1 - Superior and Posterior Mediastinum Flashcards

1
Q

Superior Mediastinum: Vessels

A

L/R Brachiocephalic Vein

Aoritic Arch

Brachiocephalic Trunk

Left Common Carotid

Left Subclavian

Superior Vena Cava

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2
Q

Superior Mediastinum: Nerves

A

Left Recurrent laryngeal Nerve

Phrenic Nerve

Vagus Nerve

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3
Q

Superior Mediastinum: Structures

A

Trachea

Esophagus

Thoracic Duct

Thymus (degrades with age)

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4
Q

Aoritic Arch: Location

A

Begins and ends at level of sternal angle (forms arch)

Located entirely in Superior Mediastinum

Courses Right to Left, and Anterior to Posterior

Branches: Braciocephalic Trunk, Left Common Carotid A. , Left Subclavian A.

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5
Q

Aortic Arch: Brachiocephalic Trunk

A

Largest branch of aortic arch

At right sternoclavicular joint, the trunk divides into: Right Common Carotid Artery, and Right Subclavian Artery

Arteries located slightly superior and posterior to corresponding veins

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6
Q

Aortic Arch: Left Common Carotid

A

Ascends left side of trachea

Left Head/Neck

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7
Q

Aortic Arch: Left Subclavian Artery

A

Ascends left side of trachea

Left upper extremity

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8
Q

Descending Thoracic Aorta: Location

A

Inferior to the level of sternal angle

Starts on left of thoracic vertebrae, gradually moves anterior

Passes through the Aortic Hiatus in the Diaphragm at Level T12

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9
Q

Descending Thoracic Aorta: Paired Branches

A

Paired Parietal Branches:

a. Nine pairs of Posterior Intercostal arteries supply 3-11 (1-2 supplied from Sup. Intercostal Br. of Costocervial Trunk - Branch of Subclavian)

b. One pair Subcostal Arteries (bellow rib 12)

c. One pair Superior Phrenic Arteries to upper side diaphragm

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10
Q

Descending Thoracic Aorta: Unpaired Branches

A

Unpaired Branches to Viscera

a. Two Left Bronchial Arteries
b. Two Esophageal Arteries

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11
Q

Veins in Sup/Post Mediastina: Right and left Brachiocephalic Veins

A

Formed by union of the internal jugular veins (head and neck) and the subclavian veins (upper extremities)

Begins posterior to Sternoclavicular Joints

- - -

Right - Goes basically straight down to Superior Vena Cava

Left - Oblique Cross over to join Right and form Superior Vena Cava; Located between Thymus and Brachiocephalic Truink and L Common Carotid

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12
Q

Veins in Sup/Post Mediastina: Superior Vena Cava

A

Formed by union of Right and left Brachiocephalic Veins

Extends from levels of right Ribs 1-3

Receives Azygos Vein at Sternal Angle, enters Right Atrium

Contains DEOXYGENATED blood from ALL STRUCTURES ABOVE DIAPHRAGM

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13
Q

Veins in Sup/Post Mediastina: Azygos Vein Location

A

Lies right of thoracic vertebrae

Superior continuation of right ascending lumbar vein

Passes through Aortic Hiatus of Diaphragm

Arches superior to root of right lung, to empty in Superior Vena Cava @ Sternal Angle

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14
Q

Veins in Sup/Post Mediastina: Azygos Drainage Pattern

A

Right Thoracic Wall via Posterior Intercostal Veins

Left Thoracic Wall vis Hemiazygos and Accessory Hemiazygos Veins

Esophagus (esophageal veins), lung tissue (bronchial veins), and the vertebral column and spinal cord (vertebral venous plexus)

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15
Q

Veins in Sup/Post Mediastina: Hemiazygos Vein (Inferior Hemiazygos)

A

Continuation of Left Ascending Lumbar Vein as it passes posterior diaphragm; drains left posterolateral abdominal wall into inferior vena cava (this branch becomes Hemiazygos)

Drains lower left intercostal spaces

Empties into Azygos

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16
Q

Veins in Sup/Post Mediastina: Accessory Hemiazygos Vein (Superior Hemiazygos)

A

Drains middle left intercostal spaces, empties into Azygos

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17
Q

What is the venous drainage patter for upper intercostals?

A

Right / Left Superior Intercostal Veins

These are NOT located in the posterior mediastinum, but do dump into veins there (Azygos, Left Brachiocephalic V.)

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18
Q

What provides a collateral pathway to right atrium for venous drainage?

A

Azygos Vein and Ascending Lumbar Veins provide collateral pathway to right atrium if Superior Vena Cava OR Inferior Vena Cava is blocked.

If they’re both blocked, you’re probably dead.

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19
Q

Clinical: Superior Vena Cava Syndrome

A

Bronchogenic Tumor of Right Lung can compress Superior Vena Cava

Head/Neck blood as difficulty returning to right atrium

Signs: Distended internal/external jugular veins in neck, subclavian tribs. in R upper limb

Still has collateral pathways (Aygos -> Asc. Lumbar V. -> Lumbar Veins -> Inferior Vena Cava)

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20
Q

Clinical: Liver Tumor Venous Compression

A

Tumor of Liver can obstruct Inferior Vena Cava

Venous blood can bypass via collaterals:

Lumbar Veins -> R/L Ascending Lumbar Veins -> Hemiazygos -> Azygos -> Superior Vena Cava

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21
Q

Lymphatics: Thoracic Duct

Overview

A

Main lymph channels of body

Everything but Right Head/Neck, Right Pec, Right Arm

Drains into venous system

1st - Drain cisterna chyli

22
Q

Lymphatics: Thoracic Duct

Locations:

Posterior Mediastinum

Supermediastinum

Neck

A

Ascends through aortic hiatus in diaphragm, enters posterior mediastinum

Posterior Mediastinum: Duct is between Azygos/Thoracic Aorta, Posterior to Esophagus

Superior Mediastinum: Duct is poster to left border of esophagus

Root of the Neck: Duct drains into the beginning of the left brachiocephalic vein

23
Q

Location of Cisterna Chyli

A

Inferior to the diaphragm, anterior to L2, right of Aorta

24
Q

Drainage to thoracic duct in root of neck?

A

Three lymph trunks:

  1. Left Jugular (head/neck)
  2. Left Subclavian (upper limb)
  3. Left Bronchomediastinal (left lung)
25
Q

Lymphatics: Right Lymphatic Duct

Location?

Drains?

Receives?

A

Not in mediastinum, found in ride side of root of the neck

Drains into right brachiocephalic vein

Drains: Right head/neck, right limb, right lung, skin of right thoracic wall

Receives: Right Subclavian, Right Bronchomediastinal, Right Jugular Lymph Trunks

These may drain independently

26
Q

Phrenic Nerve:

Superior Location (R/L)

A

Courses through superior and middle, not posterior mediastinum

- - -

Right: Enters from neck between Right Subclavian A & V

- - -

Left: Enters from beck between Left Subclavian A & V; Crosses Arch of Aorta anterior to left vagus nerve

27
Q

Phrenic Nerve:

Middle Mediastinum Location

A

Between mediastinal parietal pleura and fibrous pericardium

Anterior to root of the lung

28
Q

Phrenic Nerve:

Exit from Middle Mediastinum

A

Right: Passes through caval opening (w/Inf. Vena Cava)

Left: Pierces left dome of the diaphragm

29
Q

Vagus Nerve: Left

Superior Mediastinum Location & Branch

A

Crosses left side of aortic arch

Gives off Left Recurrent Laryngeal Nerve Branch; which hooks underneath Ligamentim Arteriosum & Aortic Arch; ascends into neck*

30
Q

Clinical: Left Recurrent Laryngeal Nerve

A

When ligating a patent ductus arteriosus in infant, DO NOT ligate the left recurrent laryngeal nerve.

Provides motor innervation to laryngeal muscles; damage = hoarse voice

31
Q

Vagus Nerve: Right

Superior Mediastinum Location/Branches?

A

Enters Anterior to Right Subclavian; descends lateral to Trachea

Gives off Right Recurrent Laryngeal Nerve, hooks around right subclavian artery, and ascends to neck b/t esophagus and trachea (does NOT enter superior mediastinum)

32
Q

Vagus Nerve: Other Minor Branches in Superior Mediastinum

A

Small cardiac / pulmonary branches leave main Vagus trunk in Superior Mediastinum and course to cardiac and pulmonary plexuses

33
Q

Vagus Nerve:

Location in Posterior Mediastinum

(in orientation to esophagus)

A

Passes posterior to root of the lung; gives additional fibers to pulmonary plexus

Forms plexus on surface of esophagus

Passes through diaphragm with esophagus.

- - -

Left = Anterior Esophagus

Right = Posterior Esophagus

34
Q

Sympathetic Trunks?

Part of?

Organization?

A

Part of Posterior Mediastinum

Two parallel cords punctuated by 11 or 12 ganglia; connected to adjacent thoracic spinal nerves by white and gray rami communicantes

35
Q

Sympathetic Trunks: Location in Mediastinum?

A

Superior - Anterior to Neck of Ribs

Inferiorly - Become medial, lie on lateral vertebrae

Covered by parietal pleura on way down

36
Q

What type of fibers originate from the upper five ganglia?

A

Small, Postganglionic Sympathetic Fibers

Also contain Visceral Afferents

37
Q

What type of fibers originate from lower seven ganglia?

A

Large Preganglionic Sympathetic Fibers

Form three thoracic Splanchnic Nerves

Also carry Visceral Afferents

38
Q

Greater Splanchnic Nerve

A

(on each side)

Usually arises from 5th or 9th or 10th thoracic ganglia

Descends across vertebral bodies medially, passes through crus of diaphragm, ends in celiac ganglion

39
Q

Lesser Splanchnic Nerves

Least Splanchnic Nerves

A

Lesser:

9+10 or 10+11 ganglia

Pass through crus of diaphragm, end in aorticorenal ganglion

- - -

Least:

12th ganglia

Pass through crus of diaphragm, end in renal plexus

40
Q

Thymus:

Organization

Location

Blood Supply

A

Bilobed, lympoid organ of the immune system–max size @ puberty

Becomes fat after

Immediately Posterior to Manubrium (Sternum)

Blood Supply: Branches of Internal Thoracic / Inferior Thyroid

41
Q

Trachea

Location

Division Location?

A

Begins in neck at level of C6

Divides into principle bronchi at level of sternal angle

Principle bronchi are within middle mediastinum

42
Q

Right Main Bronchus vs Left Main Bronchus

Clinical?

A

Right = Shorter, Wider, more vertical (erect chode)

Left = Longer, more horizonatl, crosses anterior to esophagus and aorta; may constrict esophagus

Clinical: Food more likely to enter Right Bronchus; more likely to enter middle or lower lobe of right lung

43
Q

Carina

Clinical?

A

Internal “keel” at division of trachea into main bronchi

Clinical: Landmark, visible with bronchoscope–enlargement of tracheobronchial lmph nodes due to bronchogenic carcinoma can cause distortion of the carina

44
Q

Esophagus:

Location in Neck/Superior Mediastinum

Location in Posterior Mediastinum

A

Located between trachea and vertebral column

Descends from level of sternal angle to esophageal hiatus in diaphragm at level T10

Posterior to pericardium, left atrium

Right of thoracic aorta

Anterior to thoracic aorta at esophageal hiatus in diaphragm

Deviates left (aorta right) as they descend

45
Q

Clinical: Constrictions of Esophagus

Four Types?

A

Occur only when it’s filled, due to adjacent structures compressing muscular tube. Barium Dye Swallow used to test

  1. Pharynx Narrows
  2. Arch of Aorta
  3. Left main Bronchus
  4. Diaphragm
46
Q

Clinical: Hypertrophy of Left Atrium

A

Occurs during left-side heart failure

Can be from incompetent mitral valve, resulting in back pressure of venous blood

Can be deonstrated with barium swallow by its compression and displacement of the posterior esophagus

47
Q

Esophageal blood supply?

A

In Thorax: From esophageal branches of Descending Aorta

48
Q

Diaphragm Passage: Vertebrae Level / Hole

Inferior Vena Cava

Esophagus

Descending Aorta

Greater, Lesser, Least Splanchnic Nerves

Sympathetics

A

Inferior Vena Cava - T8 - Caval Opening (R. Phrenic also)

Esophagus - T10 - Esophageal Hiatus (R/L Vagal N. trunks also)

Descending Aorta - T12 - Aortic Hiatus (Thoracic Duct, Azygous Vein also–Red (Aorta), White (Thoracic Duct), Blue (Azygous))

Greater, Lesser, Least Splanchnic Nerves - Crus

Sympathetics - Pass posterio, don’t pierce

49
Q

Anatomical Structures at Level of Sternal Angle

(Seven)

A
  1. Cotsal Cart. of Rib 2 articulate w/Sternum
  2. Arch of Aorta begins, Term. @ Descending aorta
  3. T4-T5
  4. Imaginary line between Superior/Inferior Mediastina
  5. Superior extends of fibrous pericardium
  6. Trachea divides to main bronchi
  7. Azygos Vein enters Superior Vena Cava
50
Q
A