Anatomy (Cardiorespiratory) Flashcards
1
Q
What is the dermatome?
A
Area of skin innervated by a single spinal nerve
2
Q
Where are the breasts located?
A
Superficial to the muscles of the chest wall
3
Q
Where is breast tissue found?
A
Extends towards the anterior axils (armpit), this part is called the axillary tissue
4
Q
What happens to the breasts after menopause?
A
The breast atrophies
5
Q
What does the breast contain?
A
● Fat - variable amounts
● 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
Figure 3. Anatomy of the female breast.
6
Q
What is the breast primarily supplied by?
A
● internal thoracic artery (which arises from the subclavian artery)
● axillary artery
7
Q
What is the internal thoracic artery?
A
The 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 internal thoracic vein
8
Q
What is the breast supplied with?
A
Somatic nerves and sympathetic fibres via the intercostal nerves
9
Q
What do the somatic sensory fibres do?
A
Innervate the skin of the breast
10
Q
What do the sympathetic fibres do?
A
Innervate smooth muscle in the blood vessel walls and nipple
11
Q
What are the 5 groups of lymph nodes in the axilla?
A
central
pectoral
humeral
subscapular
apical
12
Q
What do the lymph nodes in the axilla do?
A
They drain the breast, upper limb, chest wall, scapular region, and the abdominal wall
13
Q
What are the apical modes?
A
(in the apex of the axilla)
receive lymph from all other lymph nodes in the axilla.
Because they drain most of the lymph from the breast, the axillary lymph nodes are often involved in the spread of breast cancer
14
Q
What are the 3 layers of muscles in the intercostal space?
A
● the external intercostal is most superficial
● the internal intercostal lies deep to the external intercostal
● the innermost intercostal lies deep to the internal intercostal
15
Q
What are the 3 main muscles in the upper limb?
A
● Pectoralis major is the most superficial muscle of the anterior chest wall. It attaches to the upper humerus, the clavicle and the upper six ribs.
● Pectoralis minor is a smaller muscle that lies deep to pectoralis major. It attaches to the scapula (shoulder blade) and ribs 3-5.
● Serratus anterior is a superficial muscle that sweeps around the lateral aspect of the thoracic cage. It attaches to the scapula and the upper eight ribs
16
Q
What is the function of the pectoralis major?
A
Adducts the humerus
17
Q
What is the function of the pectoralis minor and serratus anterior?
A
Protracts the scapula
18
Q
Why are the upper limb muscles accessory muscles of breathing?
A
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
19
Q
What are rib fractures?
A
Result from blunt trauma to the chest wall
Painful, worse on inspiration
20
Q
What are shingles?
A
Shingles is a common skin condition that usually affects older people.
Patients present with a red, painful, and itchy rash, typically over the chest or abdomen on one side of the body only.
The rash appears in a strip-like distribution, as it affects dermatomes.
Shingles is caused by a reactivation of the herpes zoster virus in people who have previously had chicken pox.
The virus lays dormant in the dorsal root ganglion and when reactivated, it causes a rash and pain in the dermatome associated with the affected spinal nerve.
21
Q
Why does breast malignancy typically spread to the axillary lymph nodes first?
A
Most lymph from the breasts drain there
22
Q
What is a malignant axillary node palpable as?
A
As a lump in the armpit and notices before a mass in the breast itself.
If a breast mass is confirmed as malignant, the axillary lymph nodes are biopsied to assess if malignancy has metastasized to them.
If so, they are removed as part of a patient’s treatment.
23
Q
What is lymphoedema?
A
Fluid accumulation and swelling in the affected upper limb due to the removal of the axillary nodes
24
Q
What do the intercostal spaces contain?
A
● three layers of intercostal muscles and their associated membranes
● an intercostal neurovascular bundle, comprising an intercostal nerve, an
intercostal artery, and an intercostal vein.
25
What are the external intercostals?
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.
26
What are the internal intercostals?
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.
27
What are the innermost intercostals?
The innermost intercostal lies in the posterior part of the intercostal space deep to the internal intercostal. Its fibres are orientated in the same direction as those of the internal intercostal.
28
Where is the endothoracic fascia found?
Lies deep to the innermost intercostal and superficial to the parietal pleura, which surrounds the lung
29
What is the intercostal neurovascular bundle?
Neurovascular bundle which lies in the plane between the internal and innermost intercostal muscle
Supplies the intercostal muscles, the overlying skin and the underlying parietal pleura
30
What is the pleura?
Two thin layers of tissue that protects and cushions the lungs
Outer layer is called the parietal pleura and attaches to the chest wall
The inner layer is the visceral pleura and covers the lungs, blood vessels, nerves and bronchi
31
Where does the neurovascular bundle for each intercostal space lie?
Lies 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.
In medical procedures that involve piercing the intercostal space (such as placing a chest drain), the incision is made in the middle to lower part of the intercostal space, to avoid the intercostal vessels and nerve.
Smaller collateral branches run in the same tissue plane, but in the lower part of the intercostal space.
32
What does the anterior intercostal artery do?
The anterior intercostal arteries are branches of the internal thoracic artery (a branch of the subclavian artery)
Supplies the anterior parts of the intercostal space
33
What does the posterior intercostal artery do?
The posterior intercostal arteries are branches from the descending aorta in the posterior thorax.
Supplies the posterior parts of the intercostal spaces
34
What do the anterior intercostal veins do?
Anterior intercostal veins drain into the internal thoracic vein and posterior intercostal veins drain into the azygos system of veins – we will learn more about these later.
35
What are the intercostal nerves?
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
36
What do the pleurae do?
Cover the lungs and the structures passing
into and out of the lungs (the pulmonary blood vessels and the main bronchi).
● The parietal pleura lines the inside of the thorax
● The visceral pleura covers the surface of the lungs and extends into the fissures.
37
Where is the pleural cavity found?
Lies between the parietal and visceral pleura
38
Describe features of the pleurae
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.
39
What are the different parts of the parietal pleura?
● 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
40
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.
41
What is the parietal pleura innervated by?
The parietal pleura is innervated by the 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.
42
What is the visceral pleura innervated by?
The visceral pleura is innervated by autonomic sensory nerves (visceral afferents).
Sensation from visceral afferents usually does not reach our conscious perception.
43
What is the superior part of the lungs called?
Apex which projects into the root of the neck, above the clavicle
44
What is each lung formed of?
Lobes
45
How many lobes does the right lung have?
The right lung has three lobes – a superior (upper), middle, and inferior lower lobe
46
How many lobes does the left lung have?
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
47
What do fissures do?
Separate the lobes
48
What type of fissure do both lungs have?
Both 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
49
What type of fissure is only found in the right lung?
Horizontal fissure
It separates the superior lobe from the middle lobe
50
Where is the costal surface?
Adjacent to the ribs
51
Where is the mediastinal surface found?
Adjacent to the heart
52
Where is the diaphragmatic surface found?
Inferior surface of the lung
53
What structure does the anterior border have?
Sharp and tapered
54
What structure does the posterior border have?
Thick and rounded
55
What structure does the inferior border have?
Sharp and tapered
56
What do the surface of the lungs bear?
Indentations (impressions) created by adjacent structures.
Rib markings are seen on the costal surfaces of both lungs. Indentations created by the left ventricle and the descending aorta are seen on the mediastinal surface of the left lung and indentations made by the superior vena cava and azygos vein are seen on the mediastinal surface of the right lung
57
Where is the root of each lung and what does it comprise of?
Between the heart and lung
Comprises the pulmonary artery, pulmonary veins and main bronchus
Pleura encloses the root of the lung like a sleeve
58
What is the Hilum of the lung?
Region on the mediastinal surface of the lung where the pulmonary artery, pulmonary vein and main bronchus enter and exit the lung.
59
Where are the positions of the main bronchus at the Hilum in each lung?
● At the hilum of the right lung, the main bronchus lies anterior to the pulmonary artery.
● At the hilum of the left lung, the main bronchus lies inferior to the pulmonary artery.
At both the right and left hila, the two pulmonary veins are usually the most anterior and inferior vessels.
60
What does the trachea bifurcate into?
Into the left and right main bronchi at the level of the sternal angle
The right main bronchus is shorter, wider and descends more vertically than the left main bronchus thus a foreign body entering the trachea is more likely to enter the right main bronchus than the left
61
What is the bronchial tree?
Branching system of tubes that conduct air into and out of the lungs
62
What does the main bronchus divide into?
Lobar bronchi
63
What does each lobar bronchus divide into?
Divides to give rise to segmental bronchi
There are 10 segmental bronchi in each lung
64
What does the segmental bronchus do?
Supplies a functionally independent region of the lung called a bronchopulmonary segment; there are ten segments in each lung.
Because they are supplied by their own segmental bronchus and blood vessels, a segment may be resected (surgically removed) without affecting the rest of the lung.
65
What does the segmental bronchi divide into?
Bronchioles
Bronchioles become smaller with each division
The smallest bronchioles conduct air to and from the alveoli, the site of gas exchange within the lungs
66
What do the walls of the trachea and bronchi contain?
Smooth muscle and cartilage
67
What do the walls of the bronchioles contain?
Only smooth muscle
Contraction and relaxation of the smooth muscle is under autonomic control
68
What do autonomic nerves do?
Autonomic nerves innervate the lungs.
● Parasympathetic fibres stimulate:
● constriction of bronchial smooth muscle (bronchoconstriction)
● secretion from the glands of the bronchial tree.
● Sympathetic fibres:
● stimulate relaxation of bronchial smooth muscle (bronchodilation)
● inhibit secretion from the glands.
69
What do visceral afferents do?
Visceral afferents (visceral sensory fibres) accompany the sympathetic and parasympathetic nerves and relay sensory information from the lungs and visceral pleura to the CNS, but these sensations do not usually reach our conscious perception.
70
What do the lymph from the lungs do?
Ultimately drains into the venous system via the thoracic duct or right lymphatic duct
71
Where does 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).
72
Where does 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).
73
Where does the oblique fissure extend to?
Extends from the 4th rib posteriorly to the 6th costal cartilage anteriorly; the fissure runs deep to the 5th rib.
74
Where does the horizontal fissure extend to?
Extends anteriorly from the 4th costal cartilage and intersects the oblique fissure.
75
What is the diaphragm?
Broad, thin, domed sheet of skeletal muscle.
● It separates the thoracic and abdominal cavities from each other.
● Its superior (thoracic) surface is adjacent to the parietal pleura.
● Openings (apertures) in the diaphragm allow the passage of structures between
the thorax and abdomen (e.g. the aorta, inferior vena cava, and oesophagus).
● Its function is integral to the mechanics of breathing (ventilation).
76
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
77
What is the central part of the diaphragm?
Central tendon
Fibrous, not muscular
78
What happens to the diaphragm during inspiration?
Contracts, the muscle fibres of the right and left domes are pulled towards their peripheral attachments, and the domes flatten.
This increases the intrathoracic volume for the lungs to expand
79
What happens to the diaphragm during expiration?
Relaxes, and domes superiorly.
This decreases the intrathoracic volume and drives expiration of air from the lungs.
80
How is the diaphragm innovated?
The right and left phrenic nerves innervate the right and left sides of the diaphragm, respectively.
They are somatic nerves, formed in the neck by fibres from the C3, C4 and C5 spinal nerves, and hence contain motor and sensory fibres.
81
What are the basic principles of breathing?
● Muscles move the thoracic cage and change the dimensions of the thoracic cavity.
● The dimensions of the thoracic cavity determine intrathoracic volume.
● Changes in intrathoracic volume alter intrathoracic pressure.
● Pressure changes inside the thorax drive inspiration and expiration.
● Different muscles are involved in normal, vigorous, and forced ventilation.
82
How does the dimensions of the thoracic cavity change during ventilation?
● Vertically - due to the contraction and relaxation of the diaphragm.
● Laterally - due to contraction of the intercostal muscles which move the ribs.
● Antero-posteriorly (AP) – due to movement of the sternum secondary to
movement of the ribs.
83
What is the role of the pleural fluid during ventilation?
Creates surface tension between the parietal pleura lining the thoracic cavity and the visceral pleura on the surface of the lung.
Surface tension keeps the lung and thoracic wall ‘together’, so when the thoracic cavity changes volume, the lung changes volume with it.
Surface tension between the two pleural membranes keeps them in contact with each other and prevents the lung from ‘collapsing’ away from the thoracic wall.
If the surface tension is ‘broken’ (e.g. by a penetrating injury of the chest that punctures the parietal pleura and introduces air into the pleural cavity - pneumothorax) then ventilation may become dysfunctional.
84
What happens during inspiration?
● The diaphragm and external intercostal muscles contract, increasing the intrathoracic volume (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).
● The lungs expand (increase in volume) with the thoracic wall (due to surface tension).
● The pressure in the lungs decreases below atmospheric pressure and air is drawn into the lungs.
85
What happens during expiration?
● The diaphragm and external intercostal muscles relax, and the internal intercostals contract, decreasing the intrathoracic volume (the 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).
● The lungs recoil (decrease in volume).
● The pressure in the lungs increases above atmospheric pressure and air is
expelled from the lungs.
86
What muscles are involved in breathing?
● In normal, quiet breathing, inspiration is active and is mainly driven by movement
of the diaphragm, but expiration is passive.
● In vigorous breathing (e.g. exercise) the intercostal muscles become important. Active expiration uses the internal intercostal muscles.
● In very vigorous or forced breathing (e.g. in an exacerbation of asthma or COPD, or in strenuous exercise) the accessory muscles of breathing (sternocleidomastoid, pectoralis major and minor, serratus anterior) contribute to movement of the ribs and aid ventilation.
87
What is pleuritic chest pain?
The pleura can become inflamed or injured (e.g. torn by a fractured rib). Pleuritic chest pain is typically sharp, well localised (i.e. the patient can pinpoint it on the chest wall), and worse on inspiration. The pain is felt from the parietal pleura only.
88
What is pneumothorax?
A pneumothorax is the presence of air in the pleural cavity. It is usually caused by trauma (e.g. a fractured rib tearing the parietal pleura) but can happen spontaneously (tear in the visceral pleura).
If air keeps entering the pleural cavity but cannot escape, a tension pneumothorax develops, in which a 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.
89
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.
90
What is pleural effusion?
Pleural effusion describes the presence of excess fluid in the pleural cavity. It is not a diagnosis - the fluid could be pus from infection, blood, or fluid related to malignancy.
A chest drain is used to remove air and / or fluid from the pleural space. The surface anatomy of the heart and lungs must be considered to ensure the tip of the drainage tube does not injure them.
An 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.
91
What is lung cancer?
Lung cancer is one of the most common types of cancer seen in the UK.
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 primary and secondary cancer of the lung is common.
92
What is mesothelioma?
Malignancy of the pleura
93
What is pulmonary embolism?
Pulmonary embolism is a blood clot in the pulmonary circulation.
The clot usually forms in the deep veins in one of the legs and is carried in the venous circulation back to the right side of the heart and into the pulmonary trunk.
A very large clot lodging in the pulmonary trunk or in one of the pulmonary arteries 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.
94
What is dyspnoea?
Patients commonly present with breathlessness or shortness of breath (dyspnoea).
The use of the accessory muscles of respiration is a 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.
95
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.
