Posterior Mediastinum And Neck

Question 1

What does the posterior mediastinum contain

Answer 1

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

Question 2

Branches of the descending aorta

Answer 2

• Posterior intercostal arteries which supply the intercostal space
• Bronchial arteries which supply the lungs
• Oesophageal branches which supply the oesophagus
• Pericardial branches which supply the pericardium
• Phrenic branches which supply the diaphragm

Question 3

What level of vertebrae does the descending aorta pass the diaphragm through

Answer 3

T12

Question 4

What does the posterior intercostal arteries supply

Answer 4

Intercostal space

Question 5

What does the bronchial arteries supply

Answer 5

Lungs

Question 6

What does the phrenic arteries supply

Answer 6

Diaphragm

Question 7

Azygos veins

Answer 7

arises in abdomen at level of L1/L2 and transverses the diaphragm to enter posterior mediastinum
• Drains blood from posterior thoracic wall and return it to superior vena cava
• Lie on the bodies of the thoracic vertebrae

Question 8

What drains into the azygos veins

Answer 8

receives blood from the posterior intercostal veins, oesophageal veins and bronchial veins

Question 9

Azygos veins system

Answer 9

1. An azygos vein on the right side of the vertebral bodies
2. A smaller (shorter) hemiazygos vein on the left side of the vertebral bodies
3. One or more veins connecting the veins to each other

Question 10

Oesophagus

Answer 10

lies to right of aorta
• Supplied by oesophageal arteries from descending aorta
• Oesophageal veins return venous blood to azygos system
• Smooth muscle wall is under autonomic control

Question 11

oesophageal hiatus in the diaphragm at level of…

Answer 11

T10

Question 12

Thoracic duct

Answer 12

returns most of body’s lymph to venous system
• Lies between azygos vein and aorta
• Lymph from lower limbs, pelvis and abdomen flow towards the cisterns chylomicrons ( a sac-like swelling that gives rise to the thoracic duct) which ascends into the thorax
• In the thorax- duct receives lymph from intercostal spaces and lymph nodes
• Duct ascends into neck- receives lymph from left side of head, neck and left upper limb
• Terminates by opening into the venous system at junction between left internal jugular vein and left subclavian vein
• Right side of head , neck and right upper limb are drained by lymphatic ducts that enter the venous system at junction between the right internal jugular and right subclavian veins

Question 13

What do the posterior intercostal spaces contain

Answer 13

• 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

Question 14

Sympathetic trunk

Answer 14

trunks lie on posterior thoracic wall, either side of the vertebral column and posterior to parietal pleura
• Thin, longitudinal fibre tracts interspersed with ganglia (paravertebral ganglia)
• Trunk extends from skull base to coccyx

Question 15

Facial nerve (CN VII)

Answer 15

supplies platysma in neck

Question 16

glossopharyngeal nerve (CN IX)

Answer 16

pharynx (sensory innervation)
• carotid sinus (visceral sensory fibres that return to the CNS via CN IX)

Contains:
•Somatic sensory fibres > sensation in the pharynx and posterior 1/3 of the tongue
•Special sense fibres > taste posterior 1/3 of the tongue

•Vital for swallowing

Question 17

Vagus nerve (CN X)

Answer 17

vital for normal speech and swallowing
• the muscles of the pharynx (motor innervation)
• the larynx (motor and sensory innervation)
• 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.

Parasympathetic fibres > thoracic and abdominal viscera
•Visceral sensory fibres > internal monitoring and physiological reflexes

Question 18

Accessory nerve (CN XI)

Answer 18

sternocleidomastoid and trapezius muscles.
Somatic motor fibres only

Question 19

hypoglossal nerve (CN XII)

Answer 19

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.

Question 20

Phrenic nerves

Answer 20

formed by C3, C4 and C5 nerve fibres.
• It descends through the neck to enter the thorax.
• It innervates the left and right ipsilateral diaphragm (and the pericardium)

Question 21

Sympathetic fibres

Answer 21

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.

Question 22

External jugular vein

Answer 22

drains blood from scalp and face
• Joins subclavian vein

Question 23

Internal jugular vein

Answer 23

major vein in the neck, which drains blood from the brain and part of the face. (dural venous sinuses in cranium)
• 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.
Descends in neck with carotid artery and vagus nerve

Question 24

Subclavian artery

Answer 24

gives rise to several vessels.
• A large branch, the thyrocervical trunk, gives rise to the inferior thyroid artery.
• The subclavian artery supplies the upper limb.

Question 25

Common carotid arteries:

Answer 25

ascend in the right and left sides of the neck, respectively. • The pulsation of the internal carotid can be palpated immediately lateral to the larynx. • The common carotid arteries bifurcate into external and internal carotid arteries. • 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. • 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.

Question 26

internal carotid artery

Answer 26

does not give rise to any branches in the neck. It enters the cranium and supplies the brain.

Question 27

external carotid artery

Answer 27

gives rise to several branches that supply the head and neck, including the pharynx, scalp, thyroid gland, tongue, and the face.

Question 28

carotid sinus.

Answer 28

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.

Question 29

Cervical vertebra

Answer 29

7 cervical vertebrae- small and articulate with each other at facet joints orientated obliquely (allows for good range of flexion and extension in cervical spine compared to thoracic spine)

Question 30

Hyoid bone

Answer 30

slender u-shaped bone situated anteriorly in upper neck, inferior to mandible. Helps keep pharynx open and provides an attachment point for several muscles in the neck and tongue

Question 31

Larynx

Answer 31

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 Vocal ligaments within thyroid cartilage

Question 32

Suprahyoid muscle

Answer 32

4 paired muscles lie superior to hyoid bone and form floor of mouth • When contract, raise hyoid bone and larynx during speech and swallowing • mylohyoid, geniohyoid, stylohyoid and digastric

Question 33

Infrahyoid muscles

Answer 33

4 paired ‘strap’ muscles lie inferior to hyoid bone, lateral to anterior midline of neck • Draw hyoid bone and larynx inferiorly during speech and swallowing • Sternohyoid and omohyoid lie superficially; they attach the hyoid to the sternum and scapula, respectively. • Sternothyroid and thyrohyoid lie deep; they attach the sternum to the thyroid cartilage and the thyroid cartilage to the hyoid, respectively.

Question 34

Thyroid gland

Answer 34

composed of left and right lobes that lie lateral to lower larynx and upper trachea • Each lobe lies deep to sternothyroid muscle • 2 lobes joined by the isthmus, which lies anterior to trachea • Produces hormones- pituitary gland regulates its secretion • Blood supply from: left and right superior thyroid arteries (branches of external carotid arteries) and left and right inferior thyroid arteries (branches of thyrocervical trunks) • Some people have additional thyroid ima artery • Superior, middle and inferior thyroid veins drain the thyroid gland

Question 35

Isthmus

Answer 35

Joins 2 lobes of thyroid gland

Question 36

Blood supply to thyroid gland

Answer 36

left and right superior thyroid arteries (branches of external carotid arteries) and left and right inferior thyroid arteries (branches of thyrocervical trunks) • Some people have additional thyroid ima artery • Superior, middle and inferior thyroid veins drain the thyroid gland

Question 37

Parathyroid glands

Answer 37

usually 4 (right and left superior and inferior glands) located posterior to the thyroid gland • produce parathyroid hormone which plays a role in calcium regulation. • are typically supplied by the inferior thyroid arteries.

Question 38

What does the neck contain

Answer 38

• structures of the respiratory tract - the pharynx, larynx, and trachea • structures of the gastrointestinal tract - the pharynx and oesophagus • glands - the thyroid and parathyroid glands • arteries and veins that serve the neck and head, including the brain • nerves that serve the head and neck, upper limbs, thoraco-abdominal viscera (via the vagus nerves) and the diaphragm (via the phenic nerves) • several groups of muscles. These include muscles that move the head and neck, move the larynx in speech and swallowing and that form the floor of the mouth. Platysma is a very thin subcutaneous muscle deep to the skin of the neck.

Question 39

Platsyma

Answer 39

very thin subcutaneous muscle deep to the skin of the neck.

Question 40

Triangles of the neck

Answer 40

neck described in terms of anterior and posterior triangles separated by sternocleidomastoid muscle • 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).

Question 41

Anterior triangle boundaries

Answer 41

anteriorly (midline of neck), posteriorly (anterior border of sternocleidomastoid), superiorly (lower border of mandible)

Question 42

What does the anterior triangle contain

Answer 42

• the trachea and larynx • the thyroid gland, parathyroid glands, and the submandibular salivary gland • the suprahyoid muscles which connect the hyoid to the skull- form the floor of the mouth and move the hyoid and larynx in speech and swallowing. • the infrahyoid muscles (‘strap’ muscles)- they connect the hyoid to the sternum and scapula. They move the hyoid and larynx in speech and swallowing. • 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 • 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).

Question 43

Ansa cervicalis

Answer 43

fibres from C1-C3 which innervate the infrahyoid muscles

Question 44

Posterior triangle boundaries

Answer 44

anteriorly (posterior border of sternocleidomastoid), posteriorly (anterior border of trapezius), inferiorly (clavicle), superiorly (apex formed by sternocleidomastoid and trapezius)

Question 45

What does the posterior triangle contain

Answer 45

• 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.

Question 46

Pulmonary plexus

Answer 46

innervates bronchi. Sympathetic relaxes bronchi, parasympathetic constricts them

Question 47

Oesophageal plexus

Answer 47

overlies anterior surface of oesophagus. Sympathetic inhibit peristalsis, parasympathetic stimulate peristalsis

Question 48

Visceral afferents

Answer 48

relay sensory information from viscera back to CNS along paths of vagus and splanchnic nerves

Question 49

Cardiac plexus

Answer 49

innervates SAN. Sympathetic fibres increase heart rate and force of contraction, parasympathetic decrease heart rate and force of contraction

Question 50

Innervation of the thoracic viscera:

Answer 50

cardiopulmonary splanchnic nerves convey postganglionic sympathetic fibres to the thoracic viscera • Vagus nerves convey parasympathetic fibres to the thoracic viscera • Form autonomic plexuses (fine meshes) around the viscera: cardiac plexus, pulmonary plexus, oesophageal plexus

Question 51

Cardiac referred pain:

Answer 51

Cardiac pain is typically felt in the central chest, left side of the neck and left arm- referred pain (felt in another region of the body) • heart is innervated by the cardiac plexus, composed of sympathetic and parasympathetic fibres. The sympathetic fibres travel to the cardiac plexus and heart from spinal cord segments T1 -T5 via the cardiopulmonary splanchnic nerves. • The heart is also innervated by visceral sensory nerves, which convey sensory information from the heart back to the CNS - this sensation normally does not reach our conscious perception. However, if the myocardium is ischaemic this sensation does reach our conscious perception, and is interpreted as pain, tightness, crushing pressure or burning, which may be severe. • Because the visceral sensory nerves travel back to the CNS alongside the sympathetic fibres that innervate the heart, 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. For reasons that are not fully understood, the brain interprets the cardiac pain as coming from the chest, neck, and arm.

Question 52

referred pain is shoulder pain resulting from pathology of the diaphragm.

Answer 52

Cervical spinal cord segments 3-5 contribute spinal nerve fibres to the phrenic nerve. Cord segments C3-5 also contribute to the nerves that innervate the skin of the neck and shoulder. The brain interprets pain coming from the diaphragm as coming from the shoulder region.

Question 53

Pathway of sympathetic trunk

Answer 53

• Cell bodies of preganglionic sympathetic neurons lie in thoracic and upper lumbar spinal cord segments (T1-L2/3) • Are visceral motor fibres that leave the pineal cord from its ventral aspect and enter spinal nerves T1-L2/3 along with somatic motor nerves (cell bodies lie in ventral grey horn) • sympathetic trunk allows the sympathetic fibres arising from T1 - L2/3 to be distributed to all parts of the body • Preganglionic sympathetic fibres exit the spinal cord in spinal nerves T1 - L2/3. • Almost immediately, they separate from the spinal nerves and enter the sympathetic trunk via a short communicating / connecting branch (white ramus communicans).

Question 54

3 things that preganglionic axon does in sympathetic trunk

Answer 54

1. synapses in the ganglion at its level of entry 2. ascends or descends in the trunk before synapsing in a ganglion 3. travels through a ganglion (and the trunk) without synapsing

Question 55

If the preganglionic axon 1. synapses in the ganglion at its level of entry 2. ascends or descends in the trunk before synapsing in a ganglion

Answer 55

In scenarios 1 and 2, the postganglionic axons leaving the ganglia: 1. enter spinal nerves via a communicating branch (grey ramus communicans). Through this arrangement, sympathetic fibres enter all 31 pairs of spinal nerves 2. form visceral nerves that convey sympathetic fibres to the head 3. form visceral nerves that convey sympathetic fibres to the thoracic viscera (cardiopulmonary splanchnic nerves).

Question 56

If the preganglionic axon 3. travels through a ganglion (and the trunk) without synapsing

Answer 56

• In scenario 3, the sympathetic preganglionic axons travel through the sympathetic trunk without synapsing. These fibres exit the trunk and form the abdominopelvic splanchnic nerves: • Greater splanchnic nerve (sympathetic preganglionic fibres originating from T5-T9 segments of the spinal cord) • Lesser splanchnic nerve (from T10-11) • Least splanchnic nerve (from T12) • Lumbar splanchnic nerves (from L1–L2)

Question 57

greater, lesser, and least splanchnic nerves

Answer 57

formed in the posterior mediastinum and traverse the diaphragm to enter the abdomen. • The preganglionic sympathetic fibres in these splanchnic nerves do ultimately synapse with second neurons in prevertebral ganglia that lie close to major blood vessels in the abdomen. • After synapsing, the postganglionic fibres innervate abdominal viscera

Question 58

cisterns chylomicrons/ cisterna chyli

Answer 58

Lymph from lower limbs, pelvis and abdomen flow towards the cisterns chylomicrons ( a sac-like swelling that gives rise to the thoracic duct) which ascends into the thorax

Question 59

Greater splanchnic nerve

Answer 59

sympathetic preganglionic fibres originating from T5-T9 segments of the spinal cord Supplies: stomach, first half of duodenum, liver, gallbladder and pancreas

Question 60

Lesser splanchnic nerve

Answer 60

from T10-11 Supplies: second half of duodenum, small intestine, large intestine up to 2/3 along transverse colon

Question 61

Least splanchnic nerve

Answer 61

from T12 Supplies first half of rectum and rest of large intestine

Question 62

Lumbar splanchnic nerves

Answer 62

from L1–L2

Question 63

4 suprahyoid muscles

Answer 63

mylohyoid, geniohyoid, stylohyoid and digastric

Question 64

4 infrahyoid strap muscles

Answer 64

Sternohyoid and omohyoid Sternothyroid and thyrohyoid

Question 65

Transverse foramina

Answer 65

Transmit and protect the vertebral arteries-> brain

Question 66

Which cervical vertebra are structurally different

Answer 66

C1 and C2 to be able to turn neck

Question 67

Cervical vertebral foramen

Answer 67

Triangle-shaped and relatively large compared to size of vertebrae- allows extra room for cervical spinal cord

Question 68

Oblique joints between C spine

Answer 68

Good range of movement: flexion, extension, lateral flexion But more likely to get injuries

Question 69

Which 2 laryngeal cartilages are palpable in the anterior midline of the neck

Answer 69

Thyroid and cricoid

Question 70

Epiglottis

Answer 70

Cartilage that Closes of larynx when swallowing

Question 71

Cranial nerves

Answer 71

Attached to the brain or brainstem 12 pairs (left and right) Contains combinations of somatic motor, somatic sensory, special sensory and parasympathetic fibres CNs IX, X, XI and XII found in neck

Question 72

Pharynx

Answer 72

Muscular tube •Part of the respiratory and GI systems •Three parts > nasopharynx, oropharynx, laryngopharynx Formed by constrictor muscles •Swallowed fluid and food prevented from entering the larynx by the epiglottis > diverted into the oesophagus instead

Question 73

3 parts of pharynx

Answer 73

nasopharynx, oropharynx, laryngopharynx

Question 74

Branches of external carotid artery

Answer 74

Maxillary artery Facial artery Lingual artery Occipital artery Superficial temporal artery Posterior auricular artery

Question 75

Extrinsic laryngeal muscles

Answer 75

Move the larynx as a whole ‘unit’ with speech and swallowing •Suprahyoid and infrahyoid muscles

Question 76

Intrinsic laryngeal muscles

Answer 76

Move the individual cartilages and the vocal cords •Innervated by the vagus nerve (most via the recurrent laryngeal branch)

Question 77

Lymphatics of neck

Answer 77

Superficial and deep nodes •Superficial nodes along the path of the external jugular vein •Deep nodes along the internal jugular vein – ultimately receive all lymph from the head and neck •Can become enlarged in local and systemic disease •Examined and can be biopsied

Question 78

Major nerves in neck

Answer 78

phrenics and CNs IX, X, XI and XII.

Question 79

Where do Recurrent laryngeal nerves lie

Answer 79

lie close to the thyroid gland and are potentially at risk in thyroid surgery.

Question 80

carotid sheath

Answer 80

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

Question 81

Why is there no parasympathetic trunk

Answer 81

Nerves arise from vagus nerve and sacrum

Question 82

Nucleus

Answer 82

Cell bodies inside CNS

Question 83

How many neurones per sympathetic pathway

Answer 83

2

Question 84

Sections of spinal cord

Answer 84

Cervical Thoracic Lumbar Sacral Coccygeal

Question 85

Plexus

Answer 85

Fibres converge

Question 86

White ramus communicans

Answer 86

Connecting branch To ganglion

Question 87

Grey ramus communicans

Answer 87

Fibres away from ganglion

Question 88

Transverse foramina

Answer 88

Protects vertebral artery which supplies the brain

Question 89

Goiter

Answer 89

Enlarged thyroid

Question 90

Which blood vessels are protected by the transverse foramina? What do these blood vessels supply?

Answer 90

Vertebral arteries- supply brain (posteriorly) and spinal cord

Question 91

Why is the hyoid bone unique

Answer 91

Only bone that doesn’t articulate with any other bones

Question 92

Scalene muscles

Answer 92

three paired muscles (anterior, middle and posterior), located in the lateral aspect of the neck. Collectively, they form part of the floor of the posterior triangle of the neck. The scalenes act as accessory muscles of respiration and perform flexion at the neck.

Question 93

The infrahyoid ('strap') muscles depress which TWO structures during speech and swallowing?

Answer 93

Hyoid bone Larynx

Question 94

Sympathetic fibres that travel to the cardiac plexus originate from which segments of the spinal cord?

Answer 94

T1-T5

Question 95

Sympathetic fibres that travel to the brachial plexus originate from which segments of the spinal cord?

Answer 95

C5-T1

Question 96

The superior thyroid artery is a branch of which other artery

Answer 96

External carotid artery

Question 97

Muscles of larynx: superficial to deep

Answer 97

Platysma Sternocleidomastoid Sternohyoid Cricothyroid Vocalis