5. Heart and nerves of the thorax Flashcards

(63 cards)

1
Q

Pericardium

A
Fibro-serous sac surrounding heart and its great vessels 
Consists of 2 layers: Fibrous and Serous
Serous has 2 parts:
Parietal: lines fibrous
Visceral: adheres to heart
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2
Q

How many pericardial sinuses are there? Describe each

A

2
Transverse pericardial sinus: separates arteries from veins
Oblique pericardial sinus: is formed by reflection onto the pulmonary veins of heart

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3
Q

Where would you palpate to feel the apex beat of the heart?

A

5th intercostal space

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4
Q

Describe the outflow of chambers of the heart

A

Right atrium: Blood returns via SVC and IVC (body) and coronary sinus (heart)
Left atrium: Blood returns via pulmonary veins
Right ventricle: Outflow to the pulmonary trunk
Left ventricle: Outflow to the ascending aorta

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5
Q

Coronary sinus

A

Point at which main drainage veins of heart (Coronary veins) empty into right atrium

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6
Q

What does the foramen oval provide?

A

1st opportunity for blood to bypass lungs in foetal circulation
Blood can flow from the right atrium to the left atrium

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7
Q

What happens to the foramen oval after birth?

A

Closes after birth

Becomes the fossa ovale

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8
Q

What happens to the ductus arteriosus after birth?

A

Becomes the Ligamentum arteriosum connects PT to aortic arch

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9
Q

Chordae tendonae in the right ventricle

A

Chordae tendonae stop inversion of tricuspid valve.

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10
Q

How are chordae tendonae arranged in the ventricles

A

Embedded in the wall of the ventricle by projections (papillary muscles)

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11
Q

Pair of semilunar valves

A

Pulmonary valve

Aortic valve

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12
Q

Pair of atrioventricular valves

A

Mitral

Tricuspid

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13
Q

Left ventricle structure

A

Much thicker left ventricle wall
Trabecular carnae: net like structure
Papillary muscles tether chordae tendonae, preventing eversion of mitral valve

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14
Q

What are the “bowl” like structures forming the aortic valve are called?

A

Aortic sinuses

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15
Q

Describe the aortic sinuses

A

In the walls of 2 aortic sinuses there is a hole for the coronary arteries (2 have holes as we have 2 coronary arteries). These with holes are called coronary aortic sinsues.

The 1 aortic sinus with no hole is called a non-coronary aortic sinus

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16
Q

Myocardial Infarction

A

Lack of blood to the heart muscle causes it to die
Ischaemic event
Blood supply issue

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17
Q

Cardiac arrest

A

Arrest of beat of heart

Electrical issue

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18
Q

Interventricular branches

A

Branches that go down between ventricles

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19
Q

Marginal branches

A

Branches that run across margins

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20
Q

Circumflex branches

A

Branches that turn back on themselves

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21
Q

Right dominant coronary artery

A

More common variation

Posterior interventricular branch arises from the right coronary artery

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22
Q

Left dominant coronary artery

A

Less common variation

Posterior interventricular branch arises from the left coronary artery

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23
Q

Where do coronary veins drain?

A

All Coronary veins drain into coronary sinus
(vessel that sits between left atrium and left ventricle).
Collects deoxygenated blood from heart muscle and returns it to the right atrium

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24
Q

Describe the conducting system of the heart

A

Excitation begins in SAN
Spreads wave of depolarization across atria causing contraction
Concurrently wave stimulates AVN
Travels through the bundle of His
Then along bundle branches, through Purkinje fibres, causing ventricular contraction

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25
What does the somatic nervous system innervate? (voluntary)
Skin | Skeletal muscles
26
What does the autonomic nervous system innervate?
Organs and parts of organs such as smooth muscle and glands
27
Describe the somatic spinal nerves
Motor to skeletal muscle only (cannot function without them) | Sensory to body wall but not to viscera
28
Composition of dorsal and ventral root and rami
Dorsal root has only sensory fibres Dorsal ramus has motor and sensory fibres Ventral root has only motor fibres Ventral ramus has motor and sensory fibres
29
What may happen to somatic spinal nerves that are segmental?
Segmental nerves may combine to form plexi supplying specialised areas (cervical, brachial, lumbosacral)
30
Ramus
Division of already mixed spinal nerve: | motor and sensory neurones
31
Dermatome
An area of skin which is supplied by a single spinal nerve on one side or from a single spinal cord segment
32
Myotome
Part of a skeletal muscle supplied by a single spinal nerve on one side or from a single spinal cord segment
33
How many pairs of intercostal nerves are there?
11 intercostal + 1 subcostal
34
Composition of intercostal nerves
Mixed: | Motor and sensory
35
What are the branches of the intercostal nerves?
Lateral cutaneous branch (anterior and posterior branches) | Anterior cutaneous branch (medial and lateral branches)
36
What structures do the phrenic nerves provide sensory and motor innervation to?
``` Motor: diaphragm Sensory: Central diaphragm Mediastinal pleura Pericardium Peritoneum of central diaphragm ```
37
Where are the phrenic nerves derived from?
Anterior rami of spinal nerves C3, C4 and C5
38
Location of phrenic nerves (with relation to lung root)
In front of the lung root
39
Parasympathetic pathway
Craniosacral: as the nuclei it comes from and goes back to are in the brain or sacral part of spinal cord
40
Sympathetic pathway
Thoracolumbar: as it only emerges from the thoracic and lumbar parts of the spinal cord
41
Which nervous system do phrenic and vagus nerves belong to?
Autonomic nervous system Phrenic nerve supplies skeletal muscle of diaphragm. Although its automatic, it is under voluntary control (can hold breath)
42
Where do sympathetic preganglionic neurones to the body wall synapse?
In the ganglia of the sympathetic trunk
43
What runs either side of the vertebral column? Describe this
A “chain” runs on each side of the vertebral column which has enlargements (sympathetic ganglia). At sympathetic ganglia, the sympathetic nerves can get out and go to their destination
44
Where does sympathetic outflow from the spinal cord occur?
T1 to L2
45
Describe the grey matter from T1-L2
There is an extra horn (the intermediate/ intermediolateral horn) between dorsal and ventral horn Cell bodies giving rise to sympathetic nerve are located here
46
Where do sympathetic preganglionic neurons to the viscera synapse?
In unpaired ganglia
47
Difference between white and grey ramus communicans
White ramus communicans contains myelinated fibres | Grey ramus communicans contains unmyelinated fibres
48
The sympathetic trunk receive which spinal nerves?
Branches from spinal nerves T1 to L2
49
Function of sympathetic trunks
Distribute sympathetic nerves to smooth muscle and glands throughout body Also bring pain fibres back to CNS from viscera
50
What is the significance of sympathetic fibres in spinal nerves T5-T12?
=Thoracic splanchnic nerves that carry sympathetic fibres to the abdomen.
51
What are the 5 sets of nerves that contain parasympathetic fibres?
``` Occulomotor (III) c. nerves Facial (VII) c. nerves Glossopharyngeal (IX) c. nerves Vagus (X) c. nerves Sacral spinal nerves (S2-S4) ```
52
Which spinal nerves do sympathetic fibres to the heart and lungs come from?
T2-T4 passing through cervical and upper thoracic ganglia of sympathetic trunk
53
Where do many of the sympathetic fibres to the heart and lungs synapse?
In micro-ganglia of the pulmonary and cardiac plexuses rather than in the trunk ganglia
54
What effect do sympathetic and parasympathetic nerves have on bronchioles?
Sympathetic: bronchodilation | Parasympathetic (vagus): bronchoconstriction
55
What are the effect of sympathetic and parasympathetic efferents to the heart?
Sympathetic: increase HR and force of contraction | Parasympathetic (vagus): decrease HR and vasoconstrict coronary arteries
56
What are the roles of sympathetic and parasympathetic afferents from the heart?
Sympathetic: relay pain sensations from the heart | Parasympathetic (vagus): relay BP and chemical information from the heart
57
Where does the vagus nerve arise and where does it leave the skull?
Vagus nerves arise in the medulla and it leaves the skull via the jugular foramina
58
Describe the path of descent of the vagus nerve.
The 2 vagus nerves pass postero-laterally to the common carotid arteries. Right vagus passes posterior to the right lung root Left vagus nerve crosses over anterior to the aortic arch and then posterior to the left lung root Both vagi form a plexus round the oesophagus Separate to form anterior and posterior oesophageal/gastric nerves
59
What are roles of sympathetic and parasympathetic afferents from the oesophageal plexus?
Sympathetic: relays pain sensation from the oesophagus Parasympathetic: senses normal physiological information from the oesophagus
60
Branches of the vagus provide sensory content from…?
Gut and lungs | Branches of the vagus provide NO AUTONOMIC SUPPLY to the body wall.
61
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 have large sensory fibres (enteroceptor) from gut and lungs Unlike sympathetic they provide no autonomic supply to the body wall (eg arterioles and sweat glands)
62
Describe the recurrent laryngeal branch of vagus nerve
Not parasympathetic: runs back up neck to supply most skeletal muscles of larynx
63
Intrinsic nerves of the oesophagus
This plexus of ganglia and axons within the oesophageal wall coordinates its activity. Can be up- or down-regulated by autonomic nerves. Part of the enteric nervous system.