THORACIC CAVITY:
Divided into:
1-mediastinum: central part contains heart (in part), aorta & trachea.
2-pleural sacs: contains the lungs.
*Thoracic cavity is bounded sup. By thoracic inlet, inf. By outlet which is called the diaphragm.
LUNGS:
-each of them is a pyramidal shaped, red, spongy & softy organ.
-located inside the pleural cavity.
PLEURA:
-it's a thin translucent continuous membrane surrounding each lung & lining thoracic cavity, so it's divided into 2 parts:
1-visceral pleura: the inner part which is lining the lungs, closely fixed to the structure of the lung itself taking its shape.
2-parietal pleura: it's part of the pleura that lines the thoracic cavity, divided into 4 parts named according to structures related to them:
1-cervical p. (not thoracic): located above the level of clavicle @ the root of the neck, that’s why(try @ home☺) if a knife insert above clavicle it will insert cervical p., & the cavity won't stay potential space(vacuumed).
2-costal pleura: 2nd & largest part, lining the ribs & its CC. (costal cartilage).
THE LARGEST→ that’s why the commonest to be involved in diseases or exposed to air drafts
.
3-diaphragmatic p.: it lines superior Surface of the domes of diaphragm.
*diaphragm has 2 domes; right & left.
4-mediastinal p.: it's med. , related to the structures in the mediastinum especially The heart trachea and mediastinum.
*we divide them in these parts to know what are the related structures to them.
**suppose that we've a problem:
1-@ the neck → cervical p. will be involved.
2-@ the ribs (# rib) → costal p. will be involved.
3-in peritonium→ diaph. P. will be involved.
4-in the heart or trachea or mediastinum→ mediastinal will be involved.
*parietal p. is highly sensitive to pain & stretching, while visceral p. is insensitive because its supplied by A.N.S (autonomic nervous system).
**in pneumonia, the pain comes from bronchi not from pleura or tissue of the lungs, so we call them bronchitis (not lungitis) because of the reason above.
PLEURAL CAVITY:
*the lung has TIDAL VOLUME: means full capacity of inflation of lung, if it wont inflated full, this means the patient suffering from DYSPNEA.
TRACHEA:
-wind(air) pipe tube ~ 5 inches in length= 13 cm.
-extending from lower end of larynx (precisely from C6V) to the sternal angle where, it bifurcates into right & left primary bronchi (singular: bronchus).
-form of ~ 20 "C" shaped cartilaginous rings defected post. Where it replaced by a muscle called trachealis.
*the lower end of larynx located @ the level of C6.
**suppose we've a patient with bronchial asthma, his trachealis m. will compress the trachea causing constricted breath, but when he takes the inhaler trachealis will widen and relax.
***trachealis is involuntary m. → supplied by A.N.S → part of it sympathetic n. s. →so we give it sympathomimetic drugs.
****remember that trachea form of malleable (flexible) C shaped rings.
TRACHEA:
-located ant. To esophagus, that’s why if we swallow a large bolus of food, it 'll compress the trachealis & 'll cause hard breathing, so we should push him to bring that bolus in or out to allow trachealis & trachea returning back to its normal diameter.
-located post. to aorta.
-behind esophagus we've V.C.
*so we've this order from ant. To post.:
aorta → trachea→ esoph. → V.C
these are neighbors standing in front of each others, so any problem in one will affect the others because they 'll disturb their function & others.
-trachea bifurcated (bi=2) into right & left primary bronchi, each of them go to its specific lung:
1-right 1° bronchus:
-vertical in direction..
-wider in diameter.
-shorter in length.
*that’s why inhaled foreign body (e.g. chickpea) usually go to the right, because it's straight & wider→ examine the right not the left.
2-left 1° bronchus:
-horizontal.
-narrower.
-longer.
-crossing the curve of aortic arch (concavity of aortic arch), so problem in the left 'll affect blood current in aorta.
-each 1° bronchus 'll give finally 10 bronchial branches.
1(trachea) → 2(bronchi)→ each give 10
LUNGS: 
GENERAL FEATURES:
1]apex @ the root of neck.
2]base over domes of diaph. (1,2 coz pyramidal)
3]3 borders:
a-ant. Sharp border.
b-inf. Border: which is sharp on the periphery of the domes of diaph.
c-post. border: smooth & rounded, located @ both sides of V.C.
*the lungs extending from sternum ant. To the post. part of V.C post., that’s why when we put our stethoscope we put it on the back to listen to the lunges clearly.
4]3 surfaces:
a-costal surface(sternocostal surface):the widest , below sternum, C.C & ribs ("C" shaped below them).
b-inf. Surface: called diaphragmatic surface, related to the domes of diaph.
c-mediastinal surface: med. & related to the structures in mediast.
LEFT LUNG:
-its ant border is notched by the heart forming cardiac notch to expose the ant surface of the heart.
-has 2 lobes: sup. & inf. Lobe separated by oblique fissure.
-it grows (developed) inside a small space, that’s why it's:
1-less functional than right..
2-has 2 lobes.
3-has 1 fissure.
4-longer.
5-narrower.
6-lighter in wt.
7-related to arterial supply of the heart à with the highest blood pressureà so receiving higher blow from heart.
RIGHT LUNG:
-it grow in larger space that’s why it's:
1-more functional than left.
2-heavier. 3-shorter. 4-wider.
5-has 3 lobes: sup. , middle & inf. Lobes.
6-separated by 2 fissures: oblique & horizontal fissures.
7-related to the right venous side of the heart, i.e , with the lower blood pressure.
*pressure on the right ~30 mmHg, while on the left ~120 mmHg .
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