topic 7: The surface projections of thoracic organs. Topography of the thoracic cavity, the divisions of the mediastinum

Question 1

heart prjections

Answer 1

apex-5th intercostal space, cm left from middle of sternum to midclavicular line
opening of SVC in right atrium- stenrla end of 3rd costal cartilage on right side
projection of coronary groove on left - 2cm to right from sternal end of sixth rib
projection of coronary grove on right-3ccm to left from sternal end of 3rd rib

Question 2

lungs projection

Answer 2

apex-from above plane of sup portion of clavicle
then @ costal cartlage of 4th rib left lung turns 3-4cm laterally due to cardiac noth
@ 6th rib it extends to margin of stenrum
lower border-line running laterally from xyphoidprocess to vertebral column exactly @ sup portion of vertal end of 11 rib
lower border of left lung begins 2 fingers to the left from middle portion of xyphoid process

Question 3

diaphragrm

Answer 3

Separates the thoracic and abdominal cavities.
Its dome-shaped surface projects up to the 5th rib anteriorly in the midclavicular line during quiet respiration.

Question 4

thymus

Answer 4

Located in the superior mediastinum, anterior to the great vessels.
Its size and prominence decrease with age.

Question 5

trachea

Answer 5

Extends from the larynx (C6) to the carina (T5-T6) where it bifurcates into the main bronchi.
Lies anterior to the esophagus and is palpable in the lower part of the neck.

Question 6

Topography of the Thoracic Cavity

Answer 6

Boundaries: Superiorly by the thoracic inlet, inferiorly by the diaphragm, laterally by the ribs and intercostal muscles.
Contents: Lungs (in pleural cavities), heart (in pericardial cavity), esophagus, major blood vessels, nerves, lymphatics, and thoracic duct.

Question 7

Divisions of the Mediastinum

Answer 7

-visceral compartment in
the middle of the thoracic cavity
-Thoracic cavity = Right pleural cavity + Mediastinum + Left
pleural cavity

borders:
Anterior border: Sternum
Posterior border: Thoracic part of the vertebral column
Lateral border: Mediastinal pleura
Inferior border: Diaphragm
Superior border: Thoracic inlet

divisions: Primary dividing plane: From the sternal angle to the
intervertebral disc between Th IV and V vertebrae
(horizontal plane above the heart, so-called ”transthoracal
plane”)

• Superior mediastinum / supracardiac mediastinum
• Inferior mediastinum = Anterior mediastinum, Middle
  mediastinum and Posterior mediastinum

Question 8

contents of divisons

Answer 8

1.Anterior mediastinum
 Sternopericardiac ligaments
 Internal thoracic vessels
 Parasternal lymph nodes

2.Middle:
Heart
 Pericardium
 The initial (Ascending aorta, Pulmonary trunk)
or last parts (SVC, IVC, Pulmonary veins) ofthe great vessels
 Phrenic nerves
 Pericardiacophrenic vessels

Sup:
thymus
SVC & tributaries
aoric arch w/ branches

Posterior:
-Oesophagus (C VI  Th XI), thoracic part
 Vagus nerves (Cranial nerve X)
 Thoracic aorta + parietal and visceral branches
 The azygos vein and hemiazygos vein with tributaries
 Thoracic duct
 Sympathetic trunk
 (Thoracic) splanchnic nerves