CVR session 2B- The pleura and lungs

Question 1

intercostal spaces-
external intercostal muscle? direction? purpose? features?

Answer 1

External intercostal muscle fibres are orientated antero-inferiorly, contraction of these pulls ribs superiorly (in active inspiration), closer to the sternum the msucle becomes membranous and forms external intercostal membrane.

Question 2

Internal intercostal muscle- direction? purpose?

Answer 2

Internal intercostal muscle fibres run posterior-inferior direction (perpendicular to external, contraction pulls robs inferiorly and are active in forced expiration

Question 3

innermost intercostal muscle- direction?

Answer 3

same orientation as internal intercostal muscles (posterior-inferior direction)

Question 4

Intercostal neurovascular bundle-

Answer 4

neurovascular bundle contains- vein, artery and nerve,
runs superior to the intercostal space between each layer of intercostal muscle, supplies intercostal muscle, skin and parietal pleura
travels in a costal groove on the deep surface of the rib (chest drains are placed in lower part of intercostal space to avoid the bundle)

Question 5

anterior arteries and veins that supply intercostal muscle? posterior arteries and veins that supply intercostal muscle?

Answer 5

anterior intercostal arteries are brances of the internal thoracic artery (branch of subclavian artery) and supply anterior parts, anterior intercostal veins drain into thoracic artery

posterior intercostal arteries are branches of the descending aorta , posterior intercostal veins drain into azygous system of veins

Question 6

nerves present in vascular bundles?

Answer 6

intercostal nerves are somatic and contain motor and sensory fibres. They innervate intercostal muscle, skin of chest and parietal pleura. can also carry sympatheic fibres

Question 7

pleura of the lungs- layers? space?

Answer 7

parietal pleura (visible) lines inside of thorax, visceral pleura (not visible) lines surface of lungs and extends down into the fissures, pleurae are continuos with eachother, pleural cavity inbetween them with pleural fluid

Question 8

names of the different pleura? what is costomediastinal recess? what is costodiaphragmatic recess?

Answer 8

cervical pleura- apex of lung
costal pleura- adjacent to ribs
mediastinal pleura- adjacent to heart and mediastinum
diaphragmatic pleura- adjacent to diaphragm

costodiaphragmatic recess is where costal pleura becomes continuous with diaphragmatic pleura.
costomediastinal recess lies in junction between costal and mediastinal pleura. These spaces allow lungs to expand during deep inspiration.

Question 9

innervation of pleura: parietal vs visceral

Answer 9

parietal pleura- intercostal nerves that innervate skin, somatic sensory fibres in these nerves carry info to consciousness
visceral pleura- autonomic sensory nerves, do not reach consciousness

Question 10

Lobes of the lung- number and name of lobes? fissures- different types and specific location?

Answer 10

• right lung has 3 lobes: superior, middle, inferior
• left lung has 2 lobes: superior and inferior (anterior extension of superior sits over heart- lingula

oblique fissures seperate each lobe (horizontal fissure between middle lobe and superior lobe in right lung), oblique - extend from 4th rib posteriorly to 6th costal cartilage anteriorly
horizontal- extend anteriorly from 4th costal cartilage and intersects oblique fissure

Question 11

surfaces of the lung?

Answer 11

costal surface- adjacent to rib
mediastinal surface - adjacent to heart and mediastinum
diaphragmatic surface - inferior surface of lung

indenation from adjacent structures e.g. ribs, ventricles etc.

Question 12

space between inferior border of lungs and parietal pleura?

Answer 12

costodiaphragmatic recess

Question 13

position of borders of lungs vs parietal pleura

Answer 13

apex of lung- superior to medial end of clavicle

inferior border of lungs-
6th rib midclavicular line
8th rib midaxillary line
10th rib just lateral to vertebral column

parietal pleura-
8th rib mid-clavicular line
10th rib midaxillary line
12th rib just lateral to vertebral column

Question 14

hilum of the lung- what is it? differnece in left and right lung?

Answer 14

region on mediastinal surface where pulmonary artery, pulmonary vein and main bronchus enter and exit lung.
-Hilum of right lung- pulmonary artery is anterior to main bronchus
-Hilum of left lung- pulmonary artery is superior to main bronchus

Question 15

whre does trachea bifurcate? what is the ridge of cartilage present there called?

Answer 15

trachea bifurcates at sternal angle and is internall marked by a ridge of cartilage called carina

Question 16

differnce in left and right bronchus?

Answer 16

right main broncus is shorter, wider and dscends more vertically than left (foreign body more likely to enter right lung)

Question 17

Bronchial tree:

Answer 17

main bronchus divides into lobar bronchi, 2 on left side, 3 on right side, lobar brochi then divide to segmental bronchi, 10 in right , 8/9 in left

Question 18

what is a bronchopulmonary segment?

Answer 18

each segmental bronchi supplies a bronchopulmonary segment, each segment supplied by own bronchi and blood vessel so 1 can be removed without affecting others

Question 19

whats present in trachea, brionchi and bronchioles walls?

Answer 19

trachea and bronchi- smooth muscle and cartilage
bronchioles- only smooth muscle

Question 20

bronchial arteries and veins- where from? where drain to?

Answer 20

• bronchial arteries from descending aorta supply lung tissue with oxygenated blood.
• bronchial veins return blood to the azygos system of veins

Question 21

role of parasympathetic and sympathetic in lungs?

Answer 21

autonomic nerves innervate the lungs:
- parasympathetic fibres stimulate constriction of bronchial smooth muscle and secretion from glands in bronchial tree
- sympathetic fibres stimulate relaxation of bronchial smooth muscle and inhibit gland secretion

Question 22

visceral afferents role in lungs?

Answer 22

visceral afferents (sensory fibres) acompoany autonomic nerves and relay sensory information from lungs and visceral pleura to CNS - not reach consciousness.

Question 23

lymph drainage in lungs- where to?

Answer 23

venous system via thoracic duct or right lymphatic duct

Question 24

Inspiration and expiration mechanics?

Answer 24

diaphragm is attached to xiphoid process, costal margin and lumar vertebrae

Central part of diaphragm is fibrous (central tendon)

When diaphragm contracts during inspiration muscle fibres of right and left domes pulled towards their peripheral attachments and the domes flatten. Increase in intrathoracic volume

Diaphragm relaxes and returns to it’s domed shape. This decreases intrathoracic volume and exepels air

Question 25

what nerves innervate diaphragm? where do they come from?

Answer 25

right and left phrenic nerves innervate the right and left sides of the diaphragm (somatic nerves formed from C3, C4, C5 and contian motor and sensory)

Question 26

3 planes of movement of chest cavity in ventilation?

Answer 26

vertical- contraction and relaxation of diaphragm
lateral- contraction and relaxation of intercostal muscles
antero-posteriorly (AP)- moveemnt of the sternum

Question 27

Ventillation-
role of pleural fluid
inspitration and expiration?

Answer 27

Pleural fluid creates surface tension between parietal and visceral pleura which keeps lung and thoracic wall stuck together. If punctured lung will colapse and ventilation is dysfunctional

Inspiration: diaphragm and external intercostal muscles contract, increase intrathoracic volume, external intercostal muscle pulls ribs superiorly and laterally, ribs pull sternum inferiorly and posteriorly, lungs recoiland decrease volume, pressure in lungs is lowere than atmosphreic pressure and air is drawn in.

Expiration: diaphragm and external intercostal muscles relax, decrease intrathoracic volume, internal intercostal muscle pulls ribs inferiorly, ribs pull sternum superiorly and anteriorly, lungs expand due to surface tension, pressure in lungs is higher than atmosphreic pressure and air is pushed out.

Question 28

muscles involved in breathing?
inspiration
expiration-
vigorous expiration
very vigrous exercise/forced breathing-

Answer 28

inspiration- active, uses diaphragm (no use of intercostal muscles)
expiration- passive
vigorous expiration-active, uses internal intercostal muscles
very vigrous exercise/forced breathing- active, use of accesory muscles

Question 29

clinical relevance: pleuritic chest pain

Answer 29

pleura are inflammed or injured, chest pain is sharp, localised and worse on inspiration

Question 30

clinical relevance: pulmonary embolism

Answer 30

blood clot in pulmonary circulation, formed typically in deep veins in leg and carried to pulmonary trunk where it blocks.

Question 31

clinical relevance: paralysis of the diaphragm

Answer 31

injry to phrenic nerve, C3-5 spinal nerves or C3-5 cord segements on 1 side may paralyse ipsilateral side of diaphragm

Question 32

clinical relevance: pneumothorax and haemothorax

Answer 32

pneumothorax- air in pleural cavity, tension pneumothorax occurs if pressure builds
haemothorax- collection of blood in pleural cavity