diaphragm, mechanism of respiration, surface projections Flashcards
describe the stricture of the thoracic diaphragm?
musculotendinous sheet separating thoracic and abdominal cavity
- central tendon, surrounded by muscle
- inverted J
- domed structure (right is 1cm higher than the left)
when maximally expired, what will the right and left dome reach to?
right dome reaches rib 5 level
left = 5th intercostal space
what are the attachments of the diagram?
sternal attachments?
costal attachment?
attaches to the inferior thoracic aperture:
sternal part = diploid process (T8/9 vertebral levels)
costal part= costal cartilages 7-10, ribs 11 and 12
what are the 4 lumbar attachments of the diaphragm?
- right and left crura
- median arcuate ligaments
- medial acute ligaments
- lateral arcuate ligaments
what are the right and left crura attachments?
what are the median arcuate ligaments made from?
1- left L1 to L2, right L1 to L3 bodies, anterior longitudinal ligament and IV discs
2- median arcuate ligaments will be formed by the crura
what are the medial arcuate ligaments made from?
what are the lateral arcuate ligaments made from?
medial arcuate ligaments = thickened poses major fascia spanning L1 vertebral body and transverse process
lateral arcuate ligaments = thickened quadrates lumborum fascia
what are the diaphragmatic attachments?
what is it continuous with?
what level is this attachment at?
- insertion to central tendon
- continuous with fibrous pericardium
- central tendon at level of Xiphosternal synchondrosis
what are the 3 major openings in the diaphragm?
1- caval opening
2- oesophageal hiatus
3- aortic hiatus
what level is the naval opening at?
what structures pass through it?
what are the IVC connections?
1- level of T8, through central tendon
2- IVC and right phrenic nerve
3- IVC is connected to the margins so diameter changes during action of diaphragm (widens during contraction)
at what level is oesophageal hiatus?
what travels through it?
1- level T10, within fibres of right crus 9which have sphincter function)
2- oeopghagus, right and left vagal trunks, oesophageal branches of left gastric vessels.
at what level is the aortic hiatus?
what passes through here?
is the aorta effected by the actions of the diaphragm?
1- level T12, posterior to the median arcuate ligaments
2- aorta, thoracic ducts
- sometimes azygous and hemiazygous veins
(if they don’t pass through here, they will pass through the crura)
aorta is not effected by the actions of the diagram.
what 6 smaller structures will also cross the diaphragm?
1- left phrenic nerve
2- sympathetic trunks (posterior to medial arcuate ligaments)
3- greater, lesser and least splanchnic nerve through crura
4- intercostal nerves
5- superior epigastric vessels
6- musculophrenic vessels
arterial supply of diaphragm:
superior surface?
inferior surface?
superior surface:
1- superior phrenic from thoracic aorta
2- musculophrenic from internal thoracic
inferior surface:
1- inferior phrenic from abdominal aorta
describe the venous drainage of the diaphragm?
right side?
posterior superior surface veins will drain where?
where will the left phrenic vein drain?
essentially minor arteries
- superior phrenic vein on the right
- some of the posterior superior surface veins will drain to azygos/hemiazygous system
- left phrenic will drain to suprarenal then renal vein
innervation of the diaphragm?
where is the additional peripheral sensory innervation from?
1- phrenic nerve (C3, C4, C5)
Motor, sensory to central diaphragm (and partial pleura and pericardium)
2- additional peripheral sensory innervation from intercostals (T5-T11) and subcostals (T12) nerves
overview of breathing
1- at rest, inspiration is mostly driven by the thoracic diaphragm (external intercostal contribute)
2- diaghragm contraction increases thoracic volume, drawing air into lungs
3- gases exchange occurs
4- diaghragm relaxes, thoracic volume falls and air is inhaled
5- exhaling at rest is passive (elastic recoil)
6- higher demand for O2/ CO2 removal can involve accessory muscles
7- smooth movement is aided by the pleurae
inspiration?
- peripheral muscle of diaphragm contracts
- domes descend
- external intercostals act to move ribs superiorly and laterally
- thoracic volume increases and air is drawn in to compensate for the volume change
forced inspiration?
1- diaghram can aid in creasing thoracic volume by raising ribs when anchored via pericardium
2- minimises costodiaphragmatic recess
3- accessory muscles can increase force/speed of inspiration but not alter the volume of air inspired
what 4 actions are involved in forced expiration and what are the 4 muscles involved?
fixing ribes = SCM, scalenes, trapezius
inspiration = pectorales major and minor
inspiration and expiration = lat dorsi
expiration = abdominal wall muscles
surface anatomy of the lungs and pleura?
- apex = 3cm superior to the mid clavicle
- at middle from 2nd to 6th CC on the right
- deviation laterally between 4th to 6th CC on the left
surface anatomy of the lungs?
- midclavicular line - 6th rib
- midaxillary line - 8th rib
- scapular line and midline (posteriorly) - 10th rib
surface anatomy of pleurae?
add 2 ribs to the level of the lungs
- midclavicular line - 8th rib
- midaxillary line - 10th rib
scapular line and midline (posteriorly) -12th rib
surface anatomy - oblique fissures
posteriorly=
laterally=
anteriorly=
posteriorly = level T3/T4
laterally = midaxillary line (5th intercostal space)
anteriorly = rib 6
surface anatomy of the horizontal fissure?
where will the horizontal and oblique fissure merge?
moving lateral from sternum, 4th rib/intercostal space
merges with oblique fissure at 5th rib
surface anatomy- 4 anterior auscultation sites?
1- apex of right lung
2- superior lobe of right lung
3- middle lobe of right lung
4- inferior lobe of right lung
surface anatomy- 3 posterior auscultation sites?
1- apex of lung
2- superior long of left lung
3- inferior lobe of left lung
what are the 2 lungs recesses?
costodiaphragmatic
costomediastinal
costodiapghragmatic recess:
where is it?
what is it?
what is it a site of?
how do you treat this?
1- it is in the space below lungs around periphery of diagram
2- it is a double fold of parietal pleural
3- it is a site of fluid collection
4- needle angled upwards at 9th intercostal space on mid axillary line during expiration can remove the fluid
costomediastinal recess:
where is it?
what is it?
where is it more pronounced?
1- behind manubrium
2- is It made of costal and mediastinal pleura
3- it is more pronounced on the left
- lingual partly occupies during breathing
pneumothorax:
what is it?
how are the lungs still held in place?
what can they be?
- lungs tend to a collapse state due to their elasticity
(air enters pleural space) - they are held in place against thoracic wall by surface tension of pleural fluid between the visceral and parietal pleura
- can be traumatic or spontaneous
chest drain:
does what?
inserted where?
1- used to evacuate air or fluid from pleural space
2- safety triangle
what are the borders of the safety triangle?
lateral?
anterior?
apex?
base?
lateral border = pectorals major
anterior border = latissimus dorsi
apex = towards axilla
base = nipple/5th intercostal space
what can an incorrect placement of chest drain cause?
risk perforating the pericardium, part or liver
what is flail chest?
when does it occur?
- it is paroxical chest wall motion, loose section of the thoracic wall is drawn inwards upon inspiration
- occurs after severe trauma (fracture > 3ribs)
In a traverse section of the thorax, what will you find at:
T12
T9
T5
T2
T12 = transverse colon
duodenum
pancreas
costodiaphragmatic recess
liver
spleen
T9=
- liver
- lungs
- aorta
- oesophagus
- IVC
- left ventricle
- right ventricle
T5=
- SCV
- ascending aorta
- carina
- pulmonary trunk
- descending aorta
- oesophagus
- azygous vein
T2=
- left lung apex
- rib 1
- trachea
- manubrium
- clavicle
