Download Document

MEDIASTINUM
G.LUFUKUJA
1
The mediastinum
The mediastinum is the central
compartment of the thoracic
cavity that contains a group of
structures within the thorax. The
mediastinum
contains
the heart and its vessels,
the esophagus, trachea, phrenic
and cardiac nerves, the thoracic
duct, thymus and lymph
nodes of the central chest
G.LUFUKUJA
2
G.LUFUKUJA
3
MEDIASTINUM: The superior mediastinum
The mediastinum is artificially divided into superior and
inferior parts for purposes of description. The superior
mediastinum extends inferiorly from the superior thoracic
aperture to the horizontal plane that includes the sternal angle
anteriorly and passes approximately through the junction (IV
disc) of the T4 and T5 vertebrae posteriorly, often referred to
as the transverse thoracic plane
G.LUFUKUJA
4
 It contains the lower ends of sternohyoid,
sternothyroid on each side; the aortic arch; the
brachiocephalic artery and the thoracic portions of the
left common carotid and left subclavian arteries; the
brachiocephalic veins and the upper half of the superior
vena cava; the vagus, cardiac, phrenic and left recurrent
laryngeal nerves; the trachea, oesophagus, and thoracic
duct; the remains of the thymus, and lymph nodes.
G.LUFUKUJA
5
The inferior mediastinum
The inferior mediastinum is further subdivided by the
pericardium into anterior, middle, and posterior parts. The
pericardium and its contents (the heart and roots of its great
vessels) constitute the middle mediastinum.
Some structures, such as the esophagus, pass vertically
through the mediastinum and therefore lie in more than one
mediastinal compartment.
G.LUFUKUJA
6
anterior mediastinum:
†Sternopericardial ligaments
†Retro-sternal lymph nodes
†Branches of Internal thoracic artery
G.LUFUKUJA
7
MIDDLE MEDIASTINUM:
The middle mediastinum contains the heart enclosed in the
fibrous pericardium, the ascending aorta, the lower half of the
superior vena cava with the azygos vein opening into it, the
bifurcation of the trachea and the right and left principal
bronchi, the pulmonary artery dividing into its two branches,
the right and left pulmonary veins and phrenic nerves, and
some bronchial lymph nodes.
G.LUFUKUJA
8
Pericardium…
• Nerve Supply
• The fibrous pericardium and the parietal layer of the
serous pericardium are supplied by the phrenic nerves.
• The visceral layer of the serous pericardium is
innervated by branches of the sympathetic trunks and
the vagus nerves
G.LUFUKUJA
9
Applied Anatomy
• Pericarditis
• Pericarditis is swelling and irritation of the pericardium, the
thin sac-like membrane surrounding your heart.
Pericarditis often causes chest pain and sometimes other
symptoms. The sharp chest pain associated with
pericarditis occurs when the irritated layers of the
pericardium rub against each other.
• In pericarditis pericardial fluid may also accumulate
excessively, which can compress the thin-walled atria
and interfere with the filling of the heart during diastole.
This compression of the heart is called cardiac
tamponade. Cardiac tamponade (heart compression) is a
potentially lethal condition because the fibrous pericardium
is tough and inelastic
G.LUFUKUJA
10
POSTERIOR MEDIASTINUM:
• It contains the descending thoracic aorta and the
azygos, hemiazygos and accessory azygos veins; the
right and left sympathetic chains, the splanchnic
nerves and the right and left vagus nerves; the
oesophagus; the thoracic duct and posterior
mediastinal lymph nodes.
G.LUFUKUJA
11
HEART & GREAT VESSELS
G.LUFUKUJA
12
G.LUFUKUJA
13
EXTERNAL FEATURES


Atrioventricular groove (coronary sulcus)
Interventricular groove

Auricles – extensions of each atria
G.LUFUKUJA
14
SURFACES AND BORDERS:

Surfaces:
Anterior (Sternocostal) & Inferior (diaphragmatic)

 Borders:
Superior, Inferior, Right , Left
G.LUFUKUJA
APEX: Formed by
the left ventricle,
Located in the left
5th intercostal
space Just medial
to the
midclavicular line
15
BASE: Formed by the left atrium and a small part of the right atrium; Openings of four
pulmonary veins & Openings of superior and inferior vena cavae
G.LUFUKUJA
16
G.LUFUKUJA
17
G.LUFUKUJA
18
ARTERIAL SUPPLY TO THE HEART
Right and Left coronary arteries
G.LUFUKUJA
19
TCAO
LCO
RCO
RAV
LAV
G.LUFUKUJA
20
AA
LCA
LCA
G.LUFUKUJA
21
VENOUS DRAINAGE OF THE HEART
G.LUFUKUJA
22
G.LUFUKUJA
23
Applied Anatomy
• Angina pectoris – commonly known as angina – is chest
pain due to ischemia of the heart muscle, generally due
to obstruction or spasm of the coronary arteries. The
main cause of Angina pectoris is coronary artery
disease, due to atherosclerosis of the arteries feeding
the heart
G.LUFUKUJA
24
RIGHT ATRIUM
 Receives venous blood from the whole body & Sends it to the right ventricle
through the tricuspid orifice
G.LUFUKUJA
25
RIGHT ATRIUM – INTERNAL FEATURES
Divided into three parts
 Smooth posterior wall – sinus venarum
 Rough anterior wall – pectinate part
 Septal wall
 Sinus venarum
Fossa ovalis
 Superior vena cava
 Inferior vena cava
 Coronary sinus
Thebasian valve
Eustachian valve
G.LUFUKUJA
26
RIGHT VENTRICLE
Receives blood from the right atrium & Pumps it
through the pulmonary trunk to the lungs
Chordae tendinae –
Strings that attach the
tips of the papillae to the
free edges of the cusps
Have trabeculae carneae
G.LUFUKUJA
27
LEFT ATRIUM
Receives the four pulmonary veins
 Most of the interior is smooth
 Musculi pectinati are present only in the left auricle
 Fossa lunata – corresponds to the fossa ovalis
G.LUFUKUJA
28
LEFT VENTRICLE
Interior has a rough inflow
part and a smooth outflow
part
Inflow part has trabeculae
carneae
G.LUFUKUJA
29
G.LUFUKUJA
30
G.LUFUKUJA
31
Lymphatic drainage
• Subendocardial plexus
subpericardial plexus
trunks
myocardial plexus
bronchomediastinal
G.LUFUKUJA
32
Nerve supply of heart
- Nerve of the heart are
derived from cardiac
plexus,
which
is
formed
by
the
sympathetic
and
parasympathetic
(vagal) fibres.
cardiac plexus
G.LUFUKUJA
G.LUFUKUJA
33
33
Effect of sympathetic and
parasympathetic fibres
1) Sympathetic
fibres
supply
the
atria,ventricles and conducting system of
heart.
-sympathetic stimulation lead to
(a) increase in heart rate.
(b) increase in cardiac output.
(c) vasodilation of coronary artery.
2) Parasympathetic will do the reverse
G.LUFUKUJA
34
Conducting system of the heart
1) Sinuatrial node ( SA node)
2) Atrioventricular Bundle(AV Bundle of HIS)
3) Right and left branches
G.LUFUKUJA
35
G.LUFUKUJA
36
G.LUFUKUJA
37
G.LUFUKUJA
38
G.LUFUKUJA
39
Applied anatomy- arrhythmias
• Failure of the Conduction System of the Heart
• The sinuatrial node is the spontaneous source of the cardiac
impulse. The atrioventricular node is responsible for picking up
the cardiac impulse from the atria. The atrioventricular bundle
is the only route by which the cardiac impulse can spread from
the atria to the ventricles. Failure of the bundle to conduct the
normal impulses results in alteration in the rhythmic
contraction of the ventricles (arrhythmias) or, if complete
bundle block occurs, complete dissociation between the atria
and ventricular rates of contraction.
• The common cause of defective conduction through the
bundle or its branches is atherosclerosis of the coronary
arteries, which results in a diminished blood supply to the
conducting system.
G.LUFUKUJA
40
G.LUFUKUJA
41