The Mediastinum
- It is a thick moveable partition between right & left pleural sacs & lungs.
- It includes all the structures which lie in the intermediate compartments of the thoracic cavity
Boundaries:
- Superior: Thoracic outlet: (manubrium, 1st rib &T1)
- Inferior: Diaphragm
- Anterior: Sternum
- Posterior: 12 Thoracic vertebrae
- Lateral: Lungs & pleurae
Divisions
by a horizontal plane from sternal angle to lower border of T4 into:
- Superior mediastinum (1 part): above the plane
- Inferior mediastinum (3 parts): below the plane
Subdivided into:
- Posterior mediastinum: behind the heart
- Middle mediastinum: contains the heart
- Anterior mediastinum: in front of the heart
Level of T4
- It is the Level of:
- Sternal angle
- Second costal cartilage
- Why the Level of T4 is important:
- Bifurcation of trachea
- Bifurcation of pulmonary trunk
- Beginning & termination of arch of aorta
Boundaries
- Superior: Thoracic outlet
- Inferior: Horizontal plane
- Anterior: Manubrium of sternum
- Posterior: Upper 4 thoracic vertebrae
- Lateral: lungs & pleurae
Contents :From superficial to deep:
- (1) Gland :Thymus gland
- (3) Veins:
- right & left brachiocephalic
- superior vena cava
- (4) Arteries:
- arch of aorta & its branches
- brachiocephalic artery
- left common carotid
- left subclavian
- (4) Nerves:
- right & left vagus
- right & left phrenic
- (2) Tubes:
- Trachea
- Esophagus (most posterior)
- (1) Duct: thoracic duct (beside the esophagus)
- Lymph nodes