Anatomy Flashcards
In surgical removal of the heart, which organ must you remove first?
The lung
Which nerves pass anterior to the root of the lung?
Phrenic nerves
First step in removing the heart (after lungs are removed)
Make an incision in the fibrous pericardium. This is tough and you will have to cut through it with scissors
Pericardial cavity
Cavity between the two layers of pericardium
2 layers of pericardium
Fibrous pericardium - tough, protective layer
Serous pericardium - thin layer which secretes pericardial fluid
Haemopericardium
When the peritoneal cavity fills with blood
Cardiac tamponade
When the pressure around the heart prevents cardiac contraction
2 layers of serous pericardium
Visceral serous pericardium - in contact with the heart
Parietal serous pericardium - in contact with the walls
Second step in removing the heart
Rotate the heart forwards a little out of the pericardial sac
Pericardiocentesis:
- What is it?
- Describe the procedure
- Drainage of fluid from the pericardial cavity
- Needle is inserted via the infrasternal angle and directed superoposteriorly towards the pericardial sac, aspirating continuously.
In pericardiocentesis, how do you know that you are in the pericardial sac and are beginning to clear blood from the pericardium?
When the syringe begins to fill with blood
Transverse pericardial sinus:
- Where is it?
- Why is this of use to cardiac surgeons?
- A space within the pericardial cavity posterosuperiorly. It lies posterior to the ascending aorta and pulmonary trunk
- Cardiac surgeons use this to identify and isolate the great vessels in order to commence cardiopulmonary bypass for open heart surgery. The surgeons fingertip emerges from the sinus anterior to the SVC
Clinically important surfaces of the heart (3)
Anterior (sternocostal) surface
Base (posterior) surface
Inferior (diaphragmatic) surface
Clinically important borders of the heart (4)
Right (lateral) border
Left (lateral) border
Inferior border
Superior border
Where do you usually palpate the apex beat?
The 5th intercostal space midclavicular line
What forms the superior vena cava
Brachiocephalic veins which are formed by the internal jugular and subclavian veins
Auricles of the heart
Extensions of the atria and this is to do with maximal filling
Vein that separates base of the heart from the diaphragmatic surface
Coronary sinus
Coronary arteries are the arterial blood supply to what?
Epicardium and myocardium
Where do the coronary arteries arise from?
The ascending aorta
First branches of the aorta
Coronary arteries
What happens if a coronary artery becomes blocked?
Myocardial infarction
Where is the right coronary artery?
In the right atrioventricular groove
Branches of the right coronary artery
Right marginal artery (supplies right hand margin of heart) Posterior descending (interventricular) artery
Where is the left coronary artery?
In the left atrioventricular groove between pulmonary trunk and left auricle
Branches of the left coronary artery
Left anterior descending, which gives off the lateral (diagonal) branch
Left marginal
Circumflex artery
What does the circumflex artery anastomose with?
The right coronary artery
Coronary sinus:
- What is it?
- Where is it?
- What does it do?
- Short venous conduit
- Atrioventricular groove
- Receives deoxygenated blood from most of the cardiac veins and drains into right atrium. Venous blood rains into the coronary sinus and back towards right atrium
Surface features of grooves in the heart (2)
Surface groove and atrioventricular groove
What divides the heart into two sides?
Septum (internal muscular wall)
Part of septum between 2 atria:
- What is it called?
- What is its position indicated by?
- Interatrial septum
- Interatrial groove
Part of septum between 2 ventricles:
- What is it called?
- What is its position indicated by?
- Interventricular septum
- Interventricular groove
Atrial septal defect
Hole in the interatrial septum
Ventricular septal defect
Hole in the inter ventricular septum
Problem with septal defect in the heart
Mixing of venous and arterial blood which can lead to hyperaemia
What differentiates the smooth part of the right atrium from the rough part?
Crista terminalis
Pulmonary valve:
- Where is it?
- How many cusps does it have?
- Name the cusps
- Between right ventricle and pulmonary trunk
- 3 cusps
- Right cusp, left cusp, anterior cusp
Tricuspid valve:
- Where is it?
- How many cusps does it have?
- Name the cusps
- Between right atrium and right ventricle
- 3 cusps
- Anterior cusp, posterior cusp, septal cusp
Mitral (bicuspid) valve:
- Where is it?
- How many cusps does it have?
- Name the cusps
- Between left atrium and left ventricle
- 2 cusps
- Anterior cusp, posterior cusp
Aortic valve:
- Where is it?
- How many cusps?
- Name the cusps
- What other structure does it contain?
- Between the left ventricle and aorta
- 3 cusps
- Right cusp, left cusp, posterior cusp
- Sinuses (spaces between cusps)
Leaflet valves
Tricuspid and mitral valves. Shaped like a flat leaf
Semilunar valves
Pulmonary and aortic valves. Shaped like a half moon
Which valves have ‘pockets’ and what is the function of these ‘pockets’?
Semi-lunar valves. Catch blood as it tries to flow back through the valve.
Papillary muscles:
- What do they do?
- Attach to the cusps of the atrioventricular valves and prevent prolapse of the valves when they are opening
Function of the moderator band
Carries fibres of right bundle branch to the papillary muscle of anterior cusp. Provides a shortcut for electrical activity to the anterior capillary muscle to ensure coordination in contraction of papillary muscles
How do the sympathetic, parasympathetic and visceral afferent nerves reach the heart?
Via the cardiac plexus
Where do the presynaptic sympathetic fibres from the brain exit the spinal cord?
In one of T2-L2/3 spinal nerves
What things can presynaptic sympathetic fibres do after they exit the spinal cord? (5)
- Go straight to the ganglion of that level and synapse
- Travel superiorly in the sympathetic chain to another ganglion and synapse
- Travel inferiorly in the sympathetic chain to another ganglion and synapse
- Pass straight through the sympathetic chain ganglion without synapsing, as abdominopelvic splanchnic nerves to synapse in one of the prevertebral ganglia of the abdomen
- Pass straight to the adrenal medulla without synapsing as an abdominopelvic splanchnic nerve
Cardiopulmonary splanchnic nerves
Sympathetic nerves to heart and lungs
Route taken by postsynaptic sympathetic nerve fibres to the heart
- Travel in cardiopulmonary splanchnic nerves to essentially midline organ e.g. heart where there will be bilateral sympathetic innervation
Cardiac plexus
Sympathetic fibres, parasympathetic fibres, visceral afferent fibres
Parasympathetic signals reach the organs via which cranial nerves?
CN III (oculomotor nerve), CN VII (facial nerve), CN IX (glossopharyngeal nerve), CN X (vagus nerve)
What are baroreceptor afferents relayed via?
Vagus nerve
What is the sensory information of the heart relayed via?
Visceral afferents
Potential somatic sources of central chest pain
Muscular, joint, bony, intervertebral disc, fibrous pericardial, nerve
Nature of somatic pain
Typically sharp, stabbing, well localised
Potential visceral sources of central chest pain
Heart and great vessels, trachea, oesophagus, abdominal visceral
Nature of visceral pain
Dull, aching, nauseating, poorly localised
Radiating pain in from the chest
Pain felt in the centre of chest and is felt spreading from there
Where can chest pain radiate to?
Upper limbs, back, neck, jaw
Referred pain in the chest
Pain felt only at a site remote from area of tissue damage in the chest
Where can referred pain from the chest be felt?
Upper limbs, back, neck
Pain pathway with a painful prod
- Painful prod (pain associated with body wall)
- Skin mechanoreceptors stimulated in right T5 dermatome
- Signal relayed from anterior ramus, to spinal nerve T5, then will pass to the posterior root, posterior rootlets and then the spinal cord
- When in spinal cord, the fibres will cross spinal cord to the other side
- Sensation reaches consciousness at the cerebral cortex
Is the postcentral gyrus of parietal lobe somatosensory or somatomotor?
Somatosensory
What do action potentials arriving in the postcentral gyrus of the parietal lobe do?
Bring somatic sensations into consciousness
What do action potentials arriving in the precentral gyrus of the frontal lobe do?
Bring about contractions of somatic skeletal muscle
Is the precentral gyrus of the frontal lobe somatosensory or somatomotor?
Somatomotor
Somatic central chest pain sources
Herpes zoster (shingles), muscle, joint and bone, parietal pleura and fibrous pericardium
Shingles developing at what dermatome can present with somatic central chest pain?
T5/T5
Muscle, joint and bone causes of somatic central chest pain
Pectoralis major or intercostal muscle strain, dislocated costochondral joint, costovertebral joint, ‘slipped’ thoracic intervertebral disc
Parietal pleura and fibrous pericardium causes of somatic central chest pain
Pleurisy, pericarditis
Visceral central chest pain sources
Inflammation of any organ:
- Trachea (tracheitis)
- Oesophagus (oesophagitis)
- Aorta (ruptured aneurysm of aortic arch)
- Heart (angina and myocardial infarction)
- Abdominal viscerae (astritis, cholecystitis, pancreatitis, hepatitis etc)
Subdivisions of the mediastinum?
Sternal angle, sternum, vertebral column, diaphragm
Which part of the lung does the vagus nerve pass?
Behind the hilum of the lung
Best way to find the vagus nerve on the right side of the lung
Look for the trachea on the lateral surface
Where does the azygous vein drain into?
Intercostal spaces
Where does the azygous vein run?
Behind the trachea but also crosses over the top of the root of the lung into the SVC
How do pain signals from the organs reach the brain and CNS?
Visceral afferents pass bilaterally to the thalamus and hypothalamus and then diffuse areas of the cortex
In radiating pain, where does the pain radiate along?
The affected dermatome(s)
What is referred pain due to?
Afferent fibres from soma and afferent fibres from viscera entering the spinal cord at the same levels
In most patients, which coronary artery supplies most of the heart?
Right coronary artery
Triple vessel disease:
- Which coronary arteries are affected?
- How is this treated?
- Left anterior descending, right coronary artery, circumflex branch of left coronary artery
- Triple bypass
Commonly used grafts for coronary artery bypass grafting
Radial artery, internal thoracic artery, great saphenous vein
Mediastinum
The area that lies between the lungs
Superior mediastinum
Everything above the transverse thoracic plane
What is the thoracic inlet bounded by?
Ribs 1, T1 vertebra and the jugular notch
Where is the transverse thoracic plane?
Between the sternal angle and T4/5 intervertebral disc
Where is the anterior mediastinum?
Between the sternum and the fibrous pericardium
What does the middle mediastinum contain?
Everything contained in the pericardial sac:
- Pericardium
- Heart
- Inferior part of SVC
- Superior part of IV
- Pulmonary trunk and pulmonary arteries
- Pulmonary veins
- Ascending aorta
What is in the superior posterior mediastinum?
Bifurcation of the trachea, the vagus nerves, the azygous vein
What is in the inferior posterior mediastinum?
Azygous vein, sympathetic chains/trunks, thoracic aorta, thoracic duct, oesophagus, both vagal trunks (branches of vagus nerves)
Where does the azygous vein drain blood from?
The intercostal spaces. Blood drains from intercostal vein, to azygous vein, to SVC
Where do the right and left lymphatic ducts drain into?
Right lymphatic duct drains into right venous angle
Left lymphatic duct drains into left venous angle
Where is the thoracic duct?
Between the oesophagus and the azygous vein - ‘duck between two gooses’
Where does the thoracic duct drain into?
Left venous angle to drain lymph back into the body
Venous angle
Angle formed between the internal jugular vein and the subclavian vein
What is the larynx supplied by?
Vagus nerve
When does the thoracic aorta become the abdominal aorta?
When it passes through the diaphragm
What is the ligamentum arteriosum
The remnants of the ductus arteriosus
Structures found in the superior mediastinum from anterior to posterior
Brachiocephalic veins and SVC Arch of aorta Trachea Oesophagus Thoracic duct
Structures found in the superior mediastinum from lateral to medial
Phrenic nerves, vagus nerves, recurrent pharyngeal nerves
What are central veins?
Veins close enough to the heart such that the pressure within them is said to reflect the pressure in the right atrium
Which veins are central veins?
Internal jugular veins, subclavian veins, brachiocephalic veins, SVC, right atrium, IVC, iliac veins, femoral veins
Which veins are the most common access points in central venous cannulation?
Internal jugular veins and femoral veins
What are phrenic nerves formed from?
Combined anterior rami of cervical spine 3, 4 and 5
Phrenic nerves:
- Somatic motor to what?
- Somatic sensory to what? (4)
- Somatic motor to the diaphragm
- Somatic sensory to mediastinal parietal pleura, fibrous pericardium, diaphragmatic parietal pleura, diaphragmatic parietal peritoneum
Great arteries in the mediastinum
Right common carotid artery, right subclavian artery, left common carotid artery, left subclavian artery
Why can diaphragmatic pathology present as shoulder tip pain?
Pain from the diaphragm irritates the parietal peritoneum that is supplied by the phrenic nerve. The supraclavicular nerves supply the dermatomes over the shoulder tip and enter the spinal cord at the same levels as the phrenic nerve. The brain refers to the pain in the more superficial structure - the skin on the shoulder tip
What are recurrent pharyngeal nerves?
Branches of the vagus nerve that supply the pharynx and larynx
Post-cardiac arrest syndrome
Post-cardiac arrest brain injury, post-cardiac arrest myocardial dysfunction, systemic ischaemia/reperfusion response, persisting precipitating pathology
Goal of post-resuscitation care
To restore quality of life, normal cerebral perfusion/function, normal perfusion/function of other organs, stable cardiac rhythm
What temperature should unconscious adults with return of spontaneous circulation be cooled to?
32-36 degrees C
Pre-arrest factors that reduce the odds of survival after a cardiac arrest
Male, ≥60 years old, active malignancy, chronic kidney disease
Intra-arrest factors that increase the odds of survival after a cardiac arrest
Witnessed arrest, monitored arrest, arrested during daytime hours and had initial shockable rhythm
Intra-arrest factors that reduce the odds of survival after a cardiac arrest
Intubation during arrest and duration of resuscitation ≥15 mins
