Mediastinum
**Space between the two pleural cavities situated at the center of the thorax
Boundaries of mediastinum.
Anterior – Sternum
Posterior – 12 thoracic vertebrae
Superior – Superior thoracic aperture
Inferior – Inferior thoracic aperture
On each side - mediastinal pleurae
Divisions
Imaginary plane through sternal angle of Louis &
lower border of T4 divides mediastinum into
Mediastinum
Superior Inferior
Anterior Middle Posterior
What is the anatomical significance of the plane through sternal angle?
Superior mediastinum
Boundaries
- anterior - manubrium sterni
- posterior- upper 4 thoracic vertebrae
- superior- superior thoracic aperture
- inferior- imaginary plane through sternal angle and lower border of T4
- on each side- mediastinal pleura
Contents:
- Trachea, oesophagus, thymus, thoracic duct
- Nerves - Vagi, phrenic, left recurrent laryngeal, cardiac nerves
- Veins - Left & right brachiocephalic, SVC, left superior intercostal veins
- Arteries - Left common carotid, left subclavian, brachiocephalic artery & arch of aorta
- Muscles - Sternothyroid, sternohyoid
- Lymph nodes – paratracheal, brachiocephalic, tracheobronchial
1
, CLINICALS
Superior mediastinal syndrome
Cause: enlargement of mediastinal lymph nodes, aortic aneurysm, bronchogenic carcinoma
Compression of mediastinal structures results in:
- Oesophagus– dysphagia (difficulty in swallowing)
- Trachea – dyspnea (difficulty in breathing)
- Phrenic nerves – paralysis of diaphragm (paralyzed diaphragm is raised,
paradoxical movements), shoulder tip pain (C4 – pain referred from
diaphragmatic peritoneum)
- Left recurrent laryngeal nerve – hoarseness of voice(dysphonia)
- SVC – dilatation of neck & facial veins *thoracoepigastric vein
- Stellate ganglion (sympathetic trunk) – Horner’s syndrome
- Vertebral bodies – erosion
- Intercostal nerves - intercostal neuralgia
Mediastinitis
Little loose connective tissue
Lots of dead space – expand veins, more on the right side
Easy spread of infection
Large surface area
Toxins get absorbed
Attachment of prevertebral fascia to T4 – infections spread from the neck to the sup
mediastinum
Attachment of pretracheal fascia with arch of aorta – neck infections
spread to sup mediastinum & through it to posterior mediastinum
2
**Space between the two pleural cavities situated at the center of the thorax
Boundaries of mediastinum.
Anterior – Sternum
Posterior – 12 thoracic vertebrae
Superior – Superior thoracic aperture
Inferior – Inferior thoracic aperture
On each side - mediastinal pleurae
Divisions
Imaginary plane through sternal angle of Louis &
lower border of T4 divides mediastinum into
Mediastinum
Superior Inferior
Anterior Middle Posterior
What is the anatomical significance of the plane through sternal angle?
Superior mediastinum
Boundaries
- anterior - manubrium sterni
- posterior- upper 4 thoracic vertebrae
- superior- superior thoracic aperture
- inferior- imaginary plane through sternal angle and lower border of T4
- on each side- mediastinal pleura
Contents:
- Trachea, oesophagus, thymus, thoracic duct
- Nerves - Vagi, phrenic, left recurrent laryngeal, cardiac nerves
- Veins - Left & right brachiocephalic, SVC, left superior intercostal veins
- Arteries - Left common carotid, left subclavian, brachiocephalic artery & arch of aorta
- Muscles - Sternothyroid, sternohyoid
- Lymph nodes – paratracheal, brachiocephalic, tracheobronchial
1
, CLINICALS
Superior mediastinal syndrome
Cause: enlargement of mediastinal lymph nodes, aortic aneurysm, bronchogenic carcinoma
Compression of mediastinal structures results in:
- Oesophagus– dysphagia (difficulty in swallowing)
- Trachea – dyspnea (difficulty in breathing)
- Phrenic nerves – paralysis of diaphragm (paralyzed diaphragm is raised,
paradoxical movements), shoulder tip pain (C4 – pain referred from
diaphragmatic peritoneum)
- Left recurrent laryngeal nerve – hoarseness of voice(dysphonia)
- SVC – dilatation of neck & facial veins *thoracoepigastric vein
- Stellate ganglion (sympathetic trunk) – Horner’s syndrome
- Vertebral bodies – erosion
- Intercostal nerves - intercostal neuralgia
Mediastinitis
Little loose connective tissue
Lots of dead space – expand veins, more on the right side
Easy spread of infection
Large surface area
Toxins get absorbed
Attachment of prevertebral fascia to T4 – infections spread from the neck to the sup
mediastinum
Attachment of pretracheal fascia with arch of aorta – neck infections
spread to sup mediastinum & through it to posterior mediastinum
2
