Lecture 12: Mediastinum Flashcards
Describe the superior mediastinum
The region SUPERIOR to the horizontal line running from the sternal angle to the T4 vertebra
What is found in the superior mediastinum (8 things)
Thymus
Great vessels
Trachea
Esophagus
Thoracic duct
Phrenic nerves
Vagus nerves
Sympathetic trunks
Describe the inferior mediastinum
Region inferior to the line from the sternal angle to the T4 vertebra
What is the inferior mediastinum bound by (inferiorly)
Diaphragm
Describe the anterior mediastinum
Sternum to pericardial sac
What is found in the anterior mediastinum?
Thymus and/or adipose tissue
What is found in the middle mediastinum?
Pericardium and heart
What is found in the posterior mediastinum?
Pericardial sac - thoracic vertebrae
What are the contents of the posterior mediastinum?
Esophagus
Thoracic duct
Aorta (descending thoracic)
Azygos (& hemi) veins
Nerves (sympathetic trunk, vagus)
What is the bilobed organ found in the superior mediastinum?
Thymus
What is the importance of the thymus
Site for T-lymphocyte maturation and differation
After puberty, what happens to thymus?
Replaced with adipose tissue
Where does the trachea split into L/R primary bronchi?
Level of sternal angle
What is the fibromuscular tube found in the mediastinum?
Esophagus
What are the three constrictions in the esophagus?
Arch of aorta
Left primary bronchus
Diaphragm
Why would these esophageal constrictions be important to know? What is their clinical significance?
Individuals with swallowing problems likely will experience blockage/greatest difficulty along these three constrictions
If something (like a large pill) gets lodged in the esophagus, it is most likely to get lodged in one of these three constrictions
What comes off of the aortic arch?
Brachiocephalic artery
Left common carotid artery
Left subclavian artery
(ABCS)
What comes off the brachiocephalic artery?
Right common carotid artery
Right subclavian artery
What comes off the descending thoracic aorta?
Posterior intercostal arteries
Bronchial arteries
Esophageal arteries
What are the important veins of the mediastinum?
Left/Right brachiocephalic veins
SVC
IVC
Azygos vein
Hemiazygos vein
What nerves are found anterior to the root of the lung
Phrenic nerves
What nerve is found along the fibrous pericardium?
Phrenic
What nerve is posterior to the root of the lung
Vagus
What nerve comes off of vagus?
Reccurent Laryngeal Nerves
Thoracic splanchnic nerves come from
Sympathetic trunks
What are the thoracic splanchnic nerves?
Greater, lesser, & least
What are the two major lymphatic structures of the mediastinum
Thoracic duct
R. Lymphatic duct
Define lymph
Fluid from arterioles/capillaries enters the extra-cellular space. This fluid will collect large proteins and other cellular junk.
(AKA - material that is unable to pass through the walls of veins)
What structures collect lymph and carry it from the tissues into progressively larger vessels?
Lymphatic vessels
T/F: Lymph vessels do not have veins
False
Where do lymph vessels lead to?
Lymph nodes
What happens when lymphocytes encounter antigens?
They multiply and produce antibodies, this will enlarging the node.
Lymph from the lower limb and abdomen/pelvis goes where?
Cisterna chyli
What is the flow of lymph from the cisterna chyli?
Thoracic duct –> left subclavian vein
Where does the thoracic duct orginate?
In the abdomen at cisterna chyli
The right lymphatic duct drains lymph from
Right upper limb, neck, and head
What’s the innervation of the thoracic viscera?
ANS vis cardiac plexus
What pathway of ANS does the thoracic viscera follow?
Pathway/Option 2
What is the vascular supply to the lungs
I. Pulmonary system
II. Bronchial (systemic) system
Describe the pulmonary system (vascular supply) to the lungs
Blood to/from lungs for reoxy
Describe the bronchial (systemic) system to the lungs
Supply bronchi and larger bronchioles
Where do bronchial arteries branch from?
Thoracic aorta
Describe bronchial veins
They drain into the azygos vein or accessory hemiazygos vein - sometimes drain into pulmonary veins
Describe the lymphatics of the lungs
Lymph from bronchopulmonary lymph nodes goes to the tracheobronchial lymph nodes then to L/R bronchomediastinal lymph trunks and finally to right lymphatic duct or thoracic duct
What supplies innervation to the lungs?
ANS
What is the pulmonary plexus?
Nerves that consist of sympathetic and parasympathetic axons
What is the parasympathetic innervation to the lungs?
CN X - Vagus
What is the main function of CN X in the lungs
Bronchoconstrictor
What is the sympathetic innervation of the lungs
T1-T5
What is the main function of lung sympathetic innervation
Bronchodilator
What ANS component is believed to be the cause of referred visceral pain (referred pain)
Afferent component
Define referred visceral pain
visceral pain not felt in the viscera itself, but in a dermatome supplied by the same segments of the spinal cord
Visceral pain for stomach
Epigastrum (T5-T9)
Visceral pain for appendix
Umbilicus (T10)
Visceral pain for heart
Upper left part of trunk (T1-T5)
