Flashcards in L05 Anatomy of Mediastinum, ANS and Lymphatic drainage of upper trunk Deck (59):
What are the three compartments of thoracic cavity?
Mediastinum = space between lungs extending to root of neck and
below to diaphragm
How is the mediastinum divided into Superior and Inferior?
angle of Louis (T4 - T5)
Sternal angle/ Bifurcation/ carina of trachea
Boundary of superior mediastinum?
Between thoracic inlet and T4-T5
What categories of organs are present in the Sup. Med?
1) Remains of thymus
2) Great vessels
4) Ducts: Trachea, esophagus, thoracic duct
5) Lymph nodes
6) Sympathetic trunks, plexus
Name the 5 great vessels in the Sup. Med.
brachiocephalic veins / artery
superior vena cava,
left common carotid artery, left subclavian artery,
arch of aorta
Name the 4 nerves that run through Superior Med.
left recurrent laryngeal cardiac
Inferior Med. is divided into which compartments?
Anterior, middle, posterior
Boundaries of anterior mediastinum?
between sternum and pericardium
What 3 things are in Ant. Med.?
1) Mainly lymph nodes
2) Sternopericardial ligaments (connects pericardium to ribcage)
3) Remains of thymus
(If remains and not regress in adulthood > thymoma)
Boundaries of Middle Med?
between anterior and posterior mediastinum
Name 5 things present in Middle Med.
Pericardium and heart
Bifurcation of trachea
Root of great vessels
Boundaries of Posterior med.
between pericardium and vertebral column
Name the structures present in Posterior Med. (9)
Descending thoracic aorta
azygous and hemiazygous veins,
Nervous system divided into 2 classes. Which?
Anatomical and functional classifications
Anatomical/ structural classification divided further into 2 sub-types. Which ones?
CNS and PNS
Explain each of the two Anatomical/ Structural classifications of CNS and PNS
1. Central nervous system (CNS): brain and spinal
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)
Divide the Functional classification.
Somatic and Autonomic
Divide Somatic and Autonomic systems.
Somatic- Sensory and Motor (voluntary)
Autonomic- Sympathetic and Parasympathetic (involuntary)
Functions of Sympathetic vs Parasympathetic systems.
A. Sympathetic nervous system (SNS): uses energy in fight or flight situation
B. Parasympathetic nervous system (PNS): restores energy (rest and digest)
Autonomic organisation elaborate.
Can be influenced by higher control (hypothalamus)
Has efferent and afferent nerve fibers
Explain ANS pathways.
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
Give an example of integrated pathway.
Cranial nerve 3,7,9,10 (belonging to PNS) carries parasympathetic and motor fibers
SNS. Where do the nerve outflow from?
Thoracolumbar: T1-L2 (middle, e.g. gut)
PNS. Where do the nerves outflow from?
Craniosacral (head and tail):
- CN 3 (oculomotor), 7 (facial), 9 (glossopharyngeal), 10 (vagus)
Preganglionic fibers (PRGF)
of SNS and PNS are myelinated or not?
What neurotransmitter is used in PRGF?
Myelinated. (PARA= LONG PREgranglionic fibres)
What are the similarities and differences between SNS and PNS POSTganglionic fibers?
Similar: both unmyelinated
Difference: SNS has long postganglionic
PNS has short postganglionic
Where are the ganglions of SNS located?
Closer to spine than to organ
Paravertebral: sympathetic trunk
Prevertebral: celiac, superior and
Where are the ganglions of PNS located?
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)
What is the difference in activity between SNS and PNS? Why?
SNS= Widespread (release of NE, Epi from adrenal medulla)
PNS= Discrete (few postganglionic fibers)
What neurotransmitter is used in PGF?
SNS= NE (most) and ACh (few, e.g. sweat glands)
PNS= All Ach
Where is the higher control centre for both SNS and PNS?
Give three examples of how CNS and PNS are integrated with ANS.
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)
Run through sequence of efferent SNS pathways. What structures are involved?
Lateral column (anterior horn) > white rami communicantes > paravertebral ganglia of
How does SNS efferent fibers reach Head and Neck? PNS?
SNS: T1-T2 uses sympathetic trunk > passes through CERVICAL GANGLION > reaches blood vessels in head, neck
PNS: Brainstem: cranial nerves III, VII, IX, X
How does SNS innervate cardiac and pulmonary plexus?
T2-T5 > sympathetic trunk > heart (cardiac plexus) & lungs (pulmonary plexus)
How does SNS innervate GIT?
T5-T11 > sympathetic trunk > GIT (aortic plexus)
How does SNS innervate kidneys?
T12 > sympathetic trunk > kidneys (renal plexus)
How does SNS innervate pelvic organs?
L1-L2 > pelvic organs (hypogastric plexus)
Name the pathways Cranial Nerve 3,7,9 take in Head?
3 > eye
7 > lacrimal gland
9 > Parotid Gland
CN 3. Name what structures are controlled by PNS
PNS: Ciliary muscle, Pupils
Motor: Extra-occular muscles
CN 7. Name what structures are controlled by PNS
(SNS has 2 components)
PNS: submandibular and sublingual glands
Motor: facial muscles
Special Visceral Sensory (taste) in Anterior 2/3 of tongue
CN 9. Name what structures are controlled by PNS
(plus 3 additional components)
PNS: Parotid gland
Motor: Pharyngeal muscle
Special Visceral Sensory (taste) in Palate
(Sensory) in Posterior 1/3 tongue, oropharnyx
CN 10, Vagus, is the longest cranial nerve. Where do its fibers reach?
PNS: Heart, Lungs, GIT, Kidneys, Pelvic Organs
Motor: Muscles of pharynx and larynx
Sacral plexus: S2-S4 is involved in PNS or SNS? (Think Craniosacral)
How does cranial Plexus (a PNS component along with CN) reach its target organs?
Anterior horn cell (S2-S4) >
sacral nerves > pelvic
splanchnic nerve > hypogastric plexuses > excitor neurons (post-ganglionic) > target organs
Which target organs are controlled by PNS Sacral nerve S2-S4? (5)
bladder, uterus, sphincters, rectum, descending colon
Elaborate on SNS innervation of Heart causing increase in HR and BP.
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
Elaborate on PNS innervation of heart causing decrease in HR and BP.
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
Elaborate on SNS control of lung function.
T2-T5 > sympathetic trunk > pulmonary plexus > blood vessels of lungs and bronchi > Vasoconstriction and Bronchodilation
Elaborate on PNS innervation on lungs.
Dorsal nucleus of CN X > Vagus nerve > synapses with postganglionic neurons in pulmonary plexus > blood vessels of lungs and bronchi > Vasodilation and Bronchoconstriction
AFFERENT pathways of SNS and PNS. (back to CNS)
Elaborate on the pathways.
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
Lymphatic drainage of trunk.
What 2 things does the lymphatic system consist of?
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
Which 2 large ducts drain the entire upper body?
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)
Right lymphatic duct. Which three trunks drain into it?
1) Right head and neck > right jugular trunk
2) Right upper limb > right subclavian trunk
3) Right hemithorax > right bronchomediastinal trunk
Jugular, subclavian, bronchomediastinal
Run through the sequence of right lymphatic duct drainage.
Right lymphatic duct > Bronchiocephalic Vein > Superior Vena Cava > Right Atrium
Which three trunks drain into the Left Thoracic duct on the UPPER BODY?
1) Left head and neck > left jugular
2) Left upper limb > left subclavian
3) Left hemithorax > left
What structures in the LOWER BODY drain into the Left Thoracic Duct?
Lymph collected by intestinal and lumbar trunk > cysterna chyli > all drained to thoracic