28 SupPostMediastinum Lymph

Superior + inferior borders of superior mediastinum

• superior border: TV1 - Rib 1

• inferior border: sternal angle

Contents summary of superior mediastinum

• retrosternal

  • thymus + great veins

• Intermediate structures

  • aortic arch + vagus n. + phrenic n. + sympathetic branches

• Prevertebral

  • trachea + esophagus

  • left recurrent laryngeal n.

  • thoracic duct + lymph nodes

Thymus

lymphoid organ that gradually becomes replaced by fat

• differentiation of lymphocytes

Left brachiocephalic v.

great vein in retrosternal mediastinum formed by union of internal jugular + subclavian veins

Right brachiocephalic v.

great vertical vein in retrosternal mediastinum that joins w SVC + azygous v.

Ligamentum arteriosum

embryonic remnant of ductus arteriosus

• connected pulmonary trunk/arteries + aortic arch when lungs were still in development

Anastomoses

• superior epigastric a. ←→ inferior epigastric a.

• anterior intercostal a. ←→ posterior intercostal a.

Trachea characteristics

• btwn CV6 - sternal angle

• can be compressed by aortic arch + brachiocephalic trunk

Contents of retrosternal mediastinum

great veins

• left brachiocephalic v.

• right brachiocephalic v.

• lymphatic ducts (L + R jugular angles)

Contents of intermediate mediastinum

• aortic arch

• ligamentum arteriosum

Nerves

• phrenic n.

  • more superficial n.

• vagus n.

  • more lateral n.

• sympathetic branches

• left recurrent laryngeal n.

  • runs behind ligamentum arteriosum

Contents of prevertebral mediastinum

• trachea

• left recurrent laryngeal n.

• esophagus

  • behind heart + trachea

• thoracic duct + lymph nodes

Sup/ant/post borders of posterior mediastinum

• Superior border: TV4-5 disc / below sternal angle

• Anterior border: pericardium

• Posterior border: vertebrae

Summary contents of posterior mediastinum

• thoracic aorta

• thoracic duct

• primary bronchi

• tracheobronchial nodes

• azygous system

• esophagus

• ANS/ Splanchnic n.

• vagus n.

posterior mediastinum from right side

• can see azygous system

posterior mediastinum from left side

• can see aortic arch + descending aorta

Branches form thoracic aorta

• bronchial a.

• pericardial a.

• posterior intercostal a.

  • subcostal a. (last intercostal a.)

• superior phrenic a.

  • goes to diaphragm

• esophageal a.

• mediastinal a.

Thoracic aorta vertebrae levels

TV4 - TV12

Esophagus innervation

vagus n.

Esophageal anatomose

• upper portion: caval system

• lower portion: portal system

Azygous system of veins

drains body wall + provides alternative if IVC is blocked

• intercostal veins

• hemizygous veins

• accessory hemizygous veins

Vulnerable to metastasis

thoracic duct

major lymphatic channel

Cisterna chyli

lymphatic sac at TV12 in abdomen that ascends towards left brachiocephalic v.

Somatic lymph nodes (for body wall)

• axillary

• parasternal

• intercostal

• diaphragmatc

Visceral lymph nodes (for viscera)

• anterior mediastinal

• posterior mediastinal

• tracheobronchial

Lymphatic drainage of breasts

• inferior breast → abdominal/inferior phrenic lymph nodes

• medial breast → parasternal nodes

• most of breast → axillary nodes

Lymphatic drainage of thoracic wall

• superior half → axillary nodes (+ parasternal nodes)

• inferior half → superior inguinal nodes

Lymphatic drainage of heart

• right → brachiocephalic nodes

• left → tracheobronchial nodes

Lymphatic drainage of lungs

• right lung → tracheobronchial nodes + R paratracheal nodes

• left superior → superior tracheobronchial → L paratracheal

• left inferior → inferior tracheobronchial/ carinal nodes → R paratracheal » L paratracheal

Tracheobronchial node branches

• pulmonary

  • within lungs

• bronchopulmonary (hilar)

  • around hilum of lungs

• inferior tracheobronchial (carinal)

  • below carina

• superior tracheobronchial

  • above tracheal bifurcation

• tracheal (paratracheal)

  • along trachea