Podcast
Questions and Answers
What is the primary cause of cyanosis in Tetralogy of Fallot?
What is the primary cause of cyanosis in Tetralogy of Fallot?
What is the key characteristic of Transposition of Great Vessels that makes it incompatible with life without intervention?
What is the key characteristic of Transposition of Great Vessels that makes it incompatible with life without intervention?
What is the common feature among Tetralogy of Fallot, Transposition of Great Vessels, and Persistent Truncus Arteriosus?
What is the common feature among Tetralogy of Fallot, Transposition of Great Vessels, and Persistent Truncus Arteriosus?
In the context of Transposition of Great Vessels, what is the implication of a patent foramen ovale?
In the context of Transposition of Great Vessels, what is the implication of a patent foramen ovale?
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What is the anatomical defect associated with Persistent Truncus Arteriosus?
What is the anatomical defect associated with Persistent Truncus Arteriosus?
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Which of the following is NOT a consequence of Tetralogy of Fallot?
Which of the following is NOT a consequence of Tetralogy of Fallot?
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What is the commonality between the membranous ventricular septal defect (VSD) in Tetralogy of Fallot and Persistent Truncus Arteriosus?
What is the commonality between the membranous ventricular septal defect (VSD) in Tetralogy of Fallot and Persistent Truncus Arteriosus?
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Why is a shunt, such as a VSD or PDA, essential for survival in Transposition of Great Vessels?
Why is a shunt, such as a VSD or PDA, essential for survival in Transposition of Great Vessels?
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When is blood flow into the coronary arteries?
When is blood flow into the coronary arteries?
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What is the largest vein in the coronary system?
What is the largest vein in the coronary system?
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Which of these is NOT a common site of coronary artery occlusion during a myocardial infarction?
Which of these is NOT a common site of coronary artery occlusion during a myocardial infarction?
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What is the position of the coronary sinus?
What is the position of the coronary sinus?
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Which of these is typically the most common site of coronary artery occlusion during a myocardial infarction?
Which of these is typically the most common site of coronary artery occlusion during a myocardial infarction?
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Which branch of the coronary artery travels between the left auricle and ventricle?
Which branch of the coronary artery travels between the left auricle and ventricle?
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What does the circumflex artery supply?
What does the circumflex artery supply?
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During ventricular systole, which valve should be closed?
During ventricular systole, which valve should be closed?
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What type of tumour arises in the lung apex and may invade surrounding tissues?
What type of tumour arises in the lung apex and may invade surrounding tissues?
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Which syndrome can result from a Pancoast tumour due to nerve involvement?
Which syndrome can result from a Pancoast tumour due to nerve involvement?
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What is the primary function of the conducting zone in the respiratory system?
What is the primary function of the conducting zone in the respiratory system?
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At which anatomical level does the trachea bifurcate?
At which anatomical level does the trachea bifurcate?
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What is the shape and configuration of the cartilages in the trachea?
What is the shape and configuration of the cartilages in the trachea?
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Which part of the respiratory system participates in gas exchange?
Which part of the respiratory system participates in gas exchange?
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Why are foreign bodies more often aspirated into the right primary bronchus?
Why are foreign bodies more often aspirated into the right primary bronchus?
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What is the role of smooth muscle in the walls of the conducting airways?
What is the role of smooth muscle in the walls of the conducting airways?
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Which structures are contained within the superior mediastinum?
Which structures are contained within the superior mediastinum?
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What branches off the brachiocephalic trunk?
What branches off the brachiocephalic trunk?
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Where does the trachea bifurcate into the main bronchi?
Where does the trachea bifurcate into the main bronchi?
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Which statement about the vagus nerve is correct?
Which statement about the vagus nerve is correct?
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The presence of which nerve structure is associated with the esophagus's position?
The presence of which nerve structure is associated with the esophagus's position?
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What happens to the thymus after childhood?
What happens to the thymus after childhood?
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Which structure is located posterior to the aortic arch?
Which structure is located posterior to the aortic arch?
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What is the starting level of the trachea?
What is the starting level of the trachea?
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Which artery is a branch of the subclavian artery that supplies the anterior thoracic wall?
Which artery is a branch of the subclavian artery that supplies the anterior thoracic wall?
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What nerve innervates the intrinsic muscles of the thorax and the skin of the anterior thoracic wall?
What nerve innervates the intrinsic muscles of the thorax and the skin of the anterior thoracic wall?
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Which veins drain the anterior intercostal area?
Which veins drain the anterior intercostal area?
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To avoid pneumothorax during an intercostal nerve block, what is the first step that should be taken?
To avoid pneumothorax during an intercostal nerve block, what is the first step that should be taken?
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From which artery do the posterior intercostal arteries arise?
From which artery do the posterior intercostal arteries arise?
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The female breast typically extends from which ribs?
The female breast typically extends from which ribs?
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What artery is described as supplying the superior part of the thoracic wall?
What artery is described as supplying the superior part of the thoracic wall?
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What is the primary purpose of avoiding the intercostal neurovascular structures during thoracentesis?
What is the primary purpose of avoiding the intercostal neurovascular structures during thoracentesis?
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What occurs during a tension pneumothorax?
What occurs during a tension pneumothorax?
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Which lobe corresponds to the lingula of the left lung?
Which lobe corresponds to the lingula of the left lung?
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Which structure enters or leaves the lungs at the hilum?
Which structure enters or leaves the lungs at the hilum?
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What is a classic sign of tension pneumothorax?
What is a classic sign of tension pneumothorax?
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How many lobes does the right lung have?
How many lobes does the right lung have?
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What is the function of the oblique fissure?
What is the function of the oblique fissure?
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Which side does the horizontal fissure belong to?
Which side does the horizontal fissure belong to?
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What effect does positive pressure ventilation have on a tension pneumothorax?
What effect does positive pressure ventilation have on a tension pneumothorax?
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Flashcards
Pain fibers
Pain fibers
Nerve fibers that transmit pain signals to the spinal cord segments T1 – T5.
Parasympathetic stimulation
Parasympathetic stimulation
Nervous system activity that reduces heart rate.
Vagus nerve
Vagus nerve
Cranial nerve X, involved in heart and lung reflexes.
Mediastinum
Mediastinum
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Superior mediastinum
Superior mediastinum
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Thymus gland
Thymus gland
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Branches of the aorta
Branches of the aorta
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Recurrent laryngeal nerve
Recurrent laryngeal nerve
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Internal Thoracic Artery
Internal Thoracic Artery
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Anterior Intercostal Arteries
Anterior Intercostal Arteries
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Thoracic Aorta
Thoracic Aorta
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Intercostal Nerves
Intercostal Nerves
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Posterior Intercostal Veins
Posterior Intercostal Veins
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Intercostal Neurovascular Bundle
Intercostal Neurovascular Bundle
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Thoracocentesis
Thoracocentesis
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Female Breast Anatomy
Female Breast Anatomy
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Pancoast tumour
Pancoast tumour
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Thoracic inlet syndrome
Thoracic inlet syndrome
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Horner syndrome
Horner syndrome
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Conducting zone
Conducting zone
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Respiratory zone
Respiratory zone
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Trachea
Trachea
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Bronchi
Bronchi
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Aspiration of foreign bodies
Aspiration of foreign bodies
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Tension pneumothorax
Tension pneumothorax
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Signs of tension pneumothorax
Signs of tension pneumothorax
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Pleural space
Pleural space
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Lungs lobes
Lungs lobes
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Oblique fissure
Oblique fissure
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Horizontal fissure
Horizontal fissure
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Lingula
Lingula
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Hilum of the lung
Hilum of the lung
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Ventricular Systole
Ventricular Systole
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Mitral Valve Function
Mitral Valve Function
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Aortic Valve Function
Aortic Valve Function
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Coronary Arteries
Coronary Arteries
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Right Coronary Artery
Right Coronary Artery
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Left Coronary Artery
Left Coronary Artery
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Myocardial Infarction
Myocardial Infarction
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Coronary Sinus
Coronary Sinus
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Pulmonary Stenosis
Pulmonary Stenosis
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Right Ventricular Hypertrophy
Right Ventricular Hypertrophy
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Overriding Aorta
Overriding Aorta
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Ventricular Septal Defect (VSD)
Ventricular Septal Defect (VSD)
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Right to Left Shunt
Right to Left Shunt
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Transposition of Great Vessels
Transposition of Great Vessels
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Persistent Truncus Arteriosus
Persistent Truncus Arteriosus
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Cyanosis
Cyanosis
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Study Notes
Thorax
- Netter's clinical Anatomy 2nd ed., J.T. Hansen, Elsevier
- Clinically oriented anatomy 6th ed., K.L. Moore, A.F. Dalley, A.M.R. Agur, LWW 2010
- Prometheus atlas of anatomy
- Gray's Anatomy for students
- Sobotta Atlas of human anatomy
Skeleton of back and thorax
- Superior thoracic aperture is the base of the neck
- Posteriorly - Body of T1 vertebra
- Laterally - 1st pair of the ribs
- Anteriorly - superior border of manubrium
- Conveys large vessels, nerves, thoracic lymphatic duct, trachea, and esophagus
- Inferior thoracic aperture is closed by the diaphragm
- Posteriorly - body of T12
- Posterolaterally - 11th and 12th pairs of ribs
- Anterolaterally - costal cartilages of ribs 7 - 10
- Anteriorly - xiphisternal joint. Conveys inferior vena cava, aorta, esophagus, thoracic lymphatic duct
Mediastinum
- Thorax contains two pleural cavities laterally and a central middle space called the mediastinum
- Superior mediastinum – lies above an imaginary horizontal plane through the manubrium of the sternum (sternal angle of Louis and intervertebral disc between the T4 and T5 vertebra)
- Inferior mediastinum compartment below the same horizontal plane, which is further subdivided into an anterior, middle (contains the heart) and posterior mediastinum
Thoracic Walls
- Topographic lines: Anterior middle line, Sternal Line, Parasternal line, Midclavicular line, Anterior axillary Line, Middle axillary Line, Posterior axillary Line, Scapular line, Paravertebral Line, Posterior middle Line
- Pectoralis major muscle: Origin - medial half of clavicle, sternum and related costal cartilages; Insertion - lateral lip of the intertubercular groove of humerus; Actions - adduction, flexion and medial rotation of the arm, elevation of the ribs (inspiration muscle); Innervation - lateral and medial pectoral nerves (C6 – T1)
- Subclavius muscle: Origin - inferior surface of the shaft of clavicle; Insertion - first rib; Action - pulls the tip of the shoulder inferiorly; Innervation - subclavian nerve (C5, C6)
- Serratus anterior muscle: Origin - lateral parts of the ribs from 1st to 9th; Insertion - medial border of the scapula; Actions - rotates the scapula, protracts scapula, elevates the glenoid cavity, holds the scapula against thoracic wall, elevates the ribs (inspiration muscle); Innervation - long thoracic nerve (C5, C6, C7)
- Levatores costarum muscles
- 12 fan-shaped muscles that elevate the ribs
- Origin - transverse prosesses from t7 – T11
- Insertion- Post surface and angle of rib below
- Action- Elevates ribs
- Nerve- Post primary rami C8 – T11. -External intercostal muscles -Origin- Inferior border of the ribs; direction to the sternum
- Insertion - Superior border of the ribs;
- Action - elevate the ribs during inspiration
- Innervation - intercostal nerves
- Internal intercostal muscles: Origin - Inferior border of the ribs; direction toward the sternum; Insertion - Superior border of the ribs; Action - depress the ribs during expiration; Innervation - intercostal nerves
- Internal innermost intercostal muscles: Origin - Inferior border of the ribs; direction toward the sternum; Insertion - Superior border of the ribs; outside the subclavian groove; Action - depress the ribs during expiration; Innervation- intercostal nerves
- Subcostal muscles: Origin- Internal surface of the lower ribs near their angles; Insertion- Superior border of the 2nd or 3rd ribs below; Action- depress the ribs during expiration; Innervation- intercostal nerves
- Transverse thoracic muscle: Origin - Posterior surface of the lower sternum; Insertion - Internal surface of costal cartilages from 2nd to 6th; Action - depress the ribs during expiration; Innervation- intercostal nerves
- Diaphragm
Thoracic Walls - Additional Topics
- Structures travelling between the thorax and abdomen pass through the diaphragm or between the diaphragm and its peripheral attachments:
- Caval opening provides inferior vena cava at vertebral level TVIII;
- The oesophagus passes through the muscular part of the diaphragm, just to the left of the midline, approximately at vertebral level TX; together with vagus nerves;
- Aortic hiatus is located behind the middle arcuate ligament at vertebral level TXII,the thoracic duct passes together with the aorta
Thoracic Walls- Vessels and Nerves
- Arteries of the thoracic wall: internal thoracic artery, anterior intercostal arteries, musculophrenic artery, superior epigastric artery -Anterior intercostal veins to internal thoracic vein, superior epigastric vein, musculophrenic vein -Posterior intercostal veins and subclavian vein to azygos veins (right side) and hemiazygos vein (left side)
- Innervation- The diaphragm is innervated by the phrenic nerves (C3 to C5}, which penetrate the diaphragm and innervate it from its abdominal surface.
Breast
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Female breast extends from second to six rib and from parasternal to midaxillary line.
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Mammary tissue composed of 15 to 20 lobes separated by connective tissue septa.
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Breast – fatty tissue containing glands that produce milk, lies in superficial fascia, which lies above deep pectoral fascia, enveloping the pectoralis major muscle
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Areola - pigmented skin surrounding the nipple.
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Nipple – site of opening for the lactiferous ducts, at the level of fourth intercostal space.
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Axillary tail – extension of mammary tissue superolaterally toward the axilla
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Deep pectoral fascia
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Lobules of mammary gland (lactating)
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Fat lobule
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Lactiferous ducts
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Lactiferous sinus
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Nipple
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Cooper ligaments are suspensory ligaments that attach the mammary gland to the skin to the deep fascia.
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During the radical mastectomy, the long thoracic nerve may be lesioned during ligation of the lateral thoracic artery. Woman can present a wing scapula and weakness in abduction of the arm above 90 degrees. THe thoracodorsal nerve may be also injured during mastectomy, resulting in weakness of extension and medial rotation of the arm.
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Arterial supply to the breast: internal thoracic artery (internal mammary), lateral thoracic artery
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Venous supply: internal thoracic vein, lateral thoracic vein.
Lower respiratory development complications
- Pulmonary hypoplasia or aplasia is part of the spectrum of malformations characterized by incomplete development of lung tissue.
- It's a condition characterized by a reduction in the number of lung cells, airways, and alveoli that results in a lower organ size and weight.
- Pulmonary hypoplasia can be either unilateral or bilateral.
Pleura and pleural cavity
- Parietal pleura lines the inner surface of the chest wall, diaphragm, and mediastinum. It can be divided into costal parietal pleura, diaphragmatic parietal pleura, Mediastinal parietal pleura, and Cervical parietal pleura (dome of pleura, pleural cupula)
- Visceral pleura adheres and covers the lung.
- Innervation of parietal pleura comes from intercostal nerves for costal pleura and phrenic nerve for central portion of the diaphragmatic pleura and mediastinal pleura. Visceral pleura is supplied by the visceral sensory nerves that course with autonomic nerves.
Pleural cavity
- Pleural cavity is the potential space between the parietal and visceral layers of the pleura. It contains a small amount of serous fluid that lubricates the opposing parietal and visceral layers.
- Introduction of the air into the pleural cavity may cause the lung to collapse resulting in a pneumothorax with chest shortness of breath, and pain on deep inspiration. Lung collapses due to the loss of a negative pressure of the pleura cavity during a pneumothorax.
Pneumothorax
- Open pneumothorax occurs when there is a pneumothorax associated with a chest wall defect, such that the pneumothorax communicates with the exterior.
- During inspiration, air is entrained into the chest cavity not through the trachea but through the hole in the chest wall, which has less resistance to flow.
Tension pneumothorax
- Progressive build-up of air within the pleural space, usually due to a lung laceration which allows air to escape into the pleural space but not to return.
- Positive pressure ventilation may exacerbate this effect.
- Progressive build-up of pressure in pleural space pushes the mediastinum to the opposite hemithorax and obstructs venous return to the heart. Causes circulatory instability and may result in traumatic arrest
Lungs
- Surfaces and regions (costal surface, mediastinal surface, diaphragmatic surface)
- Apex projects into the root of the neck and is adjacent to the subclavian vein, subclavian artery.
Lobes and fissures
- Right lung - 3 lobes (superior, middle, inferior) separated by oblique and horizontal fissures.
- Left lung - 2 lobes (superior and inferior) separated by an oblique fissure.
Lobes and fissures - Additional details
- Horizontal fissure extends along the 4th rib, present on the right lung only.
- Oblique fissure extends from T2 to 6th costal cartilage, present on both lungs.
- Impressions of the lungs are made by adjacent structures. Hilum is the place where structures enter or leave lungs: main bronchus, pulmonary artery, pulmonary veins superior and inferior, bronchial arteries and veins, autonomic nerves and lymphatics.
- Lingula is a tongue-shaped feature of the left lung.
- Cardiac notch is an irregularity in the anterior margin of the left lung.
- Pulmonary ligament hangs up from the root of the lung and directs the visceral pleura into the parietal pleura. Is created by double layer of parietal pleura.
- Each lung has 10 bronchopulmonary segments supplied by segmental bronchus, artery and vein pulmonary circulation.
Lung Circulation
- Lungs have double circulation:
- Pulmonary artery (from pulmonary trunk).
- Pulmonary veins (superior and inferior).
- Nutrient circulation provided by bronchial arteries (anterior from internal thoracic artery and posterior directly from thoracic aorta) and bronchial veins (anterior drainage blood into internal thoracic vein and posterior into azygos veins system).
Lung Innervation
- Lungs get autonomic innervation from two sources:
- Sympathetic fibers from the sympathetic trunk - thoracic part for bronchodilators muscles.
- Parasympathetic fibers from vagus nerves for bronchoconstrictors muscles, increasing mucus secretion.
Lymphatic Drainage
- Drains by way of superficial and deep lymphatic plexuses. Superficial plexus is immediately under the visceral pleura. Deep plexus is deep in the lungs.
- Major nodes: Bronchopulmonary (hilar) nodes – receives lymph from both plexuses and drain into tracheobronchial nodes
- Tracheobronchial nodes – at bifurcation of the trachea and drain into bronchomediastinal nodes
- Bronchomediastinal nodes on the right and left sides of the trachea and drain into right lymphatic duct and thoracic duct.
Lymphatic Drainage – additional details
- Lymphatic drainage of left lung can drain to the right bronchomediastinal lymphatic trunk and nodes, then to the right lymphatic duct. This is the most important according to analysis of the metastases of the lung cancer.
Thoracic duct carries
- the lymph from the inferior part of the body under the diaphragm ( lower limbs, pelvis, abdomen).
- Left side of the superior part of the body (left superior limb, left half of the thorax, and left half of the head)
- The right lymphatic duct drains the lymph from the right superior part of the body (right upper limb, right half of the thorax and right side of the head)
Breath sounds
- Listen to the breath sounds of the superior lobe of both lungs – superior area of the anterior chest above 4th cartilage.
- Breath sounds from the middle lobe – anterior chest wall, posterior inferior to the 4th cartilage.
- Inferior lobes of both lungs – posterior chest wall.
Pulmonary embolism
- Pulmonary embolism is when one or more pulmonary arteries in your lungs become blocked.
- In most cases, pulmonary embolism is caused by blood clots that travel to the lungs from the legs (deep vein thrombosis, or DVT).
- Causes are called Virchow’s triad: Venous stasis, trauma, and coagulation disorders
- Pulmonary embolism can be life-threatening.
Lung cancer
- Bronchogenic tumor may impinge adjacent structures.
- A Pancoast tumor arises in the lung apex and invades the surrounding soft tissues.
- May result in thoracic inlet syndrome: injuries to the subclavian vessels and brachial plexus, nerve palsy (most often C8 – T1 roots (ulnar nerve), Horner syndrome.
- Miosis – constricted pupil, Ptosis – minor drooping of the upper eyelid, Anhidrosis – lack of sweating, Flushing – subcutaneous vasodilation.
Respiratory tree
- Conducting zone: nose, pharynx, trachea, bronchi, bronchioles, terminal bronchioles.
- Cartilage is present only in the trachea and bronchi.
- Warms, humidifies, filters air.
- Anatomic death space.
- Walls of conducting airways contain smooth muscle.
- Respiratory zone: consists of respiratory bronchioles, alveolar ducts, and alveoli. Participates in gas exchange.
Trachea
- Is the single airway tube starting at the level of cricoid cartilage CVI and extends to its bifurcation at the T4 (sternal angle Louis) level.
- Is composed of 16 - 20 C-shaped cartilages connected by the annular ligaments.
- Lies anterior to the esophagus and posterior to the aortic arch
- At bifurcation trachea shows carina - internal keel - like cartilage
- Posterior part of the trachea consists of membranous wall, created by the muscular fibers: longitudinal and circular creating the tracheal muscle.
Bronchi
- Aspiration of a foreign body is more often to the right main bronchus because of their shape differences.
- Right bronchus is shorter, wider and more vertical located than the left one.
- Usually aspired forign body is present in posterior basal segment of the right inferior lobe.
- Main bronchi (primary) divides into lobar bronchi (secondary) 2 or 3; segmental bronchi (tertiary) for 10 bronchopulmonary segments.
- The bronchi and respiratory airways continue dividing until they terminate in alveolar sacs.
Fetal circulation
- Oxygenated blood from placenta to the fetus passes through the umbilical vein.
- Three vascular shunts develop in the fetal circulation:
- Ductus venosus bypasses the sinusoids of the liver into the IVC Foramen ovale allows oxygenated blood to bypass the pulmonary circulation.
- Ductus arteriosus shunts deoxygenated blood from pulmonary trunk to the aorta to bypass pulmonary circulation.
- Right to left pressure gradient provides the blood by foramen ovale and ductus arteriosus.
Postnatal circulation
- Change in pressure gradient provides for closing those three shunts:
- Foramen ovale closure is the result of left atrial pressure increase and right atrial pressure reduction.
- Ductus arteriosus closure is the result of contraction of the smooth muscles in its walls and oxygen tension.
Fetal circulation remnants
- Medial umbilical ligaments – after closure of the umbilical arteries.
- Ligamentum teres of the liver – after closure of the umbilical vein
- Ligamentum venosum – after closure of ductus venosus
- Fossa ovalis – after closure of foramen ovale
- Ligamentum arteriosum – after closure of ductus arteriosus
Atrial Septal Defect (ASD)
- ASD – congenital heart defect that is more common in females than males.
- Results in left-to-right shunting and non-cyanotic conditions.
Ventricular Septal Defects (VSD)
- Results in left-to-right shunting of blood.
- Patients complain excessive fatigue upon exertion. Not cyanotic initially, but can become cyanotic as pulmonary vascular resistance increases.
- Pulmonary hypertension and proliferation of intima pulmonary muscular arteries - pulmonary resistance becomes higher than systemic; right to left shunting.
Patent ductus arteriosus (PDA)
- Is the specific condition when ductus arteriosus fails to close after birth.
- In the fetal period, the shunt is right-to-left.
Tetralogy of Fallot
- Most common cyanotic congenital heart defect.
- Pulmonary stenosis
- Right ventricular hypertrophy
- Overriding aorta (receives blood from both ventricles)
- Ventricular septal defect (membranous).
- This causes right-to-left shunting of blood, with cyanosis present sometimes after birth (Boot shape heart).
Transposition of great vessels
- Transposition of great vessels occurs due to failure of aortopulmonary septum to spiral.
- Without surgical correction, most infants die within the first few months of life.
- Aorta arising from the right ventricle and pulmonary trunk arising from the left ventricle. This causes a right-to-left shunt and cyanosis.
- Not compatible with life unless a shunt is present to allow adequate mixing of blood (VSD, PDA, patent foramen ovale).
Persistent truncus arteriosus
- There is only partial development of aorticopulmonary septum.
- In result, only one large vessel leaves the heart that receives blood from both the right and left ventricles.
- This causes a right-to-left shunt and cyanosis; always accompanied by membranous VSD.
Congenital Heart Defects
- Non-cyanotic (left-to-right shunt): atrial septal defect, ventricular septal defect, patent ductus arteriosus
- Cyanotic (right-to-left shunt): transposition of great vessels, tetralogy of Fallot, persistent truncus arteriosus
Heart
- Middle mediastinum contains pericardium, heart, and great vessels (ascending aorta and pulmonary trunk) and phrenic nerves.
- Pericardium is fibroserous membrane covering the heart and beginnings of great vessels.
- Pericardial cavity is the potential space between the parietal and visceral layers of serous pericardium, contains a little fluid to enables heart movement and beat.
Heart – additional details- Pericardial sinuses
- Transverse sinus – passage within the pericardial cavity between anterior walls of atria and posterior walls of aorta and pulmonary trunk
- Oblique -- passage limited from the right side by the superior vena cava and right pulmonary veins superior and inferior; from the left side by the left pulmonary veins superior and inferior
Cardiac tamponade
- Pathological accumulation of fluids within the pericardial cavity, might be serous fluid or blood which compresses the heart, restricts venous filling during diastole.
- During pericardiacocentesis the needle is placed at the left infrasternal angle through the cardiac notch of the left lung to remove the fluid.
Heart – Surfaces
- Anterior (sternocostal surface) - mainly right and some left ventricle and part of the left ventricle apex with the ascending aorta, SVC, pulmonary trunk, directed anteriorly to the posterior surface of the sternum and the ribs.
- Diaphragmatic (inferior) surface – mainly left ventricle and partly right ventricle and right atrium with termination of IVC, related to the central tendon.
- Right pulmonary surface—mainly right atrium.
- Left pulmonary surface– mainly left ventricle that forms a cardiac impression in left lung.
Heart – Borders
- Right border – right atrium (SVC/IVC)
- Inferior border – right ventricle and left ventricle
- Left border – left ventricle and left auricle Superior border – both atria and auricles, ascending aorta, pulmonary trunk
Heart Wall Structure
- Three layers:
- Endocardium – innermost layer, lines the cavities of heart, single layer of flat epithelium continuous with vascular endothelium in blood vessels.
- Myocardium – middle layer, thickest part of the heart wall (complex arrangement of muscle fibers)
- Epicardium – outermost layer, a serous membrane part of the pericardium.
Heart Wall
- Created by three muscular layers: External oblique, Intermediate circular (strongest), and Internal longitudinal.
Heart – Location
- Lies at the level of T6-T9 vertebrae, posterior and superior, and on the right side of the chest.
- Basis of heart creates the heart crown with the beginning of great vessels
- Apex of heart—formed mainly by the left ventricle. Lies just posterior to the left 5th intercostal space, medially to the midclavicular line.
- The right and left atria are demarcated from the ventricles by the coronary sinus. Right and left ventricles are demarcated by anterior and posterior interventricular grooves.
Heart – Surface Projections
- Upper right aspect of the heart is located at the level of 3rd right costal cartilage
- Lower right aspect reaches the 6th right costal cartilage.
- Upper left aspect reaches the left 2nd costal cartilage
- Apex of heart is located in the left intercostal space at midclavicular line.
Heart – Chambers
- Right atrium receives blood from SVC, IVC and coronary sinus.
- Part of right atrium: Right auricle— is a muscular pouch that projects out from the atrium increasing its capacity (derived from fetal atrium).
- Anterior muscular wall is composed of pectinate muscles.
- Sinus venarum—is thin, posterior part with openings of 2 vessels (SVC and IVC); is the smooth-walled portion of the atrium.
Heart – Right Atrium
- Crista terminalis—ridge that separates the smooth part of the right atrium from the rough part. Extends longitudinally from the openings of the IVC and SVC; the SA node is located in the upper part of the crista terminalis.
- Fossa ovalis—the remnant of the foramen ovale, present in fetal circulation.
- Tricuspid valve communicates with the right ventricle
Heart – Right Ventricle
- Creates a large portion of the anterior surface of the heart.
- Superiorly, it tapers into the conus arteriosus, which leads into the pulmonary trunk
- Irregular elevations called trabeculae carnea are present inside the right ventricle,
- Papillary muscles project into the cavity of the ventricle and attach to the cusps of the AV valve by strands of chordae tendineae; they correspond to the cusps of the tricuspid valves.
Heart – Right Ventricle - Papillary Muscles
- Anterior papillary muscle (biggest) arises from anterior ventricular wall and its tendinous cords attach to the anterior and posterior cusps of the tricuspid valve.
- Posterior papillary muscle (smaller) arises from posterior ventricular wall, with tendinous cords (chordae tendinae) attached to posterior and septal cusps. Septal papillary muscle arises from interventricular septum, with tendinous cords attached to the anterior and septal cusps.
Heart – Interventricular Septum
- Is composed of a thicker muscular and a thinner membranous part and forms part of the ventricular walls.
- Septal cusp of the tricuspid valve is attached to the membranous part of the septum.
- Septomarginal trabecula is a muscular bundle that traverses the right ventricle from inferior part of the IVS to the base of the anterior papillary muscle.
- It carries a part of the right branch of the AV bundle.
Heart – Left Atrium
- Creates the base of the heart. Right and left pulmonary veins (superior and inferior) drain oxygenated blood from the lungs into the left atrium.
- The tubular muscular left auricle has a trabeculated wall with pectinate muscles.
- Bicuspid (mitral) valve lies between left atrium and left ventricle in the left atrioventricular orifice.
Heart – Left Ventricle
- Blood enters the left ventricle through the mitral valve and is pumped out to the aorta.
- Trabeculae carneae are usually thicker than those in the right ventricle.
- Papillary muscles (anterior and posterior) are attached by chordae tendineae to the cusps of the bicuspid valve. Chordae tendineae are the same as in the right ventricle.
- Aortic vestibule leads to the aortic semilunar valve.
Cardiac Skeleton and Valves
-Heart has 4 valves attached to fibrous rings of dense collagen, creating the fibrous skeleton of the heart. Fibrous rings right & left for atrioventricular valves, and aortic and pulmonary rings—for semilunar. Fibrous trigons: left & right Tendon of infundibulum and membranous part of IVS
Cardiac Skeleton and Valves – additional details
- Valves: Right atrioventricular (tricuspid), Auscultation point: 5th intercostal space on the right (or left) sternal line, Left atrioventricular (bicuspid), Auscultation point: 5th intercostal space on the left midclavicular line, Aortic valve, Auscultation point: 2nd intercostal space on the right sternal line, Pulmonary valve, Auscultation point: 2nd intercostal space on the left sternal line.
- Heart sounds: First sound (S1) comes from closing atrioventricular valves and Second sound (S2) results from closing aortic and pulmonary valves.
Coronary Arteries
- Coronary arteries arise from the aortic sinuses (right and left) of the ascending aorta, and blood flow occurs during diastole.
- Right coronary artery: courses in the coronary sulcus and supplies major parts of the right atrium and the right ventricle;sinoatrial (SA), right marginal, posterior interventricular (posterior descending), atrioventricular (AV) nodal branches
- Left coronary artery: travels between left auricle and ventricle, divides into 2 branches (left anterior descending (LAD) artery and circumflex artery). The LAD artery runs within the anterior interventricular groove to supply the anterior left ventricular wall, anterior 2/3 of the interventricular septum, bundle of His, and apex. The circumflex artery courses along the left border of the heart in the coronary sulcus and supplies the left border of the heart; via the marginal branch, ends on the posterior aspect of the left ventricle and supplies the posterior/inferior left ventricular wall.
Coronary Occlusion
- Myocardial infarction (MI) is usually connected with left anterior descending (LAD) artery occlusion (50% cases). Less often with the right coronary artery occlusion (30% cases) or circumflex artery obstruction (20% cases).
Cardiac Veins
- Venous Drainage of the Heart is provided by veins that accompany the arteries.
- Coronary sinus is the biggest coronary vein; it lies in the posterior coronary sulcus draining blood to the right atrium.
- Great cardiac vein lies in the anterior interventricular groove with the LAD artery, draining into coronary sinus
- Middle cardiac vein lies in the posterior interventricular groove with the posterior interventricular artery and drains to the coronary sinus.
- Venae cordis minimae (Thebesian veins) and anterior cardiac veins open directly into the heart chambers.
Cardiac Conduction System
- Is created by few important elements which produces impulses for heart contraction. Includes cardiac muscle cells and conducting fibers, initiating and conducting impulses rapidly through the heart.
- Sinus (sinoatrial) node, Atrioventricular (AV) node, Atrioventricular bundle (bundle of His) and Purkinje fibers.
Cardiac Conduction System (Additional Details and Innervation)
- Sinus (sinoatrial) node initiates impulses for heart contraction (called the heart “pacemaker”) and is located at the superior end of the crista terminalis (point of SVC opening to the right atrium) –Atrioventricular (AV) node receives impulses from the SA node; located in the right atrium in the interatrial septum over the right fibrous trigone. It can also produce the impulse (about 50 per minute), supplied by the right coronary artery.
- Bundle of His – conducts impulses from AV node to the right and left ventricles—it’s supplied by the LAD artery. In right ventricle, septomarginal trabecula contains right bundle branch.
- Purkinje fibers—spread from the bundle branches and reach papillary muscles and ventricular myocardium.
- Innervation- Cardiac plexus created by sympathetic and parasympathetic fibers. –Sympathetic stimulation increases heart rate; pain fibers follow sympathetic fibers back to the spinal cord segments T1–T5. –Parasympathetic stimulation slows heart rate; sensory nerves that take part in reflex arches of the heart creation travel with vagus nerve.
Mediastinum
- Is the central middle space located between two pleural cavities.
- Superior mediastinum – Space between the manubrium of the sternum and bodies of the upper thoracic vertebrae (T1-T4). Includes the thymus (usually visible in children until age 2), brachiocephalic veins and the beginning of the superior vena cava, which drains to the right atrium deep to the 3rd right costal cartilage.
- Anterior mediastinum – Located between the sternum (body) and the anterior surface of the pericardium. Includes areolar tissue, anterior mediastinal lymph nodes (parasternal), and internal thoracic artery and vein.
- Posterior mediastinum – Located between the posterior surface of the pericardium and the T2-T12 thoracic vertebrae. Contains the descending aorta, thoracic duct, esophageal, posterior intercostal, and bronchial branches—it also passes through the aortic hiatus at the T12 vertebral level.
Mediastinum (Additional Details)
- Branches of the aortic arch: brachiocephalic trunk, right common carotid artery, right subclavian artery, left common carotid artery, and left subclavian artery
- Trachea located posterior to the aortic arch; starts at C6 and bifurcates at T4 to form the main bronchi. Carina as an internal projection of cartilage is present at the bifurcation.
- Esophagus is posterior to the trachea, then to the left bronchus.
- Superior mediastinum also contains vagus and phrenic nerves
- Vagus nerve (CN X)—participates for cardiac and pulmonary plexus; gives off laryngeal recurrent nerve (passes inside the groove between the esophagus and the trachea to reach the larynx). Right recurrent laryngeal nerve passes under the right subclavian artery, Left recurrent laryngeal nerve passes under the arch of the aorta Phrenic nerve – arises from C3-C6 ventral rami of spinal nerves and supplies the diaphragm with motor and sensory fibers.
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Test your knowledge on the various congenital heart defects including Tetralogy of Fallot, Transposition of Great Vessels, and Persistent Truncus Arteriosus. This quiz covers key characteristics, common features, and essential survival mechanisms related to these conditions. Perfect for medical students and healthcare professionals.
