Sup/Post Mediastinum Flashcards
Where is the Superior Mediastinum?
Superior to a “line” from the eternal angle (anteriorly) to the T4/T5 intervertebral disc (posteriorly)
Contents of the Superior Mediastinum
Thymus,
Branchiocephalic veins, Superior Vena Cava, Arch of Aorta (and branches),
Phrenic, vagus, left recurrent laryngeal nerves, and cardiac plexus
Trachea, Esophagus, and Thoracic Duct
What is the Thymus?
A 2 lobed lymphoid organ help together by dense irregular connective tissue
Where is the thymus?
Between the sternum and base of heart
Size of the thymus?
~40 grams max around 10-12 yrs, then a trophies as you age, ~6grams around 65 yrs
Function of the Thymus?
It is the maturation sure of the T-lymphocytes
The superior vena cava branches off into the:
Right Brachiocephalic vein and left brachiocephalic vein
Each brachiocephalic vein branches off into:
A subclavian vein and an internal jugular vein
The superior vena cava descends into the:
Upper part of the right atrium
The superior vena cava is located in the:
Upper part is in the superior mediastinum and the lower part I in the middle mediastinum
What is the function of the Superior Vena Cava?
To return deoxy blood to the heart from all structures superior to the diaphragm
The superior vena cava returns blood from all the structures above the diaphragm except:
The heart and the lungs
The Superior Vena Cava receives one tributary , which is:
The Azygos vein (posteriorly) from the thoracic wall
What are the parts of the aorta?
Ascending aorta, arch of the aorta, descending aorta
The descending aorta divides into the:
Thoracic aorta and abdominal aorta (divided at the diaphragm)
The ascending aorta begins at the:
Aortic orifice of the left ventricle
Where does the ascending aorta terminate?
About 2” above the left ventricle (where it meets the arch)
Where does the ascending aorta lie?
Within the pericardial sac (middle mediastinum)
What are the branches of the ascending aorta?
Right coronary artery and left coronary artery
Where does the arch of aorta terminate?
To the left of the t4 vertebral body (where it meets the descending thoracic aorta) in the posterior mediastinum
What is the ligamentum arteriosum?
A fibrous band that connects the arch of the aorta to the left pulmonary artery
What is the ligamentum arteriosum a remnant of?
The fetal Ductus Arteriosis
What are the three branches of the aortic arch?
Brachiocephalic trunk, left common carotid artery, and left subclavian artery
The brachiocephalic trunk divides into the:
Right common carotid and the right subclavian arteries
The Left common carotid artery ascends into the:
Left side of the neck
The Left subclavian artery travels to the:
Over the left first rib, toward the left upper limb
Nerves of the superior mediastinum:
Cardiac plexus, phrenic nerves, vagus nerves, and left recurrent laryngeal nerve
Phrenic nerve innervation
Motor: diaphragm
Sensory: fibrous pericardium & parietal layer of serous pericardium
-mediastinal pleura & central part of diaphragmatic pleura
- parietal peritoneum on undersurface of diaphragm
Vagus nerve originates from the:
Ventral surface of the brain stem
The vagus nerve innervation:
Root of neck: palate, pharynx, and larynx
Thorax: esophagus, trachea, heart, bronchi, and lungs
Abdomen: terminal esophagus, stomach, and intestinal tract as far as left colic flexure
Nerves that take place in esophageal plexus?
Left vagus nerve and right vagus nerve
Where are the anterior and posterior vagal trunks formed?
Close to the diaphragm, left is anterior and right is posterior
Function of both Left and Right Recurrent Pharyngeal Nerves
Innervates trachea, esophagus, and all intrinsic muscles of layrnx except cricothyroid muscle
Origination of Left and Right Recurrent Laryngeal Nerve
Left - from left vagus nerve as it crosses left side of aortic arch
Right- from right vagus nerve in root of neck
Injury to a recurrent laryngeal nerve can cause:
Hoarseness or dysphyonia
Paralysis of both recurrent laryngeal nerves can cause:
Aphonia and inspiratory stridor
Where is the Trachea located?
Anterior to the esophagus
Trachea divides into the..
Right main/primary bronchus and left main/primary bronchus
The c-shaped incomplete rings around the trachea are made of..
Hyaline cartilage
Holding the open ends of the incomplete rings is the…
Trachealis muscle
What is the carina?
an internal ridge where the trachea divides, formed by the posteroinferior projection of the last tracheal cartilage
Function/location of Esophagus?
Connects the pharynx to the stomach, descends though superior mediastinum and posterior mediastinum
What is the esophageal hiatus?
Where the esophagus pierces the diaphragm before it becomes continuous with the stomach
What is the thoracic duct?
A major lymphatic vessel that extends from the abdomen to the neck
Where is the Posterior Mediastinum?
Area posterior to the pericardial sac, anterior to T5-T12 vertebrae, inferior to the ‘line’ marking the superior mediastinum, and superior to the diaphragm
What is in the Posterior Mediastinum?
Esophagus, esophageal plexus, thoracic aorta, Azygos venous system, thoracic duct, thoracic sympathetic trunk
What is the aortic hiatus?
Where the thoracic part of the descending aorta pierces the diaphragm
Where does the blood in the Azygos vein drain into?
The superior vena cava
Azygos venous system consists of:
Azygos vein, hemiazygos vein, and accessory hemiazygos vein
Function of the Azygos Venous System
to drain blood from body walls of thorax and abdomen
Receives venous blood from some thoracic structures
What is the cisterna chyli?
An enlarged region of the lymphatic vessel, which is the beginning of the thoracic duct
Where does the thoracic duct end?
At the Union of left subclavian vein and left internal vein
Function of the Thoracic duct?
To collect lymph from the lower limbs, pelvis, abdomen, left side of thorax, left side of head and neck, and left upper limb
Where is the Thoracic sympathetic trunk?
Inferior to the cervical sympathetic trunk and superior to the lumbar sympathetic trunk
What do the splanchnic nerves of the thoracic sympathetic trunk do?
Carry preganglionic sympathetic fibers to prevertebral ganglia in the abdomen for innervation of the abdominal viscera
