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 (209 cards)
1
Q
What is the mediastinum?
A
A broad central partition that separates the two laterally placed pleural cavities (Fig. 3.50).
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)
3
Q
What is the superior border of the mediastinum?
A
Superior thoracic aperture
4
Q
What is the inferior border of the mediastinum?
A
Diaphragm
5
Q
What is the anterior border of the mediastinum?
A
Sternum
6
Q
What is the posterior border of the mediastinum?
A
Vertebral bodies (thoracic)
7
Q
What does the mediastinum contain?
A
- thymus gland
- pericardial sac
- heart
- trachea
- major arteries and veins
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
9
Q
The mediastinum serves as a passageway for structure that ___?
A
Traverse the thorax on their way to the abdomen.
10
Q
How is the mediastinum subdivided?
A
For organisational purposes, it is subdivided into several smaller regions.
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
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
13
Q
How is the inferior mediastinum further partitioned?
A
Into the ANTERIOR, MIDDLE and POSTERIOR MEDIASTINUM
14
Q
How is the inferior mediastinum partitioned into the anterior, middle and posterior mediastinum?
A
By the pericardial sac.
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)
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)
17
Q
Where is the middle mediastinum?
A
The area in the middle, which includes the pericardial sac and its contents. (Fig. 3.52)
18
Q
What is centrally located in the thoracic cavity?
A
The MIDDLE MEDIASTINUM.
19
Q
What does the middle mediastinum contain?
A
The pericardium, heart, origins of the great vessels, various nerves, and smaller vessels.
20
Q
What is the pericardium?
A
The PERICARDIUM is a fibroserous sac surrounding the heart and the roots of the great vessels.
21
Q
What components does the pericardium consist of?
A
Two components; the fibrous pericardium and the serous pericardium (Fig. 3.53).
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
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.
24
Q
What type of tissue is the fibrous pericardium?
A
Tough connective tissue
25
Which pericardium defines the boundaries of the middle mediastinum?
The fibrous pericardium (the outer layer)
26
Describe the serous pericardium
The SEROUS PERICARDIUM is thin and consists of two parts
27
What are the two parts of the serous pericardium?
The PARIETAL LAYER and the VISCERAL LAYER (EPICARDIUM)
28
Where is the parietal layer of serous pericardium?
The PARIETAL LAYER of serous pericardium lines the inner surface of the fibrous pericardium
29
What is the visceral layer of serous pericardium also known as?
EPICARDIUM
30
Where is the visceral layer of serous pericardium?
The VISCERAL LAYER (EPICARDIUM) of serous pericardium adheres to the heart and forms its outer covering.
31
Where are the parietal and visceral layers of serous pericardium continuous?
At the roots of the great vessels
32
What is the narrow space created between the two layers of serous pericaridum called?
PERICARDIAL CAVITY
33
What does the pericardial cavity contain?
A small amount of fluid
34
What is the function of the pericardial cavity?
This potential space allows for the relatively uninhibited movement of the heart.
35
Describe the shape and borders of the fibrous pericardium.
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).
36
Where, generally, is the base of the fibrous pericardium?
The diaphragm
37
Where is the apex of the fibrous pericardium?
Continuous with the ADVENTITIA (the outermost layer of a wall of a blood vessel) of the great vessels.
38
What is the base of the fibrous pericardium attached to?
The CENTRAL TENDON OF THE DIAPHRAGM and to a small muscular area of the diaphragm on the left side.
39
What is the fibrous pericardium attached to anteriorly?
The posterior surface of the sternum
40
How is the fibrous pericardium attached to the sternum?
By STERNOPERICARDIAL LIGAMENTS
41
What is the function of the sternopericardial ligaments?
These attachments help to retain the heart in its position in the thoracic cavity.
42
As well as the pericardial sac aiding movement of the heart, what else does it do?
The sac also limits cardiac distension.
43
What innervates the fibrous pericardium?
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).
44
Where is the location of the phrenic nerves in the fibrous pericaridium?
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.
45
What vessels supply the fibrous pericardium?
The PERICARDIACOPHRENIC VESSELS
46
Where are the pericardiacophrenic vessels found?
Located within and supply the fibrous pericardium as they pass through the thoracic cavity.
47
Where are the parietal and visceral layers of serous pericardium continuous?
Around the roots of the great vessels.
48
Where do the reflections of serous pericardium occur?
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.
49
What does the superior reflection of the serous pericardium surround?
The arteries, the aorta and the pulmonary trunk.
50
What does the more posterior reflection of the serous pericardium surround?
The veins, the superior and inferior vena cava and the pulmonary veins.
51
The zone of reflection from the serous pericardium surrounding the veins is what shape?
J-shaped
52
Where is the oblique pericardial sinus?
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.
53
What is the passage between the two sites of reflected serous pericardium called?
The TRANSVERSE PERICARDIAL SINUS
54
Where is the transverse pericardial sinus?
This sinus lies posterior to the ascending aorta and the pulmonary trunk, anterior to the superior vena cava, and superior to the left atrium.
55
What is the transverse pericardial sinus' anterior border?
Ascending aorta and the pulmonary trunk
56
What is the transverse pericardial sinus' posterior border?
The superior vena cava
57
What is the transverse pericardial sinus' inferior border?
The left atrium
58
What is the clinical significance of the transverse sinus?
When the pericardium is opened anteriorly during surgery, a finger placed in the transverse sinus separates arteries from veins.
59
Where does the pericardium need to be opened to access the transverse sinus?
Anteriorly during surgery
60
How can the transverse sinus separate the arteries from veins?
A finger can be placed there during surgery.
61
How can the oblique sinus be accessed during surgery?
A hand placed under the apex of the heart and moved superiorly slips into the oblique sinus.
62
How can the transverse and oblique sinuses be accessed during surgery?
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
63
What supplies the pericardium?
```
The pericardium is supplied by branches from the
- internal thoracic
- pericardiacophrenic
- musculophrenic
- inferior phrenic
arteries, and the
- thoracic aorta
```
64
Where do veins from the pericardium enter?
- the azygos system of veins
- internal thoracic v.
- superior phrenic v.
65
What nerves supply the pericardium?
Nerves supplying the pericardium arise from the
- vagus nerve [X]
- sympathetic trunks
- phrenic nerves
66
Where is the source of somatic sensation (pain) from the parietal pericardium from?
Somatic sensation (pain) is carried by somatic afferent fibres in the phrenic nerves.
67
Where might pain related to a pericardial problem be referred to?
The supraclavicular region of the shoulder or lateral neck area dermatomes for spinal cord segments C3, C4 and C5.
68
Why might pain be referred to the supraclavicular region of the shoulder or lateral neck area?
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.
69
Somatic sensation from the pericardium is carried by somatic ______ fibres from which nerves?
Afferent; phrenic nerves
70
What is the general shape and orientation of the heart?
Cardiac orientation is that of a pyramid that has fallen over and is resting on one of its sides.
71
Where is the apex of the heart?
Placed in the thoracic cavity, the apex of the heart projects forward, downward, and to the left.
72
Where is the base of the heart?
Opposite the apex and faces in a posterior direction (Fig. 3.56).
73
What direction does the base of the heart face?
Posteriorly (Fig. 3.56).
74
What do the sides of the pyramid consist of?
- Diaphragmatic surface
- Sternocostal surface
- Right pulmonary
- Left pulmonary
75
What is the inferior surface of the heart?
A diaphragmatic (inferior) surface on which the pyramid rests
76
What is the anterior surface of the heart?
An anterior (sternocostal) surface oriented anteriorly
77
What is the right surface of the heart?
A right pulmonary surface
78
What is the left surface of the heart?
A left pulmonary surface
79
Describe the base of the heart?
The BASE (posterior surface) OF THE HEART is quadrilateral and directed posteriorly.
80
What does the base of the heart consist of?
- The left atrium
- A small portion of the right atrium
- Proximal parts of the great veins
81
Which atrium does the base of the heart mainly consist of?
The left atrium
82
Which atrium does the base of the heart consist of a small portion of?
The right atrium
83
Which parts of the great veins does the base of the heart contain?
The proximal parts
84
Which great veins does the base of the heart contain?
Superior and inferior venae cavae and the pulmonary veins.
85
Where do the great veins enter the heart?
At the base of the heart
86
Where do the pulmonary veins enter the heart?
The right and left sides of the left atrium
87
Where do the vena cavae enter the heart?
The superior and inferior venae cavae at the upper and lower ends of the right atrium, respectively.
88
Where is the base of the heart fixed?
Posteriorly to the pericardial wall, opposite the bodies of vertebrae TV to TVIII (TVI to TIX when standing).
89
Why is the base of the heart fixed posteriorly to the pericardial wall?
Due to where the great veins enter the heart
90
Which vertebrae is the heart fixed to, when standing and when not?
TV to TVIII
| TVI to TIX when standing.
91
What structure lies immediately posterior to the base of the heart?
The oesophagus
92
Describe the orientation of the heart from the base?
From the base the heart projects forward, downward, and to the left, ending in the apex.
93
What forms the apex of the heart?
The APEX OF THE HEART is formed by the inferolateral part of the left ventricle (Fig. 3.58).
94
Where is the apex of the heart?
Deep to the left fifth intercostal space, 8-9 cm from the midsternal line.
95
Which intercostal space can you find the apex of the heart?
Deep to the left fifth intercostal space
96
Where is the apex of the heart in relation to the midsternal line?
8-9 cm from it (left)
97
Describe the anterior surface of the heart.
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
Describe the diaphragmatic surface of the heart.
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
Describe the diaphragmatic surface of the heart in relation to the overall orientation of the heart.
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
Where is the left pulmonary surface of the heart?
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
Where is the right pulmonary surface of the heart?
The RIGHT PULMONARY SURFACE faces the right lung, is broad and convex, and consists of the right atrium (Fig. 3.59).
102
What are the general margins of the heart?
Some general descriptions of cardiac orientation refer to right, left, inferior (acute), and obtuse margins.
103
What are the right and left margins of the heart?
The RIGHT and LEFT MARGINS are the same as the right and left pulmonary surfaces of the heart.
104
Define the inferior margin of the heart.
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
What forms the inferior margin?
It is formed mostly by the right ventricle and a small portion of the left ventricle near the apex.
106
What does the obtuse margin separate?
The OBTUSE MARGIN separates the anterior and left pulmonary surfaces (Fig. 3.56)
107
Describe the shape of the obtuse margin
It is round
108
Where does the obtuse margin extend from?
The left auricle to the cardiac apex (fig. 3.58)
109
What forms the obtuse margin?
It is formed mostly by the left ventricle and superiorly by a small portion of the left auricle.
110
Describe the shape of the obtuse and inferior margins.
Inferior - sharp edge
| Obtuse - round
111
A thorough understanding of the structures defining the cardiac borders is critical for what?
For radiological evaluations.
112
The right border in a standard posteroanterior view (radiology) consists of what?
```
The
- superior vena cava
- right atrium
- inferior vena cava
(Fig. 3.60A)
```
113
The left border in a standard posteroanterior view (radiology) consists of what?
- Arch of the aorta
- Pulmonary trunk
- Left ventricle
114
The inferior border in a standard posteroanterior view (radiology) consists of what?
- Right ventricle
- Left ventricle
- Apex
115
What is seen on a lateral view of the heart?
The right ventricle is seen anteriorly
| The left atrium is visualised posteriorly (Fig. 3.60B)
116
What is seen anteriorly on a lateral view of the heart?
Right ventricle (Fig. 3.60B)
117
What is seen posteriorly on a lateral view of the heart?
Left atrium (Fig. 3.60B)
118
What divides the heart into four chambers?
Internal partitions
119
What are the four chambers of the heart?
Two atria and two ventricles
120
Internal partitions divide the heart into four chambers, producing what?
Surface or external grooves, referred to as sulci
121
Which sulcus circles the heart?
The CORONARY SULCUS
122
What does the coronary sulcus separate?
The atria from the ventricles (Fig. 3.61)
123
What does the coronary sulcus contain?
As it circles the heart, it contains the
- right coronary artery
- small cardiac vein
- coronary sinus
- circumflex branch of the left coronary artery
124
What do the anterior and posterior interventricular sulci separate?
The ANTERIOR and POSTERIOR INTERVENTRICULAR SULCI separate the two ventricles.
125
Where is the anterior interventricular sulcus?
On the anterior surface of the heart
126
What does the anterior interventricular sulcus contain?
- Anterior interventricular artery
| - Great cardiac vein
127
Where is the posterior interventricular sulcus?
On the diaphragmatic surface of the heart
128
What does the posterior interventricular sulcus contain?
- Posterior interventricular artery
| - Middle cardiac vein
129
What separates the atria from the ventricles?
CORONARY SULCUS
130
What separates the two ventricles?
ANTERIOR and POSTERIOR INTERVENTRICULAR SULCI
131
Where are the anterior and posterior sulci continuous?
Inferiorly, just to the right of the apex of the heart
132
How does the heart function schematically?
The heart functionally consists of two pumps separated by a partition (Fig. 3.62A).
133
What does the right pump of the heart do?
Receives deoxygenated blood from the body and sends it to the lungs.
134
What does the left pump of the heart do?
Receives oxygenated blood from the lungs and sends it to the body.
135
What is the structure of each pump of the heart?
Each pump consists of an atrium and a ventricle separated by a valve.
136
Describe the walls of the atria.
Thin-walled
137
What do the atria receive?
Blood coming into the heart
138
Describe the walls of the ventricles.
Relatively thick-walled
139
What do the ventricles do?
Pump blood out of the heart.
140
Which ventricle wall is thicker?
The muscular wall of the left ventricle
141
Why is the left ventricle wall thicker than the right?
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
What septa separate the four chambers of the heart?
- Interatrial
- Interventricular
- Atrioventricular
septa (Fig. 3.62B)
143
What is important about the internal anatomy of each chamber?
The internal anatomy of each chamber is critical to its function.
144
What are the walls of the ventricles made of?
Muscle
145
What forms the right border of the heart?
In the anatomical position, the right border of the heart is formed by the RIGHT ATRIUM.
146
As well as forming the right border of the heart, what does the right atrium contribute to?
The right portion of the heart's anterior surface.
147
Where does blood returning to the right atrium enter through?
One of three vessels:
- superior vena cava
- inferior vena cava
- coronary sinus
148
What do the superior and inferior venae cavae do?
Together deliver blood to the heart from the body
149
What does the coronary sinus do?
Returns blood from the walls of the heart itself
150
Where does the superior vena cava enter the heart?
The upper posterior portion of the right atrium
151
Where does the inferior vena cava enter the heart?
Lower posterior portion of the right atrium
152
Where does the coronary sinus enter the heart?
Lower posterior portion of the right atrium
153
Through which gap does blood pass from the right atrium into the right ventricle?
The RIGHT ATRIOVENTRICULAR ORIFICE
154
What is the orientation of the right atrioventricular orifice?
This opening faces forward and medially
155
When is the right atrioventricular orifice closed?
During ventricular contraction
156
What closes the right atrioventricular orifice?
The tricuspid valve.
157
Where is the right atrioventricular orifice located?
Between the right atrium and right ventricle.
158
How is the interior of the right atrium divided?
Into two continuous spaces.
159
What separates the right atrium into two continuous spaces externally?
A shallow, vertical groove - the SULCUS TERMINALIS CORDIS
160
What is the sulcus terminalis cordis?
An external shallow, vertical groove that separates the right atrium into two continuous spaces.
161
Where does the sulcus terminalis cordis extend from?
The right side of the opening of the superior vena cava to the right side of the opening of the inferior vena cava.
162
What separates the right atrium into two continuous spaces internally?
CRISTA TERMINALIS (Fig. 3.63).
163
How is the right atrium divided into two continuous spaces?
Externally - SULCUS TERMINALIS CORDIS
| Internally - CRISTA TERMINALIS
164
What is crista terminalis?
An internal, smooth, muscular ridge that separates the right atrium into two continuous spaces.
165
Where does the crista terminalis begin?
On the roof of the atrium just in front of the opening of superior vena cava
166
Where does the crista terminalis extend down?
The lateral wall of the atrium
167
Where does the crista terminalis end?
The anterior lip of the inferior vena cava
168
What is the space posterior to the crista terminalis called?
The SINUS OF VENAE CAVAE
169
Where is the sinus of venae cavae derived embryologically?
From the right horn of the sinus venosus.
170
Describe the walls of the sinus of venae cavae.
This component of the right atrium has smooth, thin walls.
171
Where do the venae cavae empty into?
Both venae cavae empty into the space known as the SINUS OF VENAE CAVAE.
172
What is the space anterior to the crista referred to as?
The ATRIUM PROPER
173
What does the ATRIUM PROPER include?
RIGHT AURICLE
174
What is the terminology of the atrium proper based on?
Its origin from the embryonic primitive atrium
175
What are the walls of atrium proper covered by?
Ridges called MUSCULI PECTINATI (PECTINATE MUSCLES)
176
What are the musculi pectinati?
Ridges on the walls covering atrium proper.
177
What is another name for musculi pectinati?
PECTINATE MUSCLES
178
What are pectinate muscles also known as?
MUSCULI PECTINATI
179
How are the musculi pectinati arranged?
They fan out from the crista like the "teeth of a comb".
180
Where are the musculi pectinati also found?
In the right auricle of the heart
181
What is the right auricle of the heart?
An ear-like, conical, muscular pouch that externally overlaps the ascending aorta
182
What does the right auricle overlap?
It externally overlaps the ascending aorta.
183
As well as the sinus of venae cavae, what additional structure is found in the right atrium?
The OPENING OF THE CORONARY SINUS
184
What occurs in the opening of the coronary sinus?
This receives blood from most of the cardiac veins.
185
Where does blood from most of the cardiac veins go?
Into the OPENING OF THE CORONARY SINUS
186
Where does the opening of the coronary sinus open medially?
To the OPENING OF THE INFERIOR VENA CAVA
187
What is associated with the openings of the coronary sinus and inferior vena cava?
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
Small folds of tissue are associated with the opening of the coronary sinus. Where are these derived from?
The VALVE OF THE CORONARY SINUS, from the valve of the embryonic sinus venosus
189
Small folds of tissue are associated with the opening of the inferior vena cava. Where are these derived from?
The VALVE OF THE INFERIOR VENA CAVA, from the valve of the embryonic sinus venosus
190
What does the valve of the inferior vena cava do during development?
Helps direct incoming oxygenated blood through the foramen ovale and into the left atrium.
191
Incoming oxygenated blood is directed through the valve of the inferior vena cava in development, via which structures?
Through the foramen ovale and into the left atrium.
192
What separates the right atrium from the left atrium?
The INTERATRIAL SEPTUM
193
Where does the interatrial septum face?
Forward and to the right
194
Why does the interatrial spetum face forward and to the right?
Because the left atrium lies posteriorly and to the left of the right atrium.
195
What is clearly visible in the septum just above the orifice of the inferior vena cava?
A depression
196
What is the depression in the septum, located just above the orifice of the inferior vena cava?
FOSSA OVALIS (OVAL FOSSA)
197
What is prominent margin of FOSSA OVALIS known as?
The LIMBUS FOSSA OVALIS (BORDER OF THE OVAL FOSSA)
198
What is the limbus fossa ovalis?
The prominent margin of fossa ovalis
199
What does the fossa ovalis mark the location of?
The embryonic FORAMEN OVALE
200
What is clinically significant about the embryonic formane ovale?
It is an important part of fetal circulation.
201
What does the foramen ovale do?
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
The foramen ovale allows blood in the foetus to pass where?
Blood from the right atrium to pass directly to the left atrium (bypassing the lungs)
203
Where does oxygenated blood enter the right atrium in a foetus?
The inferior vena cava
204
Why is it important for a foetus to allow blood to enter the left atrium directly from the right atrium?
This means oxygenated blood bypasses the lungs, which are nonfunctional before birth.
205
What is found scattered along the walls of the right atrium?
Numerous small openings
206
What are the openings on the walls of the right atrium called?
The OPENINGS OF THE SMALLEST CARDIAC VEINS
207
What are the openings of the smallest cardiac veins (scattered along the walls of the right atrium) also known as?
The FORAMINA OF THE VENAE CORDIS MINIMAE
208
What are the foramina of the venae cordis minimae also known as?
The OPENINGS OF THE SMALLEST CARDIAC VEINS
209
What do the smallest cardiac veins drain?
The myocardium directly into the right atrium
