Nerves in Thorax - Olinger Flashcards by Jes Testa

Superior and inferior mediastinum are separated by

The sternal angle

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The inferior mediastinum is divided into

Anterior
Middle
Posterior

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Middle mediastinum

The heart

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Esophagus

Joining the laryngopharynx to the stomach
Double layered
Muscular tube with an internal circular layer and external longitudinal layer
The upper 2/3 a combo of smooth and skeletal

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Regions of the esophagus

Cervical part
Thoracic part
Abdominal part

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Thoracic part of esophagus

Between T1 and the esophageal hiatus of the thoracic diaphragm
Travels through the posterior mediastinum

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Constrictions of the esophagus

At the cricophayngeus m. - clinically referred to as the upper esophageal sphincter
At aortic arch
At the left bronchus
At the esophageal hiatus of the thoracic diaphragm - clinically referred to as the lower esophageal sphincter

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Vagus N

Left recurrent laryngeal n.
Pulmonary and inferior cardiac branches —> in posterior mediastinum produces esophageal branches on esophagus
In abdomen become anterior and posterior vagal trunk

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Left recurrent laryngeal n.

Loops under aortic arch and ligamentum arteriosum to return to the larynx

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Phrenic N.

Anterior rami of C3-5
Space between mediastinal parietal pleura and fibrous pericardium
Innervate the thoracic diaphragm
Conveys sensory info from central diaphragmatic and mediastinal pleura and the pericardium

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Intercostal N.

1-11th pair of anterior rami of the thoracic spinal nerves
Travel along the inferior edge of the superior rib in the intercostal space between internal and innermost intercostal m.
Innervates skin, subcutaneous tissue, musculature and costal and diaphragmatic parietal pleura

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Typical Intercostal nerves

3rd-6th
Rami communicantes
Collateral branches
Lateral cutaneous branches
Anterior cutaneous branches
Muscular branches

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Rami communicates

Connect intercostal n. to ipsilateral sympathetic trunk

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Collateral branches

Assist in innervating intercostal m., travels on the superior edge of the rib inferior to the intercostal space

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Lateral cutaneous branches

Become anterior and posterior branches and suppy the skin of the thoracic wall

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Which lateral cutaneous branches supply the breast?

T4-T6 - teat 4

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Anterior cutaneous branches

Supply anterior aspect of the thoracic wall

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Muscular branches

Supply intercostal m., subcostal m., and transversus thoracic thoracic m.

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Atypical intercostal n.

1st and 2nd

7th - 11th

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1st intercostal n.

No cutaneous branches and majority superior portion joins the brachial plexus

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2nd intercostal n.

Majority travels in costal groove as a typical intercostal n. with a small part joining with the BP, the lateral cutaneous branch supplies the skin and subcutaneous tissue of the axilla and is called an intercostbrachial n.

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7th-11th intercostal n.

Begin as intercostal n. but as they travel anteriorly cease to exist between ribs and transition over the abdomen to become thoracoadbominal n.

Thoracoabdominal n.

What 7th-11th intercostal n become

Sympathetic stimulation

Catabolic
fight or flight
ALL vascular areas of the body

Parasympathetic stimulation

Anabolic Normal function and energy conservation Limited distribution - head, neck and trunk viscera

Glandular secretion

Stimulated by the parasympathetic nervous system (except sweat glands) The sympathetic nervous system can indirectly decrease non-sweat gland glandular secretion through vasoconstriction

Symp division presynaptic fibers are

Short

Sympathetic division presynaptic fibers

Cell bodies exist in the lateral horn of the spinal cord Always travels in the ventral root Always travel into the ventral ramus Quickly exit ventral ramus and enters the paravertebral ganglia

Sympathetic synaptic options

1. Can enter paravertebral ganglion and synapse on postsynaptic neuron on SAME spinal level 2. DIFFERENT level 3. Can leave through an abdominopelvic splanchnic nerve on their way to a postsynaptic neuron in paravertebral ganglion

Sympathetic presynaptic fibers

Long | Cell bodies exist in the paravertebral or pre vertebral ganglia

Prevertebral ganglia

Ganglia and corresponding plexuses surrounding the main unpaired branches of the abdominal aorta - celiac - superior mesenteric - aorticorenal - inferior mesenteric

Thoracic sympathetic trunk

Paravertebral sympathetic ganglia, location of presynaptic sympathetic nerve fibers synapsing onto long postsynaptic nerve cell bodies

2 Cardiopulmonary splanchnic nerves

Cardiac splanchnic n. | Pulmonary splanchnic n.

Cardiac splanchnic n

Presynaptic cell bodies in the lateral horn of the spinal cord at levels T1-5 or 6 synapse onto postysynaptic cell bodies in the cervical and thoracic sympathetic trunks which send fibers to the superficial and deep cardiac plexuses

Abdominopelvic splanchnic nerves

Travel from the thoracic sympathetic trunk to corresponding pre vertebral ganglia in the abdomen Greater splanchnic n. Lesser splanchnic n. Least splanchnic n.

Greater splanchnic n.

T5-9 or 10 | Sends fibers to the esophageal plexus and to the celiac ganglion in abdomen which then feeds into the celiac plexus

Lesser splanchnic n.

T10 and T11 | Sends fibers to celiac and sup mesenteric ganglion in abd which then feeds into the superior mesenteric plexus

Least splanchnic n.

T12 | Sends fibers to the aorticorenal ganglion in abdomen

Parasympathetic nervous system

Presynaptic fibers - long

Cranial component of parasympathetic exits as

Cranial nerves - oculomotor - III - facial - VII - glossopharyngeal - IX - vagus - X

Sacral component of parasympathetic

exits spinal levels as pelvic splanchnic n.

Postsynaptic fibers of parasympathetic

Usually short | With ganglia/postsynaptic neurons near or in the target get organ

Parasympathetic presence in thorax

Vagus n.

Presynaptic parasympathetic innervation to the lungs, bronchi, pleurae, heart and pericardium

Superior cardiac branch of vagus n.

Originates in the neck descends through the superior thoracic aperture and with the cardiac splanchnic n. forms the cardiac plexus

Middle cardiac branch of vagus n.

Originates in the neck descends through the superior thoracic aperture and with the cardiac splanchnic n. forms the cardiac plexus

Inferior cardiac branch of vagus n.

Originates in the thorax and with the cardiac splanchnic n. forms the cardiac plexus

Pulmonary branches of vagus

Originates in the thorax and with the pulmonary splanchnic n. forms the pulmonary plexus

Esophageal branches of vagus

After producing pulmonary branches the vagus nerve becomes indistinguishable from the esophageal plexus that covers the inferior 2/3 of the esophagus

Pulmonary plexus

mixed sympathetic and parasympathetic Symp input from pulmonary splanchnic n Parasymp from pulmonary branches of the vagus n. Innervates the lungs, bronchi and pleurae

Superficial cardiac plexus

Anterior surface of aorta

Aortic plexus

Mixed symp and parasymp

Esophageal plexus

Mixed sump and parasymp

Esophageal glands

Parasymp | Stimulates peristalsis and esophageal glands