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What is the sympathetic nerve supply of the abdomen?
- Greater, lesser and least splanchnic nerves
- Lumbar splanchnic nerves
What does the somatic NS control?
External actions of skin and muscle
What does the autonomic NS control?
Internal activities of organs and glands
What is the spinal cord divided into?
31 segments which each segment giving rise to a pair of spinal nerves
- 8 pairs of cervical
- 12 pairs of thoracic
- 5 pairs of lumbar
- 5 pairs of sacral
- 1 pair of coccygeal
What is the dorsal horn of the spinal cord concerned with?
Receiving sensory information (afferent sensory fibres arrive)
What is the ventral horn of the spinal cord concerned with?
Sending motor information (efferent motor fibres leave)
When these efferent and afferent fibres come together, what does it make up?
A mixed spinal nerve –> enclosed by sheath
What are thoracic spinal nerves called?
Intercostal nerves supplying intercostal muscles, pleura, skin etc
What do intercostal muscles continue into the abdomen as?
Thoracoabdominal nerves suppling anterolateral muscles, peritoneum etc
Are intercostal/thoracoabdominal nerves somatic or autonomic?
Somatic nerves (e.g. consciously contract biceps or abdominal muscles)
Describe the autonomic sympathetic supply of the abdomen
- Greater, lesser and least splanchnic nerves
- Lumbar splanchnic nerves
N.B. splanchnic nerves generally refer to sympathetic nerves (one exception)
Where do greater, lesser and least splanchnic nerves begin?
Within thorax and then pierce diaphragm (emerge from the thoracic sympathetic chain)
What do the greater, lesser and least splanchnic nerves supply?
Foregut and midgut
What do the lumbar splanchnic nerves supply?
Hindgut
Describe the autonomic parasympathetic supply of the abdomen
- Vagus nerve (pierces diaphragm along with oesophagus)
- Pelvic splanchnic nerves (exception to sympathetic splanchnic)
What does the vagus nerve supply?
Foregut and midgut (all the way to the distal 1/3 of the TC)
What do pelvic splanchnic nerves supply?
Hindgut and pelvic organs
What are the only splanchnic nerves that are parasympathetic?
Pelvic splanchnic nerves
What do these autonomic nerve fibres form?
Autonomic plexuses –> around coeliac trunk, SMA, IMA then follow blood vessels to target organ
What do these autonomic nerve fibres form?
Autonomic plexuses –> around coeliac trunk, SMA, IMA then follow blood vessels to target organ
What happens if that sympathetic information needs to get to the body wall (e.g. for a sweat gland)?
It can re-enter the spinal nerve via the grey ramus communicans –> enter into the somatic spinal nerve
What happens if that sympathetic information needs to get to the body wall (e.g. for a sweat gland)?
It can re-enter the spinal nerve via the grey ramus communicans
Where does the sympathetic nervous system emerge?
From the spinal cord at the thoracic and lumbar segments (T1 down to around L2)
Where are preganglionic neurones of the sympathetic nervous system located?
In the lateral horns of spinal segments T1-L2