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Flashcards in Posterior mediastinum Deck (22):

Anterior boundary of the posterior mediastinum

Posterior pericardium


Posterior boundary of the posterior mediastinum

Vertebrae T5-T12


Lateral boundary of the posterior mediastinum

Mediastinal pleura


Superior boundary of the posterior mediastinum

Transverse thoracic plan


Contents of the posterior mediastinum

Thoracic aorta
Azygos system of veins
Thoracic duct
Vagus nerve
Sympathetic trunk
Sympathetic nerves


Transending structures

Thoracic duct
Vagus nerve
Phrenic nerve


Thoracic aorta

Continuous with arch

Descends on left side of T5-T12

Oesophagus to its right

Terminates at T12, enters abdomen through aortic hiatus

Thoracic duct and azygus veins on its right


Branches of thoracic aorta

Posterior intercostal
Superior phrenic


Azygos vein location

Right side of the thoracic vertebra

Arches over root of right lung to join SVC


Azygos vein

Drains deoxygenated blood from posterior thoraco-abdominal walls and viscera

Posterior intercostal veins, bronchial veins, vertebral venous plexus drain into it


Hemi-azygos veins

Arises on left side by junction of subcostal and ascending lumbar veins

Ascends to left side posterior to aorta draining left posterior intercostal veins T9-11

Crosses to right and joins azygos

Accessory drains T4-8 on left side

Crosses T7/8 to join azygos and sometimes hemi-azygos


Thoracic duct

Largest lymph channel

Conveys all lymph from body except head, neck, upper limb and thorax on right side

Originates in cisterna chyli in abdomen

Ascends through aortic hiatus anterior to thoracic vertebrae

Ascends into superior mediastinum and drains into venous system at the left venous angle



Descends from superior mediastinum posterior to trachea

Muscular tube from levels C6-T11

Passes posterior and to the right of aorta

Posterior to left atrium

Veers slightly left before piercing the oesophageal hiatus at T10

Becomes anterior to abdominal aorta before entering the stomach


Three constrictions of the oesophagus

Arch of aorta

Left main bronchus



Innervation of the oesophagus

CNX and sympathetic trunk via oesophageal plexus


Vagus nerve

Enters superior mediastinum posterior to sterno-clavicular joint

Left and right recurrent laryngeal nerves branch from it

Continues into posterior mediastinum to contribute to pulmonary and oesophageal plexi

Parasympathetic supply

Preganglionic fibers until they reach the plexi


Right vegus

Right recurrent laryngeal branch hooks under right subclavian artery and ascends between trachea and oesophagus

Supplies larynx

Right vagus continues posterior to the right of the trachea, posterior to right brachiocephalic vein and lung root


Left vagus

Left recurrent laryngeal nerve hooks inferiorly to the aortic arch immediately lateral to ligamentum arteriosum

Ascends similarly to the right nerve to supply the larynx

Rest of left vagus runs posteriorly to lung root


Sympathetic trunk

Vertical chain of sympathetic nerves running the entire length of the vertebral column

Located on both sides of vertebral bodies

Paravertebral ganglia located along its length

In the thoracic spine usually one ganglion per spinal nerve


Upper 5 ganglia of the sympathetic trunk

Preganglionic sympathetic fibres leave the spinal cord and synapse at the ganglion

Postganglionic sympathetic fibres leave the ganglion and pass to the pulmonary, cardiac oesophageal plexi

Upper thoracic splanchnic nerves

Carry afferent fibres from the thoracic viscera they supply back to the brain


Lower 7 ganglia of the sympathetic trunk

Preganglionic sympathetic fibres leave the spinal cord and enter the ganglion but don't synapse

Preganglionic sympathetic fibres leave these ganglia and pass to the abdominal viscera

Form the 3 splanchnic nerves


Lower thoracic splanchnic nerves

Greater splanchnic nerves arise from sympathetic runk and paravertebral ganglia at levels T5-9

Lesser splanchnic nerves arise from levels T10-11

Least splanchnic nerves arise from level T12

Descend medially from ganglia across the vertebral bodies and enter abdomen by piercing the diaphragm

Carry preganglionic sympathetic fibrs to and visceral afferent fibres from the abdominal viscera