Mediastinum : Simplified

It is the region in thoracic cavity between the pulmonary cavities (covered by mediastinal pleura and excludes the lungs).

Extent: Thoracic outlet (1st rib) to Diaphragm (T12)

Superior mediastinum:

Upper extentThoracic outlet
Contents (superficial to deep)1. Glands (Thymus and Lymph nodes)
2. 3 Veins (Brachiocephalic Lt. and Rt. and SVC)
3. 4 Arteries (Arch of aorta and it’s 3 branches)
4. 3 Nerves (Vagus, Phrenic and Left recurrent laryngeal)
5. 2 Tubes (Trachea and Esophagus)
7. 1 duct (Thoracic duct)
Lower extentLine through angle of Louis (manubriosternal joint to T4/5)
Illustration from Anatomy & Physiology, Connexions Web site., Jun 19, 2013., CC BY-SA 3.0, via Wikimedia Commons
Green (Superior mediastinum); Orange (Anterior mediastinum); Blue (Middle mediastinum); Yellow (Posterior mediastinum)

Inferior mediastinum:

Anterior mediastinumMiddle mediastinumPosterior mediastinum
Upper extentT4/5T4/5T4/5
Contents1. Thymic remnants
2. Lymph nodes
3. Fat
1. Phrenic nerve
2. Pericardium
3. Heart
4. Ascending aorta
5. Pulmonary trunk
6. SVC
7. Lymph nodes
Remember esophageal and aortic openings of diaphragm: 3 gooses And A Duck.
1. Esophagoose
2. Right vagoose
3. Left vagoose
4. Aorta (descending)
5. Azygous vein
6. throacic Duct
7. Sympathetic and Splanchnic nerves
Lower extentnT9T9T12

Mediastinal masses

Anterior mediastinum: Mnemonic – 4 Ts

  1. Thymic neoplasm
  2. Teratoma
  3. Thyroid
  4. Terrible lymphoma

Middle mediastinum:

  1. Bronchogenic and pericardial cysts
  2. Esophageal tumors
  3. Vascular masses
  4. Lymphoma and lymph nodes

Posterior mediastinum: Mnemonic – MNOP

  1. Meningocele
  2. Neurogenic tumors
  3. Osseous tumors (Chordoma, Chondrosarcoma, Ewings)
  4. Paraspinal abscess

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