Session 1: The Pectoral Region, Thoracic Cage and Lungs Flashcards
(102 cards)
1
Q
Where does the sternum lie?
A
The sternum lies anteriorly in the midline of the thoracic cage. It is composed of three parts.
- manubrium
- body
- xiphoid process/ xiphisternum
2
Q
Identify these on a skeleton
A
Clavicle
Manubrium
Sternoclavicular joint
Suprasternal notch
Manubriosternal joint
Second rib
CostaL margin
3
Q
What do the ribs form?
A
Twelve pairs of ribs form the anterior, lateral, and posterior walls of the thoracic cage.
4
Q
What are ribs classed as?
A
Ribs are classed as typical or atypical. Typical ribs look similar and share common anatomical features. Atypical ribs look different to typical ribs and / or lack some of the features of typical ribs.
5
Q
What are the thoracic vertebrae like?
A
Twelve thoracic vertebrae (T1 - T12) lie posteriorly in the midline of the thoracic cage.
The spinous processes of the thoracic vertebrae are palpable in the midline of the back.
6
Q
What is the skin of the thoracic wall innervated by?
A
By spinal nerves T1 – T12.
7
Q
What are the breasts like?
A
Also known as mammary glands
superficial to the muscles of the chest wall.
Breast tissue extends towards the anterior axilla (armpit) – this part of the breast is the axillary tail.
8
Q
What does the breasts contain?
A
● Fat
● Glandular / secretory tissue arranged in lobules.
● Ducts which converge on the nipple. The areola is the region of pigmented skin that surrounds the nipple.
● Connective tissue and ligaments.
● Blood vessels and lymphatics.
9
Q
What is the breast supplied by?
A
The breast is primarily supplied by branches from the:
● internal thoracic artery (which arises from the subclavian artery)
● axillary artery.
10
Q
What artery’s are associated with the breast?
A
internal thoracic artery courses deep to the lateral edge of the sternum.
It gives rise to anterior intercostal arteries that supply the breast and the intercostal spaces.
Venous blood returns to the axillary and internal thoracic veins.
11
Q
What is the lymphatic drainage of the breast?
A
Most lymph from the breast drains to lymph nodes in the axilla.
12
Q
What are the five groups of lymph nodes in the axilla?
A
There are five groups of lymph nodes in the axilla: central, pectoral, humeral, subscapular, and apical.
13
Q
What are the upper limb muscles?
A
● Pectoralis major is the most superficial muscle of the anterior chest wall.
● Pectoralis minor is a smaller muscle that lies deep to pectoralis major.
● Serratus anterior is a superficial muscle that sweeps around the lateral aspect of the thoracic cage.
14
Q
What are rib fractures like ?
A
Rib fractures result from blunt trauma to the chest wall (falls, traffic accidents, assault). They are painful and the pain is typically worse on inspiration.
15
Q
What are shingles?
A
Patients with shingles present with a red, painful, and itchy rash, typically over the chest or abdomen on one side of the body only. The rash typically appears in a strip-like distribution, as it affects dermatomes.
16
Q
What is breast cancer like?
A
Because most lymph from the breast drains to the axillary lymph nodes, breast malignancy typically metastasizes (spreads) to these nodes first.
A malignant axillary node may be palpable as a lump in the armpit and noticed before a mass in the breast itself.
17
Q
What do the intercostal spaces contain?
A
The spaces between the ribs are the intercostal spaces. They contain:
* three layers of intercostal muscles and their associated membranes
* an intercostal neurovascular bundle, comprising an intercostal nerve, an intercostal artery, and an intercostal vein.
18
Q
What are intercostal muscles like?
A
The muscles in the intercostal spaces attach to the rib above and rib below. Their fibres run in different directions to each other and hence act on the ribs in different ways.
19
Q
Where are the costal cartilages found?
A
- The anterior parts of the ribs are composed of costal cartilage.
- The ribs articulate with their costal cartilages at costochondral joints.
- The costal cartilages of ribs 1 - 7 articulate directly with the sternum at sternocostal joints – they are ‘true’ ribs.
- The costal cartilages of ribs 8 - 10 unite and join the seventh costal cartilage – they are ‘false’ ribs.
- The costal cartilages of ribs 7 - 10 form the costal margin, which is palpable.
20
Q
How are ribs 11 and 12 different?
A
- Ribs 11 and 12 are short and do not articulate with the sternum – they are ‘floating’ ribs.
- The ribs articulate posteriorly with the thoracic vertebrae at costovertebral joints.
- Adjacent ribs are connected to each other by intercostal muscles, which lie in the intercostal spaces.
21
Q
Describe the manubrium
A
The manubrium is the superior part of the sternum:
● the superior border has a notch in it – the suprasternal (jugular) notch.
● laterally, it articulates with the clavicle (collarbone) at the sternoclavicular joint, and with the first rib.
● inferiorly, it articulates with the body of the sternum at the manubriosternal joint, also known as the sternal angle (or the ‘angle of Louis’).
22
Q
Describe the body of the sternum
A
● it articulates with ribs 2 – 7.
● the second rib articulates with the sternum at the sternal angle
23
Q
Describe the xiphoid process of the sternum
A
● small and variable in shape.
● the seventh rib articulates with the inferior part of the body of the sternum and the superior part of the xiphoid process.
24
Q
Which ribs are typical?
A
- Ribs 3 - 9 are typical ribs. They have a head, neck, tubercle, and body (shaft).
25
Which ribs are atypical?
* Ribs 1 - 2 and 10 - 12 are atypical, for various reasons. For example, ribs 1, 11 and 12 are much shorter than typical ribs.
26
What forms the superior thoracic aperture?
The manubrium, the first ribs and the first thoracic vertebra
This the ‘passageway’ through which structures pass between the neck and the thorax.
27
What do the thoracic vertebrae articulate with?
articulates with the posterior parts of the ribs at costovertebral joints.
- the head of the rib articulates with the vertebral body
- tubercle of the rib articulates with the transverse process of the vertebra
28
How do you describe a specific location on the chest wall?
Using two sets of coordinates:
1. Ribs
2. Series of vertical lines
29
At what level is the second rib?
Sternal angle
30
What imaginary vertical lines must you know? (Show them)
- Midsternal line
● Midclavicular line
● Anterior axillary line
● Mid-axillary line
● Posterior axillary line
● Scapular line
● Midvertebral line
31
How does sensation from the skin of the thoracic wall reach our conscious perception?
via somatic sensory fibres in the spinal nerves
32
What is a dermatome?
A dermatome is an area of skin innervated by a single spinal nerve. Each pair of thoracic spinal nerves supplies a ‘strip’ of skin around the chest wall.
33
What Innervates the skeletal muscles of the thoracic walls?
Somatic motor fibres in spinal nerves T1 -12
34
When does the breast grow?
during puberty and pregnancy.
After menopause, the breast atrophies
35
What nerves supply the breasts?
somatic nerves and sympathetic fibres via the intercostal nerves
Somatic sensory fibres innervate the skin of the breast. Sympathetic fibres innervate smooth muscle in the blood vessel walls and nipple.
36
What do the lymph nodes do?
● They drain the breast, upper limb, chest wall, scapular region, and the abdominal wall.
● The apical nodes (in the apex of the axilla) receive lymph from all other lymph nodes in the axilla.
37
What are the functions of the upper limb muscles?
prime function - move the upper limb pectoralis major adducts the humerus; pectoralis minor and serratus anterior protract the scapula
However, they can also function as accessory muscles of breathing because they attach to the ribs and hence can move the ribs if the humerus and scapula are fixed. In patients, use of these muscles is a sign of respiratory distress.
38
What are the intercostal muscles?
Within each intercostal space, there are three layers of muscles:
• External intercostal is most superficial.
• Internal intercostal lies deep to the external intercostal.
• Innermost intercostal lies deep to the internal intercostal.
39
What is the function of the intercostal muscles?
Collectively they move the ribs and alter the dimensions of the thoracic cavity with inspiration (breathing in) and expiration (breathing out).
40
How can you investigate a rib fracture?
If there is concern about multiple rib fractures or a pneumothorax, a chest X-ray or CT scan may be required to assess the extent of the injury.
41
How are rib fractures treated?
Isolated rib fractures are treated conservatively (i.e. left to heal on their own) but patients need adequate pain relief. Multiple rib fractures are more serious (and complex to manage), as they can lead to dysfunctional movements of the chest wall and inadequate ventilation.
42
Who does shingles affect?
Shingles affects people who have previously had chickenpox. After an infection with chickenpox, the virus lays dormant in the dorsal root ganglion.
43
What occurs if a breast mass is confirmed?
biopsied to assess if malignancy has metastasized to them. If so, they are removed as part of a patient’s treatment.
Can lead to a condition called lymphoedema.
44
What do intercostal spaces contain?
• three layers of intercostal muscles and their associated membranes
• an intercostal neurovascular bundle, comprising an intercostal nerve, an intercostal artery, and an intercostal vein.
45
What are the intercostal muscles called?
1. External intercostal
2. Internal intercostal
3. Innermost intercostal muscle
46
Describe the external intercostal muscle
External intercostal is most superficial.
Its fibres are orientated antero-inferiorly.
• Contraction pulls the ribs superiorly, hence is it most active in inspiration.
• In the anterior part of the intercostal space, the muscle becomes membranous and forms the external intercostal membrane.
47
Describe the internal intercostal muscle
Internal intercostal lies deep to the external intercostal.
Its fibres run perpendicular to those of the external intercostal, running in a postero-inferior direction.
• Contraction pulls the ribs inferiorly, hence is it most active in expiration.
• The internal intercostal becomes membranous in the posterior part of the intercostal space and forms the internal intercostal membrane.
48
Describe the innermost intercostal muscle
lies in the posterior part of the intercostal space deep to the internal intercostal.
fibres are orientated in the same direction as those of the internal intercostal.
49
Where does the intercostal neuro vascular bundle lie?
lies in the plane between the internal and innermost intercostal muscle.
along the inferior border of the rib superior to the space. It lies in a shallow costal groove on the deep surface of the rib.
50
How is the location of the intercostal neurovascular bundle clinically relevant?
When piercing the intercostal space (such as placing a chest drain), the incision is made in the middle to lower part to avoid the intercostal vessels and nerve.
51
What do the intercostal arteries supply?
- Anterior and posterior intercostal arteries supply the anterior and posterior parts of the intercostal space, respectively.
• The anterior intercostal arteries are branches of the internal thoracic artery (a branch of the subclavian artery).
• The posterior intercostal arteries are branches from the descending aorta in the posterior thorax.
52
What do the intercostal veins drain into?
Anterior intercostal veins - internal thoracic vein
Posterior intercostal veins - azygos system of veins
53
What is the nerve supply of the intercostal spaces?
The intercostal nerves are somatic and contain motor and sensory fibres. They innervate the intercostal muscles, the skin of the chest wall and the parietal pleura. Intercostal nerves also carry sympathetic fibres.
54
What layers of membrane cover the lungs?
The parietal pleura lines the inside of the thorax.
• The visceral pleura covers the surface of the lungs and extends into the fissures.
A very thin pleural cavity (or space) lies between the parietal and visceral pleura.
55
What are the pleura like?
The parietal pleura is visible with the naked eye, but the visceral pleura is not. The two layers of pleura are continuous with each other.
The pleural cells produce a small amount of pleural fluid, which fills the pleural cavity. The pleura and pleural fluid are integral to the mechanics of breathing.
56
What are the names of all the pleura and their associates?
The cervical pleura covers the apex of the lung.
• The costal pleura lies adjacent to the ribs.
• The mediastinal pleura lies adjacent to the heart.
• The diaphragmatic pleura lies adjacent to the diaphragm.
57
What is the costodiaphragmatic recess?
The costodiaphragmatic recess is a ‘gutter’ around the periphery of the diaphragm, where the costal pleura becomes continuous with the diaphragmatic pleura.
A smaller costomediastinal recess lies at the junction of the costal and mediastinal pleura. These are potential spaces that the lungs expand into during deep inspiration.
58
What is the nerve supply of the pleura?
• parietal pleura is innervated by intercostal nerves that innervate the overlying skin of the chest wall
- Somatic sensory fibres in these nerves carry sensation to our consciousness. Injury to the parietal pleura (e.g. tearing by a fractured rib) is typically very painful.
• The visceral pleura is innervated by autonomic sensory nerves (visceral afferents). Sensation from visceral afferents usually does not reach our conscious perception.
59
What is the structure of the lung like?
The most superior part of the lung is the apex which projects into the root of the neck, above the clavicle. The base of the lung ‘sits’ on the diaphragm.
60
What is the lung formed from?
Each lung is formed of lobes:
● The right lung has three lobes – a superior (upper), middle, and inferior (lower) lobe.
● The left lung has two lobes – a superior and inferior lobe. An anterior extension of the superior lobe – the lingula (Latin for ‘small tongue’) – extends over the heart.
61
What separates the lobes?
Fissures separate the lobes:
• Both lungs have an oblique fissure. In the left lung, it separates the superior and inferior lobes. In the right lung, it separates the superior and middle lobes from the inferior lobe.
• The right lung has a horizontal fissure. It separates the superior lobe from the middle lobe.
62
What are the surfaces of the lung ?
• Costal surface - adjacent to the ribs.
• Mediastinal surface - adjacent to the heart.
• Diaphragmatic surface - the inferior surface of the lung.
63
What are the borders of the lung?
• Anterior border - sharp and tapered.
• Posterior border – thick and rounded.
• Inferior border - sharp and tapered.
64
What is the root of the lung composed of?
The root of each lung lies between the heart and the lung and comprises the pulmonary artery, pulmonary veins, and main bronchus. Pleura encloses the root of the lung like a sleeve.
65
What is the hilum of the lung?
The hilum of the lung (plural = hila) is the region on the mediastinal surface of the lung where the pulmonary artery, pulmonary veins and main bronchus enter and exit the lung.
66
Where does the pulmonary artery lie?
At the hilum of the right lung, the pulmonary artery lies anterior to the main bronchus.
• At the hilum of the left lung, the pulmonary artery lies superior to the main bronchus.
67
Where are the pulmonary veins?
At both the right and left hila, the two pulmonary veins are usually the most anterior and inferior vessels.
68
What does the trachea bifurcate into?
- left and right main bronchi (at sternal angle). Internally, the point of bifurcation is marked by a ridge of cartilage called the carina.
Right main bronchus - shorter, wider and descends more vertically
- thus a foreign body entering the trachea is more likely to enter the right main bronchus
69
What is the bronchial tree?
The bronchial tree is the branching system of tubes that conduct air into and out of the lungs.
70
Describe the bronchial tree
main (primary) bronchus - lobar (secondary) bronchi - segmental (tertiary) bronchi - bronchioles - alveoli
- three in the right lung and two in the left lung (i.e. one lobar bronchus for each lobe).
• are approximately ten segmental bronchi in each lung.
71
What are the walls of the trachea made up of?
The walls of the trachea and bronchi contain smooth muscle and cartilage, but the walls of bronchioles only contain smooth muscle.
Contraction and relaxation of the smooth muscle is under autonomic control.
72
What is the blood supply of the lungs?
The pulmonary arteries carry deoxygenated blood to the lungs. Bronchial arteries from the descending aorta also supply the lungs.
73
What is the drainage of the lungs?
The pulmonary veins return oxygenated blood to the heart from the lungs.
Bronchial veins return blood to the azygos system of veins
74
What is the nerve supply of the lungs?
Autonomic nerves innervate the lungs.
• Parasympathetic fibres stimulate:
• bronchoconstriction
• secretion from the glands of the bronchial tree.
Sympathetic fibres:
•bronchodilation
• inhibit secretion from the glands.
75
What are visceral affrerents?
- Visceral afferents (visceral sensory fibres) accompany the sympathetic and parasympathetic nerves
- relay sensory information from lungs, visceral pleura to the CNS
- these sensations do not usually reach our conscious perception.
76
What is the lymph drainage of the lungs?
Lymph from the lungs ultimately drains into the venous system via the thoracic duct or right lymphatic duct
77
Where is the apex of the lungs?
The apex of each lung projects into the lower neck, just superior to the medial end of the clavicle.
78
Where do the inferior border of the lungs lie?
The inferior border of the lungs lies at the level of the:
• 6th rib anteriorly (midclavicular line)
• 8th rib laterally (midaxillary line)
• 10th rib posteriorly (at the vertebral column).
79
Where do the parietal pleura extend to?
The parietal pleura extends to the:
• 8th rib anteriorly (midclavicular line)
• 10th rib laterally (midaxillary line)
• 12th rib posteriorly (at the vertebral column).
80
Where are the oblique and horizontal fissures?
The oblique fissure of both the left and right lungs extends from the 4th rib posteriorly to the 6th costal cartilage anteriorly; the fissure runs deep to the 5th rib.
The horizontal fissure of the right lung extends anteriorly from the 4th costal cartilage and intersects the oblique fissure.
81
Where do we place a stethoscope?
For superior lobes of lungs: posterior chest wall superior to the markings of the oblique fissures
For the right middle lobe, place stethoscope anteriorly or laterally
We cannot auscultate the middle lobe over the posterior chest wall.
82
Where is the diaphragm located?
• Its superior (thoracic) surface is adjacent to the parietal pleura.
• Its function is integral to the mechanics of breathing (ventilation).
83
What is the diaphragm attached to?
The diaphragm is attached to the xiphoid process, costal margin (and to the tips of the 11th and 12th ribs) and the lumbar vertebrae. The central part of the diaphragm is not muscular, but fibrous - the central tendon.
84
How does the diaphragm act during breathing?
When the diaphragm contracts during inspiration, the domes flatten. This increases the intrathoracic volume for the lungs to expand.
• During expiration, the diaphragm relaxes and domes superiorly. This decreases the intrathoracic volume and drives expiration of air from the lungs.
85
What Innervates the diaphragm?
The right and left phrenic nerves
- somatic nerves
-formed in the neck by fibres from the C3, C4 and C5 spinal nerves
- contain motor and sensory fibres.
86
What are the basic mechanisms of breathing?
The mechanics of ventilation.
The basic principles are:
• Muscles move the thoracic cage and change the dimensions of the thoracic cavity.
• These determine intrathoracic volume.
• which alters intrathoracic pressure.
• drive inspiration and expiration.
• Different muscles are involved in normal, vigorous, and forced ventilation.
87
How is the pleural fluid integral to ventilation?
- creates surface tension
- keeps the lung and thoracic wall ‘together’, so when the thoracic cavity changes volume, the lung changes volume with it.
- prevents the lung from ‘collapsing’ away from the thoracic wall
If the surface tension is ‘broken’ (e.g. introduces air into the pleural cavity - pneumothorax) then ventilation may become dysfunctional.
88
What occurs during inspiration?
1. diaphragm and external intercostal muscles contract
2. increasing the intrathoracic volume
3. the external intercostals pull the ribs superiorly and laterally, and the ribs pull the sternum superiorly and anteriorly, increasing the AP and lateral dimensions of the thoracic cavity
4. lungs expand - ^Vol - with the thoracic wall (due to surface tension).
5. Pressure in the lungs decreases below atmospheric pressure and air is drawn into the lungs.
89
What occurs during expiration?
1. Diaphragm and external intercostal muscles relax, the internal intercostals contract
2. Decreasing the intrathoracic volume
3. internal intercostals pull the ribs inferiorly, and the ribs pull the sternum inferiorly and posteriorly, decreasing the AP and lateral dimensions of the thoracic cavity).
4. The lungs recoil (decrease in volume).
5. The pressure in the lungs increases above atmospheric pressure and air is expelled from the lungs.
90
What is inspiration and expiration like (state, muscle involvement)?
In normal, quiet breathing:
- inspiration is active (mainly driven by diaphragm)
- expiration is passive.
• vigorous breathing (e.g. exercise) - intercostal muscles imp
- Active expiration uses the internal intercostal muscles.
• Very vigorous/forced breathing (e.g. exacerbation of asthma or COPD, strenuous exercise) - accessory muscles of breathing contribute to movement of the ribs and aid ventilation. The anterior abdominal wall muscles contribute to forced expiration.
91
What is pleuratic chest pain?
When pleura is inflamed or injured (fractured rib)
- Pleuritic chest pain is typically sharp, well localised and worse on inspiration
- The pain is felt from the parietal pleura only.
92
What is pneumothorax?
Presence of air in the pleural cavity
- usually by trauma (e.g. a fractured rib tearing the parietal pleura)
- can happen spontaneously (tear in the visceral pleura)
93
What is haemothorax?
Haemothorax describes a collection of blood in the pleural cavity and occurs secondary to trauma when blood vessels are torn or cut.
94
What is pleural effusion?
Pleural effusion - the presence of excess fluid in the pleural cavity.
A chest drain is used to remove air and / or fluid from the pleural space.
Incision is made in the lower part of the chosen intercostal space, to avoid the neurovascular bundle, which lies in the costal groove of the rib superior to the space.
95
What is lung cancer?
Lung cancer may be primary (i.e. cancer of the lung tissue or bronchi) or secondary (i.e. cancer from elsewhere that has metastasized to the lungs).
Both are common.
Mesothelioma is a malignancy of the pleura.
96
What is a pulmonary embolism?
Pulmonary embolism is a blood clot in the pulmonary circulation.
Clot usually forms in deep veins in one of the legs - carried in venous circulation - to right side of the heart and into the pulmonary trunk.
causes severe respiratory distress and may be rapidly fatal. Smaller clots that occlude smaller pulmonary vessels may cause infarction of the part of the lung they supply.
97
What is dyspnoea?
Patients commonly present with breathlessness or shortness of breath (dyspnoea).
Use of the accessory muscles of respiration - sign of respiratory distress.
Patients in respiratory distress will often ‘fix’ their upper limbs steady (e.g. by holding onto the side of the bed or chair), which allows the upper limb muscles that attach to the chest wall (pectoralis major, pectoralis minor and serratus anterior) to move the ribs and aid ventilation.
98
What is paralysis of the diaphragm?
Injury to the phrenic nerve, the C3-5 spinal nerves or the C3-5 spinal cord segments on one side may paralyse the ipsilateral side of the diaphragm, but in a healthy person, this may not cause symptoms. Patients with bilateral paralysis of the diaphragm require ventilatory support.
99
What are upper limb muscles attached to?
100
What do sympathetic fibres innervate?
sweat glands and the smooth muscle of blood vessels and hair follicles in the skin (arrector pili).
101
Why can a segmental bronchi be removed without affecting the rest of the lung?
Each segmental bronchus supplies a functionally independent region of the lung called a bronchopulmonary segment; there are ten segments in each lung.
Because they have their own bronchus and blood supply, a segment may be surgically removed without affecting the rest of the lung.
102
What can pneumothorax lead to?
If air keeps entering the pleural cavity but cannot escape, a Tension pneumothorax develops:
- rapidly increasing volume of air progressively compresses the lung, heart, great vessels and the opposite lung over to the contralateral side of the thorax
- This is rapidly fatal without immediate intervention.
- Patients with a tension pneumothorax present with severe respiratory distress.
