Term
| Superior mediastinum (yellow) – posterior to manubrium and anterior to vertebrae T1 – T4 |
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Definition
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| Posterior mediastinum (blue) – posterior to pericardial sac & diaphragm and anterior to vertebrae T5 – T12 |
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Lateral border of the superior and posterior mediastinum is more specifically mediastinal pleura.
Posteriorly we can see the vertebral line of pleural reflection in the above cross section, where the mediastinal pleura is continuous with the costal pleura. Anteriorly we can see the sternal line of pleural reflection, where the mediastinal pleura is continuous with the costal pleura. |
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| what are the contents of the superior mediastinum? |
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Definition
Thymus
Great vessels
Vagus nerves
Phrenic nerves
Left recurrent laryngeal n.
Trachea
Esophagus
Thoracic duct |
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Term
| left recurrent laryngeal nerve? |
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Definition
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| what forms the brachiocephalic veins? |
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Definition
| formed by the junction of the internal jugular vein descending down from the neck and the subclavian vein, which is continuous with the axillary vein. |
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Term
| The brachiocephalic trunk is the first branch off the aortic arch and as it heads to the right the trunk will divide into the right common carotid artery and the right subclavian artery. The aortic arch is positioned more towards the left so the left common carotid artery and subclavian artery branch directly off of it. |
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Definition
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| phrenic nerve passes between the parietal pleura and the parietal pericardium. |
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Definition
| it is motor to the diaphragm, but GSA of the mediastinal pleura and parietal pericardium |
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Term
Vagus nerves – visceral motor efferent (or GVEs) and visceral sensory afferents (GVAs) to thoracic and abdominal viscera
Vagus nerves also carry motor efferent to muscles of the larynx and these branch off as the L and R recurrent laryngeal nerves |
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Definition
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| An aortic aneurism or mediastinal tumor can disrupt motor impulses in the left recurrent laryngeal nerve causing paralysis in muscles on the left side of the larynx resulting in hoarseness of the voice. A tumor in the apex of the right lung can impinge upon the right laryngeal nerve causing right vocal cord palsy. |
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Definition
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Definition
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Term
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Definition
Thoracic aorta & branches
Azygos venous system
Thoracic duct
Esophagus
Sympathetic trunks
Thoracic splanchnic nerves |
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Term
| First 2 posterior intercostal arteries branch off the superior intercostal arteries |
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Definition
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Term
| anterior intercostal arteries are branches off the internal thoracic, and anastamose with the posterior intercostal arteries |
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Definition
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The thoracic duct is a lymphatic structure found in the posterior mediastinum:
anterior to the vertebral bodies
Posterior to esophagus
between the azygos vein and the thoracic aorta.
It begins at a saccular dilation called the cisterna chyli located in the abdomen |
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Definition
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Term
The first neuron is called presynaptic or preganglionic and the second is postsynaptic or postganglionic
Synapse between the two motor neurons takes place at a ganglion (collection of neuron cell bodies located outside the CNS)
The presynaptic neuron is myelinated and the postsynaptic neuron is unmyelinated |
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Definition
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Sympathetic nervous system (fight or flight) prepares the body for exertion
Raises blood pressure
Increases heart rate
Dilates airways and pupils |
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Definition
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Term
Parasympathetic nervous system (rest and digest) brings the body to a resting state – conserves energy
Lowers blood pressure
Decreases heart rate
Constricts airways and pupils
Constricts smooth muscle in GI tract
Stimulates glandular secretion |
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Definition
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Term
Sympathetic division → Fight or flight
Impulses originate from thoracic & lumbar spinal cord (T1-L2) Thoracolumbar outflow
Relatively short preganglionic axons |
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Definition
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Parasympathetic division → Rest & digest
Impulses originates from brainstem and sacral spinal cord (S2-S4)
Craniosacral outflow
Relatively long preganglionic axons |
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Definition
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Postsynaptic sympathetics: norepinephrine
Postsynaptic parasympathetics: acetylcholine |
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Definition
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Term
| Cranial nerve X (vagus) will supply all thoracic viscera and most of the abdominal viscera |
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Definition
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Term
| Pelvic splanchnic nerves supply visceral motor to the latter 1/3 of large intestine and pelvic viscera |
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Definition
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| Lateral horn is only present in T1-L2 spinal segments |
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Definition
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Term
| ; presynaptic sympathetic fibers travel through the ventral rootlets and ventral root to reach the spinal nerve proper; the spinal nerve proper and the spinal nerve ventral ramus both communicate with the sympathetic trunk via gray and white ramus communicans |
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white = myelinated
grey = unmyelinated |
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Definition
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| The inferior cervical ganglion is sometimes joined with the first thoracic ganglion and together they are called the cervicothoracic or stellate ganglion. |
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Definition
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| Ganglion impar unites trunks on either side at coccyx |
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Definition
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| Above T1 and below L2 there are only gray rami communicantes. |
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Definition
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Postsynaptic sympathetics (cell body in paravertebral ganglia) travel on branches of spinal nerves to reach effectors in the body wall:
peripheral blood vessels (vasomotion)
sweat glands (sudomotion)
arrector pili muscles (pliomotion) |
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Definition
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Term
| No parasympathetics in the body wall |
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Definition
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Term
Presynaptic cell bodies in lateral horns of spinal cord segments T1-L2
↓
ventral root
↓
spinal nerve proper & spinal nerve ventral ramus
↓
white ramus communicans
(myelinated)
↓
synapse at paravertebral ganglion (at same or different level)
↓
Postganglionic fiber travels on gray ramus communicans
(unmyelinated) back to spinal nerve |
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Definition
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Sympathetics to the head:
Presynaptic sympathetic fibers will synapse in the superior cervical ganglion
postsynaptic sympathetics travel through periarterial plexuses to reach effectors to the head |
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Definition
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Sympathetics to thoracic viscera:
Presynaptic cell body: T1-T5
Location of postsynaptic cell body: paravertebral ganglion (upper thoracic and cervical)
Postsynaptic sympathetics via cardiopulmonary splanchnic nerves |
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Definition
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Term
Cardiac plexus – aortic arch & tracheal bifurcation
Left and Right pulmonary plexus on main bronchi.
Autonomic fibers will converge on plexuses near effectors which will have mixed sympathetic and parasympathetic nerve fibers |
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Definition
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All autonomic plexuses will typically have:
Visceral sensory fibers
Presynaptic parasympathetic fibers
Presynaptic or postsynaptic sympathetic fibers (depending on the sympathetic pathway) |
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Definition
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Sympathetics to viscera in the abdominopelvic cavity :
Presynaptic sympathetic fibers pass through sympathetic trunk without synapsing
Travel within abdominopelvic splanchnic nerves to synapse with cell bodies of second motor neurons located in prevertebral ganglia (collateral ganglia)
Postsynaptic sympathetic fibers on periarterial plexuses to effector |
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Definition
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Term
Cardiopulmonary splanchnic nerves consist of cervical splanchnic nerves and upper thoracic splanchnic nerves (spinal cord levels T1-T5).
Abdominopelvic splanchnic nerves consist of lower thoracic splanchnic nerves, lumbar splanchnic nerves, and sacral splanchnic nerves (spinal cord levels T5-L2). |
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Definition
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| right vagal goes posterior, left vagal goes anterior |
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Definition
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| Parasympathetic stimulation produces peristaltic contractions of the esophagus |
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Definition
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Term
Visceral sensory innervation
Go along with visceral motor fibers
Those with sympathetics detect pain
Those with parasympathetics detect normal physiological processes and reflexes |
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Definition
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Term
Embryological associations:
General somatic afferent and efferent fibers will innervate derivatives of:
Ectoderm
Somatic mesoderm
Somites
General visceral afferent and efferent fibers will innervate derivatives of:
Endoderm
Splanchnic mesoderm
What is the exception to this rule? |
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Definition
| the exception is sympathetic innervation of structures in our body wall |
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Term
Neural plate:
Alar plate (dorsal) derivatives: interneurons that remain in CNS
Basal plate (ventral) derivatives: somatic motor neurons and presynaptic autonomic neurons |
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Definition
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Derivatives of the neural crest:
Sensory neurons (visceral and general somatic) and dorsal root ganglia
Postsynaptic autonomic neurons and autonomic ganglia |
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Definition
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Term
If the cell body of a neuron lies outside the CNS then it developed from the neural crest.
Somatic motor neurons, interneurons, and presynaptic autonomic neurons develop from the neural tube. |
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