Posterior Mediastinum

Question 1

What is contained in the posterior mediastinum?

Answer 1

• Oesophagus
• Descending aorta
• Thoracic duct
• Azygous venous system
• Posterior mediastinal lymph nodes
• thoracic sympathetic trunks
• splanchnic nerves

Question 2

Describe where the oesophagus begins and ends?

Answer 2

• Begins at C7
• Ends at stomach T11
• Bends more anteriorly at T7 (right of aorta—> deviates to left// progessively anterior to aorta below T7)
• Passes through diaphragm at T10
• Constrictions at 4 locations

Question 3

what is the azygous venous system

Answer 3

• Drains posterior wall of chest and upper abdomen and posterior mediastinal organs
• Usually accessory hemiazygous (upper) and hemiazygous (lower) veins of left cross thoracic vertebral vodies to join single azygous vein on right
• Azygous vein arches over right lung root to enter SVC just above right atrium
• variable

Question 4

what are the Nerves within Inferior Mediastinum

Answer 4

Phrenics (C3, 4, 5) pass anterior to lung roots and cross pericardium to diaphragm
Vagi (Cranial nerve X) pass posterior to lung roots and form plexus following oesophagus into abdomen, giving branches to heart and lungs on the way
Sympathetic trunks lie on each side of the posterior mediastinum

Question 5

what are the vagus nerves and their branches?

Answer 5

Branches to chest and abdomen are parasympathetic (control smooth and cardiac muscle + glands of gut and airways)
Also large sensory from gut and lungs
Recurrent laryngeal nerve not parasympathetic – run back up neck to supply most skeletal muscles of larynx

Question 6

where is the sympathetic trunk?

Answer 6

Receive branches from spinal nerves T1 - L2
Distribute sympathetic nerves to smooth muscle and glands throughout body
Nerves to body wall synapse in ganglia of trunks
Nerves to internal organs (viscera) synapse in local ganglia
Also bring pain fibres back to CNS from viscera
Fibres from lower T5 - T12 reach abdomen in bundles called splanchnic nerves

Question 7

where is the thoracic duct?

Answer 7

Lymph duct returning lymph from lower limbs, pelvis, abdomen & left thoracic wall to blood
Begins below diaphragm at cisterna chyli
Starts between oesophagus and aorta on right
Crosses behind oesophagus to left side between T7 and T4
Drains into left brachiocephalic vein