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.
Learning Objectives
? Identify the divisions of the mediastinum and describe
their contents.
? Describe the gross anatomy of structures in
mediastinum.
? Describe the anatomy of nerves in the mediastinum.
? Correlate this knowledge to clinical conditions.
Boundaries of mediastinum
Thoracic inlet
Sternal Angle
sternum
Thoracic vertebra
Thoracic oulet
TS: Mediastinum
CS: Mediastinum
Mediastinum
? Bulky septum
between the
pleural cavities
& lungs
Extends-
? Root of the
neck to
diaphragm
? From the
sternum to
vertebral
column
Divisions of mediastinum
? Divided by an imaginary horizontal plane from
the sternal angle to the intervertebral disc
between 4th & 5th vertebra in to
? superior mediastinum
? Inferior mediastinum ?
Anterior Middle Posterior
DIVISIONS OF MEDIASTINUM
Boundaries Of Superior Mediastinum
BOUNDARIES:
? Anterior: manubrium sterni
? Posterior: Upper 4 thoracic vertebrae
? Superior: Plane of thoracic inlet
? Inferior: Horizontal plane
? On each side: Pleura
Superior mediastinum
SUPERIOR MEDIASTINUM
SUPERIOR MEDIASTINUM
LEFT
RIGHT
Superior mediastinum
? Posterior to the sternum & anterior to the
bodies of first four thoracic vertebra
Superior mediastinum
CONTENTS:
? FROM BEHIND FORWARD:
1.Esophagus
2.Trachea
3.Arch of aorta & its 3 branches: brachiocephalic,
left common carotid & left subclavian arteries
4.Right & left brachiocephalic veins & superior vena
cava
5.Thymus gland
Other Contents of superior mediastinum
Nerves:
1. Right & left vagus
2. Right & left phrenic
3. Right & left
sympathetic trunks
4. Left recurrent
laryngeal
Lymphatic structures:
1. Thoracic duct
2. Lymph nodes
Thymus
? Asymmetric bilobed gland
? Upper extent may reach as high as thyroid
gland
? Involved in early development of immune
system
? Large in children
? Atrophies after puberty
Brachiocephalic veins
?Located immediately
posterior to thymus
?Formed at the jn. of IJ
& subclavian veins.
? Begins post to clavicle
?Tributaries: vertebral,
first post. Intercostal,
int. thoracic, inf.
Thyroid, thymic veins
Left superior intercostal vein
? Drains upper two
or three
intercostal veins,
left bronchial
veins & left
pericardiophrenic
veins
? Drains in to left
brachiocephalic
veins
Superior vena cava
? Vertically oriented
? Begins posterior
to the lower edge
of first costal
cartilage
? terminates at the
lower border of
right third costal
cartilage
Arch of aorta & it's branches
? Begins when
ascending aorta
emerges from
pericardial sac
? Terminates on left side
of vertebral level
between Th 4th - 5th
Branches-
Brachiocephalic trunk
Left CCA
Left subclavian
Thyroid ima
Trachea
? Midline structure
? Present anterior to
esophagus
? Swallowing, breathing,
disease & specialized
instrumentation causes
shift of trachea
? divides just inferior to
sternal angle (T3- T4)
into Right & Left principal
bronchus
Vagus nerve
Right Vagus
? lies between right
brachiocephalic
vein & trunk
? Descends
posteriorly to the
root of Right lung
to reach
esophagus
? Gives branches to
esophagus,
cardiac plexus &
pulmonary plexus
Left Vagus nerve
? Lies between Lt CCA &
Lt subclavian artery
? Pass posterior to the
root of lung to reach the
esophagus
? Gives branches to
esophagus, cardiac &
pulmonary plexus
? Also gives Lt recurrent
laryngeal nerve- arise at
inferior margin of arch of
aorta, winds around the
aorta & reaches the
groove between
esophagus & trachea
Left recurrent laryngeal nerve
? arise at inferior
margin of arch of
aorta, winds around
the aorta & reaches
the groove between
esophagus &
trachea
Phrenic nerve
? Right Phrenic ?enters
lateral to Right Vagus
& beginning of Right
brachiocephalic vein
? continues inferiorly on
the Right side of sup
vena cava, on
entering middle
mediastinum
descends along the
Rt side of pericardial
sac anterior to the Rt
lung root
? leaves the thorax with
inferior vena cava
Left phrenic nerve
? enters similar to
Right Phrenic nerve
? Lateral to Vagus & Lt
brachiocephalic vein
? Descends on left
lateral surface of
arch of aorta
? Passes superficial to
Lt vagus & superior
intercostal vein
Left phrenic nerve
? In middle
mediastinum lies on
the Lt side of
pericardial sac
anterior to root of Lt
lung
? Pierces the
diaphragm near the
apex of the heart
Thoracic duct
? Major lymphatic vessel
of the body
? Enters sup.
mediastinum from
below at the level of
T4/5
? continues through the
superior med. posterior
to arch of aorta
between the esophagus
& Lt pleura
Anterior Mediastinum
Lies ant. to pericardium
Boundaries:
Anterior: body of sternum
Posterior: pericardium
superior: imaginary line
separating sup. &
inf.mediastinum
Infreior: diaphragm
Lateral: mediastinal pleura
Anterior mediastinum
Thymus
contains:
Lymph nodes
fat
Thymus
Located in anterior
mediastinum.
Develops from endoderm
of 3rd pharyngeal pouch
Present in childhood,
involutes in adults
Blood supply
Arterial :i nt. Mammary arteries
Venous: internal thoracic veins
Lymphatic drainage: lower
cervical, int. Mammary and hilar
nodes
Esophagus
? Starts at the C6th &
terminates at cardiac
opening of stomach
(T12)
? Descends anterior to
vertebral bodies in
midline
? Crossed laterally by the
azygos vein on the right
side & arch of aorta on
the left side
Posterior Mediastinum
BOUNDARIES:
? Anterior: Pericardium & diaphragm
? Posterior: Lower 8 thoracic vertebrae
? Superior: Horizontal plane
? Inferior: Diaphragm
? On each side: Pleura
Posterior Mediastinum
? CONTENTS:
1. Esophagus (most anterior structure)
2. Thoracic duct
3. Right & left vagus
4. Descending aorta
5. Azygos & hemiazygos veins
6. Right & left sympathetic trunks & their
branches (splanchnic nerves)
7. Lymph nodes
POSTERIOR MEDIASTINUM
POSTERIOR MEDIASTINUM
POSTERIOR MEDIASTINUM
POSTERIOR MEDIASTINUM
POSTERIOR MEDIASTINUM
MIDDLE MEDIASTINUM
? CONTENTS:
1. Pericardium & heart
2. Arteries: ascending aorta, pulmonary trunk
3. Veins: lower half of superior vena cava,
terminations of inferior vena cava & pulmonary
veins
4. Nerves: phrenic
5. Lymph nodes
Mediastinum
VEINS
BRACHIOCEPHALIC: (Superior mediastinum)
? FORMATION: by union of internal jugular & subclavian vein
(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
right phrenic nerve & right pleura & lung, its tributaries in thorax:
right 1st posterior intercostal vein, right internal thoracic vein,
right lymphatic duct
? LEFT VEIN: longer & has an oblique course, related anteriorly to
manubrium & thymus gland, & posteriorly to branches of arch of
aorta, its tributaries in thorax: left 1st posterior intercostal vein,
left superior intercostal vein, left internal thoracic vein, thoracic
duct
VEINS
SUPERIOR VENA CAVA: (Superior & middle mediastinum)
? FORMATION: by union of brachiocephalic veins, behind lower border of
right 1st costal cartilage
? END: opens into right atrium behind right 3rd costal cartilage
? TRIBUTARIES: azygos vein
AZYGOS & HEMIAZYGOS VEINS
VEINS
AZYGOS VEIN: (Posterior mediastinum)
?
ORIGIN: by union of right ascending lumbar & subcostal veins
(passes through aortic opening of diaphragm)
?
END: forms an arch above the root of right lung & ends in S.V.C.
opposite lower border of T4
?
RELATIONS:
1. Anterior: esophagus
2. Posterior: thoracic vertebra
3. Right: right pleura & lung
4. Left: thoracic duct
?
TRIBUTARIES: superior & inferior hemiazygos veins, right
superior intercostal vein, right posterior intercostal veins (from
4th to 11th), right bronchial veins, esophageal & pericardial veins
VEINS
INFERIOR HEMIAZYGOS: (Posterior
mediastinum)
?ORIGIN: by union of left ascending lumbar
& subcostal veins (passes through left crus
of diaphragm)
?END: into azygos vein, opposite T8
?TRIBUTARIES: left posterior intercostal
veins (9th to 11th), esophageal veins
VEINS
SUPERIOR HEMIAZYGOS: (Posterior mediastinum)
? ORIGIN: by left posterior intercostal veins (4th to 8th)
? END: into azygos vein, opposite T7
? TRIBUTARIES: left bronchial veins
INFERIOR VENA CAVA: (Posterior mediastinum)
? END: passes through vena caval opening of diaphragm
& opens into right atrium behind right 6th costal
cartilage
Ar
A te
ORT rAi:
?
ASCEND e
IN s
G AORTA: (Middle mediastinum)
1. ORIGIN: at the base of left ventricle opposite lower border of left 3rd
costal cartilage
2. END: ascends upward, forward & to the right & continues as arch of
aorta
3. BRANCHES: right & left coronary arteries
Ar
? te
ARrCieH sOF AORTA: (Superior mediastinum)
1. ORIGIN: continuation of ascending aorta, opposite upper border of
right 2nd costal cartilage
2. COURSE & RELATIONS: ascends upward backward & to the left
(behind manubrium & in front of trachea) then curves backward (to
the left of trachea) then final y curves downward
3. TERMINATION: continues as descending aorta, opposite lower border
of T4
Ar
?
teBRArNiCHeESs OF ARCH OF AORTA: (Superior mediastinum)
1. BRACHIOCEPHALIC: ascends upward & to the right (behind
left brachiocephalic vein & in front of trachea) & divides
into right common carotid & right subclavian arteries
(behind right sternoclavicular joint)
2. LEFT COMMON CAROTID: ascends upward & to the left (to
the left side of brachiocephalic artery) & enters the neck
(behind left sternoclavicular joint)
3. LEFT SUBCLAVIAN: ascends upward (behind left common
carotid artery, in front of esophagus, to the left side of
trachea), arches over apex of left lung to enter neck
Ar
DES te
CENDI rNie
G AO sRTA: (Posterior mediastinum)
?
ORIGIN: continuation of arch of aorta
?
TERMINATION: passes through aortic opening of
diaphragm (opposite T12) & continues as abdominal aorta
?
RELATIONS:
1. Anterior: esophagus
2. Posterior: thoracic vertebrae
3. Right: thoracic duct
4. Left: left pleura & lung
?
BRANCHES: posterior intercostal (from 3rd to 11th),
subcostal, bronchial, esophageal, pericardial arteries
Ar
PUL te
MON rARiYe TRsUNK (Middle mediastinum)
? ORIGIN: from upper part of right ventricle, behind
sternal end of left 3rd costal cartilage
? COURSE: ascends upward & to the left & divides (at
lower border of T4) into:
1. Right pulmonary: runs behind ascending aorta &
S.V.C to enter root of right lung
2. Left pulmonary: runs in front of desending aorta to
enter root of left lung
T
? RAC
BEGIN H
NIN EA
G: continuation of larynx, opposite C6
? TERMINATION: bifurcates into 2 bronchi, opposite lower border
of T4
? RELATIONS: (in superior mediastinum)
1. Anterior: arch of aorta, brachiocephalic & left common carotid
arteries
2. Posterior: left recurrent laryngeal nerve, esophagus
3. Right: right vagus nerve
4. Left: arch of aorta, left subclavian artery
? NERVE SUPPLY: sympathetic trunks & vagus
? BLOOD SUPPLY: inferior thyroid vessels
? LYMPHATIC DRAINAGE: pretracheal & paratracheal
ESOP
? BEGINNI H
NG: AG
contin UuatiSon of pharynx, opposite C6
? TERMINATION: passes through esophageal opening of diaphragm
(opposite T10) & joins stomach
? RELATIONS: (in superior mediastinum)
1. Anterior: left recurrent laryngeal nerve, trachea, left subclavian artery
2. Posterior: thoracic vertebrae
3. Right: right pleura & lung
4. Left: thoracic duct, left pleura & lung
ESOP?RELATIHONAGS: (inU pSosterior mediastinum)
1.Anterior: pericardium, separating it from left atrium
2.Posterior: thoracic duct, descending aorta, azygos vein
3.Right: right pleura & lung
4.Left: descending aorta, left pleura & lung
? NERVE SUPPLY: as trachea
? ARTERIAL SUPPLY: descending aorta
? VENOUS DRAINAGE: azygos & hemiazygos
? LYMPHATIC DRAINAGE: posterior mediastinal lymph
nodes
THORACIC DUCT
? ORIGIN: from upper end of cysterna chyli (opposite
L1 & L2)
? COURSE: passes through aortic opening of
diaphragm, ascends in posterior mediastinum
(behind esophagus) & in superior mediastinum (to
the left of esophagus) to enter root of neck
? END: in left brachiocephalic vein
? RELATIONS: ( in posterior mediastinum)
1. Anterior: esophagus
2. Posterior: thoracic vertebrae
3. Right: azygos vein
4. Left: descending aorta
THORACIC DUCT
TRIBUTARIES:
? It drains lymph from both sides of the body below
the diaphragm through cysterna chyli
? It drains lymph from left half of the body above
diaphragm through:
1. Left jugular lymph trunk: drains left side of head &
neck
2. Left subclavian lymph trunk: drains left upper limb
3. Left bronchomediastinal lymph trunk: drains left
side of thorax
RIGHT LYMPHATIC DUCT
? ORIGIN: formed by union of:
1. Right jugular lymph trunk: drains right
side of head & neck
2. Right subclavian lymph trunk: drains
right upper limb
3. Right bronchomediastinal lymph trunk:
drains right side of thorax
? END: in right brachiocephalic vein
NERVES
PHRENIC NERVES: (Superior & middle mediastinum)
?
ORIGIN: anterior rami of C3,4,5
?
COURSE & RELATIONS IN THORAX:
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
?
BRANCHES:
1. Motor branches to: diaphragm
2. Sensory branches from:
?
Mediastinal & central part of diaphragmatic pleura
?
Fibrous pericardium & parietal layer of serous pericardium
?
Peritoneum covering central part of undersurface of diaphragm
NERVES
? VAGUS NERVES: (Superior & posterior mediastinum)
? ORIGIN: 10th cranial nerve
? COURSE & RELATIONS IN THORAX:
1. RIGHT: descends to the right side of: trachea, behind
root of right lung (pulmonary plexus), behind
esophagus (esophageal plexus), passes through
esophageal opening of diaphragm to reach posterior
surface of stomach
2. LEFT: descends to the left side of: arch aorta, behind
root of left lung (pulmonary plexus), in front of
esophagus (esophageal plexus), passes through
esophageal opening of diaphragm to reach anterior
surface of stomach
NERVES
BRANCHES IN THORAX:
? BOTH VAGI: to lungs & esophagus
? RIGHT VAGUS: to heart
? LEFT VAGUS: left recurrent laryngeal nerve:
curves below arch of aorta, behind ligamentum
arteriosum, ascends in groove between trachea
& esophagus to reach the neck. It supplies: heart,
trachea, esophagus (in thorax) & larynx (in neck)
NERVES
THORACIC PART OF SYMPATHETIC TRUNKS: (Superior &
posterior mediastinum)
? BEGINNING: the cervical part continues as thoracic
part by passing in front of neck of first rib
? TERMINATION: the thoracic part continues as lumbar
part by passing behind medial arcuate ligament
? COURSE:
1. In upper part of thorax: descend in front of heads of
ribs
2. In lower part of thorax: descend on the sides of
bodies of vertebrae
? GANGLIA: usual y 11 (1st thoracic ganglion fuses with
inferior cervical ganglion forming stel ate ganglion)
NERVES
?
BRANCHES:
1. Rami communicantes: each ganglion receives a
white ramus (preganglionic) & gives a grey ramus
(postganglionic) to corresponding thoracic spinal
nerve
2. Visceral branches (postganglionic) to thoracic organs
(from upper 5 ganglia): to heart, lungs, esophagus,
descending aorta
3. Visceral branches (preganglionic) to abdominal
organs:
? Greater splanchnic nerve (from 5th to 9th ganglia)
? Lesser splanchnic nerve (from 10th 7 11th ganglia)
? Lowest splanchnic nerve (from 12th ganglion)
Nerves in mediastinum
? The right vagus nerve descends in
the thorax, first posterolateral to the
brachiocephalic artery then lateral
to the trachea
? Passes behind the root of the right
lung and assists in the formation of
the pulmonary plexus.
? On leaving the plexus, the vagus
passes onto the posterior surface of
the esophagus and takes part in the
formation of the esophageal
plexus.
? It then passes through the
esophageal opening of the
diaphragm.
Nerves in mediastinum
? The left vagus nerve descends in
the thorax between the left
common carotid and the left
subclavian arteries
? It then crosses the left side of the
aortic arch
? The vagus then turns backward
behind the root of the left lung and
assists in the formation of the
pulmonary plexus.
? On leaving the plexus, the vagus
passes onto the anterior surface of
the esophagus and takes part in
the formation of the esophageal
plexus.
Nerves in mediastinum
? The right phrenic nerve
descends in the thorax along the
right side of the right
brachiocephalic vein and the
superior vena cava .
? It passes in front of the root of
the right lung and runs along the
right side of the pericardium, which
separates the nerve from the right
atrium.
? It then descends on the right side
of the inferior vena cava to t`he
diaphragm.
? Its terminal branches pass through
the caval opening in the
diaphragm to supply the central
part of the peritoneum on its under
aspect.
Nerves in mediastinum
? The left phrenic nerve descends
in the thorax along the left side of
the left subclavian artery.
? It crosses the left side of the aortic
arch and here crosses the left side
of the left vagus nerve.
? It passes in front of the root of the
left lung and then descends over
the left surface of the pericardium,
which separates the nerve from
the left ventricle.
? On reaching the diaphragm, the
terminal branches pierce the
muscle and supply the central part
of the peritoneum on its under
aspect.
anatomical
Acc. To felson
Clinical correlations
? Deflection of Mediastinum
?If air enters the pleural
cavity (a condition called
pneumothorax), the lung
on that side immediately
collapses and the
mediastinum is displaced to
the opposite side.
?patient's being breathless
and in a state of shock; on
examination, the trachea
and the heart are found to
be displaced to the opposite
side
Clinical correlations
? Mediastinitis
?Deep infection of the neck spread readily into the thorax,
producing a mediastinitis.
?Penetrating wounds of the chest involving the esophagus
may produce a mediastinitis.
Clinical correlations
? Mediastinal Tumors or Cysts
?Enlargement of mediastinal tumor
may compress the left recurrent
laryngeal nerve, producing
paralysis of the left vocal fold.
?An expanding cyst or tumor can
partially occlude the superior vena
cava, causing severe congestion
of the veins of the upper part of
the body.
?Other pressure effects can be
seen on the sympathetic trunks,
phrenic nerves, and sometimes
the trachea, main bronchi, and
esophagus.
Clinical correlations
? Mediastinoscopy
?diagnostic procedure by which
tracheobronchial lymph nodes
are obtained without opening the
pleural cavities.
?A small incision is made in the
midline in the neck just above
the suprasternal notch, and
the superior mediastinum is
explored down to the region of
the bifurcation of the trachea.
?The procedure can be used to
determine the diagnosis and
degree of spread of carcinoma
of the bronchus.
Summary
? Mediastinum: definition
? Extend and sub
divisions
? Contents
? Nerves passing thorax
? Clinical correlations
This post was last modified on 05 April 2022