Thorax 4 Flashcards by kanetta kirubakaran

what is the course of the aorta?

begins as the ascending aorta within the pericardial sac

continues as the arch of the aorta (at T4/T5, sternal angle) - descends as the thoracic aorta

passes down posterior mediastinum, through the aortic hiatus (T12) - become the abdominal aorta

(ascending aorta in pericardial sac > arch of aorta (T4/5) > thoracic aorta > through diaphragm aortic hiatus (T12) > abdominal aorta)

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at what vertebral level does the arch of aorta lie?

T4/5

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where does the arch of the aorta lie?

beneath the manubrium of the sternum, in front of the trachea

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what are the three main branches of the aortic arch?

brachiocephalic trunk - gives right common carotid & right subclavian
left common carotid artery
left subclavian artery

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what structures pass through the aortic hiatus?

aorta
thoracic duct
azygos vein

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what is the medial arcuate ligament?

a ligament at T12 where the right and left crura of the diaphragm join to form the anterior part of the aortic hiatus

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what clinical condition is associated with the median arcuate ligament?

MALS - compression of the coeliac trunk due to an abnormally tight ligament or a low-origin coeliac trunk

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symptoms of MALS?

abdominal pain
unintentional weight loss
abdominal bruit (blood turbulence in coeliac trunk)

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treatment of MALS?

surgical decompression of coeliac trunk

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at what vertebral level does the coeliac trunk come off the abdominal aorta?

T12

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what forms the brachiocephalic veins?

union of the subclavian and internal jugular veins behind the sternoclavicular joints

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what veins drain into the superior vena cava ?

right and left brachiocephalic veins unite to form the SVC

azygos vein drains into SVC at T4

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origin and course of the IVC?

origin: right & left common iliac arteries unite at L5

course: ascends to right of aorta, passes through the diaphragm at T8, and drains into the right atrium

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what two veins unite to form the brachiocephalic veins?

(R/L) internal jugular & subclavian veins

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what veins unite to form the SVC?

right and left brachiocephalic veins

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what veins form the IVC? at what vertebral level?

right and left common iliac veins at L5

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The inferior vena cava passes through the diaphragm at which level?
A) T8
B) T10
C) T12
D) L1

A) T8

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The aortic arch gives off three major branches. Which of the following is NOT one of them?
A) Left subclavian artery
B) Right subclavian artery
C) Left common carotid artery
D) Brachiocephalic trunk

B) Right subclavian artery

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Which vein serves as a backup drainage route if the inferior vena cava is obstructed?
A) Hemiazygos vein
B) Azygos vein
C) Brachiocephalic vein
D) Internal jugular vein

B) Azygos vein (provides an alternate route to the SVC if the IVC is blocked)

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what is the main function of the azygos vein?

main vein of the posterior thorax- drains venous blood from thoracic wall into SVC

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what two veins form the azygos vein?

right subcostal vein (below the 12th rib)
right ascending lumbar vein

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course of the azygos vein?

on the right side of the posterior mediastinum - arches over right lung root at T4 - drains into SVC

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what are the 3 main tributaries of the azygos vein? (LHR)

lower 8 right posterior intercostal veins (from ribs 5-12)
hemiazygos & accessory hemiazygos veins (cross from the left side)
right superior intercostal vein (from 2nd & 3rd posterior intercostal veins)

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where does the 1st right posterior intercostal vein drain?

drains directly into the right brachiocephalic vein, not the azygos vein

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how is the hemiazygos vein formed?

left subcostal vein + left ascending lumbar vein

course of hemiazygos vein?

formed by left subcostal & left ascending lumbar veins ascends on left posterior mediastinum - crosses to right side at T8 and drains into azygos

what are the tributaries of the hemiazygos vein?

lowest 4-5 left posterior intercostal veins (ribs 8-12)

how is the accessory hemiazygos vein formed?

2nd & 3rd left posterior intercostal veins - form the left superior intercostal vein - drains into accessory hemiazygos vein

at what vertebral level does the accessory hemiazygos drain into the azygos vein?

T7/8

where does the 1st left posterior intercostal vein drain?

directly into the left brachiocephalic vein

what is the thoracic duct?

largest lymphatic vessel - drains three-quarters of body’s lymph into the left venous angle, goes into venous system

from which quadrant does the thoracic duct not drain lymph from? what structure drains it instead?

right upper quadrant - drained by right lymphatic duct

where does the thoracic duct originate?

cisterna chyli (at L1/2) in the abdomen

what is the course of the thoracic duct?

ascends through the aortic hiatus (T12) - passes between the aorta & azygos vein crosses to the left at T4/T5 - drains into the left venous angle (junction of left subclavian & internal jugular veins)

in what division of the mediastinum is the thymus located?

superior mediastinum (immediately behind the sternum manubrium)

function of the thymus?

primary lymphoid organ responsible for T-cell maturation - produces & matures T-lymphocytes for immune response

why does the thymus shrink after puberty?

fewer new T-cells are needed; existing T-cells develop immunological memory

what is the clinical significance of thymomas?

thymomas (tumours of the thymus) - cause SVC syndrome (venous obstruction) leads to facial & upper limb swelling

A patient has an obstructed inferior vena cava (IVC). Which vein provides an alternative route for venous return? A) Hemiazygos vein B) Azygos vein C) Superior vena cava D) Internal jugular vein

B) Azygos vein

At which vertebral level does the azygos vein arch over the right lung root and drain into the SVC? A) T2 B) T4 C) T8 D) T10

B: T4

The azygos vein arches over which structure before draining into the SVC? A) Left lung root B) Right lung root C) Trachea D) Oesophagus

B: right lung root

The hemiazygos vein crosses over to the right side at which vertebral level? A) T4 B) T6 C) T8 D) T10

C: T8

The thoracic duct empties into which structure? A) Right brachiocephalic vein B) Left brachiocephalic vein C) Right venous angle D) Left venous angle

D) Left venous angle (junction of left subclavian & internal jugular veins)

What structure passes through the diaphragm at T12 along with the aorta? A) Thoracic duct B) Inferior vena cava C) Esophagus D) Phrenic nerve

A: thoracic duct

Which of the following is NOT a tributary of the azygos vein? A) Right posterior intercostal veins (5-12) B) Left superior intercostal vein C) Hemiazygos vein D) Accessory hemiazygos vein

B) Left superior intercostal vein - drains into the left brachiocephalic vein, not the azygos

The first posterior intercostal vein on the right drains into which vein? A) Azygos vein B) Right brachiocephalic vein C) Superior vena cava D) Internal jugular vein

B) Right brachiocephalic vein

A patient presents with facial swelling, dilated neck veins, and difficulty breathing. A CT scan shows a mass in the superior mediastinum compressing the SVC. What is the most likely diagnosis? A) Aortic aneurysm B) Thymoma C) Oesophageal tumour D) Pericardial effusion

B) Thymoma - can cause SVC syndrome by compressing the SVC

The thoracic duct passes through the diaphragm at which level? A) T8 B) T10 C) T12 D) L1

C) T12

at what vertebral level does the thoracic duct originate? A) T12/L1 B) T11/T12 C) L1/2 D) L2/3

C: L1/2

what are the three main functions of the lymphatic system?

1. immune defence 2. fluid balance 3. absorption of dietary fats

how does the lymphatic system contribute to immune defence?

produces lymphocytes (e.g., T-cells in the thymus, B-cells in the spleen)

how does the lymphatic system regulate fluid balance?

removes excess interstitial fluid and returns it to the bloodstream, maintaining blood volume & homeostasis

how does the lymphatic system assist in fat absorption?

lacteals in the small intestine absorb dietary lipids into the lymph

how is lymph formed?

plasma exits capillary beds - some enters interstitial space excess interstitial fluid enters lymphatic capillaries, forming lymph

how does lymph move without a pump?

skeletal muscle contractions arterial pulses one-way valves

where does lung lymph drain?

tracheobronchial LNs

what is the path of thoracic lymph drainage?

lymphatic vessels - bronchomediastinal lymph trunks - thoracic duct / right lymphatic duct (upper right quadrant)

Which of the following is NOT a function of the lymphatic system? A) Absorption of dietary lipids B) Oxygen transport C) Immune surveillance D) Removal of excess interstitial fluid

B) Oxygen transport

How does lymph move through the body? A) The heart pumps it B) It moves partly by skeletal muscle contractions C) It diffuses passively D) It is actively transported by lymph nodes

B) It moves partly by skeletal muscle contractions (+ arterial pulses and one-way valves)

Which of the following is the largest lymphatic vessel? A) Right lymphatic duct B) Cisterna chyli C) Thoracic duct D) Lymphatic capillaries

C) Thoracic duct

Where does the thoracic duct empty? A) Cisterna chyli B) Left venous angle C) Superior vena cava D) Right bronchomediastinal trunk

B) Left venous angle (junction of left subclavian & internal jugular veins)

What structure marks the origin of the thoracic duct? A) Right lymphatic duct B) Bronchomediastinal trunk C) Cisterna chyli D) Thoracic inlet

C) Cisterna chyli

A tumour in the posterior mediastinum compressing the thoracic duct would most likely cause lymphatic congestion in which areas? A) Right arm and right thorax B) Right leg and left arm C) Left arm, left thorax, abdomen, and both lower limbs D) Only the left thorax

C) Left arm, left thorax, abdomen, and both lower limbs

what is the enteric nervous system (ENS)?

a network of neurons controlling GI tract function, influenced by sympathetic & parasympathetic divisions

how does the sympathetic NS affect digestion?

inhibits digestion (redirects energy to muscles)

what is the role of the sympathetic NS in respiration?

dilates bronchi (more oxygen intake)

what are ganglia?

clusters of neuronal cell bodies where synapses occur

what are the two types of sympathetic ganglia?

1. paravertebral ganglia - in the sympathetic chain, near the vertebral column 2. prevertebral ganglia - in front of the vertebral column, near the abdominal aorta

where do preganglionic sympathetic neurons originate from?

lateral horn of the spinal cord (T1-L2) – thoracolumbar outflow

differentiate the two types of sympathetic neurons - pre- and post-ganglionic

pre-ganglionic: short, myelinated fibres that synapse in ganglia post-ganglionic: long, unmyelinated fibres that travel to organs

what are the synapsing options for preganglionic sympathetic fibres? (3)

1. synapse in the paravertebral ganglia (same or different spinal level) 2. pass through without synapsing (travel to prevertebral ganglia) 3. ascend/descend the sympathetic chain before synapsing

what neurotransmitters do sympathetic neurons release?

noradrenaline at effector organs

what are splanchnic nerves?

autonomic nerves carrying sympathetic fibres to abdominal & pelvic viscera

where do thoracic splanchnic nerves originate from?

T5-T12 sympathetic ganglia

what are the three main thoracic splanchnic nerves? their synapsing ganglions & their targets?

1. greater splanchnic nerve (T5-T9) - SYNAPSE AT coeliac ganglion = SUPPLY foregut 2. lesser splanchnic nerve (T10-T11) - superior mesenteric ganglion = midgut 3. least splanchnic nerve (T12) - aortico-renal ganglion = kidneys & adrenal glands

where do fibres of the greater splanchnic nerve (T5-9) synapse?

at the coeliac ganglion

where do fibres of the lesser splanchnic nerve (T10-11) synapse?

at the superior mesenteric ganglion

where do fibres of the least splanchnic nerve (T12) synapse?

at the aorticorenal ganglion

Which nerve carries sympathetic fibers to the foregut? A) Lesser splanchnic nerve B) Greater splanchnic nerve C) Least splanchnic nerve D) Pelvic splanchnic nerve

B) Greater splanchnic nerve

where do preganglionic sympathetic fibres originate of the thoracolumbar outflow? A) Brainstem B) Lateral horn of T1-L2 spinal cord C) Dorsal root ganglia D) T5-T12 spinal cord

B) Lateral horn of T1-L2 spinal cord

Where do thoracic splanchnic nerves synapse? A) Sympathetic chain ganglia B) Prevertebral ganglia C) Dorsal root ganglia D) Parasympathetic ganglia

B) Prevertebral ganglia

The lesser splanchnic nerve (T10-T11) synapses in which ganglion? A) Coeliac ganglion B) Superior mesenteric ganglion C) Inferior mesenteric ganglion D) Aorticorenal ganglion

B) Superior mesenteric ganglion

Which structure marks the origin of the sympathetic outflow? A) Craniosacral region B) Thoracolumbar region (T1-L2) C) Brainstem nuclei D) Sacral spinal cord

B) Thoracolumbar region (T1-L2)

What is the function of the least splanchnic nerve (T12)? A) Foregut innervation B) Midgut innervation C) Innervates kidneys & adrenal glands D) Hindgut innervation

C) Innervates kidneys & adrenal glands

Vertebral origins of the greater splanchnic nerves? A) T5-7 B) T10-11 C) T5-8 D) T5-9

D) T5-9