L05 Anatomy of Mediastinum, ANS and Lymphatic drainage of upper trunk

Question 1

What are the three compartments of thoracic cavity?

Answer 1

1. Lungs
2. Pleura
3. Mediastinum

Question 2

Define mediastinum.

Answer 2

Mediastinum = space between lungs extending to root of neck and
below to diaphragm

Question 3

How is the mediastinum divided into Superior and Inferior?

Answer 3

angle of Louis (T4 - T5)

Sternal angle/ Bifurcation/ carina of trachea

Question 4

Boundary of superior mediastinum?

Answer 4

Between thoracic inlet and T4-T5

Question 5

What categories of organs are present in the Sup. Med?

Answer 5

1) Remains of thymus
2) Great vessels
3) Nerves
4) Ducts: Trachea, esophagus, thoracic duct
5) Lymph nodes
6) Sympathetic trunks, plexus

Question 6

Name the 5 great vessels in the Sup. Med.

Answer 6

brachiocephalic veins / artery
superior vena cava,
left common carotid artery, left subclavian artery,
arch of aorta

Question 7

Name the 4 nerves that run through Superior Med.

Answer 7

Both phrenic
vagus
left recurrent laryngeal cardiac

Question 8

Inferior Med. is divided into which compartments?

Answer 8

Anterior, middle, posterior

Question 9

Boundaries of anterior mediastinum?

Answer 9

between sternum and pericardium

Question 10

What 3 things are in Ant. Med.?

Answer 10

1) Mainly lymph nodes
2) Sternopericardial ligaments (connects pericardium to ribcage)
3) Remains of thymus
(If remains and not regress in adulthood > thymoma)

Question 11

Boundaries of Middle Med?

Answer 11

between anterior and posterior mediastinum

Question 12

Name 5 things present in Middle Med.

Answer 12

 Pericardium and heart
 Bifurcation of trachea
 Root of great vessels
 Phrenic nerves
 Lymph nodes

Question 13

Boundaries of Posterior med.

Answer 13

between pericardium and vertebral column

Question 14

Name the structures present in Posterior Med. (9)

Answer 14

 Descending thoracic aorta
 Vagus nerves
 Sympathetic trunks
 Esophagus
 Thoracic duct
 azygous and hemiazygous veins,
 splanchnic nerves
 lymph nodes

Question 15

Nervous system divided into 2 classes. Which?

Answer 15

Anatomical and functional classifications

Question 16

Anatomical/ structural classification divided further into 2 sub-types. Which ones?

Answer 16

CNS and PNS

Question 17

Explain each of the two Anatomical/ Structural classifications of CNS and PNS

Answer 17

1. Central nervous system (CNS): brain and spinal
   cord
2. Peripheral nervous system (PNS)
    12 pairs of cranial nerves (nuclei originate in brainstem which connects brain
   and spinal cord)
    31 pairs of spinal nerves (and their associated ganglia)

Question 18

Divide the Functional classification.

Answer 18

Somatic and Autonomic

Question 19

Divide Somatic and Autonomic systems.

Answer 19

Somatic- Sensory and Motor (voluntary)

Autonomic- Sympathetic and Parasympathetic (involuntary)

Question 20

Functions of Sympathetic vs Parasympathetic systems.

Answer 20

A. Sympathetic nervous system (SNS): uses energy in fight or flight situation

B. Parasympathetic nervous system (PNS): restores energy (rest and digest)

Question 21

Autonomic organisation elaborate.

Answer 21

 Can be influenced by higher control (hypothalamus)

 Has efferent and afferent nerve fibers

Question 22

Explain ANS pathways.

Answer 22

ANS uses existing pathways / nerves (e.g. 12 cranial nerves, 31 spinal nerves)
 But if they do not exist, ANS will develop its own pathway (e.g. pulmonary plexus, cardiac plexus, esophageal plexus, aortic plexus) (e.g. vagus nerve abruptly branches into heart)
 Plexus = combination of sympathetic and parasympathetic nerves

Question 23

Give an example of integrated pathway.

Answer 23

Cranial nerve 3,7,9,10 (belonging to PNS) carries parasympathetic and motor fibers

Question 24

SNS. Where do the nerve outflow from?

Answer 24

Thoracolumbar: T1-L2 (middle, e.g. gut)

Question 25

PNS. Where do the nerves outflow from?

Answer 25

Craniosacral (head and tail): - CN 3 (oculomotor), 7 (facial), 9 (glossopharyngeal), 10 (vagus) - S2-S4

Question 26

Preganglionic fibers (PRGF) of SNS and PNS are myelinated or not? What neurotransmitter is used in PRGF?

Answer 26

Myelinated. (PARA= LONG PREgranglionic fibres) Ach

Question 27

What are the similarities and differences between SNS and PNS POSTganglionic fibers?

Answer 27

Similar: both unmyelinated Difference: SNS has long postganglionic PNS has short postganglionic

Question 28

Where are the ganglions of SNS located?

Answer 28

Closer to spine than to organ  Paravertebral: sympathetic trunk  Prevertebral: celiac, superior and inferior mesentric

Question 29

Where are the ganglions of PNS located?

Answer 29

Closer to organ than spine  Small ganglia close to viscera (e.g. otic and ciliary ganglia), or  Ganglion cells in plexus (e.g. cardiac, pulmonary)

Question 30

What is the difference in activity between SNS and PNS? Why?

Answer 30

``` SNS= Widespread (release of NE, Epi from adrenal medulla) PNS= Discrete (few postganglionic fibers) ```

Question 31

What neurotransmitter is used in PGF?

Answer 31

SNS= NE (most) and ACh (few, e.g. sweat glands) PNS= All Ach

Question 32

Where is the higher control centre for both SNS and PNS?

Answer 32

Hypothalamus

Question 33

Give three examples of how CNS and PNS are integrated with ANS.

Answer 33

1. E.g. spinal nerve III is peripheral and somatic; carries both sympathetic and parasympathetic nerves 2. E.g. autonomic nervous system innervates blood vessels which supply skeletal muscles 3. Lungs contain both sympathetic and parasympathetic nerves (e.g. vagus > control airway and secretion)

Question 34

Run through sequence of efferent SNS pathways. What structures are involved?

Answer 34

``` Lateral column (anterior horn) > white rami communicantes > paravertebral ganglia of sympathetic trunk ```

Question 35

How does SNS efferent fibers reach Head and Neck? PNS?

Answer 35

SNS: T1-T2 uses sympathetic trunk > passes through CERVICAL GANGLION > reaches blood vessels in head, neck PNS: Brainstem: cranial nerves III, VII, IX, X

Question 36

How does SNS innervate cardiac and pulmonary plexus?

Answer 36

T2-T5 > sympathetic trunk > heart (cardiac plexus) & lungs (pulmonary plexus)

Question 37

How does SNS innervate GIT?

Answer 37

T5-T11 > sympathetic trunk > GIT (aortic plexus)

Question 38

How does SNS innervate kidneys?

Answer 38

T12 > sympathetic trunk > kidneys (renal plexus)

Question 39

How does SNS innervate pelvic organs?

Answer 39

L1-L2 > pelvic organs (hypogastric plexus)

Question 40

Name the pathways Cranial Nerve 3,7,9 take in Head?

Answer 40

3 > eye 7 > lacrimal gland 9 > Parotid Gland

Question 41

CN 3. Name what structures are controlled by PNS

Answer 41

PNS: Ciliary muscle, Pupils Motor: Extra-occular muscles

Question 42

CN 7. Name what structures are controlled by PNS | SNS has 2 components

Answer 42

PNS: submandibular and sublingual glands Motor: facial muscles + Special Visceral Sensory (taste) in Anterior 2/3 of tongue

Question 43

CN 9. Name what structures are controlled by PNS | plus 3 additional components

Answer 43

PNS: Parotid gland Motor: Pharyngeal muscle + Special Visceral Sensory (taste) in Palate + (Sensory) in Posterior 1/3 tongue, oropharnyx

Question 44

CN 10, Vagus, is the longest cranial nerve. Where do its fibers reach?

Answer 44

PNS: Heart, Lungs, GIT, Kidneys, Pelvic Organs Motor: Muscles of pharynx and larynx

Question 45

Sacral plexus: S2-S4 is involved in PNS or SNS? (Think Craniosacral)

Answer 45

SNS

Question 46

How does cranial Plexus (a PNS component along with CN) reach its target organs?

Answer 46

Anterior horn cell (S2-S4) > sacral nerves > pelvic splanchnic nerve > hypogastric plexuses > excitor neurons (post-ganglionic) > target organs

Question 47

Which target organs are controlled by PNS Sacral nerve S2-S4? (5)

Answer 47

bladder, uterus, sphincters, rectum, descending colon

Question 48

Elaborate on SNS innervation of Heart causing increase in HR and BP.

Answer 48

T2-T5 > sympathetic trunk > cardiac plexus > sinoatrial (SA), atrioventricular (AV) nodes, cardiac muscles, coronary arteries > Increase rate and force of contraction & Vasodilatation of coronary arteries

Question 49

Elaborate on PNS innervation of heart causing decrease in HR and BP.

Answer 49

Dorsal nucleus of CN X > vagus nerve > synapses with postganglionic neurons in cardiac plexus > SA, AV nodes, cardiac muscles, coronary arteries > Decrease rate and force of contraction &Vasoconstriction

Question 50

Elaborate on SNS control of lung function.

Answer 50

T2-T5 > sympathetic trunk > pulmonary plexus > blood vessels of lungs and bronchi > Vasoconstriction and Bronchodilation

Question 51

Elaborate on PNS innervation on lungs.

Answer 51

Dorsal nucleus of CN X > Vagus nerve > synapses with postganglionic neurons in pulmonary plexus > blood vessels of lungs and bronchi > Vasodilation and Bronchoconstriction

Question 52

AFFERENT pathways of SNS and PNS. (back to CNS) | Elaborate on the pathways.

Answer 52

viscera/ target organs directly > white rami communicantes > cell bodies of POSTERIOR root ganglion of corresponding nerve (or CNS in case of PNS) > higher centre / local reflex arc

Question 53

Lymphatic drainage of trunk. | What 2 things does the lymphatic system consist of?

Answer 53

1) Lymphatic tissues: contain a large number of lymphocytes that are essential for host defense 2) Lymphatic vessels = conduits that assist cardiovascular system in carrying fluids out from interstitial spaces of body

Question 54

Which 2 large ducts drain the entire upper body?

Answer 54

Right lymphatic duct: drains all fluids of upper right side of body (above the diaphragm) (Left) thoracic duct: drains all fluids from left side of body (includes those below diaphragm)

Question 55

Right lymphatic duct. Which three trunks drain into it?

Answer 55

1) Right head and neck > right jugular trunk 2) Right upper limb > right subclavian trunk 3) Right hemithorax > right bronchomediastinal trunk Jugular, subclavian, bronchomediastinal

Question 56

Run through the sequence of right lymphatic duct drainage.

Answer 56

Right lymphatic duct > Bronchiocephalic Vein > Superior Vena Cava > Right Atrium

Question 57

Which three trunks drain into the Left Thoracic duct on the UPPER BODY?

Answer 57

``` 1) Left head and neck > left jugular trunk 2) Left upper limb > left subclavian trunk 3) Left hemithorax > left bronchomediastinal trunk ```

Question 58

What structures in the LOWER BODY drain into the Left Thoracic Duct?

Answer 58

Lymph collected by intestinal and lumbar trunk > cysterna chyli > all drained to thoracic duct

Question 59

Does the left thoracic duct drain like the right lymphatic duct?

Answer 59

Yes, same pathway