Gross Anatomy Flashcards
Where Is the heart located?
The heart is in the middle pericardium surrounded by the pericardium
Why does the pericardium consist of 3 layers?
- limits acute cardiac dilation
- assists atrial filling
- mechanical and anti-friction protection
What is the structure-function of the outer fibrous layer of the pericardium?
Restrictive and attached to surrounding structures
-Superiorly to the adventitia of the great vessels
- inferiorly to the central tendon of the diaphragm (cardiophrenic ligament)
- Anteriorly to the sternum (sternopericardial ligaments)
- To the bifurcation of the trachea (bronchopericardial membrane)
What is the structure-function of the inner serous level of the pericardium?
- parietal (lines the fibrous)
- visceral (syn. Epicardium)
What is the structure-function of pericardial cavity of the pericardium?
Filled with small amount of serous fluid
What is the arterial supply of the pericardium?
- pericardiophrenic (from internal thoracic)
- musculophrenic (from internal thoracic)
- inferior phrenic
- thoracic aorta
- coronary (visceral serous)
What is the veinous drainage of the pericardium?
- Azygos
- Internal thoracic
- Superior phrenic
- Cardiac (visceral serous)
What is the innervation of the pericardium?
- phrenic nerve- somatic pain (fibrous only)
- vagus- parasympathetic
- sympathetic chain- sympathetic
- cardiopulmonary- visceral afferents
How are sinuses formed?
At the posterior aspect of the pericardial SA the serous pericardium reflects on itself forming sinuses
Where is the transverse sinus located?
Transverse sinus: this space could be entered to place a clamp around the proximal aorta and pulmonary trunk
Anterior: Aorta and pulmonary trunk
Posterior: superior vena cava
Superior: right pulmonary artery
Inferior: atria
What is the oblique sinus of the heart?
A cul-de-sac formed where the serous pericardium reflects onto the pulmonary sinus
What does the heart rest on?
The heart rests on the diaphragm and haas the shape of an inverted cone
What are the borders of the heart?
Left and right: synchronous with pulmonary surface
Obtuse margin: between with left pulmonary and anterior surface
Inferior border: between the anterior and diaphragmatic surfaces
Where is the right ventricle of the heart located?
Right ventricle directly posterior to the sternum
What is the location of left atrium?
The left atrium lies immediately anterior to the esophagus
- Sharp objects if swallowed can penetrate the left atrium
- Enlargement of the left atrium can cause difficulty swallowing (dysphagia)
- Transesophageal ultrasound
What is pericardial effusion?
Fluid accumulation in the pericardial cavity beyond the normal 30-50 ml
May be slow or rapid
What are the possible causes of pericardial effusion?
- Systemic inflammatory conditions (connective tissue disease)
- Metastasis
- Hypothyroidism
- Renal disease
- Infection
What are the symptoms of pericardial effusion?
- Dyspnea
- Reduced exercise tolerance
- Eventually progress to impaired cardiac function
- May develop into tamponade
What is a cardiac tamponade?
- Impaired cardiac output due to an accumulation of fluid, pus, gas, blood, or tissue in the pericardial space
- Pulses paradoxus: exaggerated fall in systolic blood pressure (10 mmHg) during inspiration
What is the Beck’s triad of pericardial effusion?
- Increased pressure outside the heart decreases end-diastolic ventricular filling —> decreased stroke volume —> lower systolic blood pressure
- Increased pressure reduces end-systolic atrial filling capacity—> rapid increase and higher pressure in atria —> increased pressure in and distension of the jugular veins
- Increased fluid—> reduced heart sounds
How is cardiac tamponade treated?
Pericardiocentesis:
1. Paraxiphoid approach - tip of xiphoid, or between xiphoid and left costal margin, angled towards left shoulder
- Apical approach- left 5th or 6th intercostal space
Where does the right atrium receive blood from?
-SVC, IVC & coronary sinus
What is the function of the crista terminalis?
A muscular ridge (crista terminalis) separates the smooth posterior part atrium from the area roughened by the pectineus muscles
What is the fossa ovalis?
The interatrial septum has an oval depression (fossa ovalis)
What are the structures of the right atrium ?
- crista terminalis
- interatrial septum has an oval depression(fossa ovalis)
- openings for smallest cardiac veins
Describe the internal structure of the right ventricle
- Wall is thinner than left
- Cavity is larger than left
- Moderator band connects the interventricular septum to the anterior papillary muscle and contains (Purkinje fibers) from right bundle branch
- Infundibulum is smooth
Describe the structure of atrioventricular valves
- Attached to the fibrous skeleton of the heart
- Each cusp connected to 2 papillary muscles
- As the ventricles fill with blood (during diastole) the cusps “float” closed
- During ventricular contraction, the papillary muscles hold the cups closed
- During ventricular contraction, the papillary muscles hold the cups closed to avoid eversion into the atria
What are the semilunar valves?
- pulmonary
- aortic
Describe the aortic semilunar valve
Right, left and posterior cups
- two coronary cusps -associated with the Ostia of a coronary artery
- aortic sinuses (of Valsalva) fill after ventricular contraction closing valves and simultaneously filling coronary arteries
Describe the pulmonary semilunar valve
Right, left and anterior
-no associated vessels
Where are heart valves located?
Heart valves are all located posterior to the sternum
What are auscultation sites?
Sites of greatest sound projection
What is the auscultation site of the aortic valve?
Right sternal border at 2nd intercostal space
What is the auscultation site of the pulmonary valve?
Left costal border at 2nd intercostal space
What is the auscultation site of the tricuspid valve?
Left sternal border at 5th intercostal space
What is the auscultation site of the mitral valve?
5th left intercostal space in midclavicular line
When does the atria contract in relation to ventricles?
Atria contracts 1/6th of a second before the ventricles
All parts of the ventricles contract almost simultaneously
What is a Conduction system ?
Specialized cardiac muscle cells insulated from surrounding myocardium
Initiates and coordinates contraction- unidirectional
What are the components of the conduction system?
- Sinoatrial node(pacemaker)- at the junction of the SVC and right atrium
- Atrioventricular node- in the atrioventricular septum close to the opening of the coronary sinus
- Atrioventricular bundle- membranous part of interventricular septum
- Left and right bundle branches (and their fascicles)- in the muscular portion of the interventricular septum and respective ventricular walls around the apex
- Purkinje fibers- specialized cells in the ventricular walls and papillary muscles
- Electrical activity can be detected with an ECG monitor
What splachnic nerves are part of the visceral efferent?
Preganglionic sympathetic from T1-4(5) enter the sympathetic chain via grey rami communicants—> postganglionic sympathetic cervical and upper thoracic chain ganglia
These form splachnic nerves which join with cardiac branches to form cardiac plexus
Where are cardiac branches formed by? What do they then form?
Preganglionic parasympathetic from vagus form cardiac branches then combines with splachnic nerves to form the cardiac plexus
Functions for visceral efferent of the heart
What are the divisions of the cardiac plexus?
Two divisions:
1. Superficial part around the great vessels (Ligamentum arteriosum)
- Deep part, posterior to the left atrium (anterior to tracheal bifurcation)
There are small branches to the heart structures
Both of these affect heart rate, force of contraction and cardiac output. By influencing the conduction system, coronary vessels and myocardium.
What is the role of cardiac branches in the visceral afferents?
Detect changes in blood pressure and body chemistry (aortic body and sinus) —> cardiac plexus—> cardiac branches to vagus —> goes to brain for regulation through the visceral efferent system
What is the role of splachnic nerves in the visceral afferents?
Detect/indirect tissue damaging events- visceral pain—> cardiac plexus—> splachnic nerves via sympathetic to spinal cord —>(1 possible destination) refferred to somatic body region- refferred pain (other posssible destination)
What is refferred pain?
Pain from ischemia or other noxious stimuli are transmitted via visceral afferents that pass through the cardiac plexus
Visceral afferents travel with the sympathetics to the spinal nerves soft corresponding levels
- Enter the spinal cord between T1-4 spinal cord levels (have their cell bodies in the dorsal root ganglion)
- Visceral pain is diffuse and refferred to the upper thoracic and medial arm
- The intercostobrachial nerve connects the T2 spinal nerve with medial cutaneous nerve of the arm,/forearm
What does the left coronary artery supply?
Supply:
-anterior 2/3 of interventricular septum
- majority of left ventricle
- majority of left atrium
- AV bundle and brancges
What does the anterior interventricular artery go and anastomoses ?
Anterior inter-ventricular May wrap around the apex and anastomose with the posterior interventricular
What is dominance?
There is much variation in the coronary arteries and what they supply
Dominance
-determines which of the coronary arteries is responsible for the majority of supply
- origin of the posterior interventricular artery
- Significance for the supply of the conduction system
What are the Branches of the right coronary artery and their accompanying vein?
Branch: SA node- accompanying vein: small cardiac vein
Branch: right marginal- accompanying vein: right marginal vein
Branch: posterior interventricular accompanying vein: middle cardiac vein
What are the branches and accompanying veins of the left coronary artery?
Branch: anterior interventricular circumflex- accompanying vein- great cardiac vein
What are the causes of chest pain?
Myocardial infarction
Pleural pain
Intercostal pain
Pericardial pain
What are the features of the myocardial infarction?
Severe chest heaviness or pressure for over 20 minutes, sweating, clenched fist (Levine sign) crushing pain radiating to the arm, nausea
What are the features of pleural pain?
Preceding pneumonia, pulmonary embolism, or viral respiratory infection. Acute sharp pain with breathing, coughing, or movement
What are the features of intercostal pain?
Sharp pain in the thorax unilaterally worsens with chest wall movements including breathing
What are the features of pericardial pain?
From pericarditis
Continuous central chest pain which can radiate to both shoulders but maybe alleviated by sitting forward
