Anatomy of the heart Flashcards

1
Q

What are the external features of the heart?

A
  • Conical in shape
  • Apex (formed by the left ventricle)
  • Base (Formed by the atrium of the heart “mainly in the posterior surface)
  • Four borders: (1. Upper, 2. Lower, 3. Right, 4. Left)
  • Four surfaces: (Sternocostal, diaphragmatic, left and right surfaces)
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2
Q

Describe the Apex of the heart

A
  • Downwards, forwards, and to the left
  • Formed by the left ventricle mainly
  • Lies opposite to the left 5th intercostal space, 3.5 inches from the median plane (medial to the mid-clavicular line)
  • Overlapped by the left pleura and the lung
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3
Q

Where is the location of the apex of the heart?

A

The left 5th intercostal space, 3.5 inches from the median plane (just below the left nipple)

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3
Q

Describe the base of the heart

A
  • Backwards and to the left
  • Formed by the left atrium mainly (RA to a small extent)
  • Opposite to the middle four thoracic vertebrae (T5-8)
  • Related posteriorly to the right pulmonary veins, Esophagus and the descending aorta
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4
Q

What structures overlap the apex of the heart?

A

Left pleura and the lung

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5
Q

Which vertebral segments are correlated with the base of the heart?

A

T5-T8

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6
Q

What separates the base of the heart from the inferior surface?

A

The coronary sinus

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7
Q

What are the borders of the heart?

A

1) Upper border:

  • Formed by the two atria (mainly the left)

2) Right border:

  • Formed by the right atrium (extends from the opening of the superior vena cava to the opening of the inferior vena cava)

3) Left border:

  • Formed mainly by the left ventricle and partly by the left auricle

4) Lower border:

  • Formed mainly by the right ventricle, slightly concaved downwards due to the upward convexity of the diaphragm
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8
Q

What are the structures that overlap the upper border of the heart?

A

1) Pulmonary trunk

2) Ascending aorta

3) Superior vena cava

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9
Q

What are the surfaces of the heart?

A

1) Sternocostal surface

2) Diaphragmatic surface

3) Left surface

4) Right surface

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10
Q

Describe the sternocostal surface of the heart

A
  • Divided by the coronary groove
  • Its atrial portion lies above the coronary groove and is made up of the right atrium and the auricle of the left atrium
  • Its ventricular portion lies below the coronary groove, and it is formed 1/3 by the left ventricle and 2/3 by the right ventricle separated by the anterior interventricular groove (which contains the left anterior descending artery “anterior interventricular artery” and the great cardiac vein)
  • When a tab wound behind the sternum at the fourth intercostal space it is probably hitting this surface
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11
Q

Describe the diaphragmatic surface of the heart

A
  • Directed downwards & slightly backward
  • Formed by the two ventricles (Left ventricle mainly)
  • The posterior interventricular groove divides it into right and left ventricles
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12
Q

Which structures are related to the diaphragmatic surface?

A

1) Central tendon and the left cupola of the diaphragm

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13
Q

Describe the left surface of the heart

A
  • Formed by the left ventricle mainly + THE LEFT ATRIUM AURICLE
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14
Q

Which structures are related to the left surface of the heart?

A

1) Pericardium

2) Left phrenic nerve

3) Left pericardiacophrenic vessels

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15
Q

Describe the right surface of the heart

A

Formed by the right atrium

16
Q

Which structures are related to the right surface of the heart?

A

1) Pericardium

2) Right phrenic nerve

3) Right pericardiophrenic vessels

17
Q

What are the grooves of the heart?

A

1) Atrioventricular groove (coronary groove)

2) Interatrial groove

3) Posterior interventricular groove (“on the diaphragmatic surface” Contains the posterior interventricular artery, and the middle cardiac vein)

4) Anterior interventricular groove (“lies on the sternocostal surface”, has the anterior interventricular artery “left anterior descending artery”, and the great cardiac vein)

18
Q

Describe the coverings of the heart

A

1) Fibrous Pericardium (Its base fuses with the central tendon of the diaphragm)

2) Serous pericardium (enclosed by the fibrous pericardium, consists of a parietal layer “firmly adherent to the fibrous epicardium” and a visceral layer “covers the heart and is adherent to it)

3) Pericardial cavity (space between the parietal and visceral layers, containing a thin fil of fluid which enables the heart to beat frictionless)

19
Q

Which ligament attaches the fibrous pericardium to the sternum?

A

The sternopericardial ligament

20
Q

What is the function of the fibrous pericardium?

A

It prevents the heart from overfilling

21
Q

What type of cells is the serous pericardium made of?

A
  • Simple squamous epithelium
  • It directly reflects on the roots of the great vessels
22
Q

What happens in pericarditis?

A

It is when inflammation occurs at the serous cavity of the epicardium making a detectable sound on auscultation

23
Q

What is pericardial effusion?

A

It is the accumulation of fluid within the pericardial sac

24
Q

What is a cardiac tamponade?

A

It is when the pericardial effusion reaches a limit where the movement of the heart is compromised

25
Q

What is pericardiocentesis?

A

A technique that obtains fluid from the pericardial cavity, where the needle is inserted below the xiphisternum in the left costoxiphoid angle, above the 6th intercostal space

26
Q

What is meant by the bear area in the thorax?

A

It is when pericardiocentesis is done through the 4th & 5th left intercostal space, it is an area where the pleura do not cover the heart and pericardium

27
Q

Which heart layers are pierced during pericardiocentesis?

A

1) Fibrous pericardium

2) Parietal layer of the heart “serous pericardium”

28
Q

Describe the pericardium

A

1) Pericardium

A) Fibrous pericardium

B) Serous pericardium

Ba) Parietal pericardium

Bb) Visceral pericardium/Epicardium

29
Q

What are the sinuses of the pericardium?

A
  • Occurs as the heart develops

1) Transverse sinus

2) Oblique sinus

30
Q

What is the transverse sinus?

A

It is the spaced lined posteriorly by the superior vena cava, and anteriorly by the Aorta & Pulmonary trunk

31
Q

What is the surgical significance of the transverse sinus?

A
  • A ligature can be passed to occlude the atrial hilum of the heart (which are the aorta and pulmonary trunk) during cardiac operations to stop/divert the circulation
  • The machine will take deoxygenated blood from the superior and inferior vena cava and pump them back to the aorta oxygenated
32
Q

What is the oblique sinus?

A
  • Located behind the heart
  • It is the gap between the pericardial sac and the heart
33
Q

Describe the nerve supply of the heart

A

1) Fibrous and Parietal layer: Somatic innervation (sensory/motor)

2) Visceral layer: Autonomic innervation

34
Q

Which nerve innervates the fibrous and parietal pericardium?

A

The phrenic nerve

35
Q

Can the pericardial sac be a source of pain?

A

Yes, due to its somatic innervation

36
Q

Which nerve innervates the visceral pericardium?

A

The vagus (parasympathetic nerve) and sympathetic nerves

37
Q

Describe the mechanism by which the cardiac pain gets referred to the arm

A
  • Pain originating in the heart due to myocardial ischemia is assumed to be due to oxygen deficiency & metabolite accumulation which stimulates the sensory nerve endings in the myocardium
  • Afferent nerve fibers ascend to the central nervous system via the sympathetic trunk cardiac branches, entering the spinal cord through the posterior roots of the upper four thoracic nerves
  • The pain is referred to the skin areas supplied by the corresponding spinal nerves (which are the skin areas supplied by the four intercostal nerves and by the intercostobrachial nerve “T2”)
  • The intercostobrachial nerve communicates with the medial cutaneous nerve of the arm, distributing the pain towards the medial side of the upper part of the arm
  • Sometimes the pain is felt in the neck and jaw