Thorax: Endothoracic Views Flashcards
What does the mediastinum consist of?
The thymus gland, trachea, pericardial sac and heart, major arteries and veins.
How is the mediastinum subdivided?
The transverse plane which runs at the intervertebral disc btwn T4/T5 separates it into the superior and inferior mediastinum.
The pericardial sac then further subdivides the inferior mediastinum into the anterior, middle and posterior mediastinum.
Where does the phrenic nerves arise from?
The cervical plexus, specifically in the anterior rami of C3-C5 spinal nerves.
What accompanies the phrenic nerves?
Pericardiacophrenic vessels
How do the phrenic nerves leave the thorax? (2)
The right phrenic nerve leaves the thorax with the IVC via the caval hiatus of the diaphragm (T8).
The left phrenic nerve leaves the thorax by piercing through the diaphragm near the apex of the heart.
To which part do the phrenic nerves provide innervation?
To the diaphragm
To which parts do the phrenic nerves provide innervation?
-Diaphragm
-Fibrous pericardium
-Mediastinal and diaphragmatic pleura.
-Parietal layer of serous pericardium.
Which subdivisions of the mediastinum do the vagus nerves pass through?
The superior and posterior mediastinum.
What are the roles of the vagus nerves in the thorax?
They provide parasympathetic innervation to the thoracic viscera.
Carry visceral afferents from the thoracic viscera which relay information about normal physiological processes and reflex actions, not pain.
How do the vagus nerves leave the thorax?
They leave with the oesophagus via the oesophageal hiatus of diaphragm (T10).
Which branches are given off by the vagus nerves while passing through the superior mediastinum? (3)
-Cardiac plexus
-Pulmonary plexus
-Oesophagus plexus
What does the plexus converge to form just above the diaphragm? (2)
Anterior vagal trunk and posterior vagal trunk.
Two parallel nerve cords that extend at either side of the vertebral column?
Sympathetic trunks
Two type of branches from ganglia
1st type
-Branches from upper 4/5 ganglia.
-Consists of mainly postganglionic sympathetic fibers.
-Supply various thoracic viscera.
-Relatively small
2nd type
-Branches from lower 8 ganglia.
-Consists mainly of preganglionic sympathetic fibers.
-Supply various abdominal and pelvic viscera.
-Large branches.
What are the three thoracic splanchnic nerves formed by the 2nd type of the branch from ganglia?
Greater splanchnic nerve: arises from 5-9 ganglia.
Lesser splanchnic nerve: arises from 10 and 11 ganglia.
Least splanchnic nerve: arises from the 12th thoracic ganglion.
