Anatomy Of Lungs

ANATOMY OF LUNGS

• Lungs are pyramidal or conical shaped organs.
• Right lung is shorter, wider & heavier (625 gm) than left lung (565 gm).
• Each lung has : 

1. Apex 
2. A base 
3. Three borders(anterior. posterior & inferior)   
4. two surfaces (costal & medial)

APEX

• Lies in inlet of thorax, 2.5 cm above clavicle.
• It is related anteriorly to subclavian artery & vein.
• Posteriorly it is separated from neck of first rib by (from medial to lateral) sympathetic trunk, first posterior intercostal vein, superior intercostal artery, & ascending branch of ventral ramus of 1st thoracic nerve.

BASE

• Base in concave & rests on the diaphragm, which separates the right lung from the right lobe of liver, & the left lung from left lobe of liver, the fundus of stomach & spleen.

BORDERS

• ANTERIOR BORDER– Thin & is shorter than posterior border. Anterior border on left side shows a wide cardiac notch below the level of 4th costal cartilage.
• POSTERIOR BORDER- Thick & ill defined. It extends from C7 to T10.
• INFERIOR BORDER– separates the base from the costal & medial surface. Surface marking of inferior surface of lung is 2 level above the reflection of inferior surface of pleura i.e. 6th rib in midclavicular line, 8th rib in midmaxillary line, & 10th rib at lateral border of errector spinae.

SURFACES

• COSTAL SURFACE– Large & convex.
• MEDIAL SURFACE– Divided into a posterior (or vertebral) surface & an anterior (or mediastinal) surface.
• VERTEBRAL SURFACE– is related to vertebrae, intervertebral disc, posterior intercostal vessels & splanchnic nerves.
• MEDIASTINAL SURFACE– is related to various structures (differ on right & left side).

1. Right side: Right atrium & auricle, right ventricle (partly), SVC, right brachiocephalic vein, azygous vein, esophagus, IVC, trachea, right vagus & right phrenic nerve.
2. Left side: Left ventricle, left auricle, infundibulum, right ventricle (partly), pulmonary trunk, arch of aorta, descending thoracic aorta, thoracic duct, left subclavian artery, esophagis, left brachiocephalic vein, left vagus & phrenic nerves, & left recurrent laryngeal nerve.