Anatomy of the Thorax Flashcards
(115 cards)
1
Q
What are the different forms of diagnostic imaging?
A
- Ionising radiation (risk of inducing cancer after years of exposure)
- X-ray and computer tomography (CT)
- Nuclear medicine
- Non ionising radiation
- Ultrasound
- Magnetic resonance imaging (MRI)
2
Q
What is attenuation?
A
Refers to the reduction in strength of a signal
3
Q
How are X-rays affected by different tissues?
A
- Most X-rays pass through air and fat: BLACK
- 50% of X-rays pass through soft tissue: GREY
- Few X-rays pass through bone: WHITE
- Metal: really white
This difference/contrast allows formation of an image
4
Q
Outline the use of contrast agents.
A
- Enhances differences between tissues of similar densities
- Commonly used: barium, iodine
- How: swallowed, via rectum, injected into artery or vein
- Appears very white
5
Q
Outline the use of Computed tomography (CT)?
A
- X-ray which spins around patient to produce cross-sectional map of tissue density
- Unlike X-ray can differentiate between water and soft tissue
- Has different windows to focus on different tissue e.g. bone
- Can be viewed in sagittal, axial and coronal
- Can be reconstructed in 3D
6
Q
Discuss the use of contrast agent for CT.
A
- Iodine can be injected into arm vein
- Enhances blood vessels so it’s easier to see
- Differentiates pathological from normal tissue
- Some risks: allergic reaction, kidney damage
7
Q
What is an arteriogram?
A
X-ray of the arteries
8
Q
Outline the use of Ultrasound.
A
- High frequency sound produced and detected to make an image
- No radiation, completely safe
- Can be made into 3D
9
Q
Outline the use of Magnetic resonsance imaging.
A
- Strong magnet, transmitting radio wave pulses into patient. Detects the return of radiowaves caused by interaction with protons in water in the body
- Different tissues give different intensities of returned waves producing an image
10
Q
What is the appearance of body parts in an MRI?
A
- Corticol bone: Black
- Bone marrow: White
- Soft tissue: Grey variable
- Fluid: Black (T1) and White (T2)
- Fat: White
- Air: Black
11
Q
Outline nuclear medicine.
A
- Radioactive tracers that emit radiation in different organs/parts of the body
- Images made by detecting the radiation in a patient by gamma camera
12
Q
Outline the use of Positron emission tomography (PET).
A
- Detects metabolic/functional changes in the body rather than structural
- Effective in diagnosing cancer, staging and seeing response to treatment
BUT use of PET/CT gives better anatomical localisation, and is faster and more specific that PET alone
13
Q
How many thoracic vertebrae and ribs?
A
- 12 thoracic vertebrae
- 12 pairs of ribs, and costal cartilages
14
Q
Describe the ribs.
A
- 12 pairs
- 1-7 true (reach sternum)
- 8-10 false (reach costal cartilage above)
- 11 and 12 floating (lack anterior attachment)
Articulations = joints
- With vertebral column via head and tubercle
- With costal cartilages
15
Q
What is the costal margin?
A
The lower edge of the thorax - form the 7th to 10th rib
16
Q
What are the parts of the sternum?
A
- Manubrium
- Sternal body
- Xiphoid
17
Q
Where do the ribs attach to the sternum?
A
- 1st costal cartilages attach to manubrium
- 2nd to manubriosternal joint
- 3rd-7th to sternal body
- 8th-10th to cartilage above
- 11th and 12th floating
18
Q
What is the thoracic inlet?
A
- Ring formed of 1st thoracic vertebra, 1st ribs and manubrium
- Contain great vessels heading for neck and upper limb, oesaophagus, trachea, nerves and lymphatics
19
Q
Describe the diaphragm and its position.
A
- Has a flat central tendon with muscle radiating to the costal margin and vertebrae
- 1st: dome flattens to increase vertical diameter of chest
- 2nd: pulls costal margin up to increase transverse and antero-posterior diameters
BUT - dome of the diaphragm bulges high inside the rib cage so organs such as liver are covered by diaphragm, pleura and lung.
20
Q
What is the role of intercostal muscle?
A
- Primary: Help with breathing moments
- Secondary: Stiffen chest wall to improve efficiency of breathing movements
21
Q
How do the ribs and sternum move to increase chest movement?
A
- Sternum: Up a bit, bottom out a lot (like a pump handle)
- Ribs: Out and up, elevation of lateral shaft of rib (like a bucket handle)
22
Q
How are the intercostal muscles organised?
A
- External intercostals: strands point downward and laterally on the posterior and downward and medially on the anterior (hands in pocket) from lower border of rib above to rib below. Replace b anterior intercostal membrane at costo-chondral (rib-cartilage) junction
- Internal intercostals: Attachments begin anteriorly at the sternum and from lower border of rib above to rib below. Fibres directed at right-engles to external intercostals
- Innermost intercostals: Intercostal arteries, veins and nerve lie between internal intercostal and innermost
23
Q
Where do the majority of Intercostal arteries, veins and nerves lie? What implications does this have?
A
Underneath the rib (majority) and smaller ones above the next rib.
When inserting needle for chest drain, the needle should be close to the rib below that above to avoid hitting the artery, vein and nerve
24
Q
Outline the features of the intercostal nerves.
A
- 11 pairs of intercostal nerves (between ribs) and one pair of subcostal at T12 (beneath rib)
- Mixed motor and sensory neurons
- Supply the intercostal spaces
- The lateral cutaneous branch splits into anterior and posterior
- Anterior cutaneous branch splits into lateral and medial branch
25
What is the area for inserting a chest drain?
- Anterior border of the latissimus dorsi (muscle which starts at back)
- The lateral border of the pectoralis major muscle
- Line superior to horizontal level of the nipple
- Apex below axilla
5th intercostal space anterior to mid-axillary line
26
Where do intercostal arteries join a major artery? Which artery?
Each artery joins (anastomoses) at the end of each intercostal space
- Join branches of the subclavian artery
27
List the contents of the thoracic cavity.
Filled laterally be the lungs, each lying in its pleural cavity.
Space between the pleural cavities is the MEDIASTINUM:
- Heart (in its pericardial sac)
- Great vessels
- Oesophagus
- Trachea
- Thymus
- Thoracic duct and other major lypth trunks
- Lymph nodes
- Phrenic and vagus nerves
28
What is the anatomical position of the trachea?
- Extends from vertebral level C6 to T4/5
29
Outline the structure of the Bronchial tree.
Trachea (C6-T4/5)
- held open by C-shaped cartilage rings
- lowest ring has a hook: carina
Primary bronchi (left and right)
- formed at T4/5
- right wider and more vertical than left (clinically relevant)
Lobar (secondary) bronchi
- formed within lungs
- supply the lobes of the lungs
Segmental (tertiary) bronchi
- supply the bronchopulmonary segments
30
How many lobes in the left and right lung?
Left - 2
Right - 3
31
Define bronchopulmonary segments.
Self-contained independent units of lung tissue.
10 in each lung
32
What is the pattern of branching in the bronchial tree?
Bifurcation - splitting into two
33
How is the lung positioned?
- In thorax
- Separated from each other by heart and other contents of mediastinum
- Each lies freely in its pleural cavity
- Attached to the heart via pulmonary vessels and trachea, at the lung root (hilum)
34
Describe the shape of the lungs.
- Conical in shape
- Apex: sits in thoracic inlet oblique (space above 1st rib), and rises 3-4cm above level of 1st costal cartilage
- Base: concave, rests on convex surface of diaphragm
3 borders (anterior, posterior and inferior)
3 surfaces (costal, medial (mediastinal), inferior (diphragmatic))
35
Describe the function of the diaphragm in relation to the lung and abdomen.
Diaphragm separates:
- Right lung from right lob of the liver
- Left lung from left lobe of the liver, stomach and spleen
36
Describe the mediastinal surface of the lung.
- Posterior part: in contact with thoracic vertebrae
- Anterior part: deeply concave, accommodates heart, largeer cardiac impression on left lung that right
- Above and behind cardiac impression is the hilum where vessels, bronchi and nerves enter and leave
37
Outline the parts of the left lung.
- Two lobes: superior and inferior
- Lobes separated by oblique fissure
- Superior love (above fissure) includes: apex, most of anterior part of the lung
38
Outline the parts of the right lung.
- Three lobes: superior, middle and inferior
- Lobes separated by 2 fissures;
- oblique fissure: separates inferior from the other lobes
- horizontal fissure: separates superior from middle lobe
39
Which lung is bigger?
The right is slightly larger than the left
40
What structures enter/leave at the hilum?
- Principal/primary bronchus
- Pulmonary artery (de-oxygenated blood from right ventricle)
- 2 Pulmonary veins (oxygenated blood to left atrium)
- Bronchial arteries (oxygenated blood from descending aorta) and veins
- Pulmonary plexus of nerves (autonomic)
- Lymph vessels and nodes
All are enveloped in the pleura
41
What is the Pleura?
A thin layer of flattened cells supported by connective tissue that lines each pleural cavity and covers the exterior of the lungs.
42
Describe the structure of the Pleura.
Formed from 2 layers:
- Visceral pleura: covers surface of the lungs and lines fissures between the lobes
- Parietal pleura: lines inner surface of chest walls
Both layers are continuous with each other around the hilum.
Normally the pleural cavity is collapsed, but moist surfaces allow lungs to glide as the expand and collapse.
43
Outline the pleural origin.
- Initially coelomic cavity
| - Lung bud forms and grows into the visceral pleura
44
Describe the mechanism of breathing with respect to the pleural cavity.
- Pleural cavity is expanded by muscles in walls
| - Elastic lungs expand with the pleural cavity, sucking air down into the trachea and bronchi in lungs
45
How does the diaphragm contribute to the mechanism of breathing?
- Contraction increases vertical dimension of thoracic cavity
- It presses down on abdominal viscera which initially descends
- Further descent is stopped by abdominal viscera, so as the diaphragm contracts the costal margin is raised
- Increased thoracic capacity from diaphragm and rib movement reduces intrapleural pressure, with entry of air though respiratory passages and expansion of lungs
46
Describe the role of the ribs in breathing.
- Ribs elevated: anterior ends thrust forward and upwards increasing antero-posterior dimension of thoracic cavity
- Ribs are everted (turned out) increasing transverse diameter of thoracic cavity
- Internal and external intercostal muscles stiffen the rib cage to increase efficiency of diaphragm
47
Explain the mechanism of expiration.
- Quiet expiration is a passive activity (no muscle involvement)
- Depends on elastic recoil in elastic tissue throughout the lungs and in the rib cage
- In deep or forced expiration, it's assisted by the muscles of the abdominal walls that squeeze the abdominal organs against the diaphragm and pull the lower ribs downward
48
What is the mediastinum?
- Thick midline partition separating the two pleural cavities
- Extends from the superior thoracic aperture (inlet) to inferior thoracic aperture and between the sternum arteriorly and the thoracic vertebrae posteriorly
- Acts as a conduit (channel) for structures that pass through the thorax from one body region to another and for structures that connect thoracic organs to other body regions
49
What are the principal contents of the mediastinum?
- Trachea: from larynx to bifurcation into principal bronchi (left and right)
- Oesophagus: from pharynx, muscular tube, pierces diaphragm at T10
- Heart and pericardium
- Thoracic duct - lymphatic drainage
- Nerves
- Great vessels
50
Outline the divisions of the mediastinum.
- Superior: above sternal angle
- Inferior: below sternal angle
- Anterior: Anterior to heart in pericardial sac
- Middle: Pericardial sac and heart
- Posterior: Posterior to pericardial and diaphragm
51
What are the contents the superior mediastinum?
Anterior to posterior:
- Thymus
- Phrenic nerve
- Great veins
- Main lymphatic trunks
- Vagus nerves
- Great arteries
- Trachea and main bronchi
- Upper oesophagus
52
What are the great veins?
- Superior Vena Cava (SVC), enters right atrium from above
| - Inferior Vena Cava (IVC), enters right atrium from below, through central tendon of diaphragm
53
Which veins are tributaries of the Superior Vena Cava?
- Internal jugular veins from head and Subclavian veins from upper limbs join to form the left and right braciocephalic veins
- Left brachiocephalic vein crosses posterior to manubrium to join the right brachiocephalic vein to form the SVC
54
How is the aorta positioned in the mediastinum?
- Arch of the aorta: superior
- Ascending aorta: middle
- Descending aorta: posterior
55
Outline the branches off the aorta.
Ascending aorta:
- Right and left coronary arteries (supplying heart)
Aortic arch:
- Brachiocephalic trunk: divides into right common carotid and right subclavian arteries
- Left common carotid artery
- Left subclavian artery
56
What are the relations between the aorta and and great arteries to the airway?
- Aortic arch arises anterior to trachea
- Aorta arches over the left main bronchus at the lung root
- Trachea lies behind and between brachiocephalic and left common carotid arteries
57
Describe the distribution of common carotid arteries.
- Divide into external and internal carotids high in the neck
- Main arteries of head and neck (with the vertebral arteries from the subclavian arteries)
58
What is the function and features of the pulmonary trunk?
- Outflow of right ventricle
- Carries de-oxygenated blood via left and right pulmonary arteries to lungs
- Divides into right and left pulmonary arteries
- Ligamentum arteriosum connects the trunk to aortic arch and is a remnant of the ductus arteriosus bypasses lungs in foetal life.
59
What are the contents of posterior mediastinum?
- Oesophagus
- Descending aorta
- Thoracic duct
- Azygos venous system
- Posterior mediastinal lymph nodes
- Thoracic sympathetic trunks
- Splanchnic nerves
60
Decribe the anatomical position of the oesophagus.
- Begins at C7 vertebra
- Ends at stomach, T11 vertebra
- Bends more arteriorly at T7
- Is right of aorta above T7
- Deviates to the left at T7
- Progressively anterior to aorta below T7
- Passes through diaphragm at T10
- Has constrictions at four locations
61
Where are the constrictions of the oesophagus?
- Junction of oesophagus with pharynx
- Where it's crossed by aortic arch
- Where it's compressed by the left main bronchus
- At the oesophageal hiatus
62
What is the oesophageal blood supply?
- Upper: Straight from the aorta from oesophageal branches
| - Lower part supplied by branches off unpaired abdominal arteries
63
Describe the Azygous venous system.
- Drains posterior wall of chest and upper abdomen and posterior mediastinal organs
- Usually accessory hemiazygos (upper) and hemiazygos (lower) veins on left cross thoracic vertebral bodies to join single azygos vein on right
- Azygos vein arches right lung root to enter superior vena cava just above right atrium
- Variable
64
Describe the nerves within the mediastinum.
- Phrenics (C3, 4, 5) pass anterior to lung roots and cross pericardium to diaphragm
- Vagi (Cranial nerve X) pass posterior to lung roots and form plexus following oesophagus in abdomen, giving branches to heart and lungs on the way
- Sympathetic trunks lie on each side of the posterior mediastinum
65
What are the Phrenic nerves?
- Formed in the cervical plexus from C3, 4, 5
- Motor to the diaphragm
- Sensory to:
- central tendon of the diaphragm
- mediastinal pleura (parietal)
- pericardium
- peritoneum of central diaphragm
- Right phrenic nerve reaches diaphragm lying on surface of:
- right brachiocephalic vein
- superior vena cava
- right side of heart and pericardium, in front of lung root
66
Describe the relation between the great arteries and main nerves.
- Vagus nerves lateral to common carotids
- Left vagus passes anterior to aortic arch
- Left phrenic crosses vagus to cross aortic arch more anteriorly
67
Describe the position of the left phrenic and vagus nerves.
- Cross arch of aorta
- Left phrenic descends in front of root lung
- Left vagus crosses behind root lung gives off left recurrent laryngeal nerve which turns back around ligamentum arteriosum and aortic arch
- Breaks up into many branches round oesophagus
68
Describe the anatomical position of the right vagus nerve.
- Lies on the trachea
- Crosses behind the root lung
- Recurrent laryngeal branch, which turns around right subclavian artery
- Breaks up into branches on oesophagus
69
Describe the vagus nerves and their branches.
- Branches to chest and abdomen, are parasympathetic (control smooth and cardiac muscle + glands of gut and airway)
- Also large sensory from gut and lungs
- Recurrent laryngeal nerve not parasympathetic, run back up the neck to supply most skeletal muscles of larynx
70
Describe the organisation of the sympathetic trunks.
- Recieve branches from spinal nerve T1-L2
- Distribute sympathetic nerves to smooth muscle and glands through out body
- Nerves to body wall synapse in ganglia of trunk
- Nerves to internal organ (viscera) synapse in local ganglia
- Also bring pain fibres back to CNS from viscera
- Fibres from lower T5-T12 reach abdomen in bundles called splanchnic nerves
71
What is the thoracic duct?
- Lymph duct returning lymph from lower limbs, pelvis, abdomen and left thoracic wall to blood
- Begins below diaphragm at cisterna chyli
- Starts between oesophagus and aorta on right
- Drains into left brachiocephalic vein
72
What are the functional divisions of the CNS?
- Somatic: Skin and Skeletal muscles
| - Autonomic/visceral: Organs and parts of organs such as smooth muscle and glands
73
Outline the features of the Somatic spinal nerves.
- Motor neurons to skeletal muscle only
- Skeletal muscle cannot function without them
- Sensory neurons to body wall but not to viscera
- Segmental nerve may combine to form plexi supplying specialised areas (cervical, brachial, lumbosacral)
74
Define Dermatome and Myotome.
Dermatome:
An area of skin which is supplied by a single spinal nerve on one side or from a single spinal cord
Myotome:
Part of a skeletal muscle supplied by a single spinal nerve on one side or from a single spinal cord level
75
Describe the organisation of the Intercostal nerves.
- 11 pairs of intercostal, and 1 subcostal
- Mixed (motor and sensory)
- Spinal or segmental nerves
- Arise from the anterior primary rami
- Supply the intercostal spaces
- Lateral cutaneous branch splits into anterior and posterior
- Anterior cutaneous branch splits into medial and lateral
76
Outline the features of the Phrenic Nerves.
- Derived from anterior rami of spinal nerves C3-C5
- Somatic nerves so no autonomic function or visceral distribution
- Motor fibres supply skeletal muscle of the diaphragm
- Sensory fibres supply central diaphragm, its pleural covering, mediastinal pleura and pericardium
- Also supply peritoneum on inferior surface of central diaphragm
77
What are the features of the Autonomic nervous system?
- Motor neurons to cardiac muscle, smooth muscle and glands
- Sensory neurons to visceral organs
- Divided into the Parasympathetic and sympathetic
- Different origins and distributions
- Often but not always opposite in motor actions
78
What are the features of Sympathetic outflow from the spinal cord?
- All autonomic motor pathways involve pre-ganglionic and post-ganglionic neurones
- Pathways to body wall synapse in ganglia of sympathetic trunk
- Pathways to viscera synapse in unpaired ganglia
- Trunks take fibres up or down
79
Outline the sympathetic trunks.
- Receive branches from spinal nerve T1-L2
- Distribute sympathetic nerves to smooth muscle and glands throughout the body
- Nerves to body wall synapse in ganglia of trunks
- Nerves to viscera synapse in unpaired ganglia
- Also bring pain fibres back to CNS from viscera
- Fibres from lower T5-T12 reach abdomen in bundles called splanchnic nerves
80
Which nerves contain parasympathetic fibres?
Five sets:
- Oculomotor (III) cranial nerves
- Facial (VII) cranial nerves
- Glossopharyngeal (IX) cranial nerves
- Vagus (X) cranial nerves (suppiles vescera of thorax and most of abdomen)
- Sacral (S2-S4) spinal nerves
81
Describe the sympathetic nerves to the lungs and heart.
- Mainly from spinal nerve T2-T4, passing through cervical and upper thoracic ganglia of sumpathetic trunk
- Many of their synapses are in micro-ganglia in the pulmonary and cardiac plexuses rather that in trunk ganglia
82
What happens at the Pulmonary pleuxuses?
- Sympathetic nerves dilate the bronchioles
| - Parasympathetic (vagus) nerves constrict the bronchioles.
83
What happens at Cardiac plexuses?
- Sympathetic efferent increase heart rate and force of contraction
- Sympathetic afferents relay pain sensations from the heart
- Parasympatic efferents (vagus) decrease heart rate via pacemaker tissue and constrict coronary arteries
- Parasympathetic afferents (vagus) relay blood pressure and chemistry information from the heart
84
Describe the course of the Vagus nerve.
- Cranial nerve X: arise from medulla and leave skull through jugular foramina
- Descend neck posterolateral to common carotid artery
- Left vagus crosses anterior to aortic arch then posterior to right lung root
- Right vagus passes posterior to right lung root
- Both vagi form a plexus round the oesophagus
- Separate to form anterior and posterior oesophageal/gastric nerves
85
What happens at the Oesophageal plexus?
- Sympathetic afferents relay pain sensations from the oesophagus
- Parasympathetic afferents (vagus) senses normal physiological information from the oesophagus
86
Describe the vagus nerves and their branches.
- Branches to chest and abdomen are parasympathetic (control smooth and cardiac muscle + glands of gut and airways)
- Also large sensory (enteroceptor) content form gut and lungs
- Unlike the sympathetic they provide no autonomic supply to the body wall (e.g. arterioles and sweat glands)
- Recurrent laryngeal branch of vagus nerve is not parasympathetic, runs back up neck to supply most skeletal muscles of larynx
87
Describe the position of the vagi in the posterior Mediastinum.
- Mainly right vegus contributing to oesophageal plexus
- Aquire many sympathetic fibres
- Inferior continuation of this nerve is the posterior oesophageal nerve, taking right vagal fibres through the diaphragm to the abdominal viscera
- The left vagus provides fibres to the oesophageal plexus then continues as the anterior oesophageal nerve
88
What are the intrinsic nerves of the oesophagus?
- Plexus of ganglia and axons within the oesophageal wall which coordinates its activity
- This can be up or down regulated by the autonomic nerves
- Part of the enteric nervous system
89
Why do we have a lymphatics system?
- More fluid leaves the blood capillaries than returns to them
- Uncompensated fluid movement from blood to extracellular fluid would result in oedema and loss of blood volume
- Lympatic vessels drain excess extracellular fluid back into the blood
- Ensure foreign particles come into contact with immune system
90
What is the lymphatic system?
- Network of tissues and organs consisting of lymph vessel, lymph nodes and lymph
- Includes tonsils, adenoids, spleen and thymus
- 600-700 lymph nodes in humans
- Filter the lympth before it returns to the circulatory system
91
Where do the lymph vessels drain in to?
Upper right quadrant:
- Head, neck, upp, limp and thorax drain into right subclavian vein
Rest of body:
- Thoracic duct
- Left subclavian vein (at junction between left jugular vein)
92
Describe the anatomy of a lymph node?
- Small (
93
What is enlarged lymph nodes a sign of?
Commonly: Infection
- commonly enlarged in the neck in children due to the large number of respiratory infections
Less common: Cancers
- also TB, HIV, Arthritis, reaction to drug
94
What is lymph?
- Clear and odourless in most vessels
- Opaque and milky from small intestine due to the fats absorbed (chyle)
- Contains white blood cells, pathogens, hormones, cell debris, fats
95
Describe the movement of lymph.
- Slow and sporadic as there's no pump
- Maintained by action of adjacent structures e.g. skeletal muscles, pulses in arteries
- Unidirectional due to the presence of valves
96
What are the different associations of lymph vessels, and where do they drain
- Associated with Internal thoracic arteries, drain into parasternal nodes
- Associated with Ribs, drain into intercostal nodes
- Associated with Diaphragm, drain into diaphragmatic nodes
97
Where do the parasternal, intercostal, diaphragmatic and superficial nodes drain into?
- Parasternal into Bronchomediastinal trunks
- Intercostal (upper) into Bronchomediastinal trunks
- Intercostal (lower) into Thoracic ducts
- Diaphragmatic into Brachiocephalic and Aortic/lumbar
- Superficial into Axillary or parasternal
98
Describe the anatomical position of the thoracic duct.
- Main channel draining most of the body
- Begins at the cisterna chyli: drains abdomen, pelvis, perineum and lower limbs
- Begins at L2 vertebral level
- Enters behind oesophagus through diaphragm
- Ascends on right of midline, between aorta and azygous vein
- Crosses over onto left at T5
- Empties into junction of left internal jugular and left subclavian
99
Describe the lymphatics of the lungs.
- Tracheobronchial: Around bronchi and trachea
- From within lung through hilum
- Unite with vessels from the parasternal and brachiocephalic nodes anterior to brachiocephalic veins to form the BRONCHOMEDIASTINAL (left and right)
100
Describe the lymphatics of the heart.
- Follow the coronary arteries and drain into:
- Brachiocephalic
- Tracheobronchial
101
Describe the lymphatics of the posterior mediastinum.
Nodes of aorta receive lymph from oesophagus, diaphragm, liver and pericardium and drain into:
- thoracic duct
- posterior mediastinal
102
What is the anatomical position of the female breast?
- Breast base extends from 2nd to the 6th rib in the midclavicular line
- It overlies the perctoralis major muscle
- Laterally extends to lie on serratus anterior and external oblique muscles
- Axillary tail of breast tissue sometimes extends into medial wall of axilla and lies in the subcutaneous fat
- The medial and lateral extents vary according to size, from the midline medially to the mid axillary line laterally
103
What is the breast?
A modified sweat gland, and under hormonal influence to produce milk post-partum, it is made up of glandular tissue, fat and fibrous tissue.
104
Describe the make up of the breast.
- Comprised of 15-20 ductal-lobular units, each draining into a main duct
- Complex network behind the nipple and between 4 -18 milk ducts open on the summit of the nipple or on the areola
- Fat lies interspersed between the ductal lobular units
- The organ is divided by fibrous septae that radiate from the centre outwards (suspensory ligaments of Cooper)
105
What are the methods of viewing the breast?
Mammography (X-ray) taken in two different angles:
- Mediolateral oblique (MLO) \ \
- Craniocaudal (CC) =
Breast ultrasound: 2D, 3D, 4D
106
What is the earliest sign of breast cancer?
- Ductal carcinoma in situ (DCIS)
- Presence of abnormal cells inside the milk duct of breast tissue
- Non-invasive (hasn't spread to other parts)
107
Describe the blood supply in the breast.
- Derived from branches of lateral thoracic artery, internal thoracic artery, thoraco-acromial artery, thoraco-doral artery and intercostal arteries.
- Skin is supplied by subdermal plexus which communicated with the deep parenchymal vessels.
- The nipple-areola receives a branch from the internal thoracic artery in most cases
- Venous return follows the arteries i,e lateral thoracic vein etc
108
Describe the sensory nerves in the breast.
- Sensory innervation is dermatomal, mainly from anterolateral and anteromedial branches of thoracic intercostal nerves T3-T5
- Also innervation from supraclavicular nerves to the upper and lateral parts of the breast
- The nipple has a dominant supply from the lateral cutaneous branch of T4
109
What is the difference between the make up of breast tissue in young and older women?
Younger women have more glandular tissue (appears more white, larger network in a mammography)
Older women have more fatty tissue (appears less white, smaller network in a mammography)
This is why a mammography is more useful in older women, as carcinomas and other issues are more easily spotted.
110
What colour does a carcinoma appear in a mammography?
White
111
Decribe the lymphatics of the breast.
- Lymphatic drainage from the breast is mainly towards the axilla
- Lymph capillaries make a richly anastamosing (joined) network within the breast and overlying skin
- Superficial parts drain to the sub-areolar plexus and the deep parts to the submammary plexus that lies in the deep fascia overlying pectoralis major and serratus anterior
- Lymphatic and venous channels have an important role in the spread of breast cancer
112
What is sentinel node imaging?
- Sentinel node is the hypothetical first lymph node/nodes draining a cancer
- A low-activity radioactive substance is injected near the tumor and allowed to spread. Imaging is then used to see to which lymph nodes the substance has spread
113
Describe the lymph glands of the breast.
From the sub areola and sub-mammary plexuses, lymph mostly drains to the pectoral group of axillary nodes.
But theres drainage to adjacent parts of the breasts to:
- the infraclavicular group
- parasternal nodes (along internal thoracic artery)
- mediastinal nodes (inferiorly through abdominal wall and diaphragm)
- the the opposite breast
There is free communication between the nodes above and below the clavicle and between the cervical and axillary nodes
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Why is Lymphoedema associated with the breast?
- Related to breast cancer treatment
- It can occur in the arm after surgery (axillary clearance) or radiotherapy to the axilla.
- Due to blockage of the lymphatics or as a result of impairment of venous drainage
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What congenital abnormalities can occur in the breast?
- Accessory nipples
- Accessory breast tissue
- Underdevelopment or absence of one breast (may coexist with muscle.ribcage anomaly)
