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Phase 1 Cardio > Session 3: The Posterior Mediastinum and the Neck > Flashcards

Session 3: The Posterior Mediastinum and the Neck Flashcards

1
Q

Where does the posterior mediastinum lie?

A

The posterior mediastinum lies behind the heart and pericardium.

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2
Q

What does the posterior mediastinum contain?

A

the:
* descending (thoracic) aorta
* azygos veins
* oesophagus
* thoracic duct
* sympathetic trunk and splanchnic nerves
* posterior intercostal vessels and nerves

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3
Q

What does the descending thoracic aorta divide into?

A

Via posterior mediastinum it gives rise to:
* Posterior intercostal arteries - supply intercostal spaces
* Bronchial arteries - lungs
* Oesophageal branches - oesophagus
* Pericardial branches - pericardium
* Phrenic branches - diaphragm.

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4
Q

Where does the aorta pass through the diaphragm?

A

The aorta passes through the diaphragm at the level of T12.

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5
Q

Where do azygos veins arise from?

A

arises in the abdomen at the level of L1 / L2
traverses the diaphragm to enter the posterior mediastinum

It drains blood from the posterior thoracic wall
returns it to the superior vena cava.

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6
Q

Where is the oesophagus located in the posterior mediastinum?

A

oesophagus lies to the right of the aorta

The oesophagus passes through the oesophageal hiatus in the diaphragm at the level of T10.
- most distal part lies inferior to the diaphragm.

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7
Q

Where is the thoracic duct and how does it work?

A

It lies between the azygos vein and the aorta.

  • It terminates by opening into the venous system at the junction between the left internal jugular vein and the left subclavian vein.
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8
Q

What are the right side of the head and neck and the right upper limb drained by?

A

lymphatic ducts that enter the venous system at the junction of the right internal jugular and right subclavian veins.

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9
Q

Where do the sympathetic trunks lie?

A

on the posterior thoracic wall, either side of the vertebral column and posterior to the parietal pleura.

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10
Q

Through what do sympathetic nerves reach the whole body?

A
  • Preganglionic sympathetic fibres exit the spinal cord in spinal nerves T1 - L2/3.
  • separate from the spinal nerves, enter the sympathetic trunk via a short communicating / connecting branch (white ramus communicans).
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11
Q

What are the abdominopelvic splanchnic nerve composed of?

A
  • Greater splanchnic nerve (from T5-T9)
  • Lesser splanchnic nerve (from T10-11)
  • Least splanchnic nerve (from T12)
  • Lumbar splanchnic nerves (from L1–L2)
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12
Q

Where are abdominopelvic splanchic nerves formed?

A

formed in the posterior mediastinum and traverse the diaphragm to enter the abdomen

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13
Q

What do the posterior intercostal spaces contain?

A

The posterior intercostal space contains:
* intercostal muscles
* a posterior intercostal artery (a branch of the thoracic aorta)
* a posterior intercostal vein (which drains to the azygos system)
* a posterior intercostal nerve

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14
Q

What is the thoracic viscera innervated by?

A

both sympathetic and parasympathetic fibres

  • The cardiopulmonary splanchnic nerves convey postganglionic sympathetic fibres to the thoracic viscera.
  • The vagus nerves convey parasympathetic fibres to the thoracic viscera.
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15
Q

Where do each plexus innervate?

A

The cardiac plexus innervates the sinoatrial node of the heart.

The pulmonary plexus innervates the bronchi.

The oesophageal plexus overlies the anterior surface of the oesophagus.

Visceral afferents relay info along the paths of the vagus and thoracic splanchnic nerves.

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16
Q

What is cardiac referred pain?

A

where pain from one part of the body is felt in another region

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17
Q

What is the heart innervated by?

A

The heart is innervated by the cardiac plexus, composed of sympathetic and parasympathetic fibres.

The sympathetic fibres travel from spinal cord segments T1 -T5 via the cardiopulmonary splanchnic nerves.

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18
Q

What is an aortic dissection?

A

refers to a longitudinal tear in the aortic wall that allows blood to collect between the intima and media.
- presents with sudden onset severe chest and / or back pain
Instead of flowing through the ‘true’ lumen of the aorta, blood collects in the ‘false’ lumen created by the tear.

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19
Q

What is horners syndrome?

A

Horner’s syndrome describes the presentation of three signs together:
- a small pupil (miosis)
- a drooping upper eyelid (ptosis)
- lack of sweating (anhidrosis) on one side of the face.

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20
Q

What causes a hiatus hernia?

A

A hiatus hernia occurs when the abdominal segment of the oesophagus and part of the stomach moves proximally through the oesophageal opening in the diaphragm and into the chest.

Patients may experience symptoms such as heartburn and acid reflux.

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21
Q

What do the seven cervical vertebrae do?

A
  • small and articulate with each other at facet joints that are orientated obliquely
    This allows for a good range of flexion and extension of the cervical spine, in comparison to the thoracic spine.
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22
Q

What is the hyoid bone?

A
  • slender bone situated anteriorly in the upper neck, inferior to the mandible.
  • helps to keep the pharynx open
  • provides an attachment point for several muscles in the neck and of the tongue.
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23
Q

What is the larynx?

A

‘voice box’ composed of a ‘skeleton’ of small cartilages connected by membranes and small joints.
It protects the airway.
Muscles attach to the laryngeal cartilages and move them, in turn moving the vocal cords and allowing phonation.

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23
Q

What is the neck described in terms of?

A

in terms of the anterior and posterior triangles which are separated from each other by the sternocleidomastoid muscle.

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24
Q

Where’s the sternocleidomastoid attached to?

A

Sternocleidomastoid (SCM) is attached to the sternum, clavicle, and the mastoid process (part of the temporal bone).

It can act unilaterally or bilaterally (i.e. both the left and right muscles act together). It is innervated by the accessory nerve (cranial nerve XI).

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25
Q

What are the boundaries of the anterior triangle?

A

The boundaries of the anterior triangle are:
* anteriorly: the midline of neck
* posteriorly: the anterior border of sternocleidomastoid
* superiorly: the lower border of the mandible

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26
Q

What does the anterior triangle contain?

A
  • the trachea and larynx
  • the thyroid gland, parathyroid glands, and the submandibular salivary gland
  • the suprahyoid muscles which connect the hyoid to the skull.
  • the infrahyoid muscles.
  • the common carotid artery and its terminal branches (the external and internal carotid arteries)
  • branches of the external carotid artery to the head and neck
  • the internal jugular vein
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27
Q

What are the boundaries of the posterior triangle?

A

The boundaries of the posterior triangle are:
* anteriorly: the posterior border of sternocleidomastoid
* posteriorly: the anterior border of trapezius
* inferiorly: the clavicle.

28
Q

What is the apex of the triangle formed by?

A

Superiorly, the apex of the triangle is formed by sternocleidomastoid and trapezius.

29
Q

What does the posterior triangle contain?

A
  • muscles that move the head.
  • part of the subclavian artery and the subclavian vein
  • the external jugular vein which drains the scalp and face
  • the accessory nerve (CN XI)
  • the roots of the brachial plexus (spinal nerves that supply the upper limb)
  • the cervical plexus (fibres from C1-4)
  • the phrenic nerve.
30
Q

What do the suprahyoid muscles do?

A
  • lie superior to the hyoid bone and form the floor of the mouth.
  • When they contract, they raise the hyoid bone and larynx during speech and swallowing.
31
Q

Where are the infrahyoid muscles?

A
  • four paired ‘strap’ muscles lie inferior to the hyoid bone just lateral to the anterior midline of the neck.

They draw the hyoid bone and larynx inferiorly during speech and swallowing.

32
Q

What is the thyroid gland composed of?

A

The thyroid gland is composed of right and left lobes deep to the sternothyroid muscle.

The two lobes are joined by the isthmus, which lies anterior to the trachea.

33
Q

What is the thyroid gland supplied by?

A

The thyroid gland has a rich blood supply via the:

  • left and right superior thyroid arteries - branches of the external carotid arteries.
  • left and right inferior thyroid arteries - branches of the thyrocervical trunks (which in turn are branches of the subclavian artery).
34
Q

What are the parathyroid glands?

A
  • usually four parathyroid glands
  • right and left superior and inferior glands - located posterior to the thyroid gland.
35
Q

What are the vessels in the neck?

A

The common carotid arteries ascend in the right and left sides of the neck.

The common carotid arteries bifurcate into external and internal carotid arteries.

36
Q

What does the subclavian artery give rise to?

A

A large branch, the thyrocervical trunk, gives rise to the inferior thyroid artery.

37
Q

What does the facial nerve supply?

A

The facial nerve (CN VII) supplies platysma in the neck.

38
Q

What is a thyroidectomy?

A

Removal of the thyroid gland (e.g. for thyroid cancer)

It risks injury to the recurrent laryngeal nerves, may be cut.

  • results in an inability to move the ipsilateral vocal cord and this affects the quality of the voice.
39
Q

What causes carotid artery stenosis?

A

Atheroma (fatty plaque) in a carotid artery narrows the lumen (stenosis) and impedes blood flow to the brain.

If a plaque breaks up, fragments of the plaque and thrombus will be carried up into the cerebral arteries, causing a stroke which could be fatal or severely debilitating.

40
Q

When is a central line insertion into the internal jugular vein needed?

A

In patients who are very unwell and need fluid and drugs intravenously, a large line with multiple ports can be placed into a large central vein.

The IJV is the vein of choice, as it is relatively easy to access and can be easily visualised with ultrasound.

41
Q

What course does the azygos veins take?

A
  • lie on the bodies of the thoracic vertebrae.
  • an azygos vein on the right side of the vertebral bodies
  • a smaller (shorter) hemiazygos vein on the left side of the vertebral bodies
  • one or more veins connecting the above veins to each other.

The azygos system receives blood from the posterior intercostal veins, oesophageal veins, and bronchial veins.

42
Q

What is the supply of the oesophagus?

A

It is supplied by oesophageal arteries from the descending aorta. Oesophageal veins return venous blood to the azygos system.

The smooth muscle in the wall of the oesophagus is under autonomic control.

43
Q

What are ganglia in the sympathetic trunk referred to?

A

‘paravertebral ganglia’ as they lie alongside the vertebral column.

44
Q

Where does lymph from lower limbs go?

A
  • Lymph from the lower limbs, pelvis and abdomen flows towards the cisterna chyli, a sac-like swelling that gives rise to the thoracic duct, which ascends into the thorax.
45
Q

Where does the thoracic duct receive lymph from?

A
  • In the thorax, the duct receives lymph from the intercostal spaces and lymph nodes.
  • The duct ascends into the neck, receiving lymph from the left side of the head and neck and the left upper limb.
46
Q

What do sympathetic and parasympathetic fibres form?

A

form autonomic plexuses around the thoracic viscera

Plexus - describes networks of veins and arteries.

47
Q

What plexus’ are in the thorax?

A

The autonomic nerve plexuses look like delicate, fine meshes or webs. In the thorax we find the:
* cardiac plexus
* pulmonary plexus
* oesophageal plexus

48
Q

How does the oesophageal plexus affect function?

A

Sympathetic fibres inhibit peristalsis and parasympathetic fibres stimulate peristalsis.

49
Q

Where do visceral sensory nerves enter the spinal cord?

A
  • the visceral sensory information enters spinal cord segments T1 - T5.
  • However, somatic sensory information from the skin of the chest wall, neck and arm also returns to spinal cord segments T1 - T5.
  • Therefore painful visceral sensory information from the heart and somatic sensory information from the chest wall both enter spinal cord segments T1 - T5.
50
Q

How does the brain interpret cardiac pain?

A

For reasons that are not fully understood, the brain interprets the cardiac pain as coming from the chest, neck, and arm.

51
Q

What is horners syndrome caused by?

A

It is caused by an interruption to the sympathetic nerves that innervate the head.

A cancer in the apex of the lung that invades the sympathetic chain can cause Horner’s syndrome on the ipsilateral side of the head.

52
Q

What is platysma?

A

Platysma is a very thin subcutaneous muscle deep to the skin of the neck.

53
Q

What is the supra-hyoid muscle like?

A

Suprahyoid muscle They form the floor of the mouth and move the hyoid and larynx in speech and swallowing.

54
Q

What is the infra-hyoid muscle like?

A

Infrahyoid muscle Also called the ‘strap’ muscles, they connect the hyoid to the sternum and scapula. They move the hyoid and larynx in speech and swallowing.

55
Q

What nerves does the anterior triangle contain?

A
  • branches of the facial nerve (CN VII), the glossopharyngeal nerve (CN IX), the vagus nerve (CN X), the accessory nerve (CN XI) and the hypoglossal nerve (CN XII).
  • the ansa cervicalis (fibres from C1-C3 which innervate the infrahyoid muscles).
56
Q

What are the suprahyoid muscles called?

A

Four paired muscles:
mylohyoid, geniohyoid, stylohyoid and digastric

57
Q

What are the infra-hyoid muscles?

A
  • Sternohyoid and omohyoid lie superficially
  • Sternothyroid and thyrohyoid lie deep
58
Q

Where can the internal carotid be palpated?

A

The pulsation of the internal carotid can be palpated immediately lateral to the larynx.

59
Q

What do the carotid arteries give rise to?

A
  • The internal carotid artery does not give rise to any branches in the neck. It enters the cranium and supplies the brain.
  • The external carotid artery gives rise to several branches that supply the head and neck, including the pharynx, scalp, thyroid gland, tongue, and the face.
60
Q

What occurs at the carotid sinus?

A
  • At the point of bifurcation of the common carotid artery there is a small swelling - the carotid sinus.

Baroreceptors here constantly monitor arterial blood pressure. This visceral sensory information is relayed back to the CNS via the glossopharyngeal nerve and results in reflex responses that regulate the blood pressure.

61
Q

What happens to the internal and external jugular veins?

A

The internal jugular vein:

  • It unites with the subclavian vein, which returns blood from the upper limb, to form the brachiocephalic vein.
  • The right and left brachiocephalic veins unite to form the superior vena cava.

The external jugular vein drains blood from the scalp and face. It joins the subclavian vein.

62
Q

What do the glossopharyngeal and vagus nerve supply?

A

The glossopharyngeal nerve (CN IX) supplies the:
* pharynx (sensory innervation)
* carotid sinus (visceral sensory fibres that return to the CNS via CN IX)

  • The vagus nerve (CN X) is vital for normal speech and swallowing. It supplies:
  • the muscles of the pharynx (motor innervation)
  • the larynx (motor and sensory innervation)
63
Q

What forms the carotid sheath?

A

In the neck, the vagus nerve runs between the internal jugular vein and the internal carotid artery (above its bifurcation) and between the internal jugular vein and common carotid artery (below its bifurcation). The three structures run together in a fascial sleeve called the carotid sheath.

64
Q

What does the accessory and hypoglossal nerve supply?

A
  • The accessory nerve (CN XI) supplies the sternocleidomastoid and trapezius muscles.
  • The hypoglossal nerve (CN XII) is motor to the muscles of the tongue. It does not supply any structures in the neck but travels through it. It lies lateral to the internal carotid artery and deep to the external jugular vein.
65
Q

What is the sympathetic innervation of the head and neck?

A

The sympathetic trunk extends as far as the base of the skull.

The associated sympathetic ganglia in the neck are the superior, middle, and inferior cervical ganglia. Postganglionic fibres from these ganglia innervate the head and neck.

66
Q

What is another risk of thyroidectomy?

A

parathyroid glands may be removed
disturbs calcium homeostasis.
After thyroidectomy, must take hormone replacements.

67
Q

How do you prevent carotid artery stenosis?

A

atheroma can be surgically removed from the wall of the carotid artery in carotid endarterectomy.

carries a risk of severe bleeding from the carotid artery and stroke.

68
Q

Where does the sympathetic trunk extend to?

A

The trunks extend from the skull base to the coccyx.

Phase 1 Cardio (9 decks)

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