mediastinum Flashcards
where does the remenant of the thymus lie?
in the retromanubral layer
what is the contents of the mediastinal venous layer?(3)
- Rt and Lt brachiocephalic
- upper part of the SVC
- RTphrenic nerve
what is the contents of the mediastinal arterial layer?
. Arch of the aorta and its branches.
- Bifurcation of pulmonary trunk.
- Ligamentum arteriosum.
- Lt vagus and Lt pherenic
- Lt recurrent laryngeal nerve.
what is the contents of the mediastinal tubal layer?
. Trachea.
- esophagus.
- Rt vagus.
- Thoracic duct
- Tracheobronchial LNs
what is the contents of the mediastinal prevertebral layer?
. Sympathetic chain.
- Azygos vein.
- Longus coli muscle.
what is the contents of the anterior mediastinum?
- Remains of thymus
- Superior and inferior sternopericardial ligaments
- Mediastinal branches of internal thoracic artery
what is the contents of the middle mediastinum?
Pericardium & the structures inside it
what is the contents of the posterior mediastinum?
A. Descending thoracic aorta. B. Oesophagus. C. Thoracic duct. D. Rt and Lt Vagi. E. Rt and Lt Sympathetic chains. F. Azygos, sup. Hemiazygos & inf. Hemiazygos
what is the course of the thoracic duct?(beginning and termination)
it starts at the upper end of cisterna chyli at the upper border of the t12 goes to the opposite side(left) at t5
it ends at the root of the neck in the angle formed by the junction of the left subclavian and the internal jugular vein
what is the sympathetic trunk?
it is the sympathetic ganglia and the communications between them
how many ganglia does the sympathetic trunk contain?
12
the 1st thoracic ganglia may be fused with the cervical one forming?
stellate ganglion
thoracic sympathetic trunk and it’s nerves?(3)
1-greater splanchnic (T5-T9)
2-lesser splanchnic (T10-T11)
3-least splanchnic (T12)
what is horner syndrome?
t is due to injury of sympathetic chain
what is the symptoms of the horner syndrome?(4)
1- Ptosis (eyelid drop).
2- Myosis (constriction of the pupil).
3- Anhydrosis
4- Enophthalmos
what is the Origin, Termination and branches of the ascending aorta?
begins aortic orifice opposite the 3rd left intercostal
space
ends behind the 2nd right sternocostal junction by
becoming arch of aorta
Branches: Rt and Lt coronaries.
what is the Origin and Termination of the aortic arch?
It begins at the 2nd right sternocostal It passes first upwards, backwards and to the left
It ends T4 and T5 by becoming the descending thoracic aorta
what is the branches of the aortic arch?
3 large branches:
brachiocephalic, left common carotid and left subclavian arteries
A 4th small branch, the thyroideaima,
may arise from the arch and ascend to supply the thyroid gland
what is the Origin, Termination and branches of the descending aorta?
begins disc between T4 and T5 as the continuation of the arch of the aorta
It ends at the lower border of T12, by passing through the aortic opening of the diaphragm to continue as the abdominal aorta.
branches:
- posterior intercostal arteries (from 3rd to 11th).
- subcostal arteries.
- Two left bronchial arteries.
- Four or five oesophageal branches.
- Few small twigs to the pericardium, mediastinum and diaphragm
Clinically Important Points
1- Coarctation of the aorta: aortic coartication (narrowing) may involve the segment from the left subclavian artery to the ductus arteriosus. The latter remains patent and maintains the circulation to the lower parts of the body.
• If the obstruction is distal to the attachment of the ligamentum arteriosum, the circulation to the lower limb is maintained via collaterals between branches of the subclavian arteries and those of the descending aorta.
• 2- Aortic aneurysm: this is a localized dilatation of aorta which may compress the contents of superior mediastinum causing mediastinal syndrome. Rupture of weakened wall of aortic aneurysm causes severe haemorrhage which is often fatal if surgical intervention is not prompt
• 3- Clinically, embolism of the pulmonary trunk by a blood clot is a common cause of sudden death.
revise the vagus nerve in the lec mediastinum
what is the root values of the phrenic nerve
Root value : C3, 4 and 5.
revise the course of the right phrenic
what id the mediastinal syndrome
Compression of mediastinum by a tumor or
inflammatory mass, lymph nodes or retrosternal goiter leads to :
1- dyspnea ( compression of trachea).
2- dysphagia ( compression of esophagus).
3- hoarseness of voice( compression of Lt recurrent
laryngeal nerve).
4- ischemia( compression of aorta)
5- Non-pitting edema( compression of thoracic duct)
what is the blood supply of the esophagus
Upper third : inferior thyroid artery
Middle third ; descending thoracic aorta
Lower third : left gastric artery
Venous drainage ; upper third in inferior thyroid vein, middle third in azygous vein & lower third in left gastric vein
what is the start of the esophagus?
c6
what is the constrictions of the esophagus?
1- at junction with pharynx
2- where aortic arch & left bronchus cross its anterior surface
3- when esophagus passes in diaphragm
what is the start and end of the trachea
start in the neck, at the level of the lower border of C6, as a continuation of the larynx.
end n the thorax, at the level of the sternal angle (disc between T4/T5) by dividing into 2 principal bronch
Clinically Important Points on Trachea and Bronchi
- The trachea may be compressed or displaced by enlargement of lymph nodes or arch of aorta.
- The carina may become wider or distorted (seen by a bronchoscope) if the inferior tracheobronchial lymph nodes are involved in cancer.
- A foreign body which may enter trachea will pass more commonly to right bronchus because it is wider and more in line with the trachea
