Upload
scott-yee
View
250
Download
0
Embed Size (px)
Citation preview
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 1/18
Posterior Mediastinum 10/15/2013 5:13:00 AM
Define the boundaries of posterior mediastinum
The major boundaries of the posterior mediastinum are:
Angle of Louis for superior portion
T5-T12 for the posterior portion
The posterior diaphragm for the inferior portion
And the Mediastinal cavity as the anterior portion
Describe and relate structures found in the posterior mediastinum (i.e., descending aorta, esophagus,
major veins, thoracic duct, splanchnic, sympathetic nerve and vagus nerves)
S
Structures in PM
1. Esophagus
2. Thoracic aorta / Descending aorta
3. Azygos venous system
i. Azygosii. Hemiazygosiii. Accessory hemiazygos
4. Thoracic duct
5. Sympathetic nerve
i. Sympathetic trunkii. Splanchnic nerve6. Vagus nerve
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 2/18
Posterior Mediastinal Structures
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 3/18
Aortic Arch
Begins at left of T4
Descends from T5-T12
Posterior to root of LeftLung, Esophagus, Pericardium
Most inferior portion – Midline displacing esophagus
Branches
o Anterior Unpaired (A)
Branch to Gut
Pericardial Branch
Mediastinal Arteries
o Lateral Paired (B)
Bronchial arteries and other visceral organs
Not gut
o Posterior Unpaired (C)
3-11 posterior intercostal
Rt. Posterior Intercostal is longer b/c they pass over vertebral bodies
1 subcostal art -> diaphragm
Sympathetic
trunk
Hemiazygos
Thoracic
aorta/Descending
aorta
Great splanchnic
n.
Vagus n.
Azygos v.
Esophagus
Thoracic duct
Great
splanchnic
n.
Right Left View: Left Right View:
Thoracic
duct
Azygos
vein
i i li i l i
i li l i
i i l i
l li
Posterior intercostal
arteries
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 4/18
Esophagus:
Posterior and left of atrium
Main posterior part of heart
Once cut into diaphragm, deviates to the left
Exits Esophagus Hiatus at T10 w/ anterior and posterior Vagal trunks
Anastomosis
Rt. posteriorintercostal arteries arelonger than the leftones: because they
pass over the
vertebral bodies .Thoracic aortaruns along theleft side ofvertebral bodie
3rd -11th Posterior intercostal arteries
pericardium
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 5/18
Thoracic Duct:
Largest Lymph Channel
Empty at Left Venous Angle (union of left Jugular and Subclavian Vein)
Origin: Chyle Cistern @ L2
Ascends on right side of T5-T12
Left of Azygus
Right of Thoracic Aorta
Posterior to Esophagus
Crosses to the left of sternal angle
Right Lymphatic Duct:
Enters at right Venous Angle
Drains upper right quadrant of body
Azygos Vein:
“ The duck b tween t w o gooses (duck =
thoracic duct) 2 gooses = azyGOUS and
esophaGOUS”
As viewed from
the feet
Thoracic duct
Chyle cistern
Lt. venous
angle
Thoracic aorta
Azygos v.
Azygos
vein
SVC
Accessory
hemiazygos
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 6/18
Drains:
o Back
o Thoracoabdominal Wall
o Mediastinal Viscera
Collateral Circulation with IVC and SVC
Arch over root of right lung -> join with SVC
Left Azygus Equivalents
1st Posterior Intercostal veins
o Drains into Brachiocephalic veins
Left superior intercostal vein (A)
o Drain 2nd-4th intercostal space
o Drains into left Brachiocephalic vein
Accessory Hemiazygos (B)
o Drains left 5th-8th intercostal Veins
o May drain into left bronchial vein
o Crosses to right side at T7/T8 to drain into Azygos
Hemiazygos (C)
o Drains 9th-12th intercostal space
o Crosses to right side at T9 to drain into Azygos
Nerves in Posterior Mediastinum:
Sympathetic Trunk
Splanchnic Nerves
Vagus (Esophageal plexus)
Sympathetic Trunk:
Lt. &
Renal
Ascen
lumba
Azygos
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 7/18
Splanchnic Nerves:
Splanchnic = Visceral = Internal organs
Sympathetic trunk
Splanchnic
nerve
Options followed by sympathetic nerves:1- enter chain, synapse and exit at same level2- enter chain, ascend or descend to synapse3- enter chain and pass through to prevertebral Ganglia splanchnic nerve
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 8/18
Contains presympathetic fibers to abdominal organs
At T10 is the Diaphragmatic Hiatus.
T12 is under the Diaphragm
Esophageal Vagal Plexus:
a) Greater splanchnic T5 - T9
b) Lesser splanchnic T10 - T11c) Least splanchnic T12
Greater splanchnic n.
Lesser splanchnic n.Least splanchnic n.
Intercostal n.
Sympathetic trunk
Greater splanchnic n. T5-T9
Fibers to Lesser splanchnic n.
T10-11
-Least splanchnic n. T12(inferior to diaphragm)
Sympathetic trunk
Paravertebral ganglia
Vagus n.
Phrenic n.
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 9/18
Collection of:
o POSTsynaptic sympathetic fibers
o PREsynaptic parasympathetic fibers
o Visceral Afferent
Due to embryological development, there is a twisting in the Gut tube. Causing the Left
Vagus Nerve to be turned Anteriorly and the Right Vagus Nerve to be turned Posteriorly.
o Mnemonic: LARP – Left becomes Anterior, Right become Posterior
Diaphragm:
Anterior vagal trunk
(Vagus nerve)
Left vagus nerve
Esophageal plexus
Exit Thoracic cavity
via Esophageal
hiatus at T10
90° embryologic rotation
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 10/18
Right phrenic
Inferior cavopeningEsophageal
opening
Aorticopening
Left phrenic n.
Pericardialsac
Azygosvein
Central tendon
Splanchni
nerves
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 11/18
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 12/18
Mnemonic: I Ate 10 Eggs AAT 12
o I Ate – Inferior Vena Cava, T8
o 10 Eggs – T10, Esophagus, Vagus, Left inferior Phrenic Vessels
o AAT 12 – Aorta, Azygos v, Thoracic duct
Opening Vert. level Location Structures passing through
Vena caval
hiatus
T8 Central tendon of
diaphragm
Inferior Vena Cava
Rt. phrenic n.
Esophageal
hiatus
T10 Muscular part at the
right crus of the
diaphragm
Esophagus
Vagus nerve,
Left inferior phrenic vessels,
Aortic hiatus T12 Between the
diaphragm and
vertebral column
Aorta
Azygos v.
Thoracic duct
Diaphragmatic openings I Ate 10 Eggs AAT 12
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 13/18
Explain the manifestations and clinical significance of the following: esophageal constrictions, esophageal
diverticula, laceration of thoracic duct and Troisier’s sign, thoracic aortic aneurysm, SVC obstruction,
paradoxical motion of diaphragm, swollen rt. superior tracheobronchial nodes
(CR) Thoracic Aortic Aneurysm
Aneurysm that causes separation of the Tunica Intimia And Tunica Media
Risk Factors
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 14/18
o Atherosclerosis
o Connective tissue disorder
o Inflammation of Aorta
o Trauma
Internal Bleeding
(CR) Esophageal Constrictions:
Three main sites:
Left main bronchi
Aortic Arch
Diaphragmatic Esophageal Hiatus
(CR) Esophageal Diverticula
Parabrochial Diverticulum (outside)
“True” traction diverticula
Protrusion of all layers (not a weak spot)
Pulling force from outside
Cause: Tumor
Epipherenic Diverticulum
False Pulsion Diverticula
Herniation of the mucosa and submucosa through weak spots
Pushing force from inside
Causes: Neuromuscular Dysfunction (affect Vagus Nerve)
(CR) Virchow’s Node and Troisier’s Sign
Virchow’s Node
Muscular layer
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 15/18
Lymph Nodes in Left Supraclavicular Fossa
Troisier’s Sign
Enlargment of Virchow’s Node
GI Cancer metastasized through Thoracic Duct
(CR) Laceration of Thoracic Duct
Injured during surgery. Hard to spot
Lymph escapes and produces chylothorax
o Causes:
Trauma
Lymphoma
Family History
Premature babies
o Test Pleura for triglyceride level to eliminate pleural effusion
(CR) Azygos Vein Collateral Circulation
Supra-Azygos SVC obstruction
Distended arm and neck veins
Dilated and tortuous veins on ubber chest and back
Superior Vena Cava Syndrome
Troisier ’s sign
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 16/18
Infra-Azygos SVC obstruction
Dilation of collateral vessels on the anterior and posterior abdominal walls
Back flow
Rerouted to IVC
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 17/18
(CR) Paradoxical Motion of the Diaphragm
Hemidiaphragm supplied with separate phrenic n.
Damage to phrenic n. -> paradoxical Motion
Inspiration:
o The paralyzed dome ascends instead of descending, pushed down by abdominal
vicera
Expiration:
o Paralyzed dome descends because of lungs positive pressure.
7/27/2019 Posterior Mediastinum.docx
http://slidepdf.com/reader/full/posterior-mediastinumdocx 18/18
10/15/2013 5:13:00 AM