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Anatomy (MPAS) > Anatomy of thorax and mediastinum > Flashcards

Anatomy of thorax and mediastinum Flashcards

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1
Q

What is the function of the thorax?

A

Protects the lungs, great vessels, liver and spleen

Provides the mechanical function of breathing

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2
Q

What are the skeletal components of the thoracic wall?

A

12 thoracic vertebrae

12 pairs of ribs

Sternum (manubrium, body and diploid process)

See figure

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3
Q

Parts of the manubrium and the sternum

A

Manubrium:

Jugular notch

Clavicular notch

First costal notch

Sternal angle (angle of louis)

Manobriosternal joint

Sternum:

Body

2nd-7th costal notches

Xiphisternal joint

Xiphoid process

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4
Q

What passes to the right and behind the manubrium?

A

The aortic arch

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5
Q

What does the xiphisternal joint mark?

A

The centre of the diaphragm

Marks how high the liver goes

Left side of process = inferior border of the heart

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6
Q

What are the two parts of a rib?

A

Bony part (costo-)

Cartilage part (chondro-)

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7
Q

Where do the 12 pairs of ribs attach posteriorly? Type of joints?

A

Thoracic vertebrae

Mostly synovial

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8
Q

What is the diameter of the thoracic cage?

A

Not equal

More narrow superiorly

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9
Q

Parts of typical rib

A

Head

Neck

Costal tubercule

Costal angle

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10
Q

What do the facets of the head of the rib articulate with?

A

Two facets are separated by the crest of the head

One facet articulates with the body of the numerically corresponding vertebrae

Other facet articulates with the superior vertebrae

See figure

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11
Q

Role of costal tubercle of typical ribs

A

Located at the junction of the neck and body.

Has a smooth articular part for articulating with the corresponding transverse process of the vertebra (via a synovial joint)

Rough non-articular part for a fibrous attachment to the process via the costotransverse ligament

See figure

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12
Q

Typical and atypical ribs

A

Typical: 3-9

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13
Q

What are the true ribs? What joints to they form

A

aka Vertebrosternal ribs

1st to 7th ribs

attach directly to the sternum anteriorly through their own costal cartilages.

Form sternochondral joints

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14
Q

What are the false ribs?

A

aka Vertebrochondral ribs

8-10th ribs

cartilages on their anterior ends that are joined to the cartilage of the rib just superior to them

connection with the sternum is indirect.

synchondrosis (immovable joint)

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15
Q

What are the floating ribs?

A

11th and 12th, sometimes the 10th

Rudimentary cartilages on their anterior ends that do not connect even indirectly with the sternum

instead, they end in the posterior abdominal musculature.

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16
Q

What are the distinguishing features of the 2nd rib

A

Has formations for attachment of serrates anterior and posterior scalene muscles

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17
Q

What are the costal grooves of the ribs for?

A

To protect intercostal vessels and nerves

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18
Q

What is the role of the costal cartilage?

A

Prolong ribs anteriorly

Contribute to the elasticity of the thoracic wall

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19
Q

Thoracic cavity during inspiration

A

Inspiration: The vertical dimension (height) of the central part of the thoracic cavity increases during as the contracting diaphragm descends

Elevation of sternum causes the anteroposterior (AP) dimension of the thorax to increase considerably (pump-handle movement)

Elevation of the lateral portion of the lower ribs causes the transverse dimension of the thorax to increase (bucket-handle movement)

See figures

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20
Q

Which muscles of the thoracic wall work during inspiration?

A

Elevation of ribs

Scalenus muscles (forced inspiration)

External intercostal muscles

See figures

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21
Q

Which muscles of the thoracic wall work during forced expiration?

A

Internal intercostal muscles

Innermost intercostal muscles

Transverse thoracic muscle

Subcostal muscles

See figures

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22
Q

What are the muscles of the thoracic wall innervated by?

A

Intercostal nerves

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23
Q

What are the scalenus muscles innervated by?

A

Cervical plexus

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24
Q

What do the scalene muscles attach to?

A

1st rib: anterior and middle scalene

2nd rib: posterior scalene

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25
Three layers of muscles in the intercostal spaces
outer layer: External intercostals middle layer: internal intercostal deepest: innermost intercostals
26
Orientation of muscle fibres of intercostal muscles?
External: infero-anterior (putting hands in pockets) Internal: infero-posteriorly Deepest: similar to internal (internal to the intercostal vasculature) See figure
27
What structures form the thoracic inlet?
Thoracic inlet = superior aperture of thorax First thoracic vertebra, upper margins of first ribs and manubrium of sternum
28
What structures form the thoracic outlet?
12th thoracic vertebrae behind 11th and 12th ribs on the sides cartilages of the 10th, 9th, 8th and 7th ribs (ascend on each side and form an angle into the apex) Outlet slopes obliquely downward and backward
29
What closes the thoracic outlet?
Diaphragm (forms floor of thorax)
30
What is the principal muscle of respiration?
Diaphragm
31
Diaphragm and respiration
Inspiration: diaphragm contracts and flattens. This increases the vertical diameter of the thoracic cavity, producing lung expansion and air is drawn in. Expiration: diaphragm passively relaxes and returns to its original dome shape. Reduces volume of thoracic cavity
32
Dome of diaphragm? Need to ask about this
Level of T8 on right side Level of T9 on left side
33
Parts of diaphragm
Central tendon: fused with the inferior part of the fibrous pericardium Sternal part: two muscular slips that attach to posterior aspect of diploid process Costal part: wide muscular slips that attach to the internal surfaces of the inferior six costal cartilages and their adjoining ribs on each side (forms domes of diaphragm) Lumbar part
34
Actions of diaphragm
Principle muscle of respiration Active part in coughing, forced defecation, weight lifting
35
Innervation of diaphragm
Phrenic nerve, C3, C4, C5 Keeps the diaphragm alive
36
3 major openings of the diaphragm
Vena cava aperture (level of T8) Esophageal aperture (level of T10) Aortic aperture (level of T12) See figure
37
Changes in thoracic volume during inspiration
Inspiratory muscles contract External intercostals elevate ribs Diaphragm flattens -> rib cage rises, increase in thoracic cavity in all of it's dimensions (anterior-posterior and superior-inferior)
38
Changes in thoracic volume during expiration
Inspiratory muscles relax External intercostals relax Diaphragm rises -> rib cage descends due to recall of costal cartilages, decrease in thoracic cavity volume
39
What do the arteries of the thoracic wall derive from?
Thoracic aorta -> posterior intercostal arteries Subclavian artery -> internal thoracic -> anterior intercostal arteries See figure
40
What are the intercostal veins? Branches?
Posterior intercostal -> azygous vein Anterior intercostal -> internal thoracic vein Both drain into superior vena cava See figure
41
What are the veins of the thoracic wall?
Azygous vein (right) Accessory Hemiazygous vein Hemiazygous vein (drains into azygous) See figure
42
What do the veins of the thoracic wall drain into?
The superior vena cava
43
How many pairs of spinal nerves does the thoracic wall have?
12 pairs of spinal nerves
44
What types of innervation do the nerves of the thoracic wall provide?
Provide motor supply to muscles of thoracic and abdominal wall Provide sensory supply to skin and costal parts of the diaphragm Provide sympathetic innervation to the skin (e.g. sweat glands, blood vessels)
45
What do the ventral rami of the thoracic spinal nerves supply?
The intercostal spaces of the thorax
46
Which ventral rami form the intercostal nerves? Where do they run?
T1-T11 These nerves run along the extent of the intercostal spaces See figure
47
Where is the ventral rami of T12? What is it named?
Inferior to the 12th rib Subcostal nerve
48
Where do the dorsal rami of the spinal nerves run? What do they supply?
run posteriorly (clos to vertebrae) supply bones, joints, muscles and skin of the back region of the thorax
49
What is a dermatome?
An area of skin supplied by sensory neurons that arise from a spinal nerve ganglion. Single nerve innervates single dermatome
50
Which nerves innervate the dermatomes of the thoracic wall?
Sensory branches of intercostal nerves
51
What is the content of the intercostal spaces?
Intercostal muscles (external, internal and innermost) Blood vessels Nerves See figure
52
How are intercostal spaces named?
Named after the rib superior to it
53
What are the veins, arteries and nerves sandwiched between? where are they in relation to the rib?
The internal intercostal and the innermost intercostal They are located in the costal groove **order is vein, artery, nerve from superior to inferior
54
Is there a 12th intercostal space:
No
55
Inner linings of the thorax
Endothoracic fascia Parietal pleura See figure
56
What is the end-thoracic fascia attached to?
Ribs and muscles
57
What is the parietal pleura attached to?
Endothoracic fascia
58
What is the pleura?
Serous epithelial layer with sub epithelial connective tissue
59
What are the two parts of the pleura?
Visceral: attached to lung surface Parietal: attached to the inner surface of the chest wall These are separate cavities Both are continuous at the root of the lung
60
What is the pleural cavity?
A potential space lined by the visceral and parietal pleura
61
What separates the visceral and parietal pleura?
A film of serous fluid Reduces friction during breathing
62
Different parts of the parietal pleura
Cervical part: near the cervical vertebrae Costal part: related to the ribs and intercostal space Diaphragmatic part: covers the diaphragm Mediastinal part: covers mediastinum See figure
63
What are pleural recesses?
Potential spaces between the parietal and visceral pleura
64
When do the lungs expand into the recesses?
Usually only during forced inspiration
65
Clinical significance of recesses
provide potential spaces in which fluids can collect and from which fluids can be aspirated.
66
Where are the costomediastinal recesses? Where is the largest one?
Occurs on each side where costal pleura is opposed to mediastinal pleura. The largest is on the left side in the region overlying the heart.
67
Where are the costodiaphragmatic recesses?
Occur in each pleural cavity between the costal pleura and diaphragmatic pleura
68
Which recesses are most clinically important?
Costodiaphragmatic
69
Nerve innervation of the parietal pleura
Intercostal nerves: costal pleura Phrenic nerve: mediastinal and diaphragmatic pleura See figure
70
Nerve innervation of the visceral pleura (lungs)
Autonomic innervation by PSNS and SNS fibres
71
Does the parietal pleura have pain receptors?
No
72
What are the three surfaces of the lungs?
Costal Mediastinal Diaphragmatic
73
Anatomy of the costal surface of the lungs
Superior lobe Middle lobe (right lung) Inferior lobe Oblique fissure Horizontal fissure (right lung) See figure
74
Which structures does the right lung have that the left lung does not have?
Middle lobe Horizontal fissure
75
Impressions and grooves on the mediastinal surface of the lungs
Right: esophagus, azygous vein, right atrium Left: Cardiac impression, aortic arch, left ventricle, lingula Both have hilum and pulmonary ligament See figure
76
What is the only root/attachment to the lungs?
Hium
77
What are the components of the hilum?
Pulmonary Artery (from pulmonary trunk) Pulmonary Veins (drain into left atrium) Bronchus Autonomous nerves Lymph nodes Bronchial Arteries Bronchial Veins lymphatic vessels
78
Where does aspiration of foreign bodies most likely occur?
Right bronchus Straighter and shorter
79
How many pulmonary veins per side enter the left atrium of the heart? How many pulmonary arteries exit?
2 pulmonary veins One pulmonary artery
80
Lymphatic drainage from lungs and bronchi
See figure
81
Where do the lobes of the lungs drain?
The 3 lobes of the right lung and the lower lobe the left lung drain into the right lymphatic duct The upper lobe of the left lung only drains into the left lymphatic (thoracic) duct.
82
Where does the thoracic duct drain?
Into the left-jugular subclavian junction
83
How does air enter the lungs during inspiration?
Muscles increase the thoracic space in all three of its dimensions The parietal pleura is attached to the thoracic wall, forcing expansion of the lungs. The pressure within the lungs drops below the atmospheric pressure outside, and the air passively rushes in (down the pressure gradient).
84
How does air leave the lungs during expiration?
Muscles of respiration relax. The air in the lungs is then forced to move out of the lungs because of the high elasticity and retractility of the lung tissue. See figure
85
What are the contours of the mediastinum?
Neck, arm Left lung Right lung Abdomen See figure
86
What are the three parts of the mediastinum?
Posterior Middle Anterior See figure
87
What are the major organs of the mediastinum?
Thymus Great vessels Heart Nerves Trachea Esophagus Lymph vessels
88
What are the branches of the aorta?
Coronary arteries Brachiocephalic trunk Left common carotid artery Left subclavian artery Posterior intercostal arteries Bronchial arteries Esophageal arteries Superior phrenic arteries
89
What are the branches of the aortic arch in ascending and descending order?
Ascending: Brachiocephalic (*), left common carotid (+), left subclavian (#) See figure
90
What is the origin of the phrenic nerve? What does it supply?
Origin: cervical plexus (C3-C5) Motor: diaphragm Sensory: pericardium, parietal pleura (mediastinal, diaphragmatic), parietal peritoneum (underside of diaphragm)
91
What is the location of the phrenic nerve?
Ventral of anterior scalenus muscle Descends anterior to the roots of the lungs Between the fibrous pericardium and the mediastinal pleura
92
What are the nerves of the mediastinum?
Vagus Phrenic Recurrent laryngeal
93
Where does Vagus nerve run?
CN X Runs posterior to root of lung The right and left vagal trunks are adjacent to the esophagus
94
What does the vagus nerve contribute to?
Cardiac, Esophageal and pulmonary autonomous nerve plexus
95
Where does the recurrent laryngeal nerve branch from?
The vagus nerve
96
What does the recurrent laryngeal nerve innervate?
Motor: most of the muscles of the larynx Sensory: inferior larynx
97
Course of the recurrent laryngeal nerve
Lateral to the trachea
98
Clinical significance of the recurrent laryngeal nerve
Apical lung cancer may cause hoarseness resulting from invasion of the recurrent laryngeal nerve
99
What provides sympathetic innervation of the mediastinum?
Sympathetic trunk (chain along the vertebral column) Sphlanic nerves
100
Where do the PSNS nerves in the mediastinum derive from?
Vagus nerve
101
Function of SNS and PSNS nerves in the mediastinum
Pulmonary plexus Esophageal plexus Cardiac plexus

Anatomy (MPAS) (22 decks)

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