Nerves of the thorax

Question 1

What is the autonomic nervous system under the control of?

Answer 1

• The hypothalamus

•

Question 2

How many neurones to reach the end organ in the autonomic nervous system?

Answer 2

• 2

Question 3

Where is the cell body of the preganglionic neurone located?

Answer 3

• Grey matter of the spinal cord or brainstem

* It is myelinated

Question 4

Where is the cell body of the postganglionic neurone located?

Answer 4

• Autonomic ganglion

* It is unmyelinated

Question 5

Describe the function of the parasympathetic system

Answer 5

• Rest and digest
• Slows the breathing and heart rate, reducing cardiac output and blood pressure
• Opens sphincters
• Constricts the pupils
• Secremotor to glands: salivary, lacrimal

Question 6

Describe the route of the vagus nerve

Answer 6

• 10th cranial nerve
• exits the brainstem
• Leaves the cranial cavity via the jugular foramen, descends between the internal jugular vein and internal (then common) carotid artery
•

Question 7

Describe the route of the right vagus

Answer 7

• Enters the thoracic cavity between the right subclavian and the brachiocephalic trunk

Question 8

Describe the route of the left vagus

Answer 8

• Enters the thoracic cavity posterior to the left brachiocephalic vein, between the subclavian and common carotid arteries

Question 9

What are the branches of the right vagus nerve?

Answer 9

• Recurrent laryngeal which winds around the right subclavian artery

Question 10

What are the branches of the left vagus nerve?

Answer 10

• Recurrent laryngeal which winds around the aortic arch (

aortopulmonary window), just posterolateral to the ligamnetum arteriosum

Question 11

What do the recurrent laryngeal nerves supply?

Answer 11

• Intrinsic laryngeal muscles
• Middle and inferior pharyngeal constrictor muscles
• Sensory to the laryngeal cavity below the level of the vocal folds

Question 12

What is the role of the sympathetic nervous system?

Answer 12

• Fight or flight response
• Increases the heart rate and the strength of contraction
• Dilates the coronary arteries
• relaxes bronchial smooth muscle
• Closes sphincters
• Controls body temperature

Question 13

Where are the sympathetic preganglionic cell bodies?

Answer 13

• Preganglionic cell bodies lie in the intermediolateral horn of T1-L2 spinal cord segments

Question 14

Where are the sympathetic postganglionic cell bodies?

Answer 14

• Paravertebral sympathetic ganglia 
- anterior to the neck of the ribs 
- covered by the parietal pleura 
- interconnected - sympathetic chain 
• Wraps around the origin of the abdominal aorta

Question 15

Where does the sympathetic trunk extend between?

Answer 15

• Atlas and the coccyx

* They fuse together in the single ganglion impair, opposite to the coccyx

Question 16

Are there more paravertebral sympathetic ganglia or vertebra?

Answer 16

More vertebra because some of the ganglia fuse

Question 17

Describe the different ganglia

Answer 17

• Superior (C1-4) cervical
• Middle (C5,6) cervical
• Inferior (C7,8) cervical

Question 18

What makes up the stellate ganglion?

Answer 18

The inferior cervical ganglion and the stellate ganglion

Question 19

In the sympathetic system, what are the 5 options?

Answer 19

1) synapse at its level
• Postganglionic axons pass in the grey ramus communicant and join T1-L2 spinal nerves
• Heart, thoracic wall, bit of the thigh

2) Travel up the chain to synapse in a cervical ganglion
• Postganglionic axons travel in the grey ramps communicates and join the cervical spinal nerves
• Eye, head, neck, upper torso, heart

3) Travel down the chain and synapse in a lumbar/sacral ganglion
• Postganglionic axons pass in the Grey ramus communicants and join the sacral/lumbar spinal nerves

4) Preganglionic branches pass through the trunk without synapsing
• Travel in the splanchnic nerves to the abdomen
• Synapse in the prevertebral ganglion
• Supplies the abdominal viscera

5) Leaves the sympathetic trunk and goes to the adrenal medulla

Question 20

What are the splanchnic nerves?

Answer 20

• Thoracic splanchnic nerves: 
- Greater splanchnic nerve: T5-9
- Lesser splanchnic nerve: T10-11
- Least splanchnic nerve: T12 
• Lumbar splanchnic nerve 
• Pelvic splanchnic nerve

Question 21

What are the visceral plexuses in the thorax?

Answer 21

• Sympathetic and parasympathetic fibres mix and form an autonomic or visceral plexus
• Cardiac plexus
- anterior to the bifurcation of the trachea and posterior to the ascending aorta
• Pulmonary plexus
- anterior and (mainly) posterior to the roots of the lungs
• Oesophageal plexus
- around the oesophagus

Question 22

Describe the cardiac plexus

Answer 22

• Anterior to the bifurcation of the trachea and posterior to the ascending aorta
• Sympathetics from T1-5 to the T1-5 ganglia and inferior and middle cervical ganglia
• Visceral afferent fibres travel alongside the sympathetic nerves
• Parasympathetics from the vagus

Question 23

Describe the pulmonary plexus

Answer 23

• Anterior and (mainly) posterior to the roots of the lung
• sympathetics from the T2-4
• parasympathetics from the vagus

Question 24

What does the phrenic nerve supply?

Answer 24

• Motor to the diaphragm 
• Sensory to:
- mediastinal pleura 
- parietal pericardium 
- peritoneum and pleura related to the central tendon of the diaphragm

Question 25

Describe the intercostal nerves

Answer 25

• Anterior rami of the thoracic spinal nerves
• Mixed nerves:
- motor branches to the intercostal and abdominal wall muscles
- visceromotor branches to the vessels
• With the exception of T1 which supplies the skin/a dermatome

Question 26

Describe Pancoast’s tumour

Answer 26

tumour at the apex of the lung which may affect the sympathetic trunk or stellate ganglion compromising the sympathetic supply to the head and neck on the same side

Question 27

Describe Horner’s syndrome

Answer 27

• Ptosis
• Pupillary constriction
• Anhydrosis
• Flushing of the face