thoracic cavity

Question 1

where is the thorax located

Answer 1

is the entire region from neck to abdomen

Question 2

boundaries of the thorax

Answer 2

superiorly: thoracic inlet (T1, 1st rib n manurbim)
infreioly: thoracic outlet (diaphragm)
anterioly: sternum n costal cartilages
posteriorly: thoracic vetrebrae
laterally: rib n intercostal muscles

Question 3

what is the contents of the thorax

Answer 3

boney ribcage: sternum, ribs n thoraci vert

organs: lungs (surrounded by pleural cavities), heart (located in mediastinum enclosed by pericardium) , oesophagus (connect throat to stomach), trachea (airway) and thymus

major arteries: aorta (ascending and descending), pulmonary arteries

major veins: superior/ inferior vena cava

lymphatic: thoracic duct, lymph nodes

nerves: phrenic (diaphragm), vagus, sympathetic

muscles: diaphragm, intercostal, accessory

Question 4

location of the heart

Answer 4

in mediastinum, behind sternum and pointing left, lying on diaphragm
- weighs

Question 5

location of lungs in the thorax

Answer 5

extending from just above the clavicle to around T10

Question 6

features of thr lungs

Answer 6

thymus gland: produces and matures Tcells involved in the immune system

right lung; divided into 3 lobes

left lung: divided into 2 lobes separated by 2 oblique fissure

carina: where trachea divides into right ad left main bronchi

Question 7

cavities within the chest

Answer 7

pleural cavities: surround each lung

mediastinum: in between the lungs

pericardial cavity: surround heart

Question 8

pleura

Answer 8

parietal covers outer layer of pleural cavity
visceral covers inner layer of pleural cavity

Question 9

pericardium

Answer 9

pericardial cavity
parietal covers outer layer on p cavity
visceral covers inner layer of p cavity

Question 10

where is mediastinum located

Answer 10

between pleural cavities

Anterior: Sternum and costal cartilages
Posterior: Thoracic spine
Superior: Thoracic inlet (1st rib, T1 n manubrium)
Inferior: Diaphragm
Lateral: Mediastinal pleura bounding the pleural cavities

Question 11

divisions of the mediastinum

Answer 11

• middle (heart)
• superior
• anterior
• posterior

Question 12

content of the mediastinum

Answer 12

superior: thymus, trachea, oesophagus, great vessels n nerves

anterior: fat connective tissue, part of thymus

middle: heart, pericardium, ascending aorta, pulmonary arteries and veins, SVC and main bronchi

posterior: oesophagus, descending aorta, thoracic duct, vagus nerves, sympathetic trunks

Question 13

what is the vagus nerves nd sympathetic trunks

Answer 13

VAGUS: stem from medulla oblongata and controls many involuntary movements, part of parasympathetic branch

SYMP: supply symmetric innervation to T1 TO L3, run from base of skull to coccyx

Question 14

great vessels of the mediastinum

Answer 14

lie within superior mediastinum and branches arise before passing thru the inlet

ARCH OF AORTA:
- brachiocephalic artery= supply right side of head n neck and right upper limb
- left common carotid artery= left side of head n neck
- left subclavian artery- left upper limb

SVC:
- brachiocephalic vein= drain from upper body
- left superior intercostal vein= collect from left 2nd n 3rd intercostal vein n drain into left brachiocephalic vein
- supreme intercostal vein= drain vein from 1st intercostal space directly into brachiocephalic veins

Question 15

what is the diaphragm shaped as

Answer 15

dome shaped muscle

Question 16

where is the diaphragm located

Answer 16

• inferior most aspect of the ribcage
• fills the inferior thoracic outlet
• acts as floor of thoracic cavity and roof on abdominal cavity
• separates thoracic from abdomen

Question 17

function of diaphragm

Answer 17

• primary muscle of respiration
• undergoes contraction and relaxation altering the volume of the thoracic cavity and lungs

Question 18

groups of muscular fibres in the diaphragm

Answer 18

• sternal = 2 segments that attach to back of xiphoid process
• costal = several wide segments that attach to inner surfaces of lower 6 ribs and costal cartilages
• lumbar = 2 pilars of tendon called musculotendinous crura attach to lumbar vertebrae

ALL TRAVEL MEDIALLY AND INSERT ONTO CENTRAL TENDON OF DIA

Question 19

what does central tendon fuse with

Answer 19

inferior surface of the pericardium and pleurae

Question 20

what are the diaphragm openings

Answer 20

AORTIC HIATUS (T12): aorta, thoracic duct n azygous vein (drain back of chest and abdomen to SVC)

OESOPHAGEAL HIATUS (T10) : oesophagus, vagus nerves

CAVAL HIATUS (T8): IVC

Question 21

diaphragm and breathing

Answer 21

Diaphragm contracts and flattens, moves downwards – inhalation
Diaphragm relaxes, returns to dome shape, moves upwards - exhalation