Download posterior mediastinum

ANTERIOR AND POSTERIOR
MEDIASTINUM
LEARNING OBJECTIVES
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•
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Identify the space between the two pleural cavities.
Know the boundaries and subdivisions of
mediastinum.
Know the contents and the relationships among
structures of Anterior and Posterior mediastina.
MEDIASTINUM
•The space between the pleural cavities
occupying the center of thoracic cavity is the
mediastinum
 extends superiorly to the thoracic inlet and
root of neck.
 Inferiorly extends to the diaphragm.
BOUNDARIES OF MEDIASTINUM
• Anteriorly
sternum
• Posteriorly
vertebral column
• Superiorly:
thoracic inlet
• Inferiorly
diaphragm
• On each side:
lungs & pleura
DIVISION OF MEDIASTINUM
Mediastinum is divided into
•
superior and
•
inferior mediastinum
by imaginary line passing
anteriorly through sternal
angle to the lower border of
body of fourth thoracic
vertebra posteriorly.
INFERIOR MEDIASTINUM
ANTERIOR MEDIASTINUM
Lies In front Of The Pericardium
•
MIDDLE MEDIASTINUM
Contains Heart And Pericardium
•
POSTERIOR MEDIASTINUM
Lies Behind The Pericardium
•
LEFT SIDE OF MEDIASTINUM
Left subclavian a.
Thoracic duct
Left vagus n.
Left recurrent n.
Phrenic n. &
pericardiacophrenic a.
Root of lung
Aortic arch
Thoracic aorta
Sympathetic trunk
Pericardium
Esophagus
Greater splanchnic n
RIGHT SIDE OF MEDIASTINUM
Trachea
Right vagus n.
Arch of azygos v.
Azygos v.
Sympathetic trunk
Esophagus
Inferior vena cava
Superior vena cava
Phrenic n. &
pericardiacophrenic a.
Root of lung
Pericardium
INFERIOR MEDIASTINUM
ANTERIOR MEDIASTINUM
•
Location
posterior to body of sternum and attached costal
cartilages, anterior to heart and pericardium
•
Contents
– Fat
– Remnants of thymus gland
– Anterior mediastinal
lymph nodes
THYMUS
The remains of the thymus embedded in fatty connective tissue
immediately posterior to manubrium sterni.
• The organ reaches its greatest size relative to the
remainder of the body at birth.
• It continues to enlarge until puberty, when it gradually
starts to atrophy, and very little is present in old age.
• It receives its arterial supply from the internal thoracic
arteries.
INFERIOR MEDIASTINUM
POSTERIOR MEDIASTINUM
Location:
posterior to heart and pericardium,
anterior to vertebrae T5-T12
Contents:
Esophagus
– Vagi and sphlanchnic nerves
– Thoracic aorta and its branches
– Azygos system of veins
– Thoracic duct
– Thoracic sympathetic trunk
– Posterior mediastinal lymph nodes
–
RELATIONS OF ESOPHAGUS
•
Anteriorly
– Trachea
– Bifurcation of trachea
– Left principal bronchus
– Left recurrent n.
– Right pulmonary a.
– Anterior esophageal plexus
– Pericardium
– Left atrium
– Diaphragm
• Posteriorly
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Posterior esophageal plexus
Thoracic aorta
Thoracic duct
Azygos v.
Hemiazygos v.
Accessory hemiazygos v.
Right posterior intercostal v.
RELATIONS OF ESOPHAGUS
• Left
Left common carotid a.
– Left subclavian a.
– Aortic arch
– Thoracic aorta
– Superior part of thoracic duct
–
• Right
–
Arch of azygos v.
BLOOD SUPPLY OF ESOPHAGUS
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Bronchial artery.
Thoracic aorta.
Left gastric artery.
Left inferior phrenic artery.
INNERVATION OF ESOPHAGUS
Esophageal plexus:
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Continuation of posterior pulmonary plexus.
Formed by right and left vagus nerves:
Right vagus nerve  posterior vagus nerve.
Left vagus nerve  anterior vagus nerve.
Upper third:
Voluntary muscle.
Innervated by recurrent laryngeal nerve.
Lower two-thirds:
Involuntary muscle.
Innervated by vagus and sympathetic chain.
DESCENDING THORACIC AORTA
•
Lies within posterior mediastinum.
•
Begins at level of sternal angle.
•
Ends in front of thoracic vertebra 12
•
Continuous with abdominal aorta.
RELATIONS OF THORACIC AORTA
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•
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•
Anteriorly
– Left root of lung
– Pericardium
– Esophagus
Posterior
– Hemiazygos v.
– Accessory hemiazygos v.
Right
– Azygos v.
– Thoracic duct
Left
mediastinal pleura
RELATIONS OF THORACIC AORTA
LEFT THORACIC DUCT
• Arises from cisterna chyl at union of right and left lumbar
trunks.
• Begins on front of vertebral body T12 or L1.
• Runs up through the thorax along the front of the vertebral
column.
• At first it lies to the right of midline.
• It moves over to the left side when it reaches level T-5.
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•
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Receives most of lymph from body below diaphragm.
Drains left side of thoracic cavity and part of right.
Receives lymph from left internal jugular lymph trunk.
Receives lymph from left subclavian lymph trunk.
Empties into venous system at junction of:
Left internal jugular vein.
Left subclavian vein.
RIGHT THORACIC DUCT
• Drains upper right thoracic cavity, right upper extremity, and
right side of head and neck.
• Empties into venous system
at junction of:
Right internal jugular vein.
Right subclavian vein.
THORACIC SYMPATHETIC CHAIN
• Lies against neck of ribs and costovertebral junctions.
• 12 thoracic ganglia pairs
• First one often fused with inferior cervical ganglion
• Referred to as stellate ganglion collectively
• Cervical ganglia:
Superior.
Middle.
Inferior.
• The preganglionic sympathetic supply to the thoracic
viscera is from T1–5.
• The postganglionic supply is from:
Superior, middle, and inferior cervical ganglia.
T1-T5 paravertebral ganglia.
• They exit the chain as direct fibers and travel
downwards to enter the thorax as cardiopulmonary
splanchnic nerves.
• The cardiopulmonary splanchnic nerves
travel on their own and
do not accompany
other nerves or vessels.
• Function:
Coronary artery dilation.
Increase heart rate.
Bronchodilation.
DESCENDING THORACIC AORTA
BRANCHES:
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Paired intercostal arteries.
Paired subcostal arteries.
Two or more bronchial arteries.
Two to five esophageal arteries.
AZYGOUS VEIN
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Forms in abdomen
From right subcostal and ascending lumbar veins.
Drains all right posterior intercostal veins except first.
Also receives blood from the bronchial and esophageal veins.
HEMIAZYGOUS VEIN
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Forms in abdomen
From left subcostal and left ascending lumbar veins.
Receives four posterior intercostal veins.
Crosses over thoracic vertebrae at T8 level.
Empties into azygos vein.
ACESSORY HEMIAZYGOUS VEINS
• Drains intercostal spaces 4-7(8) on left side.
• Crosses over thoracic vertebrae at level T7.
• Empties into azygos vein
• Note: Intercostal space 1 is drained by the supreme intercostal
vein emptying into the brachiocephalic vein.
AZYGOUS, HEMIAZYGOUS AND ACESSORY HEMIAZYGOUS VEINS
LYMPH NODES OF POSTERIOR
MEDIASTINUM
Posterior Mediastinal Lymph Nodes
receives lymph from esophagus,
•
•
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posterior aspect of the pericardium
diaphragm and
middle posterior ICS
JOINTS OF THORAX
LEARNING OBJECTIVES
At the end of lecture, the student should be able to know:

Different joints of thorax & their classification.

Their movements.

Ligaments attached.

boundaries of mediastinum.

division of mediastinum in superior and inferior parts.

boundaries and contents of superior mediasinum.

further division of inferior mediastinum in anterior , middle and posterior.

mediastina , their boundaries and contents .
JOINTS OF THORAX
 Manubrosternal joint
 Interchondral joints
 Costochondral joints
 Costovertebral joints
 Costotransverse joints
 Intervertebral joints
Bony Thorax (Thoracic Cage)
1. Articulation of the Manubrium and Body of the Sternum
Manubrium is united to body of the sternum
either by an amphiarthrodial joint or by a
diarthrodial joint.
The Sternum
(Composed of fused sternebrae)
• Manubrium
– Jugular (sternal) notch
– Articulation with rib #1 & 2
– Clavicular Articular facets
– Sternal Angle – 2nd rib
• Body (Gladiolus)
– Articulates w/ribs 2-7
– Xiphosternal joint
• Xiphoid process
– Cartilage-calcifies thru time
– Partial attachment of many
muscles
Sternocostal Articulations
 Articulations of cartilages of true ribs
with sternum are arthrodial joints.
 Except first, in which cartilage is
directly united with sternum called as
synarthrodial articulation.
 The ligaments connecting them are:
1. The Articular Capsules
2. The Interarticular Sternocostal.
3. The Radiate Sternocostal.
4. The Costoxiphoid.
1. The Articular Capsules
 It surrounds joints between cartilages
of true ribs and sternum.
 Very thin, intimately blended with radiate sternocostal ligament.
2. The Interarticular Sternocostal Ligament
 Found between second costal cartilages and sternum.
 Connects cartilage of second rib with sternum.
3. The Radiate Sternocostal Ligaments
 Consists of broad and thin membranous bands.
 These radiate from front and back of sternal ends of cartilages of true ribs to
anterior and posterior surfaces of sternum.
4. The Costoxiphoid Ligaments
 Connect anterior and posterior surfaces of seventh costal cartilage,
sometimes those of the sixth, to front and back of Xiphoid process.
 Vary in length and breadth in different subjects.
Synovial Membranes

None between first costal cartilage and sternum.

Two in articulation of second costal cartilage and generally one in each of
other joints.
 They apparently disappear after middle life as articular surfaces lose their
polish and become roughened.
 In old age, cartilages of most of the ribs become continuous with sternum, and
joint cavities are consequently obliterated.

Movements:
Slight gliding movements are permitted in the sternocostal articulations.
2. Interchondral Articulations
 Contiguous borders of sixth, seventh, eighth, sometimes ninth and tenth costal
cartilages articulate with each other by small, smooth, oblong facets.
Each articulation:
 Is enclosed in a thin articular capsule
 Lined by synovial membrane
 Strengthened laterally and medially by ligament us fibers (interchondral
ligaments) which pass from one cartilage to the other.
3. Costochondral Articulations
 Lateral end of each costal cartilage is received into a depression in the sternal
end of the rib.
 Two are held together by the periosteum.
4. Costovertebral Articulations
Articulations of ribs with vertebral column
may be divided into two sets:
 One connecting heads of ribs with
bodies of vertebrae.
 Another uniting necks and tubercles of
ribs with transverse processes
Articulations of the Heads of the Ribs
 These constitute a series of gliding or arthrodial joints.
 Formed by articulation of heads of typical ribs with facets on contiguous
margins of bodies of thoracic vertebrae and with intervertebral fibrocartilages
between them.
 First, tenth, eleventh and twelfth ribs each articulate with a single vertebra.
The ligaments of the joints are:
1.The Articular Capsule.
2. The Radiate.
3. The Interarticular.
Synovial Membranes
 There are two in each of the articulations where an interarticular ligament
exists
 One above and one below this structure
 However, only one in those joints where there is single cavity.
5. Costotransverse Articulations
 Articular portion of tubercle of
rib forms an arthrodial joint
with articular surface on
adjacent transverse process.
 In the eleventh and twelfth
ribs this articulation is
wanting.
The ligaments of the joint are:
1. The Articular Capsule.
2. The Posterior
Costotransverse.
3. The Anterior
Costotransverse.
4. The Ligament of the Neck of
the Rib.
5. The Ligament of the Tubercle
of the Rib.
6. Intervertebral joints
 Adjoining vertebrae are connected to each other at three joints.
 A median joint between the vertebral bodies
 Two joints right and left between the
articular processes.
 The joints between the articular processes are
plane synovial joints
 Between vertebral bodies are secondary
cartilaginous verities.
 Surfaces of vertebral bodies are lined by thin
layers of hyaline cartilage.
 Between these layers there is a thick plate of
fibro-cartilage, called intervertebral disc.
Intervertebral Disc
Annulus fibrous
 Outer portion of the disc
 Made up of lamellae
 Layers of collagen fibers
 Arranged obliquely 30°
 Reversed contiguous layers
 Outer collar of concentric rings
 Outer rings = ligaments
 Inner rings = fibrocartilage
 Great tensile strength
 Supportive/Structural
Intervertebral Disc
Nucleus Pulposus
 Inner structure/disc
 Gelatinous
 High water content


Resists axial forces
Shock absorber
 Remnant of notochord
Thoracic cavity:
• Thoracic cavity is completely filled laterally by the lungs, each lying in its pleural cavity
• The space between the pleural cavities occupying the center of thoracic cavity is the
mediastinum
BOUNDARIES OF MEDIASTINUM
• Anteriorly
sternum
• Posteriorly
vertebral column
• Superiorly:
thoracic inlet
• Inferiorly
diaphragm
• On each side:
lungs & pleura
DIVISION OF MEDIASTINUM
Mediastinum is divided into
• superior and
• inferior mediastinum by imaginary line passing anteriorly through sternal angle to the lower
border of body of fourth thoracic vertebra posteriorly.
INFERIOR MEDIASTINUM
• ANTERIOR MEDIASTINUM
Lies In front Of The Pericardium
• MIDDLE MEDIASTINUM
Contains Heart And Pericardium
• POSTERIOR MEDIASTINUM
Lies Behind The Pericardium
•
SUPERIOR MEDIASTINUM
BOUNDARIES;
• Anteriorly:
Manubrium Sterni
• Posteriorly:
Upper four thoracic vertebrae
• Superiorly:
Plane of the thoracic inlet
• Inferiorly:
An imaginary plane passing through sternal angle in front, and the lower border of
the body of the fourth thoracic vertebra behind
• On each side:
Medisatinal pleura
CONTENTS
• Tubes : trachea and esophagus.
• Muscles: origins of: (1) sternohyoid and (2) sternothyroid, and (3) lower ends of longus colli.
• Arteries: (1) arch of aorta (2) brachiocephalic artery,(3) left common carotid artery, and (4) left
subclavian artery
• Veins: (1) right and left brachiocephalic veins (2) upper half of the superior vena cava, and (3) left
superior intercostal vein.
• Nerves: (1) vagus (2) phrenic (3) cardiac verves of both sides and (4) left recurrent laryngeal
nerve.
• Thymus
• Thoracic duct
• Lymph nodes: paratracheal, brachiocephalic and tracheobronchial
INFERIOR MEDIASTINUM
The inferior mediastinum is divided into
• Anterior
• Middle and
• Posterior mediastina.
ANTERIOR MEDIASTINUM
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•
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Anterior mediastinum is a very narrow space in front of the pericardium
Overlapped by the thin anterior border of both lungs.
It is continuous through the superior mediastinum with the pretracheal space of the neck.
BOUNDARIES
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Anteriorly: body of sternum
Posteriorly: pericardium
Superiorly: imaginary plane separating the superior mediastinum from the inferior mediastinum.
Inferiorly: superior surface of diaphragm.
On each side: Mediastinal pleura
CONTENTS
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Sternopericardial ligaments
Lymph nodes with lymphatics
Small Mediastinal branches of the internal thoracic artery.
The lowest part of the thymus, and
loose areolar tissue
MIDDLE MEDIASTINUM
• Middle mediastinum is occupied by the pericardium and its contents, along with the phrenic
nerves and the pericardiophrenic vessels.
CONTENTS
• Heart enclosed in pericardium
• Arteries: (1) ascending aorta
(2) pulmonary trunk
(3) two pulmonary arteries
• Veins: (1) lower half of the superior vena cava
(2) terminal part of the azygos vein
(3) right and left pulmonary veins
• Nerves: (1) phrenic
(2) deep cardiac plexus
• Lymph nodes: tracheobronchial nodes
• Tubes: (1) bifurcation of trachea
(2) the right and left principal bronchi
POSTERIOR MEDIASTINUM
BOUNDARIES
•
Anteriorly: (1) pericardium (2) bifurcation of trachea (3) pulmonary vessels, and (4) posterior part
of the upper surface of the diaphragm
•
Posteriorly: lower eight thoracic vertebrae and intervening discs.
•
On each side: mediastinum pleura
CONTENTS
• Oesophagus
• Arteries
descending thoracic aorta and its branches
• Veins:
(1) azygos vein
(2) homozygous vein
(3) accessory hemiazygos vein
• Nerves:
(1) vagi,
(2) splanchnic, nerves
• Lymph nodes
• Thoracic duct
PROBLEM ONE
Name the mediastinum marked in red.
PROBLEM TWO
• Name the mediastinum marked in red.
• What are the contents of this mediastinum?