Anatomy - oxygen supply and exchange week 1 Flashcards
which ribs are most commonly fractured?
4th-10th
which ribs are least commonly fractured?
1-3 as they are protected by the clavicles
then 11-12 as they are mobile
risk of rib fractures in children
less likely to sustain rib fractures because their ribs are more elastic
what is the weakest part of the rib?
anterior to angle
what are the contents of the superior thoracic aperture?
sternohyoid muscle sternothyroid muscle thymic remnants trachea recurrent laryngeal nerves oesophagus thyroid veins thoracic duct internal thoracic artery sympathetic trunk intercostal vessels ventral ramus of T1 common carotid artery subclavian arteries vagus nerves brachiocephalic trunk brachiocephalic vein phrenic nerves
carina
division of trachea into 2 main bronchi
T4/5 level
signs and symptoms of tension pneumothorax
pleuritic chest pain SOB hypotension tracheal deviation reduced breath sounds hyperresonance on percussion raised JVP diaphragm pushed down kinking of vena cava worsening signs haemodynamically unstable respiratory distress reduced chest expansion distended neck veins
haemodynamically unstable
hypotension
tachycardia
elevated respiratory rate
respiratory distress
cyanosis
restlessness
diaphoresis
what is diaphoresis ?
excessive abnormal sweating
what is a needle thoracostomy?
immediate insertion of large-bore needle into 2nd intercostal space along midclavicular line
where should a chest tube be placed?
4-5th intercostal space
along nipple line
between anterior and median axillary line
always check CXR after insertion
thoracic outlet syndrome
compression of certain anatomical structures within the thoracic aperture
what is commonly compressed in thoracic outlet syndrome?
brachial plexus
subclavian artery/vein
compression of brachial plexus
pain in neck and arm
atrophy of intrinsic hand muscles
compression of subclavian vein
swelling venous distension diffuse hand/arm pain heaviness risk of thrombosis of arm
compression of subclavian artery
mild arm ache fatigue pulselessness pain pallor paresthesia poikilothermia reduced BP >20mmHg in affected arm ischaemia - ulcerations and gangrene
what is poikilothermia?
inability to control body temperature
when does haemothorax require surgery?
if >1500ml of blood has accumulated or there is ongoing production of >200ml of blood per hour
when the haemothorax cannot be treated/bleeding stopped by catheter or chest drain
most common cause of haemothorax?
penetrating trauma
gun/stab wounds
thoracic-abdominal injury
any wound below nipple line or inferior to tip of scapula
level of suprasternal notch
T2/3
level of sternal angle/ angle of louis
T4/5
level of inferior angle of scapula
T8
level of xiphisternum
T9
level of lowest part of costal margin
10th rib - L3
top part vs bottom part of rib
top part = blunt
bottom part = groove for intercostal nerve, artery and vein
fracture of lower ribs
can penetrate liver, spleen, diaphragm, abdominal viscera or chest cavity
what can fracture of the first rib cause injury to?
brachial plexus
subclavian artery or vein
pleural covering of apex of lung
apex of lung - causing pneumothorax
pathological fracture
brought on by coughing
sign of underlying bone pathology
breast, renal, prostate or lung metastases to bones
what is flail chest?
bifocal fracture of 3 or more adjacent ribs
segment of chest wall becomes unstable and free from rest of chest wall
this segment will move in on expiration and out on inspiration
needs surgical treatment/ventilation
what is a tension pneumothorax?
opening in pleura acts as a 1-way valve so air comes in on inspiration but valve closes on expiration so air cannot escape again
positive intrapleural pressure collapses lung so hypoxia and mediastinal shift occurs
pulmonary collapse
pleural cavity becomes real space
diaphragm elevates on affected side
ribs come closer together and narrow intercostal spaces
mediastinal shift towards the affected side
collapsed lung appears dense
what is primary atelectasis
collapse of previously inflated lung
what is secondary atelectasis
where mucus plugs develop and cause additional collapse
treatment of tension pneumothorax
medical emergency
large bore cannula into mid clavicular line into 2nd costal space
when bubbles stop it is drained
risk of cardiac arrest
visceral pleura innervation
afferent nerves
nociception
sympathetic fibres of upper thoracic spinal nerve sensory ganglia - autonomic
what is the visceral pleura sensitive to
not pain
sensitive to chemical burns
parietal pleura innervation
very sensitive to pain and supplied by intercostal nerves - somatic general sensory
irritation may produce local or referred pain
pain caused by irritation of phrenic nerve
referred to root of neck and over shoulder
where to give intercostal nerve block
just below rib
to avoid the intercostal neurovascular bundle go above rib
how to give an intercostal nerve block?
just below rib
draw back to ensure not in vein/artery
anaesthetic injected around intercostal nerve trunk
complete loss of sensation not usually achieved - overlap between adjacent dermatomes
2 or more intercostal spaces/nerves need to be anaesthetised for complete loss of sensation at a particular region of thoracic wall
thoracocentesis
obtain fluid sample or remove blood/pus from pleural cavity
hypodermic needle inserted superior to rib
where is a chest tube inserted?
incision into 5/6th intercostal space in mid-axillary line - nipple level
what is a haemothorax?
accumulation of blood and fluid in hemithorax
what does haemothorax do?
compresses lung
prevents adequate ventilation
can cause hypovolaemic shock
management of haemothorax?
simultaneous drainage and replacement of blood
chest drain required
thoracotomy
what is a thoracotomy?
anterior cur through costal cartilages or posterior/lateral cut between intercostal space and retractor - 5-7th intercostal spaces
rapid thoracotomy
clamshell
used in trauma - blunt trauma
gives good access to all parts of mediastinum
used in penetrating chest wound
uses of clamshell
cardiac tamponade release
to collapse and compress lung for haemostasis if unilateral lung injury
to compress thoracic aorta if exanguinating
apical lung cancer
tumours may disrupt recurrent laryngeal nerve and cause voice hoarseness
who is thoracic outlet syndrome most common in?
females 30-40 years old
symptoms/ signs of thoracic outlet syndrome
ulnar guttering
loss of intrinsics
loss of adduction and abduction of fingers
pain in neck and shoulder
weakness and paraesthesia over ulnar aspect of hand and forearm
axillary vein thrombosis
digital ischaemia
potential cause of thoracic outlet syndrome
cervical rib
diagnosis of thoracic outlet syndrome
neck x-ray
ultrasound arm
nerve conduction studies
venography
what makes up the thoracic cage?
12 pairs of ribs
rib costal cartilages
sternum
articulations of ribs
anterior and posterior
posterior rib articulations
all 12 articulate with vertebrae of spine
each rib forms 2 joints = costotransverse and costovertebral joints
costotransverse joint
between tubercle of rib and transverse costal facet of corresponding vertebrae
costovertebral joint
between head of rib, superior costal facet of corresponding vertebrae and inferior costal facet of vertebrae above
anterior rib articulation
varies depending on which rib
ribs 1-7 = attach independently to sternum
ribs 8-10 = attach to costal cartilages superior to them
ribs 11 and 12 = no anterior attachment and end in abdominal musculature
what are the muscles of inspiration?
accessory = sternocleidomastoid, scalenes group, pectoralis minor principal = external intercostals, diaphragm and interchondral part of internal intercostal muscles
what are the muscles of expiration?
quiet breathing = expiration results from passive, elastic recoil of the lungs, rib cage and diaphragm
active breathing uses muscles
what muscles are used in active expiration?
internal intercostals
abdominals
what is the intercostal space?
space between 2 ribs
how many intercostal spaces are there?
11
what are the contents of the. intercostal space?
essential respiratory muscles intercostal muscles - external, internal and innermost intercostal nerves intercostal arteries intercostal veins investing fascia
where is the intercostal neurovascular bundle found?
just below the rib
what are the compartments of thoracic cavity?
left pleural cavity
right pleural cavity
mediastinum
what are the divisions of the mediastinum?
anterior posterior inferior middle superior
what is the pleural cavity?
potential space between parietal and visceral pleura of lungs
contains pleural fluid, pleura and lungs
contents of superior mediastinum
thymus trachea oesophagus aortic arch brachiocephalic trunk left common carotid artery left subclavian artery internal thoracic arteries superior vena cava left superior intercostal vein brachiocephalic veins phrenic nerves vagus nerves left recurrent laryngeal nerve thoracic duct lymph nodes lymph vessels
contents of anterior mediastinum
portion of thymus adipose and connective tissue lymph nodes branches of internal thoracic vessels sternopericardial ligaments
contents of middle mediastinum
pericardium heart pulmonary trunk ascending aorta pulmonary veins superior vena cava inferior vena cava tracheal bifurcation main bronchi
posterior mediastinum contents
oesophagus oesophageal plexus thoracic aorta and its branches azygos and hemiazygos venous systems thoracic duct sympathetic trunk thoracic splanchnic nerves
what makes up the thoracic wall?
ribs associated costal cartilages thoracic vertebrae sternum intercostal muscles external, internal and innermost intercostal muscles internal and external membranes subcostal muscles transversus thoracis muscles serratus posterior levatores costrum muscles subcutaneous tissues skin
what are the joints of the thoracic wall?
costovertebral joints sternocostal costochondral sternoclavicular manubriosternal xiphisternal interchondral
costovertebral joints
between head of ribs and vertebral bodies/ intervertebral discs
costotransverse joints - between tubercle of rib and transverse process of vertebrae
sternocostal joint
sternum and costal cartilages
costochondral joint
costal cartilages and ribs
what makes up the thoracic cage?
12 pairs of ribs
rib costal cartilages
sternum
articulations of ribs
anterior and posterior
posterior rib articulations
all 12 articulate with vertebrae of spine
each rib forms 2 joints = costotransverse and costovertebral joints
costotransverse joint
between tubercle of rib and transverse costal facet of corresponding vertebrae
costovertebral joint
between head of rib, superior costal facet of corresponding vertebrae and inferior costal facet of vertebrae above
anterior rib articulation
varies depending on which rib
ribs 1-7 = attach independently to sternum
ribs 8-10 = attach to costal cartilages superior to them
ribs 11 and 12 = no anterior attachment and end in abdominal musculature
what are the muscles of inspiration?
accessory = sternocleidomastoid, scalenes group, pectoralis minor principal = external intercostals, diaphragm and interchondral part of internal intercostal muscles
what are the muscles of expiration?
quiet breathing = expiration results from passive, elastic recoil of the lungs, rib cage and diaphragm
active breathing uses muscles
what muscles are used in active expiration?
internal intercostals
abdominals
what is the intercostal space?
space between 2 ribs
how many intercostal spaces are there?
11
typical intercostal nerves
3rd-6th intercostal nerves
confined within their own intercostal space
connection with corresponding sympathetic trunk
where is the intercostal neurovascular bundle found?
just below the rib
what are the compartments of thoracic cavity?
left pleural cavity
right pleural cavity
mediastinum
what are the divisions of the mediastinum?
anterior posterior inferior middle superior
what is the pleural cavity?
potential space between parietal and visceral pleura of lungs
contains pleural fluid, pleura and lungs
contents of superior mediastinum
thymus trachea oesophagus aortic arch brachiocephalic trunk left common carotid artery left subclavian artery internal thoracic arteries superior vena cava left superior intercostal vein brachiocephalic veins phrenic nerves vagus nerves left recurrent laryngeal nerve thoracic duct lymph nodes lymph vessels
contents of anterior mediastinum
portion of thymus adipose and connective tissue lymph nodes branches of internal thoracic vessels sternopericardial ligaments
contents of middle mediastinum
pericardium heart pulmonary trunk ascending aorta pulmonary veins superior vena cava inferior vena cava tracheal bifurcation main bronchi
posterior mediastinum contents
oesophagus oesophageal plexus thoracic aorta and its branches azygos and hemiazygos venous systems thoracic duct sympathetic trunk thoracic splanchnic nerves
what makes up the thoracic wall?
ribs associated costal cartilages thoracic vertebrae sternum intercostal muscles external, internal and innermost intercostal muscles internal and external membranes subcostal muscles transversus thoracis muscles serratus posterior levatores costrum muscles subcutaneous tissues skin
what are the joints of the thoracic wall?
costovertebral joints sternocostal costochondral sternoclavicular manubriosternal xiphisternal interchondral
costovertebral joints
between head of ribs and vertebral bodies/ intervertebral discs
costotransverse joints - between tubercle of rib and transverse process of vertebrae
sternocostal joint
sternum and costal cartilages
costochondral joint
costal cartilages and ribs
sternoclavicular joint
clavicle and sternum
manubriosternal joint
manubrium and body of sternum
xiphisternal joint
sternum and xiphoid process
interchondral joint
costal cartilages and lower ribs
directions of internal and external muscles
external = inspiration
internal = expiration
perpendicular to each other
contents of intercostal space
intercostal muscles
intercostal muscle membranes
main and collateral intercostal vessels and nerves
naming of intercostal spaces
according to rib forming superior border of space
space below 12th rib doesn’t lie between ribs so = subcostal space
rhizotomy
posterior and anterior roots and rootlets are the only sites where motor and sensory fibres of a spinal nerve are segregated
nerve roots could be selectively sectioned to relieve intractable pain or spastic paralysis
how many intercostal nerves are there?
12 pairs of thoracic spinal nerves
11 intercostal nerves
anterior rami of T1-11 form intercostal nerves within intercostal spaces
subcostal nerve
anterior ramus of T12 runs inferior to 12th rib
what are the types of intercostal nerves?
typical and atypical
what do the typical intercostal nerves supply?
intercostal muscles serratus posterior parietal pleura skin of thoracic and abdominal walls anterior aspect of thorax and abdomen
atypical intercostal nerves
not confined to intercostal space
supply structures outside the intercostal space
1st,2nd and 7-11th intercostal nerves
T1 intercostal nerve supply
brachial plexus
skin of axilla
T2 intercostal nerve supply
intercostobranchial nerve
floor of axilla and upper medial aspect of arm
7-11th intercostal nerve supply
lateral cutaneous branches
anterior abdominal wall skin and muscles and parietal peritoneum via sensory branches
arterial supply of typical intercostal space
large posterior intercostal artery from thoracic aorta
small pair of anterior intercostal arteries from internal thoracic/ mammary artery
venous drainage of intercostal space
intercostal veins accompany intercostal arteries and nerves
intercostal neurovascular bundle
life inferior to the rib along costal groove
vein, artery, nerve, with nerve most inferior
and nerve artery vein of superior border of the rib below
cutaneous innervation of anterior thoracic wall
supraclavicular nerves - C3 and 4
T4 dermatome
nipple
T10 dermatome
umbilicus
what is referred pain?
pain felt away from site of cause
referred pain from coronary artery disease
medial side of arm
referred pain from disease of thoracic wall
dermatome that extends across the costal margin into the anterior abdominal wall
referred pain from PE/pneumonia
if costal parietal pleura involved abdominal pain and tenderness and rigidity of abdominal musculature
uses of intercostal nerve block
repair of thoracic or abdominal wall lacerations
relief from rib fracture
to allow pain free respiratory movements
thoracostomy tube insertion
herpes zoster infection/ rash distribution
infection of spinal ganglia
sensory neuropathy with dermatomally distributed skin lesions - shingles affects the dermatome of the infected spinal nerve
innervation of thoracic viscera
autonomic
sympathetic supply of thoracic viscera
cardiac branches = T1-5
T1-L2 sympathetic chain
what does sympathetic innervation of thoracic viscera do?
increases rate and strength of cardiac contraction
dilates coronary arteries
parasympathetic supply of thoracic viscera
craniosacral outflow
cranial nerves 10,9,3,7 and S2-4
main contributor is vagus nerve
what does parasympathetic innervation of thoracic viscera do?
decreases rate and strength of cardiac contraction
constricts coronary arteries
lateral horn of spinal cord
autonomic horn
gives rise to sympathetic and parasympathetic nerves
innervation of heart
cardiac plexus
sympathetic supply
innervation of SAN and AVN
cardiac plexus
visceral afferent fibres
convey reflexive.subconscious sensation and nociceptive sensation fibres from heart
detect stretch and chemical irritation
what makes up the cardiac plexus?
sympathetic, parasympathetic and visceral afferent fibres
what does atropine do?
speeds up heart rate in bradycardia
parasympathetic antagonist
innervation of lungs and visceral pleura
vagal, sympathetic and visceral afferent fibres contribute to anterior and posterior pulmonary plexuses
parasympathetic fibres to lungs and visceral pleura
motor to smooth muscle of bronchi
inhibition to pulmonary vessels
secretomotor innervation to glands
parasympathetic effect on lungs
bronchoconstriction
vasodilation
increased gland secretion
sympathetic fibres to lungs and visceral pleura
inhibition to bronchial smooth muscles
inhibition to alveolar glands
motor to pulmonary vessel smooth muscles
sympathetic effect on lungs
bronchodilation
decreased secretions
vasoconstriction
what innervates the parietal pleura
intercostal nerves
what innervates intercostal muscles?
intercostal nerves
sympathetic innervation of pulmonary vs coronary vessels
vasoconstriction of pulmonary and vasodilation of coronary
what is pleurisy?
sharp pain due to irritation of peripheral parietal pleura
irritation of diaphragmatic pleura
referred pain to neck and shoulders
parasympathetic antagonists
used in asthma
bronchodilator
ipratropium - anticholinergic
damage to phrenic nerve
traumatic injury above C3 = bilateral phrenic nerve paralysis and respiratory arrest
mediastinal/lung tumours may involve the phrenic nerve and cause unilateral diaphragmatic paralysis
new raised hemidiaphragm on CXR may indicate mediastinal malignancy
