Mediastinum Dr. P. S. Mittal

Associate Professor, DeptARTMENt of Anatomy, GIMS

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Competencies & special learning objectives

• AN21.11 Mention boundaries and contents of the superior, anterior, middle and posterior mediastinum

• Specific Learning Objectives – AN21.11.1 List the boundaries of superior mediastinum.

– AN21.11.2 Enumerate the contents of superior mediastinum.

– AN21.11.3 List the boundaries of anterior mediastinum.

– AN21.11.4 Enumerate the contents of anterior mediastinum.

– AN21.11.5 List the boundaries of middle mediastinum.

– AN21.11.6 Enumerate the contents of middle mediastinum.

– AN21.11.7 List the boundaries of posterior mediastinum.

– AN21.11.8 Enumerate the contents of posterior mediastinum.

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DEFINITION • It is a partition between

the right & left pleural sacs.

• It includes all the structures which lie in the intermediate compartments of the thoracic cavity.

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Concept

• All of organs between the left and right mediastinall pleurae is called mediastinum.

• It extends from the sternum in front to the vertebral column behind, and from the thoracic inlet above to the diaphragm below.

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Subdivisions

• Superior mediastinum

• Inferior mediastinum

– Anterior mediastinum

– Middle mediastinum

– Posterior mediastinum

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• It is divided by a horizontal plane extending from sternal angle to lower border of 4th thoracic vertebra into:

1. Superior mediastinum: above the plane

2. Inferior mediastinum: below the plane, it is subdivided into:

– Anterior mediastinum: in front of pericardium – Middle mediastinum: contains heart &

pericardium – Posterior mediastinum: behind pericardium

SubdiviSionS ConTd…

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SubdiviSionS ConTd…

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SUPERIOR MEDIASTINUM

• It is the part of Mediastinum above the horizontal plane extending from sternal angle to lower border of 4th thoracic vertebra.

BOUNDARIES:

• Anterior: manubrium sterni

• Posterior: Upper 4 thoracic vertebrae

• Superior: Plane of thoracic inlet

• Inferior: Horizontal plane

• On each side: Pleura

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Contents of Superior mediastinum

• In the Anterior part:

– Thymus

– Three veins

• Left brachiocephelic v.

• Right brachiocephelic v.

• Superior vena cava

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A. In the Middle part:

• Aotic arch and its three

branches:

1. Brachiocephalic

2. Left common carotid

3. Left subclavian arteries

• Phrenic nerve

• Vagus nerve

Contents of Superior mediastinum contd…

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• In the Posterior part:

– Esophagus

– Trachea

Contents of Superior mediastinum contd…

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• 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

Contents of Superior mediastinum contd…

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OTHER CONTENTS: – Muscles:

1. Sternohyoid 2. Sternathyroid 3. Longus colli

– 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 (Brachiocephalic & Tracheobranchial)

Contents of Superior mediastinum contd…

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SUPERIOR MEDIASTINUM

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T.S. at tHe level of T4

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CLINICAL ANATOMY

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CLiniCAL AnAToMY ConTd… Compression of mediastinal structures by any mass give rise to group of symptoms known as MEDIASTINAL SYNDROME

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THANKS