Nerves of the Thorax Flashcards
What controls the autonomic nervous system?
The hypothalamus
Name some examples of structures only supplied by sympathetic nerves
Certain blood vessels, errector pili muscles and sweat glands
Describe the course and myelination status
The cell body of the preganglionic neuron comes out from the lateral horn of grey matter and is myelinated so appears white. The postganglionic neuron arises from autonomic ganglia and is unmyelinated.
Briefly describe the function of the parasympathetic system
- Conserves energy.
- Slows breathing and HR by reducing CO and BP.
- Stimulates digestion.
- Open sphincters.
- Constricts pupils.
- Secretomotor to glands (salivary and lacrimal)
What is the parasympathetic innervation via? Where does this nerve arise from?
The vagus nerve which is the 10th cranial nerve. It leaves cranial cavity via jugular foramen and descends between internal jugular vein and internal carotid artery.
Where does the right vagus enter the thoracic cavity?
Between right subclavian artery and brachiocephalic trunk
Where does the left vagus nerve enter the thoracic cavity?
Posterior to the left brachiocephalic vein, between the subclavian and common carotid artery.
What does the right vagus nerve give off and where does it travel?
Gives off recurrent laryngeal nerve which winds around the subclavian artery
What does the left vagus nerve give off and where does it travel?
Gives off recurrent laryngeal nerve which winds around aortic arch just posterolateral to ligamentum anteriosum.
What is the function of the recurrent laryngeal nerves?
They supply:
- Intrinsic laryngeal muscles,
- Middle inferior pharyngeal constrictor muscles and,
- Sensory to laryngeal cavity below the level of vocal folds.
Briefly describe the sympathetic system (thoracolumbar outflow)
Body uses energy;
- Increases HR and strength of beat.
- Dilates coronary arteries,
- Constricts peripheral arteries.
- Relaxes bronchial smooth muscle,
- Closes sphincters,
- Controls body temp via BV and sweat glands.
Where are the preganglionic call bodies of the sympathetic system found?
In the intermediolateral (lateral) horn of grey matter in spinal segments T1-L2
Where are the postganglionic cell bodies of the sympathetic NS found?
Lie in either paravertebral sympathetic ganglia (lateral to vertebral bodies and anterior to neck or ribs, covered by parietal pleura) or in the prevertebral sympathetic ganglia, (lie around origins of branches of abdominal aorta).
Describe the ganglia of the cervical region
Superior ganglia, formed by the fusion of sympathetic nerves from C1-4, Middle ganglion by fusion of C5-6 and Inferior cervical ganglia by C7-8
What is the stellate ganglion?
It is the inferior cervical ganglia and T1. So fusion of C7-T1, it occurs occasionally