CVS DR1: Mediastinum, Pericardium, Chambers of the heart Flashcards
What cavities are enclosed in the thoracic walls?
2 pleural cavities and the mediastinum
How much of the thorax does the mediastinum contain?
Basic
Everything other than the lungs and their associated pleura
What are the sections of the thorax?
Superior
Inferior:
- Anterior
- Middle
- Posterior
What kinda important organ is NOT contained in the superior mediastinum?
The Heart
What encloses the superior mediastinum, anteriorly and posteriorly?
Manubrium - Ant.
Vertebrae T1-T4 - Post.
Which plane separates superior and inferior mediastinum?
Transverse
What arteries are contained in the superior mediastinum?
Aortic arch
Brachiocephalic
Left Common Carotid
Left Subclavian
What veins are contained in the superior mediastinum?
Brachiocephalic
Superior vena cava
What major nerves pass through the superior mediastinum?
Vagus
Phrenic
What other organs and structures are present in the superior mediastinum?
Trachea & Oesophagus
Thoracic duct - lymphatics
Thymus gland
Describe the arrangement of the inferior pericardium, and it’s sections
Anterior section is the area between the sternum and the pericardium
Middle section is basically the pericardium
Posterior section is the area behind the pericardium
What is in the anterior mediastinum?
Thymus - behind the sternum
Lymph nodes
Fat
What is in the middle mediastinum?
Heart, pericardium
Great vessels
What is in the posterior mediastinum?
Oesophagus & vagus nerve
Azygos vein
Descending aorta
Sympathetic trunk
Thoracic duct
Splanchnic nerve
What are the 2 layers of the pericardium?
Fibrous & serous
Describe the serous pericardia
Innermost of the Fibrous & serous pericardia
Composed of 2 layers with fluid filled cavity separating them:
- Parietal (outer) layer
- Visceral (inner) layer = epicardium
Describe the fibrous pericardia
Outermost of the Fibrous & serous pericardia
Inner edge is in contact with parietal layer of serous pericardium
From the outermost layer of the pericardium:
List the layers moving inwards, until the innermost layer of the heart
- Fibrous pericardium
- Parietal layer of serous pericardium
Pericardial cavity
- Visceral layer of serous pericardium = epicardium
- Myocardium
- Endocardium
What are the main features of the right atrium?
3 Openings for:
- Inferior Vena cava
- Superior vena cava
- Coronary sinus
Interarterial septum
Fossa ovalis in Interarterial septum
Musculi pectinati & crista terminalis
Tricuspid valve
What features would you look for to identify the right ventricle?
Tricuspid valve:
- 3 valve cusps
- Chordae tendineae
- Papillary muscles x3
Trabeculae carneae (contractile fleshy struts)
Moderator band (Septomarginal trabeculum)
1 Opening for pulmonary trunk
Interventricular septum
What is the purpose of the Trabeculae carneae?
Most likely to prevent suction that would occur with a flat surface and thus impair the heart’s ability to pump efficiently. The papillary muscles themselves are just a specialised form of trabeculae carneae.
What are the main features used to identify the left atrium?
4 Openings for:
l + r superior pulmonary veins
l + r inferior pulmonary veins
Bicuspid (mitral) valve
Smooth-walled, small chamber,
lying wholly postero-superiorly against
oesophagus.
Forms base of heart.
What are the main identification features of the left ventricle?
Biscuspid (mitral valve):
2 valve cusps
Chordae tendineae
Papillary muscles x2
Trabeculae carneae
1 Opening for aorta
Interventricular septum
Wall 3x as thick as right ventricular wall.
Forms apex of heart
Describe the vertebral level of the heart
T5-8
Middle 4 vertebrae^
(when in recumbent position)
Where is the apex of the heart?
5th Left intercostal space
In the midclavicular line
What forms the base of the heart?
Left atrium
This lies wholly posterior, and against the oesophagus
What forms the right border of the heart?
Superior Vena cava & right atrium
What forms the left border of the heart?
Aortic arch and left ventricle
The surface anatomy ‘area’ of the heart is a weird box thing
What forms each corner and where is it located on the surface?
Apex (bottom left) - 5th IC space in Midclavic. line
Upper left - End of 2nd left rib, in line with Sternal angle
Upper right - Intercostal cart of 3rd rib
Bottom right - IC cartilage of 6th right rib, in line with bottom of body of sternum
What are the main arteries located in the chest wall and trunk?
Descending aorta
Internal thoracic artery:
- This gives off branches of Anterior intercostal arteries
What are the main veins of the chest wall and trunk?
Inferior vena cava
Azygos vein
Internal thoracic vein:
- Receives anterior thoracic veins
What lymph vessel would you look for in the chest wall and trunk?
Where is this located?
Thoracic duct
Runs just behind the Aorta
What is the endocardium composed of?
Simple squamous epithelium sitting on basement membrane
Sits on connective tissue
What is the mycocardium made of?
Many layers of cardiac muscle (myocytes)
What is the Epicardium (visceral serous) made of?
Simple squamous epithelium sitting on BM with connective tissue
May have fatty layer separating it from the myocardium
What is cardiac tamponade?
When excess fluid accumulates in the pericardial cavity (many reasons why this can happen)
Increased pressure exerted by fluid onto the heart reduces the filling of the heart
Can lead to cardiac failure if severe enough
Describe the nervous innervation of the VISCERAL pericardium
Autonomic innervation from:
- T1-T4 nerves
- Vagus nerve via cardiac plexus (same as heart wall itself)
Describe the nervous innervation of the Parietal and fibrous layers of the pericardium
Innervated mainly by the Phrenic nerve
Which layers of the pericardium can detect pain?
Parietal layer of serous & the Fibrous layer
They’re innervated by phrenic whereas the visceral serous layer only receives autonomic innervation
What nerves link to the cardiac plexus?
Vagus nerve (branches of)
Nerves from Sympathetic trunk:
- Middle cervical ganglion
- Stellate ganglion
- T2
- T3
- T4
What chamber of the heart contains the fossa ovalis?
What is it?
Contained in the right atrium
Remnant of the foramen ovale which closes after birth
Was basically a passage from the right to left atria to avoid the pulmonary circulation which the foetus did not need when in the womb
The right atrium has an ‘auricle’
What is this?
Flappy bit at the top of the atrium
What separates the two atria?
Interatrial septum
What is the name of the bumpy, pure stringy muscle section on the walls of the atria?
Musculi pectinati
What is the name given to the large ridge/bump thing that is found at the end of the musculi pectinati?
Crista terminalis
crista sort of means ridge
What is the correlation between the number of cusps in a valve, and the number of papillary muscles in the ventricle
For each cusp, there is one papillary muscle attached to it
The moderator band (septomarginal trabeculum) is found in the right ventricle.
What is it’s function?
It carries the right bundle branch from the AV node to the papillary muscles in the RV
This means contraction of papillary muscles is coordinated with heart contraction, meaning the valve doesn’t invert
What is the difference between Musculi pectinati and trabecullae carnae?
They have the same appearance, columned, stringy walls of muscle
However, the Musculi P are only in the atria and the Trabecullae C are only in the ventricles
What valve separates the left ventricle and left atrium?
Mitral valve
bicuspid
