3. SUPERIOR MEDIASTINUM
BOUNDARIES
ANTERIORLY : Manubrium sterni
POSTERIORLY : Upper four thoracic
SUPERIORLY : Plane of thoracic inlet
INFERIORLY : Imaginary plane passing through the sternal angle
In front, lower border of body of fourth thoracic vertebra behind
5. Contents
1: Trachea and oesophagus
2 : Muscles ; origins of ( sternohyoid, sternothyroid ,lower ends of longus colli)
3: Arteries ( arch of aorta ,brachiocephalic artery ,left common carotid artery ,
Left subclavian artery)
4: Veins right and left brachiocephalic veins, upper half of the superior vana cava ,
Left superior intercostal vein )
5: Nerves ( vagus, phrenic, cardiac nerves of both sides, left recurrent laryngeal nerve,
6: Thymus
7: Thoracic duct
8: LYMPH nodes ( paratracheal, brachiocephalic and tracheobronchial).
6. Inferior mediastinum
Inferior mediastinum is divided into
Anterior, Middle and posterior mediastinum
ANTERIOR MEDIASTINUM
Very narrow space in front of pericardium,
Overlapped by thin anterior borders of both lungs.
It contains areolar tissues and part of thymus gland.
7. BOUNDARIES
Anteriorly : body of sternum
Posteriorly : pericardium
Superiorly : imaginary plane separating the superior mediastinum from inferior mediastinum
Inferiorly :superior surface of diaphragm
On each side : mediastinal pleura
8. Contents
1. sternopericardial ligaments
2. lymph nodes with lymphatics
3. small mediastinal branches of internal thoracic artery
4. lowest part of thymus
5. areolar tissue
9. Middle mediastinum
Boundaries
Anteriorly : Sternopericardial ligaments.
Posteriorly: Oesophagus, descending thoracic aorta, azygos vein.
On each side : Mediastinal pleura.
11. Contents
1. Arteries enclosed in pericardium
2. Arteries: (ascending aorta, pulmonary trunk, two pulmonary arteries)
3.veins: (lower half of superior vana cava, terminal part of azygous vein, right and left pulmonary
vein)
4. nerves: (phrenic and deep cervical plexus)
5. lymph nodes: tracheobronchial nodes
13. Boundaries
Anteriorly : 1- pericardium 2- bifurcation of trachea 3- pulmonary vessels 4-
posterior part of the upper surface of the diaphragm.
Posteriorly : lower eight thoracic vertebrae and Interventing discs.
On each side : mediastinal pleura .
15. Contents
1-Oesophagus.
2-Arteries : descending thoracic aorta and it’s branches.
3-Veins : 1- Azygos vein 2- hemizygous vein 3- accessory hemizygous vein.
4- Nerves : 1- Vagi 2- splanchnic nerves , greater , lesser , and least , arising from
the lower eight thoracic ganglia of the sympathetic chain.
16. Contents
5- lymph nodes and lymphatics:
(a) posterior mediastinum lymph nodes lying along the side the aorta.
(b) The thoracic duct .
17. Clinical anatomy
Mediastinal syndrome:
Compression of mediastinal structure by any tumour gives rise to the group of
symptoms known as “mediastinal syndrome”.
Symptoms :
(a) Obstruction of superior vena cava gives rise to engorgement of veins in the upper
half of the body.
18. Clinical anatomy
(b) Pressure over the trachea causes dyspnoea , and cough
(c) Pressure on the oesophagus causes dysphagia
(d) Pressure on the left recurrent laryngeal nerve gives rise to hoarseness of voice (dysphonia)
(e) Pressure on the phrenic nerve causes paralysis of the diaphragm on that side
(f) Pressure on the intercostal nerves gives rise to the pain in the area supplied by them. It is
called intercostal neuralgia
19. Clinical anatomy
(g) Pressure on the vertebral column may cause erosion of the vertebral bodies.
Causes :
Bronchogenic carcinoma (mediastinal syndrome)
Hodkin’s disease ( enlargement of mediastinal lymph nodes , aneurysm or dilation of
the aorta , etc.)
20.
21. Clinical anatomy
The prevertebral layer of the deep cervical fascia extends to the superior
mediastinum , and it’s attached to the fourth thoracic vertebrae. An infection
present in the neck behind this fascia can pass down into the superior
mediastinum but not lower down.
The pretracheal fascia of the neck also extends to the superior mediastinum ,
where it blends with the arch of the aorta. Neck infections between the
pretracheal and prevertebral fasciae can spread into the superior mediastinum
and posterior mediastinum. The mediastinum can result from infections in the
neck.
