Organisation of Nerves in the Thorax Flashcards Preview

LSS 1 - Thorax Anatomy - Laz > Organisation of Nerves in the Thorax > Flashcards

Flashcards in Organisation of Nerves in the Thorax Deck (23)
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What do somatic spinal nerves provide somatic sensory innervation to?

Body wall but NOT to viscera


What is a dermatome?

An area of skin that is supplied by a single spinal nerve on one side or from a single spinal cord level


What is a myotome?

Part of a skeletal muscle that is supplied by a single spinal nerve on one side or from a single spinal cord level


How many intercostal nerves are there?

11 intercostal + 1 subcostal


What are the branches of the intercostal nerves?

There is a lateral cutaneous branch (anterior and posterior branches) and an anterior cutaneous branch (medial and lateral branches)


What structures do the phrenic nerves provide sensory and motor innervation to?

Motor = diaphragm
Central diaphragm
Mediastinal pleura
Peritoneum of central diaphragm


Where do sympathetic preganglionic neurones to the body wall synapse?

In the ganglia of the sympathetic trunk


Where do sympathetic preganglionic neurons to the viscera synapse?

In unpaired ganglia


The sympathetic trunk receive which spinal nerves?



What is the significance of sympathetic fibres in spinal nerves T5-T12?

These are the thoracic splanchnic nerves that carry sympathetic fibres to the abdomen.


What are the five sets of nerves that contain parasympathetic fibres?

Occulomotor (III)
Facial (VII)
Glossopharyngeal (IX)
Vagus (X)
Sacral spinal nerves (S2-S4)


Which spinal nerves do sympathetic fibres to the heart and lungs come from?

T2-T4 passing through cervical and upper thoracic ganglia


Where do many of these fibres synapse?

In ganglia of the pulmonary and cardiac plexuses rather than in the trunk ganglia


What effect do sympathetic and parasympathetic nerves have on bronchioles?

Sympathetic - bronchodilation
Parasympathetic - bronchoconstriction


What are the effect of sympathetic and parasympathetic efferents to the heart?

Sympathetic - increase heart rate and force of contraction (inotropic and chronotropic effect)
Parasympathetic - decrease heart rate and vasoconstrict coronary arteries


What are the roles of sympathetic and parasympathetic afferents from the heart?

Sympathetic - relay pain sensations from the heart
Parasympathetic - relay blood pressure and chemical information from the heart


Where does the vagus nerve arise and where does it leave the skull?

Vagus nerves arise in the medulla and it leaves the skull via the jugular foramina


Describe the path of descent of the vagus nerve.

The two vagus nerves pass postero-laterally to the common carotid arteries.
Right vagus passes posterior to the right lung root
Left vagus nerve crosses over anterior to the aortic arch and then posterior to the left main bronchus


What are roles of sympathetic and parasympathetic efferents from the oesophageal plexus?

Sympathetic - relays pain sensation from the oesophagus
Parasympathetic - senses normal physiological information from the oesophagus


Branches of the vagus provide sensory content from…?

Gut and lungs
REMEMBER: branches of the vagus provide NO AUTONOMIC SUPPLY to the body wall.


State a feature of the left recurrent laryngeal nerve. What does it innervate?

It is NOT parasympathetic
It innervates most of the skeletal muscle of the larynx


How do the vagi in the posterior and anterior mediastinum differ?

In the posterior part of the oesophagus, you form the posterior oesophageal nerve which mainly takes right vagal fibres through the diaphragm to the abdominal viscera.
The left vagus provides fibres to the oesophageal plexus and then continutes as the anterior oesophageal nerve.


Label this diagram.

o Remember you are above the plane of the arch of the aorta so you will NOT see the aorta
o You will see the right and left brachiocephalic vein but not its branches
o Vagus is posterior to phrenic nerves