Thorax Flashcards
What lies between the pleural cavities
The mediastinum
Where is the arch of the aorta
Superior mediastinum
It passes slightly left but is direct anteroposteriorly
What forms the superior vena cava
The brachiocephalic veins
Where is the thymus gland
In the inferior mediastinum (rudimentary in adults)
What is in the inferior mediastinum (6)
Pericardium Oesophagus Descending thoracic aorta Sympathetic trunks Thoracic duct Thymus gland
What does the pericardium fuse onto
Pulmonary trunk
Ascending aorta
Pulmonary veins
Venae cavae
What does the SVC drain
Head
Neck
Upper limbs
Upper trunk
What separates the right heart chambers
Tricuspid valve
Where is the mitral valve
Between left heart chambers
True or false
The aorta and pulmonary trunk have the same kind of valve
True - tricuspid semi lunar valves to prevent back flow
What disease can damage heart valves
Rheumatic fever
Atherosclerosis
What does the left coronary artery supply mostly
Most tif the interventricular septum, containing the bundle of His
Where is venous drainage from the heart
From the coronary sinus into the right atrium
What can dysfunction of the heart’s conducting system lead to
Angina
Arrhythmia
Myocardial infarction
Sudden death
What can rubella lead to if the patient is pregnant
Cyanosis at birth
What is the oesophagus continuous of
The pharynx
Where does a hiatus hernia occur
Gastro oesophageal junction
When part of the stomach slides up into the thorax
What is the thoracic inlet formed by
T1, 1st ribs and their costal cartilages, and the manubrium
What limits the superior mediastinum
Superiorly: thoracic Inlet
Inferiorly: a transverse plane from manubriosternal joint to T4/5 disc
What is the position of the subclavian vein in relation to the scalenes
Anterior to scalenus anterior
Where does the IJV commence
In the jugular foramina from the sigmoid sinuses
Where is the SVC formed
What does this mean
Behind Lower border of the first right costal cartilage
The left brachiocephalic vein is long to reach over to the right
How many cusps in the aortic valve
3
What arises from the aortic sinuses
Coronary arteries (also know as anterior and left posterior sinuses)
Where does the arch of the aorta begin and end
T4/5
What does the arch of the aorta arch over
What are its 3 branches
Left main bronchus
Brachiocephalic artery
Left common carotid
Left subclavian artery
Describe the brachiocephalic artery
Lies to right of trachea
Divides into right subclavian and right common carotid arteries
What muscle is the subclavian artery associated with
Scalenus anterior
Tell me about the part of the subclavian artery that is behind scalenus anteruor
It is related to the apex of the lung but is posterior to structures passing into the thorax
3 branches of the subclavian artery
Internal thoracic
Vertebral
Thyrocervical trunk
What are the terminal branches of the internal thoracic artery
Musculophrenic
Superiorepigastric
Which transverse foramen does the vertebral artery enter
What happens to it eventually
C6
It unites with its partner to form the Basilar artery, supplying the cerebellum and occipital lobe
Which artery sends branches to the vertebrae and spinal cord
Vertebral artery
When does the common carotid divide
Which branch supplies the brain
Upper thyroid cartilage (C4)
Internal
Where does the thoracic duct enter the left subclavian
Behind the Sternoclavicular joint
Describe the thymus gland
Lymphoid organ
Large in childhood
Superior to and anterior to mediastinum
After puberty is atrophies and undergoes fibrofatty degeneration
Which muscle do the vagus and phrenic run on
Which is more medial
Scalenus anterior
Vagus (lying within the carotid sheath)
Describe the course of the left phrenic
Enters thorax above aortic arch and anterior to lung apex
Descends on the fibrous pericardium overlyin the ventricle
Describe the course of the right phrenic
Runs behind right brachiocephalic veins and then into right side of SVC and right atrium
What is the sensory innervation of the phrenic
What are the spinal roots
Pericardium
Mediastinal pleura
Subdiaphragmatic peritoneum
(C3,4,5)
Describe the course of the left vagus
Descends in carotid sheath with common carotid and crosses anteriorly at the aortic arch
It then descends behind left bronchus to form the pulmonary plexus. Before this it gives the left recurrent laryngeal nerves which winds laterally around ligamentum arteriosum and ascends medial to aortic arch
Describe the course of the right vagus
Runs with common carotid and brachiocephalic trunk
Runs beside trachea before descending behind right main bronchus
As it passes anteriorly over subclavian artery it gives off the right recurrent laryngeal nerve
What do the recurrent laryngeal nerves ascend in
The tracheo- oesophageal groove
What happens to the vagus after it forms the pulmonary plexus
Reforms as the oesophageal plexus
This sends an anterior and posterior Vagal trunk through the diaphragm to the stomach
How do the Vagal trunks relate to the original vagi
Anterior trunk is mostly left vagus
Posterior trunk is mostly right
How far does the vagus innervate the intestines
As far as 2/3 along the transverse colon
Where does the sympathetic outflow emerge
T1-L2
How many sympathetic ganglia one the neck
Name them
3
Inferior cervical
Middle cervical
Superior cervical
What can often happen to the inferior cervical ganglion
Where is it found
How are its branches distributed
Fuse with the upper thoracic ganglion to become the Stellate ganglion
On the 1st rib neck
Forms a plexus on the subclavian artery to be distributed with its branches
Which artery is the middle cervical ganglion associated with
Inferior thyroid artery
Where is the superior cervical ganglion
How does it send branches
Opposite the atlas and axis
As plexuses on the internal and external carotid arteries
What forms the cardiac plexus
3 cervical ganglia and vagi
What do the cervical ganglia give to other than the cardiac plexus
Grey rami communicantes to cervical somatic nerves: 4 from superior and 2 from middle and inferior ganglia
What is sympathetic innervation important for on the skin
What else in the head ?
Vasomotor
Pilomotor
Sudomotor
Pupillary dilation and raising eyelid
Which muscle raises the eyelid involuntarily
Levator palpebrae superioris
What is thoracic outlet syndrome
What is affected
What are signs and symptoms
What can cause it
Compression of neurovascular structures between 1st rib and clavicle
Lower trunk of brachial plexus, subclavian vein and artery
Ischaemia, swelling, pain, paraesthesia of hand wasting of C8-T1 muscles
Cervical rib (at C7)
What must be avoided when inserting a catheter into the subclavian veins
Hence what must be done after such a procedure
Puncturing the pleura
A chest radiograph
Why is the left brachiocephalic vein at risk in a tracheostomy in children
It may lie above the suprasternal notch in children
When might pain be referred to the tip of the shoulder
Inflammation of sub phrenic organs eg gall bladder touching the peritoneum
What is a Pancoast tumour
What can it lead to
Why
A bronchogenic carcinoma at the apex of the lung
Horner’s syndrome
It may affect cervical sympathetic chain
What are the signs and symptoms of Horner’s syndrome
Ptosis (droopy upper eye lid due to loss of sympathetic supply to levator palpebrae superioris)
Miosis (constricted pupil)
Anhyrodsis (decreases sweating) in affected side of face
Vasodilation leading to flush
What is the inferior mediastinum divided into
Anterior
Middle
posterior
Describe the anterior mediastinum
Between the sternum and anterior border of the pericardial sac
Contains some lymph nodes and the thymus gland
Describe the posterior mediastinum
Contains oesophagus with vagi, descending aorta, azygous vein and thoracic duct
Describe the middle mediastinum
contains the pericardium and heart, roots of the great veins and the holum of each lung
When are the 2 pleural layers continuous
At the hilum
Wha is the costodiaphragmatic recess
When is it deepest
A recess between the parietal pleura lining the superior diaphragmatic surface and the parietal pleura of the thoracic wall
At full expiration
Which pleural cavity is smaller
Why
Left
The heart extends into it
Describe the sensory nature of the pleura
Visceral pleura is insensitive
Parietal pleura receives segmental innervation from intercostal nerves and phrenic nerves
Which parietal pleura do the phrenic nerves innervate
Mediastinal and diaphragmatic
How are the lungs divided
Right: into 3 (upper, middle, lower) by 2 fissures (oblique and transverse)
Left: 2 by the oblique fissure
What is the lingula
A small tongue of upper lobe on the left between the oblique fissure and the cardiac notch
It corresponds to the middle lobe of the right lung
Describe the surface markings of the pleura
Apex: 2.5cm above medial 1/3 of clavicle
2nd costal cartilage: pleurae meet on both sides
4th costal cartilage: left diverges to accommodate heart
6th: right descends
8th: cross mid-clavicular line
10th: crosses mid axillary line
12th rib: reaches just below neck of 12th rib posteriorly
Describe the surface markings of the lungs
Correspond with those of the pleurae expect inferiorly where they are 2 spaces higher in full expiration
Thus lungs lie opposite the 6th costal cartilage at the mid clavicular line, the 8th at the mid axillary line and reach the 10th rib posteriorly
Where does the oblique fissure start
Where does it end
What about when atm is abducted
Posteriorly next to T3
Curves down and forward to end at 6th costal cartilage
Medial border of the scapula is in line with oblique fissure
What are the surface markings of the right lung fissures
Transverse fissure: parallel 4th costal cartilage
Oblique: meets transverse at 5th rib in mid axillary line
What are the 6 structures in the lung hilum
Bronchus Pulmonary artery Pulmonary vein Bronchial artery Lymph node Nerves of pulmonary plexus
On which side is the main bronchus longer
What is the other difference
Left
The left has 1 bronchus
On the right there are 2: the right main bronchus and upper lobe bronchus)
What lie laterally to the lungs on each side
Costal cartilages and ribs with intervening intercostal muscle
What is the left lung related to medially
Left ventricle
Aortic Arch and descending aorta
The oesophagus may also groove the left lung as it move to the left in front of the aorta
What is related to the left lung inferiorly
Diaphragm
What is the right lung related to medially
Right atrium with both vena cava vessels and the azygous arch entering the SVC
Brachiocephalic trunk
Trachea
Why is the right lung shorter and wider than the left
The liver pushes up into it
What line the bronchi
Which bronchi go to bronchopulmonary segments
How many segments does each lung have
Pseudostratified ciliated columnar epithelium
Tertiary bronchi
10
How many segments are the upper lobes of the lungs divided into
Lower lobes?
3: apical, anterior, posterior
5: apical and 4 basal (anterior, posterior, medial, lateral)
How many segments in the middle lobe?
Which lung is this?
What about the other lung?
2: medial and lateral
The right has a middle lobe
The lingula on the left also has 2 segments (upper and lower)
Where do the lymphatics run in the lungs
Where do the lymphatic plexuses converge
Where do they drain to
Along the bronchi and under the pleurae
On lymph nodes at the lung hila
Drain to nodes at the carina which drain up to mediastinal nerves and then to right lymphatic duct or Thoracic duct
What do the hilar nodes look like in smokers
Blackened
Where are the tracheobronchial nodes
Around the carina
What is the carina
Where the trachea divides into the main bronchi
What is the parasympathetic innervation to the lungs
Sympathetic?
Via the vagus
From the thoracic sympathetic chain
What is parasympathetic action on the lungs
What about sympathetic
Bronchoconstriction to decrease dead space making quiet respiration more efficient
Bronchodilation to increase airflow
How do the phrenic nerves travel around the pericardium
Left: descends over left ventricle
Right descends alongside SVC, right atrium and IVC
They both pass anterior to hilum of each lung
What is the shape of the fibrous pericardium
Conical
What does the fibrous pericardium fuse with
Ascending aorta
Pulmonary trunk
SVC
Central tendon of diaphragm
What are the layers of the pericardium
Fibrous, parietal and visceral serous layers
The fibrous pericardium is lined by the parietal layer of serous pericardium
The visceral serous pericardium covers the heart and roots of the great vessels
What is the pericardial Cavity
What does it contain and why?
The potential space between the 2 layers of serous pericardium
Contains a thin film of fluid enabling the heart to move and beat in a frictionless environment
What is the transverse sinus
How is it used clinically
Lies within pericardial sac between arterial and venous ends of the heart
Used for passing slings through when clamping off major vessels in cardiac surgery
Where is the pericardial transverse sinus
Posterior to ascending aorta and pulmonary trunk
Anterior to SVC and pulmonary veins
What is the pericardial oblique sinus
What does it allow
How is it similar to lung hila
A recess in the pericardial cavity between pulmonary veins and behind left atrium
Distension of the left atrium
It is where the visceral layer reflects to become parietal
What can cause the lung to collapse
Pneumothorax
Where are foreign bodies likely to collect in the lungs of a supine patient
Why
Apical lower lobe segment in right lung
It is the first to arise posteriorly
A foreign body is most like to be impacted where in the lungs of a standing/ sitting patient
One of the basal bronchi
What is the most common cause of cancer related death in men worldwide
What rating is this in women
Bronchogenic carcinoma (primary lung cancer)
2nd most common in women
Where do most bronchogenic carcinomas arise
What symptoms can be seen
In mucosa of the large bronchi
Persistent productive cough
Haemoptysis (coughing up blood)
Where do lung tumours metastasise to
Does this happen early?
Where are common sites of haematogenous metastases
Bronchopulmonary lymph nodes and thus to thoracic nodes
Early
Brain Bones Lung Liver Adrenals
the lungs common sites of metastasis from which cancers
Breast Stomach Colon Testes Bladder Kidney Malignant melanoma
What is pericardiocentesis ?
Fluid aspiration from the pericardium
Can a pericardiocentesis be performed without puncturing the lungs?
How is it usually performed?
Yes
The needle can be inserted immediately left of the xiphisternum and directed upwards towards the tip of the left scapula
Under ultrasound guidance to minimise complications
When is ultrasound not possible for pericardiocentesis?
In life threatening situations eg cardiac tamponade
What is the base of the heart
The posterior surface where it is attached to the great vessels
Where is the right border of the heart
Left border?
Right 3rd to 6th costal cartilages
Left 2nd costal cartilage to 5 intercostal space
What are the auscultation points for the heart valves
Pulmonary valve: 2nd /3rd left intercostal space
Aortic valve: 2nd right intercostal space radiating up neck
Tricuspid: lower left sternal edge, (maybe also on right)
Mitral: apex, 5th intercostal space, midclavicular line
How to remember auscultation points for heart valves
valves are in verticals line behind sternum: P A M T
How is the heart divided longitudinally
By a vertical septum in coronal plane
How are the atria divided from the ventricles
By the coronary (atrioventricular) groove lying in the sagittal plane
How is the right heat border formed
What is most of the anterior surface of the heart
By the right atrium with the auricle pointing left
Right ventricle
How are the left chambers of the heart arranged on the heart surface
Left atrium lies as the base of the heart posteriorly
Ventricle is on the diaphragmatic surface
What are the portions of the chambers of the heart on its surface
2/3 of anterior surface is right ventricle and 1/3 is left ventricle
2/3 of diaphragmatic surface is left ventricle and 1/3 is right ventricle
Describe the course of the right coronary artery
What are its 3 branches
Arises from right aortic sinus
Passes between pulmonary trunk and right auricle
Runs backwards and down in atrioventricular groove
Right marginal artery
Posterior interventricular artery
Nodal branches
Describe the course of the left coronary artery
Give its 3 branches
Arises from left aortic sinus
Passes between pulmonary trunk and left auricle
Anterior interventricular
Circumflex
Nodal branches
Which artery passes between the left ventricle and atrium
Circumflex
What are the 5 cardiac veins
Great cardiac vein Middle cardiac Small cardiac Anterior cardiac Venae cordis minimae
What do cardiac veins do
Return blood from the muscular wall of the heart to the coronary sinus which enters the lower right atrium, just below the IVC
Which artery does the great cardiac vein follow
Circumflex
Describe the venae cordis minimae
V small veins opening into all Heart chambers (especially RA) and these account for 20-30% of all drainage
How do the vagi provide parasympathetic innervation to the heart
Via the superficial and deep cardiac plexuses
Which thoracic and cervical ganglia provide sympathetic innervation to the heart
T1-5
All cervical
Where are the 2 cardiac plexuses found
How do they enter the heart
Tracheal bifurcation and ligamentum arteriosum
With the coronary arteries
Is all the right atrium smooth?
No
The smooth part is from the sinus venosus in embryo
The auricle is ridges by musculi pectinati
These are separated by the crista terminalis
What is the external counterpart of the crista terminalis
Sulcus terminalis
Where is the SAN
Upper end of the crista terminalis
Left of the SVC
What is the AVN near
The tricuspid valve
What prevents random propagation of conduction to the ventricles
A figure of eight fibrous skeleton which supports the atria on one side, the ventricles on the other and the valves in the middle
What is the moderator band
What is another name
Branches from the right bundle from the bundle of His in the anterior wall of the right ventricle
Septomarginal trabecula
What muscles control the tricuspid valve
What is the arrangement
What is the action
Papillary muscles connected to the chordae tendineae
Each muscle sends chordae to 2 cusps
Contraction draws the cusps together, preventing them entering the atria
What is the right ventricular muscle ridged by
Is any smooth?
Trabaculae carnae
The inner surface is smooth towards its outflow at the infundibulum to create laminar flow into pulmonary trunk
True or false
the left atrium is thin walled
True
Are there trabeculae carnae
Yes
They are finer and more numerous than on the right
How are the ventricles arranged in a cross section
Left is circular woth right wrapped around as a crescent
How much thicker is the LV wall than the RV wall
3x
How is de oxygenated blood returned to the placenta from the embryo
How is oxygenated blood returned to the foetus
Via 2 umbilical arteries from the superior vesical or internal iliac arteries
Via left umbilical vein which joins the left branch of the portal vein
Where does the left umbilical vein join the portal vein
What happens to the blood from here
In the region of porta hepatis
Some goes into liver but most takes bypass to IVC and right atrium
Where does the newly oxygenated blood from the mother than has just entered the right atrium go?
Passes through foramen ovale to left atrium and then to coronary arteries, head, and upper limbs
This blood returns via the SVC into right ventricle and onto the pulmonary trunk. It then flows into aortic arch via the ductus arteriosus
What does clamping the umbilical cord do
Close off left umbilical vein
What causes closure of the ductus arteriosus
Decreasing prostaglandin levels from mother and release of bradykinin from lungs
What can palpitation of the apex heart beat assist in
Diagnosis of cardiomegaly
Where do areas for heart auscultation tend to be
Why
Superficial to the chamber/ vessel into which the blood has passed and in line with valve orifice
Blood carries sound In the direction of flow
What can stenosis/ occlusion of coronary artery result from
Atherosclerosis due to lipid deposition in the intima
Are there anastomoses between coronary arteries
Yes but not v effective ones
How can you treat coronary artery disease
Angioplasty (radiologically controlled balloon dilation) or coronary bypass
What vessels are used in coronary bypass
Great saphenous vein
Internal thoracic artery
Radial artery
What can cause damage to the conduction system in the heart
Ischaemia
Eg by occlusion of nodal branches
Does cyanosis occur in left to right shunting due to different pressures
No
Does a persistent ductus arteriosus cause cyanosis
What can happen
How is it treated
Not initially
It only caused blood to pump round the heart repeatedly but right side is strained so increases right pressure might reverse shunting leading to cyanosis
Ligation if prostaglandin synthetase inhibitors are ineffective
What is indomethacin?
A prostaglandin synthase inhibitor
What % of times is the posterior interventricular artery supplies by the right coronary? What are these people called?
What about to the SAN and AVN
90%. Right cardiac dominant
And 10% from left coronary artery
SAN: 60% from right coronary artery
AVN: 90% from right coronary artery
Where does the descending thoracic aorta lie
Which branches does it give
On the vertebral column between T4 and T12
giving posterior intercostal, bronchial and oesophageal branches
How does the oesophagus relate to the thoracic aorta
The oesophagus crosses anterior to the aorta
When does the oesophagus cross the crus of the diaphragm
T10
What happens to the venous drainage from the lower third of the oesophageal
Forms a portosystematic anastomoses
What forms the oesophageal plexus
How does it pass through the diaphragm
Formed by 2 vagi
The plexus reforms into posterior and anterior Vagal trunks to pass through the diaphragm
What is the course of the azygous vein
Starts at abdomen (L1/2) as a union of right sub costal vein and ascending lumbar veins
Ascends to the right of the aorta through aortic opening in diaphragm
Arches over the right lung hilum to drain into SVC
How does the thoracic duct commence
Where does it enter the thorax
When does it cross to the left
As the cisterna chyli in the abdomen
To the right of the aorta
T4/5
Which sympathetic nerves innervate abdominal viscera
Where do they come from
Greater, lesser, and least splanchnic nerves
The thoracic sympathetic chain
Describe the structure of the diaphragm
Muscular peripheral portion and a central tendon which is fused with the fibrous pericardium
Where does the intercostal neurovascular bundle lie
In the costal groove of the rib at the inferior border
When does the aorta cross the diaphragm
T12
Where does the oesophagus begin
C6
Just below the cricoid cartilage
True or false
The oesophagus crosses the diaphragm at the mid line
Which structures accompany it
False
It is to the left of the midline
The posterior and anterior Vagal trunks
What are the diaphragmatic crura
Give an example of their action
Tendons that extend below the diaphragm to the vertebral Column
The right crus forms a sling around the oesophagus, providing sphincter action
What is the epithelium of the oesophagus
Stratified squamous
What is “wear and tear” epithelium
Stratified squamous epithelium
Which arteries is the upper oesophagus supplied by
Middle?
Lower?
Inferior thyroid artery
Directly by aortic branches
Branch of the left gastric artery
How does upper oesophageal venous drainage enter the main circulation
What about lower 1/3?
Via the azygous
Via left gastric vein to hepatic portal vein forming a site of portosystemic anastomoses in the submucosal layer
What innervates upper 1/3 of oesophagus
Lower 2/3?
Recurrent laryngeal and sympathetic nerves from middle cervical ganglia
Vagi and sympathetic nerves in oesophageal plexus
How many hemiazygous veins are there
2 on the left
Where do posterior intercostal veins drain into on the left
Into hemiazygous veins and then into azygous
What does the superior intercostal vein drain
How do they empty on the left and right
2nd and 3rd intercostal spaces
Right: into azygous
Left: drains anteriorly across the ascending aorta in between the vagus and phrenic nerves into left brachiocephalic vein
What drains the first intercostal space
What do these drain into on each side
Supreme intercostal vein
The respective brachiocephalic vein
Describe the course of the thoracic duct
Commences as a continuation oh cisterna chyli
Passes up on right, behind median arcuate ligament, ascending on the vertebral column behind the oesophagus, between aorta and azygous vein
At T4/5 it crosses behind oesophagus to the left
It arches forward at the level of the apex of the lung and over the subclavian artery to enter the junction of the left subclavian and internal jugular veins
Describe a key valve in the thoracic duct
A bicuspid valve is present at its termination To avoid blood reflux
Why may the proximal thoracic duct look like a vein after death
Backflow of blood into the duct
Sympathetic outflow comes from where
Preganglionic neurons emerge from which root
How do sympathetic fibres leave the spinal cord ? How do they leave the spinal cord?
T1-L2
Ventral
As white rami communicantes
As grey rami communicantes
Where do the greater, lesser and least splanchnic nerves emerge from
Are they preganglionic
T5-T12
Yes
Which 3 ribs are atypical
1
11
12
Describe the 1st rib
Relatively immobile
Its shaft is flat and its head articulates with its own vertebral body only
Describe the 11th and 12th ribs
Articulate with their own vertebral bodies only
They are tethered to their own transverse processes by fibrous tissue without forming synovial joints
Describe the cartilage associated with the true ribs
True ribs= 1-7
Each ribs forms a primary cartilaginous joint with its own hyaline costal cartilage
The first costal cartilage forms a primary cartilaginous joint with the manubrium but all other other form synovial joints with the sternum b
What is found on the joint surfaces of the ribs instead of hyaline cartilage
Fibrocartilage
What is the costal margin
The costal cartilages of ribs 8-10 join the cartilage of the ribs above
Discuss the intercostal neurovascular bundle
Found in the costal groove
The nerve is the appropriate spinal nerve
The artery is formed from the posterior intercostal artery which anastomoses with an anterior intercostal branch of the internal thoracic artery
The vein drains posteriorly to the azygous or hemiazygous veins or anteriorly to the internal thoracic veins
Describe the external intercostal muscle
Anteriorly it is a membranous sheet between costal cartilages
It becomes muscular between the ribs and fibres run downwards from one rib anteriorly to the upper edge of the rib below
Describe the internal intercostal muscle
Lies between costal cartilages and the shafts of the ribs
Fibres run downwards and backwards at right angles to the external intercostal
Replaced posteriorly by the posterior intercostal muscle
What is the 3rd layer of intercostal muscles
How are they divided
The innermost intercostals
Anteriorly: transversus thoracis arises in slips from the sternum, running up and lateral, often spanning >2 ribs
Posteriorly: subcostalis runs across several ribs
What is the pump handle movement
What is the effect
Elevating the upper ribs that slope down to push the sternum up and forward for inspiration
This increases the anteroposterior diameter of the thorax with minimal lateral expansion
Which ribs expand laterally when inspiring
What do ribs 5-9 do
Lower ribs that don’t attach to the sternum
A mixture of lateral expansion and the pump handle movement
How does rib 1 move during inspiration
It doesn’t: it acts as a fixed platform during respiration
What does the diaphragm do during inspiration
What is the effect
Contracts and its domes flatten
Increases vertical dimensions of the thorax
What does the abdominal wall do during inspiration
Relaxes to allow downward pressure on the abdominal contents
What happens to the diaphragm if there is an increase in respiratory rate and force
What limits this
The diaphragm itself and not just its dimes are drawn inferiorly
Its connection to the pericardium
What does the central tendon of the diaphragm do in deep inspiration
What is the effect
What is this called
Acts as a fixed point to allow it to pull on the 7th to 10th ribs
Causes these ribs to evert and increase transverse diameter
The bucket hand movement
What does quiet expiration rely on
Elastic recoil and passive muscular relaxation as well as accessory muscles of respiration which aid both forces inspiration and expiration eg during stress after trauma
What are the accessory muscles of respiration that aid forced inspiration
Muscles with elevate thorax
Sternocleidomastoid
Pec Major and minor
Scalenes
What are the accessory muscles of respiration that aid forced expiration
Muscles that compress the thorax
Latissimus dorsi
And anterior abdominal wall muscles which force the diaphragm upwards
What are the roles of the intercostals
External intercostals raise ribs during inspiration
Internal and innermost and under discussion
Why are the sites of “natural” constructions in the oesophagus dangerous
They are potential areas for a carcinoma to develop or for inflammation due to ingestion of corrosive substances
How can portal hypertension affect the oesophagus
Can lead to dilation of the lower oesophageal submucosal veins to give oesophageal varices
Why are oesophageal varices dangerous
How can it be treated
They can rupture and cause severe haemorrhaging which is life threatening and difficult to control surgically
Endoscopic band ligation is the treatment of choice to stop bleeding during acute episodes and to prevent recurrent bleeding
What is a chylothorax
The presence of lymphatic fluid in the pleural space secondary to leakage from the thoracic duct
What can cause a chylothorax
Malignancy eg lymphoma
Or
Traumatic eg penetrating trauma or after thoracic surgery in oesophagectomy
Where is foregut pain referred to
Why
Epigastric region
General visceral afferents run with the greater splanchnic nerve from T5-9
Where is midgut pain referred to
Why
Umbilical region
Lesser splanchnic comes from T10-11
Where is hind gut pain referred to
Why
Suprapubic region
Via least splanchnic nerve from T12
Where should the trochar be placed when a chest drain is inserted
Why
Immediately above the rib (ie low in the intercostal space)
to avoid injury to the neurovascular bundle
Where would you inject an intercostal nerve bloc
Why
Local anaesthetic is directed towards the costal groove in the upper part of the intercostal space
To produce effective anaesthesia of the intercostal nerve eg in a rib fracture
What can phrenic nerve damage lead to
What happens if the damage is bilateral
Diaphragmatic paralysis
Rapid ventilatory failure
What congenital abnormality can occur in the trachea and oesophagus
A tracheo-oesophageal fistula
Also blind ending oesophagus or atresia
How are most of the ribs curved
Latterly with the longest in the middle region
The ribs have a protective function however what else do they need to be capable of
Movement to facilitate respiration
How are the upper 6/7 ribs attached
Attached to the sternum via costal cartilages
How are ribs 6/7 - 10 ribs attached
To the rib above via costal cartilages
Are rib fractures common in children
No
They are rare due to the elasticity of the ribs
Crush injuries lead to fractures at what point in the rip
Are the fractures anterior or posterior
The angle as it is the weakest point
Both anterior and posterior leading to a Flail chest when a segment of the thoracic cage is sucked in during inspiration
How do the external intercostals run
What about internal intercostals
Downwards and forwards
Downwards and backwards
Describe the innermost intercostal space
It is incomplete and is separated from the internal intercostals by the neurovascular bundle
Describe the arrangement of the intercostal veins, arteries and nerves
The veins are superior, the arteries lie below the veins, nerves like most inferiorly
What do the intercostal veins drain into
Into the internal thoracic and azygous veins
Where do the intercostal arteries arise from
Posteriorly from the subclavian artery or descending thoracic aorta
anteriorly from the internal thoracic artery anastomosing in the space
What is thoracocentsis?
The removal of fluid from the plural cavity by insertion of a needle through the intercostal space
During thoracocentsis Where is it best to insert the needle
In the middle part of the intercostal space to avoid damage to the main vessels or nerve
Give the other name for shingles
Herpes zoster
Which nerves are commonly affected by shingles
What does this cause
The intercostal nerves
A vesicular eruption and severe pain
What is the pleura
A serous membrane that secretes fluid
What is the highest part of the parietal pleura
The cervical pleura or cupola
This extends into the root of the neck to about 2.5 cm above the middle of the medial part of the clavicle
Where do the coastal and Diaphragmatic parietal pleurae join
To form the costodiaphragmatic recess
When is the costodiaphragmatic recess filled?
Only during full inspiration of the lungs
Other than a stab and when me a pneumothorax occur
From a ruptured lung bulla e.g. in emphysema
How can a haemothorax or plural effusion be seen
When a fluid level is seen in the plural cavity on a chest radiograph in the upright position
When does the trachea divides into the two main bronchi
At the level of the sternal angle (vertebral level T4/5)
What does the right main bronchus give off before entering the lung
The upper lobar bronchus
How does the right main bronchus compare to the left
It is wider and shorter and more vertical
How does the left main bunkers relate to the oesophagus
Crosses anterior to the oesophagus
There is a greater tendency for foreign bodies to enter into which lung?
Which lobe does it usually pass into
The right because the right main bronchus is wider and more vertical than the left
The middle or lower
How can the inside of the trachea be visualised
What else can be visualised by this technique
Bronchoscopy
Main, lobar and segmental bronchi
What do you call the bifurcation of the trachea
The carina
Why might the carina be distorted?
By enlarged lymph nodes in a bronchial carcinoma
What are the smallest independent units of lung tissue
What is each supplied by
Bronchopulmonary segments
A segmental bronchus, artery and vein
How is each bronchopulmonary segment shaped
In a cone shape with the base on the lung surface and its apex pointing towards the Hilum
How do the segmental bronchus and artery distribute and each bronchopulmonary segment
What about the veins
They divide and radiate out from the centre
They drain peripherally i.e. between the bronchopulmonary segment through intersegmental veins
What is the smallest unit of lung tissue that can be removed without collapse of surrounding tissue in a lung resection
A bronchopulmonary segment
Well larger thrombi may block the main and lobar arteries what can smaller thrombi do in the lungs
Block a segmental artery which will result in necrosis/infarction of the relevant bronchopulmonary segment
How can an infection of the lungs such as pneumonia or tuberculosis be restricted
It may be restricted to a bronchopulmonary segment
What are the three functions of the fibroserous sack known as the pericardium
Describe each
Protective - Reducing friction and restricting the spread of infection from surrounding tissues
supportive - By being anchored to the central tendon of the diaphragm, it restricts swinging of the heart
restrictive - Prevents over distension of the heart diastole
What are the two compartments of the pericardium
Fibrous - A tough external layer of the sac bound to central tendon of the diaphragm
Serous - Lines the internal aspect of the fibrous pericardium (parietal) and the outer surface of the heart (visceral)
Inflammation of the pericardium can lead to what
And increase in fluid that can prevent the heart from distending in diastole
If excessive fluid is present e.g. due to the leakage of blood it can be lethal due to the inelasticity of the fibrous pericardium
This is cardiac tamponade
Perfusion from the right and left coronary arteries takes place when
Why is this unique?
During diastole
All other arteries of the body are perfused during systole
Is there some anastomosis of the right and left coronary arteries
There is some but they are essentially functional end arteries
What is a functional end artery
It means a blockage in one cannot be compensated by others including their branches
What is restrictive pericarditis
When the fibrous pericardium thickens so that it severely affects the filling of the heart.
Which coronary artery is the larger of the two
Left
Describe the course of the right coronary artery (3)
What does it give off
1) Passes between the right auriclarappendage and the pulmonary trunk
2) Descends almost vertically in the atrioventricular groove
3) curves posteriorly where are limited and anastomosis occurs between it and the circumflex branch of the left coronary artery
it gives off right marginal artery and posterior interventricular artery
And what percentage of cases does the right coronary artery supply the SA node and the AV node
SAN: 60%
AVN: 90%
Describe the course of the left coronary artery (3)
Initially lies between the pulmonary trunk and the left auricle
Enters the atrioventricular group and divides into the interior interventricular artery and the circumflex artery
The anterior interventricular artery gives off 2–9 left anterior ventricular rami over the left ventricle
In which percentage of cases does the left coronary artery supply the AVN and SAN
SAN: 40%
AVN: 10%
What is right cardiac dominance
Where the posterior interventricular artery comes from the right coronary artery
What is left cardiac dominance
Where the posterior interventricular artery comes from the left coronary artery
What does it mean if a patient has a cardiac balanced pattern
What is another name
Branches of both left and right coronary artery supply the posterior part of the interventricular septum
Co-dominance
How do the large extramural coronary arteries give branches
How deep do the penetrate the myocardium
At right angled
Almost the full thickness of the myocardium with some anastomosis at the arteriolar level
How does the innermost part of the myocardium received its blood
From small vessels coming off the chambers directly
What is angina pectoris
When there is gradual blockage of the coronary arteries due to atheroma, Exertion may induce pain due to ischaemia of the cardiac muscle which is felt substernally but may also be referred to the left arm and neck
How is pain carried in angina pectoris
The visceral afferents are carriedback to the T1–4 segments of the spinal-cord by a sympathetic nerves mainly on the left side
Why can a blockage of the coronary arteries cause arrhythmia
How can this be fixed
It may affect the conducting tissue
The blocked artery may be bypassed by a graft or a stent inserted after dilating the artery (angioplasty)
How are the AV cusps of the heart attached
They are attached to the fibre skeleton of the heart and the free edges have chordae tendinae which are attached to the papillary muscles arising of myocardium within the ventricles
How many cusps does each papillary muscle attached to?
2
How do the papillary muscles contract
Isometrically
Describe the tricuspid valve
On the right between atrium and ventricle
Has three cusps, the largest of which is the anterior one
The anterior papillary muscle is the largest and has a bundle of conducting tissue fibres going to it from the Inter ventricular wall - this is the moderator band or septomarginal trabecula
Describe the mitral valve
Between the left atrium and left ventricle
Has it to cusps, the larger of which is the anterior one
The anterior cusp is smooth on both surfaces of the inflow of blood from the left atrium and outflow through the aortic vestibule
Which atrioventricular valve is more commonly affected by stenosis
What does this lead to
The mitral valve, following a bacterial infection e.g. rheumatic fever
Reduced blood flow from the left atrium causes Pulmonary hypertension
Which atrioventricular valve is most commonly affected by incompetence
What often comes with it
What happens
Left mitral
It is often accompanied by coronary artery disease
Chordae tendinae rupture following regurgitation of blood into the left atrium during ventricular systole
How many intercostal spaces are there
11
What does tension pneumothorax lead to
Rapid buildup of pressure due to being sucked in
Collapse of the long
Shift of the mediastinum to the opposite side
Needs emergency chest drain
Does a pneumothorax lead to difficulty in lung expansion
Yes
What is important to remember about the chest drain for pneumothorax
The water trap needs to be lower than the patient to prevent regurgitation of the water into the plural cavity
What can plural effusion be related to
Lung carcinoma
What does the fibrous pericardium do
Serous pericardium?
Prevent overfilling of ventricles
Secrete small amount of fluid for lubrication
What is the origin of the left and right coronary arteries
Just above that the sinus of the respective cusp of the aortic valve
What is pectoralis quartus
A variant of pec major with an additional head
