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Download MBBS Anatomy PPT 62 Mediastinum Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 62 Mediastinum Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.

This post was last modified on 05 April 2022

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their contents.

? Describe the gross anatomy of structures in

mediastinum.

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? Describe the anatomy of nerves in the mediastinum.

? Correlate this knowledge to clinical conditions.

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Boundaries of mediastinum

Thoracic inlet

Sternal Angle

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sternum

Thoracic vertebra

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Thoracic oulet
TS: Mediastinum

CS: Mediastinum

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Mediastinum

? Bulky septum

between the

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pleural cavities

& lungs

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Extends-

? Root of the

neck to

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diaphragm

? From the

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sternum to

vertebral

column

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Divisions of mediastinum

? Divided by an imaginary horizontal plane from

the sternal angle to the intervertebral disc

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between 4th & 5th vertebra in to

? superior mediastinum
? Inferior mediastinum ?

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Anterior Middle Posterior
DIVISIONS OF MEDIASTINUM

Boundaries Of Superior Mediastinum

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BOUNDARIES:
? Anterior: manubrium sterni
? Posterior: Upper 4 thoracic vertebrae
? Superior: Plane of thoracic inlet

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? Inferior: Horizontal plane
? On each side: Pleura
Superior mediastinum

SUPERIOR MEDIASTINUM

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SUPERIOR MEDIASTINUM


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LEFT

RIGHT
Superior mediastinum

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? Posterior to the sternum & anterior to the

bodies of first four thoracic vertebra

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Superior mediastinum

CONTENTS:

? FROM BEHIND FORWARD:

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1.Esophagus

2.Trachea

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3.Arch of aorta & its 3 branches: brachiocephalic,

left common carotid & left subclavian arteries

4.Right & left brachiocephalic veins & superior vena

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cava

5.Thymus gland
Other Contents of superior mediastinum

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Nerves:

1. Right & left vagus

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2. Right & left phrenic

3. Right & left

sympathetic trunks

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4. Left recurrent

laryngeal

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Lymphatic structures:

1. Thoracic duct

2. Lymph nodes

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Thymus

? Asymmetric bilobed gland

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? Upper extent may reach as high as thyroid

gland

? Involved in early development of immune

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system

? Large in children

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? Atrophies after puberty
Brachiocephalic veins

?Located immediately

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posterior to thymus

?Formed at the jn. of IJ

& subclavian veins.

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? Begins post to clavicle

?Tributaries: vertebral,

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first post. Intercostal,

int. thoracic, inf.

Thyroid, thymic veins

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Left superior intercostal vein

? Drains upper two

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or three

intercostal veins,

left bronchial

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veins & left

pericardiophrenic

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veins

? Drains in to left

brachiocephalic

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veins
Superior vena cava

? Vertically oriented

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? Begins posterior

to the lower edge

of first costal

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cartilage

? terminates at the

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lower border of

right third costal

cartilage

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Arch of aorta & it's branches

? Begins when

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ascending aorta

emerges from

pericardial sac

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? Terminates on left side

of vertebral level

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between Th 4th - 5th

Branches-

Brachiocephalic trunk

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Left CCA
Left subclavian

Thyroid ima

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Trachea

? Midline structure
? Present anterior to

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esophagus

? Swallowing, breathing,

disease & specialized

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instrumentation causes

shift of trachea

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? divides just inferior to

sternal angle (T3- T4)

into Right & Left principal

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bronchus

Vagus nerve

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Right Vagus
? lies between right

brachiocephalic

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vein & trunk

? Descends

posteriorly to the

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root of Right lung

to reach

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esophagus

? Gives branches to

esophagus,

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cardiac plexus &

pulmonary plexus
Left Vagus nerve

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? Lies between Lt CCA &

Lt subclavian artery

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? Pass posterior to the

root of lung to reach the

esophagus

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? Gives branches to

esophagus, cardiac &

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pulmonary plexus

? Also gives Lt recurrent

laryngeal nerve- arise at

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inferior margin of arch of

aorta, winds around the

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aorta & reaches the

groove between

esophagus & trachea

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Left recurrent laryngeal nerve

? arise at inferior

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margin of arch of

aorta, winds around

the aorta & reaches

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the groove between

esophagus &

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trachea
Phrenic nerve

? Right Phrenic ?enters

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lateral to Right Vagus

& beginning of Right

brachiocephalic vein

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? continues inferiorly on

the Right side of sup

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vena cava, on

entering middle

mediastinum

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descends along the

Rt side of pericardial

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sac anterior to the Rt

lung root

? leaves the thorax with

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inferior vena cava

Left phrenic nerve

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? enters similar to

Right Phrenic nerve

? Lateral to Vagus & Lt

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brachiocephalic vein

? Descends on left

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lateral surface of

arch of aorta

? Passes superficial to

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Lt vagus & superior

intercostal vein
Left phrenic nerve

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? In middle

mediastinum lies on

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the Lt side of

pericardial sac

anterior to root of Lt

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lung

? Pierces the

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diaphragm near the

apex of the heart

Thoracic duct

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? Major lymphatic vessel

of the body

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? Enters sup.

mediastinum from

below at the level of

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T4/5

? continues through the

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superior med. posterior

to arch of aorta

between the esophagus

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& Lt pleura


Anterior Mediastinum

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Lies ant. to pericardium
Boundaries:

Anterior: body of sternum

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Posterior: pericardium

superior: imaginary line

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separating sup. &

inf.mediastinum

Infreior: diaphragm

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Lateral: mediastinal pleura
Anterior mediastinum

Thymus

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contains:

Lymph nodes
fat

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Thymus

Located in anterior

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mediastinum.
Develops from endoderm

of 3rd pharyngeal pouch

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Present in childhood,

involutes in adults
Blood supply

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Arterial :i nt. Mammary arteries

Venous: internal thoracic veins

Lymphatic drainage: lower

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cervical, int. Mammary and hilar

nodes
Esophagus

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? Starts at the C6th &

terminates at cardiac

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opening of stomach

(T12)

? Descends anterior to

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vertebral bodies in

midline

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? Crossed laterally by the

azygos vein on the right

side & arch of aorta on

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the left side

Posterior Mediastinum

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BOUNDARIES:
? Anterior: Pericardium & diaphragm
? Posterior: Lower 8 thoracic vertebrae
? Superior: Horizontal plane
? Inferior: Diaphragm

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? On each side: Pleura
Posterior Mediastinum

? CONTENTS:

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1. Esophagus (most anterior structure)

2. Thoracic duct

3. Right & left vagus

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4. Descending aorta

5. Azygos & hemiazygos veins

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6. Right & left sympathetic trunks & their

branches (splanchnic nerves)

7. Lymph nodes

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POSTERIOR MEDIASTINUM
POSTERIOR MEDIASTINUM

POSTERIOR MEDIASTINUM

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POSTERIOR MEDIASTINUM

POSTERIOR MEDIASTINUM


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MIDDLE MEDIASTINUM

? CONTENTS:

1. Pericardium & heart

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2. Arteries: ascending aorta, pulmonary trunk

3. Veins: lower half of superior vena cava,

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terminations of inferior vena cava & pulmonary

veins

4. Nerves: phrenic

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5. Lymph nodes

Mediastinum
VEINS

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BRACHIOCEPHALIC: (Superior mediastinum)

? FORMATION: by union of internal jugular & subclavian vein

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(behind medial end of clavicle)

? END: Both veins unite to form S.V.C.

? RIGHT VEIN: shorter & has a vertical course, related lateral y to

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right phrenic nerve & right pleura & lung, its tributaries in thorax:

right 1st posterior intercostal vein, right internal thoracic vein,

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right lymphatic duct

? LEFT VEIN: longer & has an oblique course, related anteriorly to

manubrium & thymus gland, & posteriorly to branches of arch of

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aorta, its tributaries in thorax: left 1st posterior intercostal vein,

left superior intercostal vein, left internal thoracic vein, thoracic

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duct

VEINS

SUPERIOR VENA CAVA: (Superior & middle mediastinum)

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? FORMATION: by union of brachiocephalic veins, behind lower border of

right 1st costal cartilage

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? END: opens into right atrium behind right 3rd costal cartilage
? TRIBUTARIES: azygos vein


AZYGOS & HEMIAZYGOS VEINS

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VEINS
AZYGOS VEIN: (Posterior mediastinum)

?

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ORIGIN: by union of right ascending lumbar & subcostal veins

(passes through aortic opening of diaphragm)

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?

END: forms an arch above the root of right lung & ends in S.V.C.

opposite lower border of T4

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?

RELATIONS:

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1. Anterior: esophagus

2. Posterior: thoracic vertebra

3. Right: right pleura & lung

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4. Left: thoracic duct

?

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TRIBUTARIES: superior & inferior hemiazygos veins, right

superior intercostal vein, right posterior intercostal veins (from

4th to 11th), right bronchial veins, esophageal & pericardial veins

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VEINS

INFERIOR HEMIAZYGOS: (Posterior

mediastinum)

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?ORIGIN: by union of left ascending lumbar

& subcostal veins (passes through left crus

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of diaphragm)

?END: into azygos vein, opposite T8

?TRIBUTARIES: left posterior intercostal

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veins (9th to 11th), esophageal veins

VEINS

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SUPERIOR HEMIAZYGOS: (Posterior mediastinum)

? ORIGIN: by left posterior intercostal veins (4th to 8th)

? END: into azygos vein, opposite T7

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? TRIBUTARIES: left bronchial veins
INFERIOR VENA CAVA: (Posterior mediastinum)

? END: passes through vena caval opening of diaphragm

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& opens into right atrium behind right 6th costal

cartilage
Ar

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A te

ORT rAi:

?

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ASCEND e

IN s

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G AORTA: (Middle mediastinum)

1. ORIGIN: at the base of left ventricle opposite lower border of left 3rd

costal cartilage

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2. END: ascends upward, forward & to the right & continues as arch of

aorta

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3. BRANCHES: right & left coronary arteries

Ar
? te

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ARrCieH sOF AORTA: (Superior mediastinum)

1. ORIGIN: continuation of ascending aorta, opposite upper border of

right 2nd costal cartilage

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2. COURSE & RELATIONS: ascends upward backward & to the left

(behind manubrium & in front of trachea) then curves backward (to

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the left of trachea) then final y curves downward

3. TERMINATION: continues as descending aorta, opposite lower border

of T4

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Ar
?

teBRArNiCHeESs OF ARCH OF AORTA: (Superior mediastinum)

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1. BRACHIOCEPHALIC: ascends upward & to the right (behind

left brachiocephalic vein & in front of trachea) & divides

into right common carotid & right subclavian arteries

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(behind right sternoclavicular joint)

2. LEFT COMMON CAROTID: ascends upward & to the left (to

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the left side of brachiocephalic artery) & enters the neck

(behind left sternoclavicular joint)

3. LEFT SUBCLAVIAN: ascends upward (behind left common

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carotid artery, in front of esophagus, to the left side of

trachea), arches over apex of left lung to enter neck

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Ar
DES te

CENDI rNie

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G AO sRTA: (Posterior mediastinum)

?

ORIGIN: continuation of arch of aorta

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?

TERMINATION: passes through aortic opening of

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diaphragm (opposite T12) & continues as abdominal aorta

?

RELATIONS:

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1. Anterior: esophagus

2. Posterior: thoracic vertebrae

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3. Right: thoracic duct

4. Left: left pleura & lung

?

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BRANCHES: posterior intercostal (from 3rd to 11th),

subcostal, bronchial, esophageal, pericardial arteries
Ar

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PUL te

MON rARiYe TRsUNK (Middle mediastinum)

? ORIGIN: from upper part of right ventricle, behind

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sternal end of left 3rd costal cartilage

? COURSE: ascends upward & to the left & divides (at

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lower border of T4) into:

1. Right pulmonary: runs behind ascending aorta &

S.V.C to enter root of right lung

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2. Left pulmonary: runs in front of desending aorta to

enter root of left lung

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T
? RAC

BEGIN H

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NIN EA

G: continuation of larynx, opposite C6

? TERMINATION: bifurcates into 2 bronchi, opposite lower border

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of T4

? RELATIONS: (in superior mediastinum)

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1. Anterior: arch of aorta, brachiocephalic & left common carotid

arteries

2. Posterior: left recurrent laryngeal nerve, esophagus

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3. Right: right vagus nerve

4. Left: arch of aorta, left subclavian artery

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? NERVE SUPPLY: sympathetic trunks & vagus

? BLOOD SUPPLY: inferior thyroid vessels

? LYMPHATIC DRAINAGE: pretracheal & paratracheal

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ESOP
? BEGINNI H

NG: AG

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contin UuatiSon of pharynx, opposite C6

? TERMINATION: passes through esophageal opening of diaphragm

(opposite T10) & joins stomach

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? RELATIONS: (in superior mediastinum)

1. Anterior: left recurrent laryngeal nerve, trachea, left subclavian artery

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2. Posterior: thoracic vertebrae

3. Right: right pleura & lung

4. Left: thoracic duct, left pleura & lung

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ESOP?RELATIHONAGS: (inU pSosterior mediastinum)

1.Anterior: pericardium, separating it from left atrium

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2.Posterior: thoracic duct, descending aorta, azygos vein

3.Right: right pleura & lung

4.Left: descending aorta, left pleura & lung

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? NERVE SUPPLY: as trachea

? ARTERIAL SUPPLY: descending aorta

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? VENOUS DRAINAGE: azygos & hemiazygos

? LYMPHATIC DRAINAGE: posterior mediastinal lymph

nodes

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THORACIC DUCT
? ORIGIN: from upper end of cysterna chyli (opposite

L1 & L2)

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? COURSE: passes through aortic opening of

diaphragm, ascends in posterior mediastinum

(behind esophagus) & in superior mediastinum (to

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the left of esophagus) to enter root of neck

? END: in left brachiocephalic vein

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? RELATIONS: ( in posterior mediastinum)

1. Anterior: esophagus

2. Posterior: thoracic vertebrae

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3. Right: azygos vein

4. Left: descending aorta

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THORACIC DUCT

TRIBUTARIES:

? It drains lymph from both sides of the body below

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the diaphragm through cysterna chyli

? It drains lymph from left half of the body above

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diaphragm through:

1. Left jugular lymph trunk: drains left side of head &

neck

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2. Left subclavian lymph trunk: drains left upper limb

3. Left bronchomediastinal lymph trunk: drains left

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side of thorax
RIGHT LYMPHATIC DUCT

? ORIGIN: formed by union of:

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1. Right jugular lymph trunk: drains right

side of head & neck

2. Right subclavian lymph trunk: drains

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right upper limb

3. Right bronchomediastinal lymph trunk:

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drains right side of thorax

? END: in right brachiocephalic vein

NERVES

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PHRENIC NERVES: (Superior & middle mediastinum)

?

ORIGIN: anterior rami of C3,4,5

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?

COURSE & RELATIONS IN THORAX:

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1. RIGHT: descends to the right side of: right brachiocephalic vein,

S.V.C., pericardium, I.V.C.

2. LEFT: descends to the left side of: arch aorta, pericardium

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?

BRANCHES:

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1. Motor branches to: diaphragm

2. Sensory branches from:

?

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Mediastinal & central part of diaphragmatic pleura

?

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Fibrous pericardium & parietal layer of serous pericardium

?

Peritoneum covering central part of undersurface of diaphragm

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NERVES
? VAGUS NERVES: (Superior & posterior mediastinum)

? ORIGIN: 10th cranial nerve

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? COURSE & RELATIONS IN THORAX:

1. RIGHT: descends to the right side of: trachea, behind

root of right lung (pulmonary plexus), behind

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esophagus (esophageal plexus), passes through

esophageal opening of diaphragm to reach posterior

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surface of stomach

2. LEFT: descends to the left side of: arch aorta, behind

root of left lung (pulmonary plexus), in front of

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esophagus (esophageal plexus), passes through

esophageal opening of diaphragm to reach anterior

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surface of stomach

NERVES

BRANCHES IN THORAX:

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? BOTH VAGI: to lungs & esophagus

? RIGHT VAGUS: to heart

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? LEFT VAGUS: left recurrent laryngeal nerve:

curves below arch of aorta, behind ligamentum

arteriosum, ascends in groove between trachea

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& esophagus to reach the neck. It supplies: heart,

trachea, esophagus (in thorax) & larynx (in neck)
NERVES

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THORACIC PART OF SYMPATHETIC TRUNKS: (Superior &

posterior mediastinum)

? BEGINNING: the cervical part continues as thoracic

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part by passing in front of neck of first rib

? TERMINATION: the thoracic part continues as lumbar

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part by passing behind medial arcuate ligament

? COURSE:

1. In upper part of thorax: descend in front of heads of

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ribs

2. In lower part of thorax: descend on the sides of

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bodies of vertebrae

? GANGLIA: usual y 11 (1st thoracic ganglion fuses with

inferior cervical ganglion forming stel ate ganglion)

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NERVES

?

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BRANCHES:

1. Rami communicantes: each ganglion receives a

white ramus (preganglionic) & gives a grey ramus

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(postganglionic) to corresponding thoracic spinal

nerve

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2. Visceral branches (postganglionic) to thoracic organs

(from upper 5 ganglia): to heart, lungs, esophagus,

descending aorta

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3. Visceral branches (preganglionic) to abdominal

organs:

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? Greater splanchnic nerve (from 5th to 9th ganglia)

? Lesser splanchnic nerve (from 10th 7 11th ganglia)

? Lowest splanchnic nerve (from 12th ganglion)

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Nerves in mediastinum

? The right vagus nerve descends in

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the thorax, first posterolateral to the

brachiocephalic artery then lateral

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to the trachea

? Passes behind the root of the right

lung and assists in the formation of

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the pulmonary plexus.

? On leaving the plexus, the vagus

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passes onto the posterior surface of

the esophagus and takes part in the

formation of the esophageal

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plexus.

? It then passes through the

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esophageal opening of the

diaphragm.

Nerves in mediastinum

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? The left vagus nerve descends in

the thorax between the left

common carotid and the left

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subclavian arteries

? It then crosses the left side of the

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aortic arch

? The vagus then turns backward

behind the root of the left lung and

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assists in the formation of the

pulmonary plexus.

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? On leaving the plexus, the vagus

passes onto the anterior surface of

the esophagus and takes part in

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the formation of the esophageal

plexus.

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Nerves in mediastinum
? The right phrenic nerve

descends in the thorax along the

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right side of the right

brachiocephalic vein and the

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superior vena cava .

? It passes in front of the root of

the right lung and runs along the

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right side of the pericardium, which

separates the nerve from the right

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atrium.

? It then descends on the right side

of the inferior vena cava to t`he

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diaphragm.

? Its terminal branches pass through

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the caval opening in the

diaphragm to supply the central

part of the peritoneum on its under

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aspect.

Nerves in mediastinum
? The left phrenic nerve descends

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in the thorax along the left side of

the left subclavian artery.

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? It crosses the left side of the aortic

arch and here crosses the left side

of the left vagus nerve.

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? It passes in front of the root of the

left lung and then descends over

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the left surface of the pericardium,

which separates the nerve from

the left ventricle.

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? On reaching the diaphragm, the

terminal branches pierce the

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muscle and supply the central part

of the peritoneum on its under

aspect.

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anatomical

Acc. To felson

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Clinical correlations
? Deflection of Mediastinum
?If air enters the pleural

cavity (a condition called

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pneumothorax), the lung

on that side immediately

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collapses and the

mediastinum is displaced to

the opposite side.

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?patient's being breathless

and in a state of shock; on

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examination, the trachea

and the heart are found to

be displaced to the opposite

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side


Clinical correlations

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? Mediastinitis
?Deep infection of the neck spread readily into the thorax,

producing a mediastinitis.

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?Penetrating wounds of the chest involving the esophagus

may produce a mediastinitis.

Clinical correlations

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? Mediastinal Tumors or Cysts
?Enlargement of mediastinal tumor

may compress the left recurrent

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laryngeal nerve, producing

paralysis of the left vocal fold.

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?An expanding cyst or tumor can

partially occlude the superior vena

cava, causing severe congestion

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of the veins of the upper part of

the body.

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?Other pressure effects can be

seen on the sympathetic trunks,

phrenic nerves, and sometimes

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the trachea, main bronchi, and

esophagus.

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Clinical correlations
? Mediastinoscopy

?diagnostic procedure by which

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tracheobronchial lymph nodes

are obtained without opening the

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pleural cavities.

?A small incision is made in the

midline in the neck just above

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the suprasternal notch, and

the superior mediastinum is

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explored down to the region of

the bifurcation of the trachea.

?The procedure can be used to

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determine the diagnosis and

degree of spread of carcinoma

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of the bronchus.

Summary
? Mediastinum: definition
? Extend and sub

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divisions

? Contents
? Nerves passing thorax

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? Clinical correlations