenic
nerves
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22. Cardiac
plexus
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• Contains sympathetic,
parasympathetic (vagal)
fibers and visceral
afferents
• Are superficial & deep
Superficial
• Inferior to the aortic
arch and between it
and the pulmonary
trunk
Deep
• Located anterior to the
bifurcation of the
trachea

23. Trachea
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• A membrano/fibro-cartilaginous tube
which forms the upper part of lower
respiratory passage
Situation
 Partly in the lower part of the neck
 Partly in the superior mediastinum
Beginning
 Continuation of larynx from lower
border of cricoid cartilage at C6 level
End
 Bifurcates into a right and a left main
bronchus at T4/5 level, at the carina
Length = 10-15cm

24. Cont’d
Oesophagu
s
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• A muscular tube, which forms a portion
of the gastrointestinal tract between
pharynx and stomach
Beginning
• At the pharyngoesophag
D
eia
am
l ju
et
n
ec
rt=
io~
n2ic
n
m
the lower part of the neck at C6 level
Course
• Posterior to the trachea from C7-T4
• Anterior to the vertebral bodies of C7-T8
Termination
• Over left dome of the diaphragm through
esophageal hiatus at T10 level
Length = ~ 25cm

25. Oesophagus …
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• The esophagus normally has 4
constrictions where adjacent structures
produce impressions
🗸 Cervical constriction
• At C6 (pharyngoesophageal junction)
🗸 Thoracic (broncho-aortic) constrictions:
2 constriction
• At T2/3 where crossed by arch of aorta,
• At T4/5 where crossed by left main
bronchus
🗸 Diaphragmatic constriction
• At T10 where it passes through the
esophageal hiatus of the diaphragm,
apprx. 40 cm from the incisor teeth

26. Thoracic duct
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27. • Is the narrow part of
the Mediastinum
Boundaries
 Anteriorly – body of the
sternum
 Posteriorly – fibrous
pericardium
 Superiorly - an
imaginary plane passing
from the sternal angle to
the intervertebral disc
between vert. T4 and T5
 Inferiorly - upper
surface of diaphragm
 On each side –
mediastinal pleura
Anterior mediastinum
Contents
 Sternopericardial ligaments
 Lymph nodes & areolar tissues (in
most of the space)
 Some mediastinal branches of
Me
in
n
g
t
is
e
tu
r
.D
nal thoracic arteries
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28. • Is the widest part of the
mediastinum occupied by the
pericardium & its contents
Contents
 Heart & its pericardium
 Ascending aorta, pulmonary
trunk & its branches
 Four pulmonary veins, lower
part of Sup. Venacava, &
azygus vein (terminal part)
 Pericardiacophrenic vessels
 Phrenic & deep cardiac plexus
 Tracheobronchial lymph nodes.
 Bifurcation of trachea into right
& left bronchi
Middle
mediastinum
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29. Pericardium and Heart
Pericardium
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• Is a fibroserous sac invaginated by the heart
and great vessels during development
• Has two parts
 Outer fibrous & inner double serous
1. Fibrous pericardium - a cone shaped
bag with blunt apex upward continuous
with great vessels
Attachments
Infront – with sternum by sterno pericardial
ligaments
Above – with pre-tracheal layer of deep
cervical fascia
Below - adherent with central tendon of
the diaphragm
Function
 Anchorage of heart
 Minimizes friction during
action of the heart

30. 2. Serous pericardium - a closed serous sac within fibrous
pericardium enclosing the heart
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Pericardium …
• Consists of two layers
A.Visceral pericardium - lines the surface of the heart –
becomes the outer layer (epicardium)
B.Parietal pericardium - lines the inner surface of fibrous sac
 Pericardial cavity is a potential space between the above
two layers contains a fluid called pericardial fluid
(lubricant serous fluid)

31. Pericardial sinuses
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• Are potential spaces formed in the
serous pericardium
• There are two major Pericardial
sinuses
1) Transverse sinus
 Is a transversely disposed
space lined by visceral layer of
pericardium
 B/n arterial end of primitive heart tube containing pulmonary trunk
& asc.Aorta, and venous end of primitive heart tube enclosing the
six veins (four pulmonary veins & two vena cavae)
2) Oblique sinus
 Is a J-shaped cavity of serous pericardium
 B/n parietal & visceral pericardium separating the right & left
pulmonary veins as they get into the left atrium

32. Heart
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Location : In the middle mediastinum (enclosed by pericardium)
 between the lungs, behind the body of the sternum,
in front of T5-8 and above the diaphragm
• It has the following features
Shape-more or less conical
Situation
• Obliquely placed with ~ 1/3rd of it to the right and
~ 2/3rd of it to the left of the median plane
🗸 Base (superoposteriorly)
🗸 Apex (inferolaterally)
🗸 3-Surfaces, 3-Grooves &
3-layered Wall
🗸 4-Borders, 4-Chambers
A hollow, muscular organ - pump blood
& 4-Major valves

33. The base of
the heart
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• Is the posterior part, directed to the right
• Most fixed part
• Mainly formed by the following structures
 2/3rd by the left atrium wit the terminal part
of the 4 pulmonary veins
 Partly (1/3rd) by the right atrium
Here, it forms the oblique pericardial sinus
The apex of the heart
• Is the most moveable part
• Formed by tip of left ventricle
• Located in the left 5th intercostal space 9cm from mid s ternal line

34. The base and apex of the heart
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Base - 2/3rd by the left atrium
- 1/3rd by the right atrium
Apex - by the tip of left ventricle

35. Surfaces of the heart
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• Three surfaces
Anterior (sternocostal)
 Left (plumonary)
 Inferior (diaphragmatic)
1. Anterior (sternocostal) surface
• It is facing to the sternum & costal
cartilages
• Formed by anterior surface of
 Right auricle & atrium (small part)
 Right ventricle ( 2/3rd )
 Left ventricle ( 1/3rd )
• It presents the following features
 Anterior part of atrioventricular groove
 Anterior interventricular groove

36. Anterior (sternocostal) surface
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37. 2. Left
surface
 Sometimes called the pulmonary
surface
 B/c it lies towards the cardiac
impression or notch of the left lung
 It presents the left part of
atrioventricular groove
 Formed by left auricle &
left ventricle(mainly)
3. Inferior (diaphragmatic) surface
 Is the flat surface directed down
ward & backward
 Formed by the left ventricle (2/3rd ) &
the right ventricle (1/3rd )
 It presents the posterior
interventricular groove
Surfaces of the heart …
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38. Inferior (diaphragmatic) surface
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39. Grooves/sulci of the heart
s
e
• Are shallow depressions on the
surface of the heart
• Externally three important grooves
demarcate junctions (septum) of
chambers of the heart
1. Interatrial groove –
demarcat the right & left
atrium
 Posteriorly – not well visible
 Anteriorly – hidden by the
Aorta & pulmonary trunk
2. Atrioventricular groove – demarcates the two atria above &
the two ventricles below
 Anterior part – present in the sternocostal surface mostly towards
the right and it lodges the right coronary artery & small cardiac vein
 Posterior part – it forms posterior boundary of the base and it lodges
coronary sinus & anastomoMseinsgisotuf.Dright & left coronary artery
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40. 3. Interventricular groove
• Demarcates the right & left ventricles
 Anterior Interventricular groove
• Lies on the sternocostal surface
nearer to the left boarder
downward
• It lodges anterior Interventricular
branch of left coronary artery &
great cardiac vein
 Posterior interventricular groove
• Lies on the diaphragmatic surface
• It runs for ward to apex to meet
anterior Interventricular groove
• It contains posterior
Interventricular branch of right
coronary artery & middle cardiac
vein
Grooves/sulci of the heart …
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41. Boarders of the heart
• Four --- Right, inferior, left & superior
boarders
1. Right boarder
• Rounded & convex, extending from
right end of the opening of superior
vena cava to inferior vena cava
• Formed by right atrium
• It separates sternocostal surface
from base of the heart
2. Inferior boarder
• A sharp boarder separating sternocostal from diaphragmatic
surface
• Extends from opening of inferior vena cava to the apex
• Marginal branch of right coronary & corresponding veins run
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42. 3. Left
boarder
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Boarders of the heart …
• It is a convex ill defined boarder
separating the sternocostal
surface from the left surface
• Formed by left auricle & left
ventricle
• Extends from left auricle to the
apex of the heart
• Marginal branch of left coronary
artery runs along this boarder
4. Superior boarder
• Is the upper boarder where the great vessels enter & leave the heart
• Formed by the right & left auricles with the conical portion of right
ventricle (infundibulum)

43. s
Wall and chambers of
the Heart
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Wall of the heart
 Structurally it is composed of three layer
1.Epicardium – the outer wall derived
from visceral serous pericardium
2. Myocardium – is the middle muscular
layer responsible for pumping action
3.Endocardium – is the inner epithelial
layer continuous with the epithelium of
the great vessels
Chambers of the heart
• Its interior has four chambers separated by septum
 Two atria - receiving chamber
 Two ventricles - pumping chambers

44. Chambers of the heart …
🗸 2 receiving
chambers
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Right atrium
Left atrium
🗸 2 pumping chambers
Right ventricle
Left ventricle

45. Right atrium /RA
Forms the right margin of the heart
with the right auricle projecting
superiorly and anteriorly
The interior of the right atrium is
divided by the crista terminalis into
anterior & posterior parts
 The anterior part has a ridge area
with musculi pectinati
(pectinate muscles) capable of
contraction
 The posterior is smooth where
great vessels open into the RA &
has openings of the;
1. Superior vena cava
2. Inferior vena cava
3. Coronary sinus
4. Right atrioventricular
opening
Chambers …
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 On the interatrial wall superior to the
opening of the inferior vena cava
there is a depression area, the fossa
ovalis
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46. Left
atrium
• Forms 2/3 of base of heart
The auricle is visible
anteriorly from the left side
of the pulmonary trunk
• Lies superior to the coronary
sulcus
• The interior of the left atrium
presents the following features
 Smooth posterior part
⚫ Has 4 openings of pulmonary veins & one left atrioventricular opening
 Rough anterior part
⚫ Has musculi pectinati (pectinate muscles) capable of contraction
⚫ It is an opening of communication b/n left atrium & left ventricle
Chambers …
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47. Ventricles
The right ventricle / RV
• Forms most of the anterior
(sternocostal) & small inferior surface
of the heart and the inferior margin
• The interior of the right ventricle
consists of two parts - Rough &
smooth
1) Rough or inflowing part – is the
ventricle proper continuous with right
atrium & receive blood from RA
• It is lined with trabeculae carnae
(contractile tissue)
Some form papillary muscles which
arise from the anterior and posterior
walls
The right ventricle also has septal
papillary muscles (3rd) Don. Siyum
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48. The apex of the above papillary muscles
are attached to the cusp of right
atrioventricular (tricuspid) valve by the
chordae tendinae (thread like
tendinous cord)
The three papillary muscle groups
attached to the three cusps pull the
cusps down to the R.ventricle during
ventricular systole
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49.  The portion of out flow continuous with the pulmonary trunk
The pulmonary orifies located at the apex of the infundibulum
is guarded by a valve which has three cusps (right, left &
anterior)
2) Infundibulum or
smooth part
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50. Aortic vestibule
Inflowing
part
• The interior of the LV has 2 parts
1. Rough (inflowing) part
ventricle
(LV)
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• Is lined with trabeculae carnae
(ridges) from which the papillary
muscles arising from anterior &
posterior walls
 Two papillary muscles are present
 They are anterior & posterior
 Attached to both cusps of the mitral
(bicuspid) valve by cordae tendinae
• It forms
 The apex
 1/3rd of the sternocostal surface
 Most of the left boarder & surface
 2/3rd of the diaphragmatic surface

51. The left ventricle …
Aortic vestibule
2.The smooth (out
flow) part
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• The out flow part known as
aortic vestibule
• Is just below & continuous with
the aortic orifice
 The aortic orifice is at the
beginning of the ascending
aorta guarded by aortic valve
which has three cusps (right,
left & posterior)
 Three dilatations/sinuses
(aortic) are present
above the cusps which give
origin to coronary arteries
(they supply the heart)

52. The difference between the two ventricles
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• Thickness of the wall:- the
left ventricle is about 5 times
thicker than the right
 Because more work is
done by the left than the
right
 The right pump blood
to lungs where as the
left is to whole body

53. Valves of the Heart
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Tricuspid Valve: Right AV valve
• Has 3 cusps made of endocardium & CT
• The cusps anchored in the Rt. Ventricle
by Chordae Tendinae
 Prevent eversion of cusps into atrium
• Flow of blood pushes the cusps open
Bicuspid (mitral) valve: left AV valve
• Has 2 cusps anchored in left ventricle
by chordae tendinae
• Functions in the same way as R.AV valve
🗸They, both AV valves, close together

54. Semilunar Valves
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Pulmonary Semilunar Valve
🗸Between RV & pulmonary trunk
Aortic Semilunar Valve
🗸Between LV & ascending aorta
• They are made of 3 cusps
(have no tendinous cords)
• Prevent backflow of blood
from large arteries to the
ventricles
• As blood leaves the ventricle
 The cusps are pushed up
into the artery & project
toward its walls

55. Surface Anatomy of Heart Valves
• Pulmonary valve lies behind the
medial end of 3rd left costal
cartilage and adjoining part of
sternum
• Aortic valve lies behind the left half
of sternum in the 3rd intercostal
space.
• Mitral valve lies behind the left half
of sternum in the 4th costal
cartilage.
• Tricuspid valve lies behind the right
half of sternum behind the fourth
intercostal space.
55
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56. 5/3/2022
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57.  Pulmonary semilunar valve - 2nd I.C.S of left sternal margin
 Aortic semilunar valve - 2nd I.C.S right sternal margin
 Mitral valve - 5th intercostal space (I.C.S) at the apex
 Tricuspid valve –right 5th I.C.S of right sternal margin
57
The sounds can be heard(auscultated) at the following points :
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58. • The heart is supplied by two
arteries
 The right and left coronary
arteries
• They are branches of the
ascending aorta, arise from;
 The right and left coronary
sinuses of the aortic valves
respectively
Blood supply of
the heart
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59. Coronary arteries
Origin
Course
Termination
Branches
Right coronary artery (RCA)
left coronary artery (LCA)
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60. • RCA runs in the coronary
sulcus b/n the right atrium
and right ventricle anteriorly
• Over the right margin, gives
off a right marginal branch
 Supplies the right ventricle
Coronary arteries …
 At the junction of the septum and the four chambers, it gives rise to a nodal
branch, which supplies the AV node & to this area of the R. atrium
• Finally, RCA terminates in the posterior interventricular sulcus as the
posterior interventricular artery, supplying mainly
 The posterior aspect of the right and left ventricles as well as the posterior
1/2 of the interventricular septum
Nodal
Marginal
Post. Interventricular
Right coronary artery (RCA)
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61. left coronary
artery (LCA)
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• Passes anteriorly between
the pulmonary trunk and
the tip of the auricle of the
left atrium.
• It divides on the anterior
aspect of the heart into
Anterior interventricular
branch
Circumflex branch
Coronary arteries …

62. 1. Anterior
interventricular branch
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• Descends in the anterior interventricular
sulcus to the inferior margin of the heart
• Continues into the posterior interventricular
sulcus on the diaphragmatic surface
 It supplies anterior aspects of the
right and left ventricles, and anterior
1/2 of the interventricular septum
2. Circumflex branch
• Runs to the left in the atrioventricular
sulcus b/n the left atrium and ventricle
 It gives off a marginal branch for the lateral margin of the left ventricle
and continues onto the posterior aspect of the heart
 It forms an anastomosis with the arteries derived from the right
coronary artery in the posterior interventricular sulcus
Coronary arteries …

63. the heart and the
• Accompany coronary arteries
and their branches
• Lie superficial to the arteries in
the sulci
 Most of the veins drain into the coronary sinus
The coronary sinus
• Lies in the coronary sulcus between the left margin of
posterior interventricular sulcus
• It drains into the right atrium by an opening to the left of the entrance of
the inferior vena cava
 The heart is drained by
 Three major veins
 Other small veins
Cardiac veins
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64. ium
A. Great cardiac vein
• Formed in the anterior interventricular sulcus
 Left marginal vein is a tributary of the great cardiac vein
• Joins the coronary sinus near the left margin of the heart
• Drains the area of the heart supplied by left coronary a.
B. Middle cardiac vein
• It occupies the posterior interventricular sulcus
• Enters coronary sinus near the entrance to the right atr
C. Small cardiac vein
• Follows the right marginal branch of the right coronary a
• Joins the coronary sinus near the junction with the middle cardiac
vein at the left of the right atrium posterorly
 The middle & small cardiac veins drains the area of the
heart supplied by right coronary a
The three major veins
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65. The cardiac veins and the coronary sinus
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66. Other small veins
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Oblique vein
• Drains the left atrium and merges
with the great cardiac vein to form
the coronary sinus (left posterior
ventricular vein also join them??)
Anterior cardiac veins
• Drain the anterior surface of the
right ventricle
• Open directly into the right atrium
Venae cordis minimae
• Are tiny veins draining the heart wall & open directly into the chambers
• Although called veins, they are valveless & may carry blood from the
heart chambers to the myocardium.

67. Lymphatic Drainage of the Heart
• Lymphatic vessels in the myocardium
and subendocardial connective tissue
pass to the subepicardial lymphatic
plexus
 Vessels from this plexus pass to
the coronary groove and follow
the coronary arteries
 A lymphatic vessel, formed by the union
of various vessels from the heart
 Ascends between the pulmonary
trunk and the left atrium
 Ends in the inferior
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68. • The heart has specialized
junctional ‟myocytes” concerned
for origin & propagation of heart
beat.
There by coordinate the
contractions of the four
chambers. They are -
1) The sinoatrial (SA) node
 Is the pacemaker of the heart
 Located b/n right auricle &
Sup.venacava in the RA
 Is vascularized by the nodal branch of the right coronary artery
Conduction system of the heart
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69. 2) The Atrioventricular
(AV) node
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Conduction system …
• Is a smaller collection of nodal tissue
• Located in the right atrium, postero
inferior region of the interatrial
septum anterior to the mouth of the
coronary sinus.
• Receives impulse from SA node &
passes to AV bundle
3) The Atrioventricular (AV)
bundle /bundle of His/
• Connects atria to ventricle in the
interventricular septum
• Divides into right and left bundle
branches (crura) at the junction of
the membranous and muscular
parts of the interventricular septum

70. Conduction system …
4) Purkinje’s
cells
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• Subendothelial plexus consists of straited fibers

71. • By autonomic nerve fibers from
superficial & deep cardiac
plexuses
Superficial plexus - lies
anteroinferior to the aortic arch
Between the aortic arch &
pulmonary trunk
Deep plexus - posteroinferior to
the aortic arch
Between the aortic arch & the
tracheal bifurcation
• The plexuses contain;
1. Sympathetic
2. Parasympathetic
3. Visceral afferent (sensory)
Innervations of the heart
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72. Innervations …
1.Sympathetic - is via cardiac
branches of the cervical and upper thoracic
portions of the sympathetic trunks
Cervical cardiac nerves - from superior
(C1-4) and middle (C5&6) cervical ganglia
Cervicothoracic (inferior) cardiac nerve -
from stellate (cervicothoracic) ganglion
(C7-T1)
Thoracic branches - from T2-4/5 sym. trunk
2.Parasympathetic - … via Vagus
 Both the sympathetic and parasympathetic
branch and fuse - cardiac plexus
 A cardiac plexus courses around the right
pulmonary artery to the posterior aspect of
the atria
 They distribute to the SA node, AV node & to
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73. Sympathetic and Parasympathetic components
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74. Other structures in the middle
mediastinum
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Arteries
 Ascending aorta
 pulmonary trunk
Veins
 Four pulmonary veins
 Lower part of sup. Venacava
 Terminal part of azygus vein
Nerves
 Phrenic & deep cardiac plexus
Lymph nodes- Tracheobronchial nodes

75. Contents of the posterior mediastinum
• Tube – Oesophagus with oesophageal
nerve plexus
• Arteries – Descending thoracic aorta
& its branches
• Veins – Azygos, hemiazygos,
accessory hemiazygos and
posterior intercostal veins
• Nerves – Vagus &
Sympathetic trunks and
splanchnic nerves
• Lymph vessels &nodes –
Thoracic duct & posterior
mediastinal lymph node
Posterior mediastinum
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76. Contents of posterior mediastinum
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77. Descending
aorta
• From the left side of the body of T5,
descends on the left of the vertebral
column posterior to the root of the
left lung
• Passes through the aortic hiatus at
T12
• The greater splanchnic nerve from
the sympathetic trunk joins the
descending aorta and enters the
abdomen with it
•The visceral branches of the
descending aorta are
 Bronchial arteries (left)
 Esophageal arteries
 Branches to pericardium and diaphragm …
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78. Descending aorta
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79. • The right and left posterior
intercostal arteries from the 3rd
intercostal space to the subcostal
arteries
• The right posterior intercostal
arteries from T3-T8 cross the
vertebral column anterior to the
vertebrae
They anastomose with the anterior
intercostal arteries of the internal
thoracic artery
• The 1st and 2nd intercostal spaces
are supplied by the costocervical
trunk of the subclavian arteries
The parietal (thoracic)
branches are
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Descending aorta …

80. Azygos vein
Drain the posterior thoracic wall and
upper lumbar region
Connects superior and inferior venae
The azygos & Hemiazygos
venous systems
• cavae
Originate in the abdomen by union of lumbar azygos, right ascending
lumbar and right subcostal veins
• Course
Enter thoracic cavity through aortic opening or pierce right crus of
diaphragm
ascends on the right side of the vertebral column and to enter the
posterior aspect of the superior vena cava at the level of T4.
80
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81. Tributaries
1. Right superior intercostal vein
2. Right 5 – 11 intercostal veins
3. Right sub costal vein and right
ascending lumbar
4. Right bronchial vein
5. Esophageal, Mediastinal &
pericardial veins
6. Hemiazygos vein
7. Accessory hemiazygos azygos
vein
81
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82. Hemiazgos vein
Origin
In the abdomen by union of left
ascending lumbar and left
subcostal
Course
Enter thoracic cavity piercing the
left crus of diaphragm  at T9
crosses to the right behind
thoracic aorta, esophagus &
thoracic duct  end in azygos
vein
Tributaries
1. 9th – 11th left intercostal
2. Left subcostal
3. Left ascending lumbar
82
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83. Accessory hemiazygos vein
Originate at medial end of 4th and 5th
intercostal space on the left of the
vertebral column.
Crosses to the right at T8 behind
aorta, esophagus and join azygos
vein.
Tributaries
 Left 5th - 8th intercostal veins
 Left bronchial vein
83
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84. Thoracic duct
 Largest lymphatic vessel
 Begins at the cisterna chyli,
posterior to the abdominal
aorta, inferior to the
diaphragm
 Enters the thorax posterior
to the descending aorta
 Ascends on the right of the
vertebral column
 At T5 cross to left side
 Terminating at the junction
between the left subclavian
and left internal jugular
veins
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85. Thoracic duct
• The thoracic duct thus conveys to the blood
all lymph from the lower limbs, pelvic cavity,
abdominal cavity, left side of the thorax, and
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86. 86
Tributaries
• Posterior mediastinal nodes
• Intercostal nodes
• Left jugular trunk
• Left subclavian trunk
• Left mediastinal trunk
• It drains all the lymph of the
body except for the right
thorax, right upper limb and
right side of the head and neck.
• These remaining areas drain
into the right lymphatic duct
which joins the junction of the
right internal jugular and
right subclavian veins
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87. Vagus nerves
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• Inferior to the root of the lung, the
left vagus lies anterior to the
esophagus and the right vagus lies
posteriorly
 Their branches form the anterior
and posterior esophageal
plexuses
• They form single nerves to pierce the
diaphragm at the esophageal hiatus
• Below the diaphragm they are
renamed as the anterior and
posterior gastric nerves
• Vagal branches induce peristalsis
in the esophagus and are
secretomotor to mucous glands

88. Sympathetic trunks
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• The symathetic trunk and
their associated ganglia form a
major portion of the ANS
• The thoracic sympathetic trunks
are in continuity with the
cervical and lumbar
sympathetic trunks
• The thoracic sympathetic trunks
lie against
The heads of the ribs in
the superior part of the
thorax
The costovertebral
joints in the midthoracic
level
The sides of vertebral
bodies in the lower part
of the thorax

89. This sympathetic trunks consists of
two parallel cords punctuated by
11 or 12 ganglia
 Two types of medial branches
are given off by the ganglia
 The first type includes branches
from the upper four/five
ganglia
 The second type includes
branches from the lower eight
/seven ganglia
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90. Sympathetic trunks and the splanchnic nerves
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91. Sympathetic …
The first type, from the upper four/five
ganglia
 Consists mainly of postganglionic
sympathetic fibers, which supply the
various thoracic viscera
 These branches are relatively
small, also contain visceral
afferent fibers
The second type, from the lower
eight/seven ganglia
 Consists mainly of preganglionic
sympathetic fibers, which supply the
various abdominal and pelvic
viscera
 Form the 3 thoracic splanchnic
nerves greater, lesser, and least
splanchnic nerves
 These branches are large, also carry
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92. Sympathetic …
• Solid lines indicate
pre-ganglionic axons
while broken lines
indicate post-
ganglionic axons
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93. The splanchnic nerves → Greater, lesser and least
• The lower thoracic splanchnic nerves, also known as greater, lesser,
and least splanchnic nerves, are part of the abdominopelvic
splanchnic nerves
 Because they supply viscera
inferior to the diaphragm
• They consist of presynaptic fibers
from the 5/6th to 12th
sympathetic ganglia, which pass
through the diaphragm
 They synapse in prevertebral
ganglia in the abdomen
Greater splanchnic nerve
• On each side usually arises from the 5th - 9th/10th thoracic ganglia
• It descends across the vertebral bodies moving in a medial
direction, passes into the abdomen through the crus of the
diaphragm, and ends in the cM
ee
ln
ig
ais
t
cu.D
ganglion
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94. The splanchnic nerves …
• Usually arises from tenth and
eleventh thoracic ganglia
 It descends across the
vertebral bodies moving in
a medial direction, and
passes into the abdomen
through the crus of the
diaphragm to end in the
aorticorenal ganglion
Least splanchnic nerve
• Usually arises from the twelfth thoracic ganglion
 It descends and passes into the abdomen through the crus of the
diaphragm to end in the aorticorenal plexus
Lesser splanchnic nerve
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95. Thank you!
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