Session 1.2g - Gray's Anatomy for Students - Thorax - Regional anatomy - Mediastinum (Part I) Flashcards

https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780702051319000031?scrollTo=%23hl0002009

1
Q

What is the mediastinum?

A

A broad central partition that separates the two laterally placed pleural cavities (Fig. 3.50).

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2
Q

Where does the mediastinum extend?

A
  • from the sternum to the bodies of the vertebrae, and

- from the superior thoracic aperture to the diaphragm (Fig. 3.51)

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3
Q

What is the superior border of the mediastinum?

A

Superior thoracic aperture

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4
Q

What is the inferior border of the mediastinum?

A

Diaphragm

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5
Q

What is the anterior border of the mediastinum?

A

Sternum

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6
Q

What is the posterior border of the mediastinum?

A

Vertebral bodies (thoracic)

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7
Q

What does the mediastinum contain?

A
  • thymus gland
  • pericardial sac
  • heart
  • trachea
  • major arteries and veins
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8
Q

What does the mediastinum serve as a passageway for?

A

Structures such as the:

  • oesophagus
  • thoracic duct
  • various components of the nervous system
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9
Q

The mediastinum serves as a passageway for structure that ___?

A

Traverse the thorax on their way to the abdomen.

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10
Q

How is the mediastinum subdivided?

A

For organisational purposes, it is subdivided into several smaller regions.

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11
Q

Where is the mediastinum separated into the superior and inferior mediastinum?

A

A transverse plane extending from the sternal angle (the junction between the manubrium and the body of the sternum) to the intervertebral disc between vertebrae TIV and TV

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12
Q

A transverse plane from the sternal angle to the intervertebral disc between vertebrae TIV and TV separtes the mediastinum into the:

A

SUPERIOR MEDIASTINUM and INFERIOR MEDIASTINUM

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13
Q

How is the inferior mediastinum further partitioned?

A

Into the ANTERIOR, MIDDLE and POSTERIOR MEDIASTINUM

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14
Q

How is the inferior mediastinum partitioned into the anterior, middle and posterior mediastinum?

A

By the pericardial sac.

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15
Q

Where is the anterior mediastinum?

A

The area anterior to the pericardial sac and posterior to the body of the sternum. (Fig. 3.52)

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16
Q

Where is the posterior mediastinum?

A

The region posterior to the pericardial sac and the diaphragm and anterior to the bodies of the vertebrae. (Fig. 3.52)

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17
Q

Where is the middle mediastinum?

A

The area in the middle, which includes the pericardial sac and its contents. (Fig. 3.52)

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18
Q

What is centrally located in the thoracic cavity?

A

The MIDDLE MEDIASTINUM.

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19
Q

What does the middle mediastinum contain?

A

The pericardium, heart, origins of the great vessels, various nerves, and smaller vessels.

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20
Q

What is the pericardium?

A

The PERICARDIUM is a fibroserous sac surrounding the heart and the roots of the great vessels.

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21
Q

What components does the pericardium consist of?

A

Two components; the fibrous pericardium and the serous pericardium (Fig. 3.53).

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22
Q

Name the layers between the fibrous pericardium to the heart.

A

From superficial to deep

  • Fibrous pericardium
  • Junction between fibrous pericardium and adventitia of great vessels
  • Serous pericardium:
  • —– Parietal layer of serous pericardium
  • —– Pericardial cavity
  • —– Visceral layer of serous pericardium
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23
Q

What is the fibrous pericardium?

A

The FIBROUS PERICARDIUM is a tough connective tissue outer layer that defines the boundaries of the middle mediastinum.

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24
Q

What type of tissue is the fibrous pericardium?

A

Tough connective tissue

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25
Q

Which pericardium defines the boundaries of the middle mediastinum?

A

The fibrous pericardium (the outer layer)

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26
Q

Describe the serous pericardium

A

The SEROUS PERICARDIUM is thin and consists of two parts

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27
Q

What are the two parts of the serous pericardium?

A

The PARIETAL LAYER and the VISCERAL LAYER (EPICARDIUM)

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28
Q

Where is the parietal layer of serous pericardium?

A

The PARIETAL LAYER of serous pericardium lines the inner surface of the fibrous pericardium

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29
Q

What is the visceral layer of serous pericardium also known as?

A

EPICARDIUM

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30
Q

Where is the visceral layer of serous pericardium?

A

The VISCERAL LAYER (EPICARDIUM) of serous pericardium adheres to the heart and forms its outer covering.

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31
Q

Where are the parietal and visceral layers of serous pericardium continuous?

A

At the roots of the great vessels

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32
Q

What is the narrow space created between the two layers of serous pericaridum called?

A

PERICARDIAL CAVITY

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33
Q

What does the pericardial cavity contain?

A

A small amount of fluid

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34
Q

What is the function of the pericardial cavity?

A

This potential space allows for the relatively uninhibited movement of the heart.

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35
Q

Describe the shape and borders of the fibrous pericardium.

A

The FIBROUS PERICARDIUM is a cone-shaped bag with its base on the diaphragm and its apex continuous with the ADVENTITIA of the great vessels (Fig. 3.53).

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36
Q

Where, generally, is the base of the fibrous pericardium?

A

The diaphragm

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37
Q

Where is the apex of the fibrous pericardium?

A

Continuous with the ADVENTITIA (the outermost layer of a wall of a blood vessel) of the great vessels.

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38
Q

What is the base of the fibrous pericardium attached to?

A

The CENTRAL TENDON OF THE DIAPHRAGM and to a small muscular area of the diaphragm on the left side.

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39
Q

What is the fibrous pericardium attached to anteriorly?

A

The posterior surface of the sternum

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40
Q

How is the fibrous pericardium attached to the sternum?

A

By STERNOPERICARDIAL LIGAMENTS

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41
Q

What is the function of the sternopericardial ligaments?

A

These attachments help to retain the heart in its position in the thoracic cavity.

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42
Q

As well as the pericardial sac aiding movement of the heart, what else does it do?

A

The sac also limits cardiac distension.

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43
Q

What innervates the fibrous pericardium?

A

The phrenic nerves, which innervate the diaphragm and originate from spinal cord levels C3 to C5.

They pass through the fibrous pericardium from the point of origin to the diaphragm (their final destination). (Fig. 3.54).

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44
Q

Where is the location of the phrenic nerves in the fibrous pericaridium?

A

Their location, within the fibrous pericardium, is directly related to the embryological origin of the diaphragm and the changes that occur during the formation of the pericardial cavity.

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45
Q

What vessels supply the fibrous pericardium?

A

The PERICARDIACOPHRENIC VESSELS

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46
Q

Where are the pericardiacophrenic vessels found?

A

Located within and supply the fibrous pericardium as they pass through the thoracic cavity.

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47
Q

Where are the parietal and visceral layers of serous pericardium continuous?

A

Around the roots of the great vessels.

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48
Q

Where do the reflections of serous pericardium occur?

A

In two locations:

  • one superiorly, surrounding the arteries, the aorta and the pulmonary trunk;
  • one more posteriorly, surrounding the veins, the superior and inferior vena cava and the pulmonary veins.
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49
Q

What does the superior reflection of the serous pericardium surround?

A

The arteries, the aorta and the pulmonary trunk.

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50
Q

What does the more posterior reflection of the serous pericardium surround?

A

The veins, the superior and inferior vena cava and the pulmonary veins.

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51
Q

The zone of reflection from the serous pericardium surrounding the veins is what shape?

A

J-shaped

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52
Q

Where is the oblique pericardial sinus?

A

The zone of reflection from the serous pericardium surrounding the veins is J-shaped, and the cul-de-sac formed within the J, posterior to the left atrium, is the OBLIQUE PERICARDIAL SINUS.

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53
Q

What is the passage between the two sites of reflected serous pericardium called?

A

The TRANSVERSE PERICARDIAL SINUS

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54
Q

Where is the transverse pericardial sinus?

A

This sinus lies posterior to the ascending aorta and the pulmonary trunk, anterior to the superior vena cava, and superior to the left atrium.

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55
Q

What is the transverse pericardial sinus’ anterior border?

A

Ascending aorta and the pulmonary trunk

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56
Q

What is the transverse pericardial sinus’ posterior border?

A

The superior vena cava

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57
Q

What is the transverse pericardial sinus’ inferior border?

A

The left atrium

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58
Q

What is the clinical significance of the transverse sinus?

A

When the pericardium is opened anteriorly during surgery, a finger placed in the transverse sinus separates arteries from veins.

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59
Q

Where does the pericardium need to be opened to access the transverse sinus?

A

Anteriorly during surgery

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60
Q

How can the transverse sinus separate the arteries from veins?

A

A finger can be placed there during surgery.

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61
Q

How can the oblique sinus be accessed during surgery?

A

A hand placed under the apex of the heart and moved superiorly slips into the oblique sinus.

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62
Q

How can the transverse and oblique sinuses be accessed during surgery?

A

Transverse - open the pericardium anteriorly and place a finger in the transverse sinus to separate arteries from veins

Oblique - A hand placed under the apex of the heart and moved superiorly

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63
Q

What supplies the pericardium?

A
The pericardium is supplied by branches from the 
- internal thoracic
- pericardiacophrenic
- musculophrenic
- inferior phrenic
arteries, and the 
- thoracic aorta
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64
Q

Where do veins from the pericardium enter?

A
  • the azygos system of veins
  • internal thoracic v.
  • superior phrenic v.
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65
Q

What nerves supply the pericardium?

A

Nerves supplying the pericardium arise from the

  • vagus nerve [X]
  • sympathetic trunks
  • phrenic nerves
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66
Q

Where is the source of somatic sensation (pain) from the parietal pericardium from?

A

Somatic sensation (pain) is carried by somatic afferent fibres in the phrenic nerves.

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67
Q

Where might pain related to a pericardial problem be referred to?

A

The supraclavicular region of the shoulder or lateral neck area dermatomes for spinal cord segments C3, C4 and C5.

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68
Q

Why might pain be referred to the supraclavicular region of the shoulder or lateral neck area?

A

The source of somatic sensation (pain) from the pericardium is carried by somatic afferent fibres in the phrenic nerves.

This may lead to referred pain in the dermatomal spinal cord segments C3, C4 and C5.

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69
Q

Somatic sensation from the pericardium is carried by somatic ______ fibres from which nerves?

A

Afferent; phrenic nerves

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70
Q

What is the general shape and orientation of the heart?

A

Cardiac orientation is that of a pyramid that has fallen over and is resting on one of its sides.

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71
Q

Where is the apex of the heart?

A

Placed in the thoracic cavity, the apex of the heart projects forward, downward, and to the left.

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72
Q

Where is the base of the heart?

A

Opposite the apex and faces in a posterior direction (Fig. 3.56).

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73
Q

What direction does the base of the heart face?

A

Posteriorly (Fig. 3.56).

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74
Q

What do the sides of the pyramid consist of?

A
  • Diaphragmatic surface
  • Sternocostal surface
  • Right pulmonary
  • Left pulmonary
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75
Q

What is the inferior surface of the heart?

A

A diaphragmatic (inferior) surface on which the pyramid rests

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76
Q

What is the anterior surface of the heart?

A

An anterior (sternocostal) surface oriented anteriorly

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77
Q

What is the right surface of the heart?

A

A right pulmonary surface

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78
Q

What is the left surface of the heart?

A

A left pulmonary surface

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79
Q

Describe the base of the heart?

A

The BASE (posterior surface) OF THE HEART is quadrilateral and directed posteriorly.

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80
Q

What does the base of the heart consist of?

A
  • The left atrium
  • A small portion of the right atrium
  • Proximal parts of the great veins
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81
Q

Which atrium does the base of the heart mainly consist of?

A

The left atrium

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82
Q

Which atrium does the base of the heart consist of a small portion of?

A

The right atrium

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83
Q

Which parts of the great veins does the base of the heart contain?

A

The proximal parts

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84
Q

Which great veins does the base of the heart contain?

A

Superior and inferior venae cavae and the pulmonary veins.

85
Q

Where do the great veins enter the heart?

A

At the base of the heart

86
Q

Where do the pulmonary veins enter the heart?

A

The right and left sides of the left atrium

87
Q

Where do the vena cavae enter the heart?

A

The superior and inferior venae cavae at the upper and lower ends of the right atrium, respectively.

88
Q

Where is the base of the heart fixed?

A

Posteriorly to the pericardial wall, opposite the bodies of vertebrae TV to TVIII (TVI to TIX when standing).

89
Q

Why is the base of the heart fixed posteriorly to the pericardial wall?

A

Due to where the great veins enter the heart

90
Q

Which vertebrae is the heart fixed to, when standing and when not?

A

TV to TVIII

TVI to TIX when standing.

91
Q

What structure lies immediately posterior to the base of the heart?

A

The oesophagus

92
Q

Describe the orientation of the heart from the base?

A

From the base the heart projects forward, downward, and to the left, ending in the apex.

93
Q

What forms the apex of the heart?

A

The APEX OF THE HEART is formed by the inferolateral part of the left ventricle (Fig. 3.58).

94
Q

Where is the apex of the heart?

A

Deep to the left fifth intercostal space, 8-9 cm from the midsternal line.

95
Q

Which intercostal space can you find the apex of the heart?

A

Deep to the left fifth intercostal space

96
Q

Where is the apex of the heart in relation to the midsternal line?

A

8-9 cm from it (left)

97
Q

Describe the anterior surface of the heart.

A

The ANTERIOR SURFACE faces anteriorly and consists mostly of the right ventricle, with some of the right atrium on the right and some of the left ventricle on the left (Fig. 3.58).

98
Q

Describe the diaphragmatic surface of the heart.

A

The heart in the anatomical position rests on the DIAPHRAGMATIC SURFACE, which consists of the left ventricle and a small portion of the right ventricle separated by the posterior interventricular groove (Fig. 3.59).

99
Q

Describe the diaphragmatic surface of the heart in relation to the overall orientation of the heart.

A

This surface faces inferiorly, rests on the diaphragm, is separated from the base of the heart by the coronary sinus, and extends from the base to the apex of the heart.

100
Q

Where is the left pulmonary surface of the heart?

A

The LEFT PULMONARY SURFACE faces the left lung, is broad and convex, and consists of the left ventricle and a portion of the left atrium (Fig. 3.59).

101
Q

Where is the right pulmonary surface of the heart?

A

The RIGHT PULMONARY SURFACE faces the right lung, is broad and convex, and consists of the right atrium (Fig. 3.59).

102
Q

What are the general margins of the heart?

A

Some general descriptions of cardiac orientation refer to right, left, inferior (acute), and obtuse margins.

103
Q

What are the right and left margins of the heart?

A

The RIGHT and LEFT MARGINS are the same as the right and left pulmonary surfaces of the heart.

104
Q

Define the inferior margin of the heart.

A

The INFERIOR MARGIN is defined as the sharp edge between the anterior and the diaphragmatic surfaces of the heart (Fig. 3.56 and 3.58)

105
Q

What forms the inferior margin?

A

It is formed mostly by the right ventricle and a small portion of the left ventricle near the apex.

106
Q

What does the obtuse margin separate?

A

The OBTUSE MARGIN separates the anterior and left pulmonary surfaces (Fig. 3.56)

107
Q

Describe the shape of the obtuse margin

A

It is round

108
Q

Where does the obtuse margin extend from?

A

The left auricle to the cardiac apex (fig. 3.58)

109
Q

What forms the obtuse margin?

A

It is formed mostly by the left ventricle and superiorly by a small portion of the left auricle.

110
Q

Describe the shape of the obtuse and inferior margins.

A

Inferior - sharp edge

Obtuse - round

111
Q

A thorough understanding of the structures defining the cardiac borders is critical for what?

A

For radiological evaluations.

112
Q

The right border in a standard posteroanterior view (radiology) consists of what?

A
The
- superior vena cava
- right atrium
- inferior vena cava
(Fig. 3.60A)
113
Q

The left border in a standard posteroanterior view (radiology) consists of what?

A
  • Arch of the aorta
  • Pulmonary trunk
  • Left ventricle
114
Q

The inferior border in a standard posteroanterior view (radiology) consists of what?

A
  • Right ventricle
  • Left ventricle
  • Apex
115
Q

What is seen on a lateral view of the heart?

A

The right ventricle is seen anteriorly

The left atrium is visualised posteriorly (Fig. 3.60B)

116
Q

What is seen anteriorly on a lateral view of the heart?

A

Right ventricle (Fig. 3.60B)

117
Q

What is seen posteriorly on a lateral view of the heart?

A

Left atrium (Fig. 3.60B)

118
Q

What divides the heart into four chambers?

A

Internal partitions

119
Q

What are the four chambers of the heart?

A

Two atria and two ventricles

120
Q

Internal partitions divide the heart into four chambers, producing what?

A

Surface or external grooves, referred to as sulci

121
Q

Which sulcus circles the heart?

A

The CORONARY SULCUS

122
Q

What does the coronary sulcus separate?

A

The atria from the ventricles (Fig. 3.61)

123
Q

What does the coronary sulcus contain?

A

As it circles the heart, it contains the

  • right coronary artery
  • small cardiac vein
  • coronary sinus
  • circumflex branch of the left coronary artery
124
Q

What do the anterior and posterior interventricular sulci separate?

A

The ANTERIOR and POSTERIOR INTERVENTRICULAR SULCI separate the two ventricles.

125
Q

Where is the anterior interventricular sulcus?

A

On the anterior surface of the heart

126
Q

What does the anterior interventricular sulcus contain?

A
  • Anterior interventricular artery

- Great cardiac vein

127
Q

Where is the posterior interventricular sulcus?

A

On the diaphragmatic surface of the heart

128
Q

What does the posterior interventricular sulcus contain?

A
  • Posterior interventricular artery

- Middle cardiac vein

129
Q

What separates the atria from the ventricles?

A

CORONARY SULCUS

130
Q

What separates the two ventricles?

A

ANTERIOR and POSTERIOR INTERVENTRICULAR SULCI

131
Q

Where are the anterior and posterior sulci continuous?

A

Inferiorly, just to the right of the apex of the heart

132
Q

How does the heart function schematically?

A

The heart functionally consists of two pumps separated by a partition (Fig. 3.62A).

133
Q

What does the right pump of the heart do?

A

Receives deoxygenated blood from the body and sends it to the lungs.

134
Q

What does the left pump of the heart do?

A

Receives oxygenated blood from the lungs and sends it to the body.

135
Q

What is the structure of each pump of the heart?

A

Each pump consists of an atrium and a ventricle separated by a valve.

136
Q

Describe the walls of the atria.

A

Thin-walled

137
Q

What do the atria receive?

A

Blood coming into the heart

138
Q

Describe the walls of the ventricles.

A

Relatively thick-walled

139
Q

What do the ventricles do?

A

Pump blood out of the heart.

140
Q

Which ventricle wall is thicker?

A

The muscular wall of the left ventricle

141
Q

Why is the left ventricle wall thicker than the right?

A

More force is required to pump blood through the body than through the lungs, so the muscular wall of the left ventricle is thicker than the right.

142
Q

What septa separate the four chambers of the heart?

A
  • Interatrial
  • Interventricular
  • Atrioventricular
    septa (Fig. 3.62B)
143
Q

What is important about the internal anatomy of each chamber?

A

The internal anatomy of each chamber is critical to its function.

144
Q

What are the walls of the ventricles made of?

A

Muscle

145
Q

What forms the right border of the heart?

A

In the anatomical position, the right border of the heart is formed by the RIGHT ATRIUM.

146
Q

As well as forming the right border of the heart, what does the right atrium contribute to?

A

The right portion of the heart’s anterior surface.

147
Q

Where does blood returning to the right atrium enter through?

A

One of three vessels:

  • superior vena cava
  • inferior vena cava
  • coronary sinus
148
Q

What do the superior and inferior venae cavae do?

A

Together deliver blood to the heart from the body

149
Q

What does the coronary sinus do?

A

Returns blood from the walls of the heart itself

150
Q

Where does the superior vena cava enter the heart?

A

The upper posterior portion of the right atrium

151
Q

Where does the inferior vena cava enter the heart?

A

Lower posterior portion of the right atrium

152
Q

Where does the coronary sinus enter the heart?

A

Lower posterior portion of the right atrium

153
Q

Through which gap does blood pass from the right atrium into the right ventricle?

A

The RIGHT ATRIOVENTRICULAR ORIFICE

154
Q

What is the orientation of the right atrioventricular orifice?

A

This opening faces forward and medially

155
Q

When is the right atrioventricular orifice closed?

A

During ventricular contraction

156
Q

What closes the right atrioventricular orifice?

A

The tricuspid valve.

157
Q

Where is the right atrioventricular orifice located?

A

Between the right atrium and right ventricle.

158
Q

How is the interior of the right atrium divided?

A

Into two continuous spaces.

159
Q

What separates the right atrium into two continuous spaces externally?

A

A shallow, vertical groove - the SULCUS TERMINALIS CORDIS

160
Q

What is the sulcus terminalis cordis?

A

An external shallow, vertical groove that separates the right atrium into two continuous spaces.

161
Q

Where does the sulcus terminalis cordis extend from?

A

The right side of the opening of the superior vena cava to the right side of the opening of the inferior vena cava.

162
Q

What separates the right atrium into two continuous spaces internally?

A

CRISTA TERMINALIS (Fig. 3.63).

163
Q

How is the right atrium divided into two continuous spaces?

A

Externally - SULCUS TERMINALIS CORDIS

Internally - CRISTA TERMINALIS

164
Q

What is crista terminalis?

A

An internal, smooth, muscular ridge that separates the right atrium into two continuous spaces.

165
Q

Where does the crista terminalis begin?

A

On the roof of the atrium just in front of the opening of superior vena cava

166
Q

Where does the crista terminalis extend down?

A

The lateral wall of the atrium

167
Q

Where does the crista terminalis end?

A

The anterior lip of the inferior vena cava

168
Q

What is the space posterior to the crista terminalis called?

A

The SINUS OF VENAE CAVAE

169
Q

Where is the sinus of venae cavae derived embryologically?

A

From the right horn of the sinus venosus.

170
Q

Describe the walls of the sinus of venae cavae.

A

This component of the right atrium has smooth, thin walls.

171
Q

Where do the venae cavae empty into?

A

Both venae cavae empty into the space known as the SINUS OF VENAE CAVAE.

172
Q

What is the space anterior to the crista referred to as?

A

The ATRIUM PROPER

173
Q

What does the ATRIUM PROPER include?

A

RIGHT AURICLE

174
Q

What is the terminology of the atrium proper based on?

A

Its origin from the embryonic primitive atrium

175
Q

What are the walls of atrium proper covered by?

A

Ridges called MUSCULI PECTINATI (PECTINATE MUSCLES)

176
Q

What are the musculi pectinati?

A

Ridges on the walls covering atrium proper.

177
Q

What is another name for musculi pectinati?

A

PECTINATE MUSCLES

178
Q

What are pectinate muscles also known as?

A

MUSCULI PECTINATI

179
Q

How are the musculi pectinati arranged?

A

They fan out from the crista like the “teeth of a comb”.

180
Q

Where are the musculi pectinati also found?

A

In the right auricle of the heart

181
Q

What is the right auricle of the heart?

A

An ear-like, conical, muscular pouch that externally overlaps the ascending aorta

182
Q

What does the right auricle overlap?

A

It externally overlaps the ascending aorta.

183
Q

As well as the sinus of venae cavae, what additional structure is found in the right atrium?

A

The OPENING OF THE CORONARY SINUS

184
Q

What occurs in the opening of the coronary sinus?

A

This receives blood from most of the cardiac veins.

185
Q

Where does blood from most of the cardiac veins go?

A

Into the OPENING OF THE CORONARY SINUS

186
Q

Where does the opening of the coronary sinus open medially?

A

To the OPENING OF THE INFERIOR VENA CAVA

187
Q

What is associated with the openings of the coronary sinus and inferior vena cava?

A

Small folds of tissue derived form the valve of the embryonic sinus venosus (the VALVE OF THE CORONARY SINUS and the VALVE OF INFERIOR VENA CAVA, respectively).

188
Q

Small folds of tissue are associated with the opening of the coronary sinus. Where are these derived from?

A

The VALVE OF THE CORONARY SINUS, from the valve of the embryonic sinus venosus

189
Q

Small folds of tissue are associated with the opening of the inferior vena cava. Where are these derived from?

A

The VALVE OF THE INFERIOR VENA CAVA, from the valve of the embryonic sinus venosus

190
Q

What does the valve of the inferior vena cava do during development?

A

Helps direct incoming oxygenated blood through the foramen ovale and into the left atrium.

191
Q

Incoming oxygenated blood is directed through the valve of the inferior vena cava in development, via which structures?

A

Through the foramen ovale and into the left atrium.

192
Q

What separates the right atrium from the left atrium?

A

The INTERATRIAL SEPTUM

193
Q

Where does the interatrial septum face?

A

Forward and to the right

194
Q

Why does the interatrial spetum face forward and to the right?

A

Because the left atrium lies posteriorly and to the left of the right atrium.

195
Q

What is clearly visible in the septum just above the orifice of the inferior vena cava?

A

A depression

196
Q

What is the depression in the septum, located just above the orifice of the inferior vena cava?

A

FOSSA OVALIS (OVAL FOSSA)

197
Q

What is prominent margin of FOSSA OVALIS known as?

A

The LIMBUS FOSSA OVALIS (BORDER OF THE OVAL FOSSA)

198
Q

What is the limbus fossa ovalis?

A

The prominent margin of fossa ovalis

199
Q

What does the fossa ovalis mark the location of?

A

The embryonic FORAMEN OVALE

200
Q

What is clinically significant about the embryonic formane ovale?

A

It is an important part of fetal circulation.

201
Q

What does the foramen ovale do?

A

Allows oxygenated blood entering the right atrium through the inferior vena cava to pass directly to the left atrium and so bypass the lungs, which are nonfunctional before birth.

202
Q

The foramen ovale allows blood in the foetus to pass where?

A

Blood from the right atrium to pass directly to the left atrium (bypassing the lungs)

203
Q

Where does oxygenated blood enter the right atrium in a foetus?

A

The inferior vena cava

204
Q

Why is it important for a foetus to allow blood to enter the left atrium directly from the right atrium?

A

This means oxygenated blood bypasses the lungs, which are nonfunctional before birth.

205
Q

What is found scattered along the walls of the right atrium?

A

Numerous small openings

206
Q

What are the openings on the walls of the right atrium called?

A

The OPENINGS OF THE SMALLEST CARDIAC VEINS

207
Q

What are the openings of the smallest cardiac veins (scattered along the walls of the right atrium) also known as?

A

The FORAMINA OF THE VENAE CORDIS MINIMAE

208
Q

What are the foramina of the venae cordis minimae also known as?

A

The OPENINGS OF THE SMALLEST CARDIAC VEINS

209
Q

What do the smallest cardiac veins drain?

A

The myocardium directly into the right atrium