Download mediastinum - Yeditepe University Pharma Anatomy

Salvador Dali - Anthropomorphic Chest of Drawers, 1936
Kaan Yücel M.D., Ph.D.
14.October.2011 Friday
1
The thorax is the part of the body between the neck and abdomen.
Posterior surface:: 12 thoracic vertebrae & posterior parts of the ribs
Anterior surface: Sternum & costal cartilages
Lateral surfaces: Ribs, separated from each other by the intercostal spaces
2
The floor of the thoracic cavity is deeply invaginated inferiorly
by viscera of the abdominal cavity.
3
Regions
Thoracic wall
Thoracic cavity
4
The thorax includes the primary
organs of the respiratory and
cardiovascular systems.
The thoracic cavity
3 major spaces
Mediastinum – central compartment
Right & left pulmonary cavities
The majority of the thoracic cavity
lungs
Heart & structures involved in conducting the air and blood to and
from the lungs
+Esophagus
5
The true thoracic wall includes:
• The thoracic cage and the muscles that extend between the
ribs as well as the skin, subcutaneous tissue, muscles, and
fascia covering its anterolateral aspect.
• The mammary glands of the breasts lie within the
subcutaneous tissue of the thoracic wall.
6
The domed shape of the thoracic cage provides its components
enabling to:
 Protect vital thoracic and abdominal organs (most air or fluid filled)
from external forces.
 Resist the negative (sub-atmospheric) internal pressures generated
by the elastic recoil of the lungs and inspiratory movements.
 Provide attachment for and support the weight of the upper limbs.
 Provide the anchoring attachment (origin) of many of the muscles
that move and maintain the position of the upper limbs relative to
the trunk, as well as provide the attachments for muscles of the
abdomen, neck, back, and respiration.
 The thorax is one of the most dynamic regions of the body.
• 12 pairs of ribs and associated costal cartilages
• 12 thoracic vertebrae and the intervertebral (IV) discs
• Sternum
Ribs & costal cartilages largest part of the thoracic cage
Both are identified numerically, from the most superior (1st
rib or costal cartilage) to the most inferior (12th).
8
Characteristic features of thoracic vertebrae
• Bodies, vertebral arches, 7 processes
for muscular & articular connections
Costal facets (demifacets) on the vertebral bodies,
inferior & superior pairs, articulation w/ the heads of the ribs
Costal facets on the transverse processes articulation w/ the
tubercles of the ribs, except inferior 2 or 3 Th vertebrae
• Spinous processes
9
Ribs (L. costae)
12 pairs of curved, flat bones
Form most of the thoracic cage
10
3 types of ribs
True (vertebrocostal) ribs
Carticalages’ direct connection
w/ the sternum
False (vertebrochondral) ribs
Indirect connection with the
sternum
Cartilages’ connection w/ the
superior rib
Floating (vertebral, free ribs)
No connection w/ the sternum
VIIII- X
XI-XIIII
11
Typical ribs (3rd to 9th)
• Head Has two articular facets
• articulate with numerically corresponding vertebra
• articulate with one superior vertebra
• Neck Connects the head with the body at the tubercle
• Tubercle Between the shaft and the neck. Has an articular
facet for articulating with the transverse process of the
corresponding vertebra.
• Body Concave internal surface has the costal groove for
the intercostal nerve and vessels. Bears the angle.
12
13
 Atypical ribs 1st, 2nd, and 10th-12th ribs are dissimilar.
 Costal cartilages prolong the ribs anteriorly and contribute to the
elasticity of the thoracic wall, providing a flexible attachment for
their anterior ends.
15
Intercostal spaces separate the ribs and their costal cartilages
from one another.
Named according to the rib forming the superior border of
the space
The 4th intercostal space lies between ribs 4 and 5.
11 intercostal spaces and 11
intercostal nerves
16
G. sternon, chest
Has three parts:
1. Manubrium
2. Body
3. Xiphoid process
Jugular notch
@ sup. margin of the manubrium
Level of T2 vertebra
Clavicular notch
17
Sternal angle
is formed by the junction of
the manubrium with the body
of the sternum.
Lies at the level of 2nd costal
cartilage anteriorly
Xiphoid process is an
important for the inferior
border of the heart and upper
border of the liver.
18
 While the thoracic cage provides a complete wall
peripherally, it is open superiorly and inferiorly.
 The superior opening is a passageway that allows
communication with the neck and upper limbs.
 The larger inferior opening provides the ring-like origin of
the diaphragm, which completely occludes the opening.
19
Structures that pass between the thoracic cavity and the neck through
the superior thoracic aperture:
 Trachea
 Esophagus
 Nerves, and vessels that supply and drain the head, neck,
and upper limbs.
20
1.
2.
3.
4.
5.
Costa transverse joints
Sterno costal joint
Costachondralis joint
Intercondral Joints
Sternal JointsManubrium, body, xiphoid process of the
sternum.
21
22
 Some muscles attached to and/or covering the thoracic cage
are primarily involved in serving other regions.
 Several (axioappendicular) muscles extend from the thoracic
cage (axial skeleton) to bones of the upper limb
(appendicular skeleton).
 Muscles, such as sternocleidomasteoid muscle, abdominal
muscles, pectoral muscles, function as accesory muscles of
respiraton and work in forced respiration; when the person
needs to breathe in and out more than usual; 100 meter
sprinters, patients with respiratory problems.
23
Muscles of the thoracic wall
 Serratus posterior muscles
 Levator costarum muscles
 Intercostal muscles(External, internal and innermost)
 Subcostal muscle
 Transverse thoracic muscle
These muscles either elevate or depress the ribs helping to
increse the volume of the thoracic cavity.
24
The diaphragm is a shared wall (actually floor/ceiling)
separating the thorax and abdomen. Although it has functions
related to both compartments of the trunk, its most important
(vital) function is serving as the primary muscle of inspiration.
25
26
27
In general, the pattern of vascular distribution in the thoracic
wall reflects the structure of the thoracic cage—that is, it
runs in the intercostal spaces, parallel to the ribs.
28
Arteries of Thoracic Wall
Branches of the
 Thoracic aorta
 Subclavian artery
 Axillary artery
29
Arteries of Thoracic Wall
The intercostal arteries course through the thoracic wall between
the ribs.
30
Veins of Thoracic Wall
Intercostal veins accompany the intercostal arteries &
nerves Most superior in the costal grooves
11 posterior intercostal veins + 1 subcostal vein on each
side.
Posterior intercostal veins anastomose anterior intercostal
veins
Most posterior intercostal veins (4-11) end in the
azygos/hemiazygos venous system
SVC.
31
32
The 12 pairs of thoracic spinal nerves supply the thoracic
wall.
As soon as they leave the IV foramina in which they are
formed, the mixed thoracic spinal nerves divide into
anterior and posterior (primary) rami or branches.
The anterior rami of nerves T1-T11 form the intercostal
nerves that run along the extent of the intercostal spaces.
33
 The intercostal nerves pass to and then continue to
course in or just inferior to the costal grooves, running
inferior to the intercostal arteries (which, in turn, run
inferior to the intercostal veins).
 The neurovascular bundles (and especially the vessels)
are thus sheltered by the inferior margins of the
overlying rib.
34
35
The
byaasegment
segment
Theskin
skinarea
area supplied
supplied by
of of
thethe
spinal
spinalcor.d
cord.
36
• The breasts (L. mammae) are the most prominent
superficial structures in the anterior thoracic wall,
especially in women.
• Accessory to reproduction in women
• Rudimentary and functionless in men, consisting of
only a few small ducts or epithelial cords.
• Mammary glands lie superficial to the pectoralis major
muscle
• The anterior part is called the nipple and
it is surrounded by a circular pigmented area of skin,
called the areola
37
Lymphatic drainage
 Axillary lymph nodes ,
 Parasternal lymph nodes
 Abdominal lymph nodes
38
39
Arterial supply of the breast
1. Medial mammary branches
2.Lateral mammary branches, lateral thoracic & thoracoacromial
arteries
3. Posterior intercostal arteries 2nd-4th
40
41
42
Venous drainage of the breast
Mainly to the axillary vein, some to the internal thoracic vein
43
Nerves of the breast
Anterior and lateral cutaneous branches of
the 4th-6th intercostal nerves
44
45
The thoracic cavity is divided into three major spaces:
 The central compartment or mediastinum that houses the
thoracic viscera except for the lungs and, on each side
 The right and left pulmonary cavities housing the lungs.
48
 The mediastinum (Mod. L. middle septum, L, mediastinus,
midway), occupied by the mass of tissue between the two
pulmonary cavities, is the central compartment of the thoracic
cavity.
 It is covered on each side by mediastinal pleura and contains all
the thoracic viscera and structures except the lungs.
•anterior
mediastinum (1)
•middle
mediastinum (2)
•posterior
mediastinum (3)
Mediastinum
Superior to Inferior
From superior thoracic aperture to the diaphragm
Anterior to Posterior
From sternum & costal cartilages to the bodies of the thoracic vertebrae
The looseness of the connective tissue and the elasticity of the lungs
and parietal pleura on each side of the mediastinum enable it to
accommodate movement as well as volume and pressure changes in
the thoracic cavity, for example,
 those resulting from movements of the diaphragm, thoracic wall,
and tracheobronchial tree during respiration,
 contraction (beating) of the heart and pulsations of the great
arteries,
 passage of ingested substances through the esophagus.
Superior mediastinum
Inferior mediastinum
Superior mediastinum
Superior to sternal angle
Inferior mediastinum
 Inferior to sternal angle
 Further subdivided by the pericardium into anterior, middle, and
posterior parts.
Anterior mediastinum
Between the anterior surface of pericardium and posterior surface of
the sternum
Middle mediastinum
Pericardium, heart and beginings of the great vessels emerging from
the heart lie here
Posterior mediastinum
Lies posterior to the pericardium and diaphragm
55
56
The pericardium and its contents (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.
Contents of the superior mediastinum
1) Thymus
2) Great vessels related to the heart with the veins
3) Inferior continuation of the cervical viscera (trachea anteriorly and
esophagus posteriorly) and related nerves (left recurrent laryngeal
nerve)
4) Thoracic duct and lymphatic trunks
5) Prevertebral muscles
60
The posterior mediastinum
The posterior mediastinum (the posterior part of the inferior
mediastinum) is located
 inferior to the sternal angle,
 posterior to the pericardium and diaphragm,
 between the parietal pleura of the two lungs.
Contents of the posterior mediastinum








Thoracic aorta
Thoracic duct
Posterior mediastinal lymph nodes
Azygos and hemiazygos veins
Esophagus
Esophageal nerve plexus
Thoracic sympathetic trunks
Thoracic splanchnic nerves
CARDIOVASCULAR SYSTEM
The vascular system is divided for descriptive purposes into
(a) the blood vascular system, which comprises the heart and blood
vessels for the circulation of the blood
(b) the lymph vascular system, consisting of lymph glands and
lymphatic vessels, through which a colorless fluid, the lymph, circulates.
The two systems communicate with each other and are intimately
associated developmentally.
 The heart is the central organ of the blood vascular system, and
consists of a hollow muscle; by its contraction the blood is pumped to
all parts of the body through a complicated series of tubes, termed
arteries.
 The arteries undergo enormous ramification in their course
throughout the body, and end in minute vessels, called arterioles,
which in their turn open into a close-meshed network of microscopic
vessels, termed capillaries.
 After the blood has passed through the capillaries it is collected
into a series of larger vessels, called veins, by which it is
returned to the heart.
 The passage of the blood through the heart and blood-vessels
constitutes what is termed the circulation of the blood.
HEART
• Slightly larger than a clenched fist
• A double, self-adjusting suction and pressure pump
• Propel blood to all parts of the body
The right side of the heart (right heart) receives poorly
oxygenated (venous) blood from the body through the superior
vena cava (SVC) and inferior vena cava (IVC) and pumps it
through the pulmonary trunk and arteries to the lungs for
oxygenation.
The left side of the heart (left heart) receives well-oxygenated (arterial)
blood from the lungs through the pulmonary veins and pumps it into
the aorta for distribution to the body.
The heart has four chambers:
Right & Left atria
Right & Left ventricles
The atria are receiving chambers that pump blood into
the ventricles (the discharging chambers).
The synchronous pumping actions of the heart's two
atrioventricular (AV) pumps (right and left chambers) constitute
the cardiac cycle.
The cycle begins with a period of ventricular elongation and filling
(diastole) and ends with a period of ventricular shortening and
emptying (systole).
The wall of each heart chamber consists of three layers:
• Endocardium, a thin internal layer or lining membrane of the
heart that also covers its valves.
• Myocardium, a thick, helical middle layer composed of cardiac
muscle. The walls of the heart consist mostly of myocardium,
especially in the ventricles.
• Epicardium, a thin external layer (mesothelium) formed by the
visceral layer of serous pericardium.
Externally, the atria are demarcated from the ventricles by the
coronary sulcus (atrioventricular groove), and the right and left
ventricles are demarcated from each other by anterior and
posterior interventricular (IV) sulci (grooves).
The heart appears trapezoidal from an anterior or posterior view,
but in three dimensions it is shaped like a tipped-over pyramid
with its apex (directed anteriorly and to the left), a base (opposite
the apex, facing mostly posteriorly), and four sides.
The four surfaces of the heart
Anterior (sternocostal) surface
Diaphragmatic (inferior) surface
Right pulmonary surface
Left pulmonary surface
Anterior (sternocostal) surface
Diaphragmatic (inferior) surface
77
Right atrium
• Forms the right border of the heart and receives venous
blood from the SVC, IVC, and coronary sinus.
• The ear-like right auricle is a conical muscular pouch
that projects from this chamber like an add-on room,
increasing the capacity of the atrium as it overlaps the
ascending aorta.
79
• The interior of the right atrium has a smooth, thin-walled,
posterior part (the sinus venarum) on which the venae
cavae (SVC and IVC) and coronary sinus open, bringing
poorly oxygenated blood into the heart.
• Rough, muscular anterior wall composed of pectinate
muscles (L. musculi pectinati).
• Opening of the coronary sinus
The interatrial septum separating the atria has an oval, thumbprintsize depression, the oval fossa (L. fossa ovalis), a remnant of the
oval foramen (L. foramen ovale) and its valve in the fetus.
83
• Forms the largest part of the anterior surface of the
heart, a small part of the diaphragmatic surface, and
almost the entire inferior border of the heart.
• The right ventricle receives blood from the right
atrium through the right AV (tricuspid) orifice.
Tendinous cords (L. chordae tendineae) attach to the free edges
and ventricular surfaces of the anterior, posterior, and septal cusps,
much like the cords attaching to a parachute.
• The tendinous cords arise from the apices of papillary
muscles, which are conical muscular projections with
bases attached to the ventricular wall.
• The papillary muscles begin to contract before
contraction of the right ventricle, tightening the
tendinous cords and drawing the cusps together.
The interventricular septum (IVS), is obliquely placed partition between
the right and left ventricles
 The left atrium forms most of the base of the heart. The
valveless pairs of right and left pulmonary veins enter the
atrium.
 The tubular, muscular left auricle, its wall trabeculated with
pectinate muscles, forms the superior part of the left border of
the heart.
 A semilunar depression in the interatrial septum indicates the
floor of the oval fossa; the surrounding ridge is the valve of the
oval fossa (L. valvulae foramen ovale).
The interior of the left atrium has:
 Pectinate muscles
 Four pulmonary veins (two superior and two inferior)
 An interatrial septum
 A left AV orifice through which the left atrium discharges the
oxygenated blood it receives from the pulmonary veins into the left
ventricle.
A semilunar depression in the interatrial septum indicates the floor
of the oval fossa; the surrounding ridge is the valve of the oval
fossa (L. valvulae foramen ovale).
 The left ventricle forms the apex of the heart, nearly all its left
(pulmonary) surface and border, and most of the diaphragmatic
surface.
 Because arterial pressure is much higher in the systemic than in
the pulmonary circulation, the left ventricle performs more work
than the right ventricle.
The interior of the left ventricle has:
 A smooth-walled, non-muscular, superoanterior outflow part,
the aortic vestibule, leading to the aortic orifice and aortic
valve.
 A double-leaflet mitral valve that guards the left AV orifice.
 The mitral valve has two cusps. The semilunar aortic valve,
between the left ventricle and the ascending aorta, is
obliquely placed.
96
97
Vasculature of the Heart
The blood vessels of the heart
• Comprise the coronary arteries and cardiac veins, which
carry blood to and from most of the myocardium.
Coronary Arteries
•
•
•
The first branches of the aorta
Supply the myocardium and epicardium.
Supply both the atria and the ventricles.
The right and left coronary arteries arise from aorta.
Anastomoses between the branches of the coronary arteries
exist, which enables the development of the collateral circulation.
Veins of the heart
The heart is drained mainly by veins that empty into the
coronary sinus and partly by small veins that empty into the
right atrium.
Veins of the heart
• All of the veins (except the smallest cardiac veins) open
into the coronary sinus, which runs on the posterior part of
the coronary groove .
• Coronary sinus opens into the right atrium at the opening
of the coronary sinus.
Lymphatic Drainage of the Heart
• A single lymphatic vessel, formed by the union of various
lymphatic vessels from the heart ends in the inferior
tracheobronchial lymph nodes, usually on the right side.
Stimulating and Conducting System of the Heart
 The conducting system consists of nodal tissue that initiates the
heartbeat and coordinates contractions of the four heart
chambers, and highly specialized conducting fibers for conducting
them rapidly to the different areas of the heart.
 The impulses are then propagated by the cardiac striated muscle
cells so that the chamber walls contract simultaneously.
.
106
Impulse generation and conduction can be summarized as follows:
The SA node (pacemaker of the heart; in the right atrium) initiates
an impulse that is rapidly conducted to cardiac muscle fibers in the
atria, causing them to contract.
The impulse spreads by myogenic conduction, which rapidly
transmits the impulse from the SA node to the AV node (in the right
atrium).
The signal is distributed from the AV node through the AV
bundle and its branches (the right and left bundles), which pass
on each side of the IVS to supply subendocardial branches to
the papillary muscles and the walls of the ventricles.
Innervation of the Heart
Innervation of the heart is through the autonomic
nerves (both sympathetic and parasympathetics)
from the cardiac plexus.
PERICARDIUM
The pericardium is a fibroserous membrane that covers the heart
and the beginning of its great vessels.
The pericardium is a closed sac composed of two layers:
–Fibrous pericardium (external)
continuous with the central tendon of the diaphragm
– Serous pericardium (internal)
• Parietal layer
• Visceral layer (epicardium)
Visceral and parietal layers are continuous with each other where
the great vessels enter and leave the heart.
114
The fibrous pericardium is continuous superiorly with the tunica
adventitia of the great vessels entering and leaving the heart and with
the pretracheal layer of deep cervical fascia.
• Attached anteriorly to the sternum by the sternopericardial ligaments
• Continuous inferiorly with the central tendon of the diaphragm
as the pericardiacophrenic ligament
 Inner surface is lined by the parietal layer of the serous
pericardium and these layers are strictly attached to each other.
 The fibrous pericardium protects the heart against sudden
overfilling because it is so unyielding and closely related to the
great vessels that pierce it superiorly.
Pericardial cavity
Potential space between opposing layers of the parietal and
visceral layers of serous pericardium.
Contains a thin film of fluid that enables the heart to move and
beat in a frictionless environment.
Transverse pericardial sinus
Oblique pericardial sinus
The arterial supply of the pericardium is mainly from a slender branch of
the internal thoracic artery, the pericardiacophrenic artery.
The venous drainage of the pericardium is from the pericardiacophrenic
veins, tributaries of the brachiocephalic (or internal thoracic) veins and
variable tributaries of the azygos venous system.
pericardiacophrenic artery
GREAT VESSELS
The right and left brachiocephalic veins are formed posterior to
the sternoclavicular (SC) joints by the union of the internal
jugular and subclavian veins.
120
 The brachiocephalic veins unite to form the SVC.
121
The superior vena cava (SVC) returns blood from all structures superior
to the diaphragm, except the lungs and heart. It ends by entering the
right atrium of the heart.
122
 The ascending aorta begins at the aortic orifice. Its only branches
are the coronary arteries, arising from the aortic sinuses.
 The arch of the aorta (aortic arch) is the curved continuation of the
ascending aorta.
The usual branches of the arch
1) Brachiocephalic trunk
2) Left common carotid artery
3) Left subclavian artery
123
124
The ligamentum arteriosum, the remnant of the fetal ductus
arteriosus, passes from the root of the left pulmonary artery to the
inferior surface of the arch of the aorta.
125