Cardiovascular Strand: Lecture 13 - Autonomic Nerves of the Thorax Flashcards
what protects the spinal chord?
our bony vertebral column
How is the verterbral column divided?
What is a mixed nerve?
Contains sensory (afferent) and motor (efferent)
Which nerves do you need to be able to identify? Which is which?
- phrenic nerves (blue nerve in image 1)
- intercostal nerves
- vagus nerves (green in image 2)
- recurrent laryngeal nerve (red in image 2 - branch off vagus nerve)
- sympathetic chain (red branches in image 3 and 4 on either side of the vertebral column)
What does innervated mean?
supplied by nerves
How is the nervous system divided?
somatic and autonomic nerves are motor and sensory
image 2 - all impulses emerge from CNS or go to it
Eeverthing in green is CNS, everything in purple is peripheral
What type of control are somaticand autonomic nerves involved in?
somatic - concious
autonomic - involuntary
What are sensory fibres in the sympathetic nervous system?
Pain fibres (nociceptors)
What are sensory fibres in the parasympathetic nervous system?
autonomic fibres that tell us about the general condition of the viscera (internal organs)
How is our spinal chord organised?
It is divided into 31 segments (pairs). At each vertrebral level, there is a pair of spinal nerves
Each segment gives rise to a PAIR of spinal nerves
There are:
8 pairs of cervical spinal nerves
12 pairs of thoracic spinal nerves
5 pairs of lumbar spinal nerves
5 pairs of sacral spinal nerves
1 pair of coccygeal spinal nerve
What are these spinal nerves called within the thorax?
Intercostal nerves emerging from the spinal chord, that contain sensory and motor fibres
Label and describe this segment of the spinal chord (a segmental spinal nerve)
inner grey matter - contains nuclei/cell bodies
outer white matter - contains axons
D - dorsal
V - ventral
blue lines - dorsal rootlets (contain sensory fibres)
red lines - ventral roots (contain motor fibres)
Dorsal root ganglion: dilated part - where the cell bodies for the dorsal rootlets are
Spinal nerve - dorsal and ventral roots come together - sensory and motor fibres become ensheathed in one nerve
Ventral and dorsal ramus - Outer fibres going towards the dorsal aspect or going to ventral aspect
What is a ganglia?
A cell body (nucleus) that is outside the CNS
Describe the two neurone pathway for all autonomic fibres
Involves two neurone pathways: pre ganglionic fibre (before cell body crosses synapse) and post ganglionic fibre (after cell body crosses synapse)
This is because cell body leaves CNS and becomes a ganglion
What is the main parasympathetic nerve of the trunk?
The vagus nerve
where does the vagus nerve stem from?
the medulla in the brain stem
Where do parasympathetic fibres occur/emerge from?
ONLY the cranial region and the sacral region
What are the relative lengths of pre and post ganglionic fibres?
pre-ganglionic fibre is really long - post is much shorter e.g the vagus nerve; pre-ganglion fibre runs all the way to the thorax/heart)
Where do the sympathetic fibres emerge from?
ONLY the thoracic and lumbar segments (T1 to L2)
Where do the sympathetic fibres go when they leave the spinal column?
They enter the sympathetic chains and are then distributed to the body
is there a two neurone nerve pathway for the sympathetic system aswell?
Yes; from the spinal chord (thoarcic and lumbar segments) to the sympathetic chain is the pre ganglionic fibre then heads towards target organ (post ganglion fibre)
What is a ramus?
branch (in latin)
Annotate and explain the top diagram
SC - spinal chord segment
T1,T2,T3 - vertebral levels
DV and VR - dorsal and ventral roots: come together to form spinal nerve
2 extra branches are white ramus communicans (white as contains myelin sheath) and grey ramus communicans (dosen’t contain myelin)
red - efferent/motor fibre leaving via ventral route to form the spinal nerve
What is occuring in this diagram
Autonomic nerves innervating our viscera
Jumps into sympathetic chain via white ramus communican
It then synapses (becomes sympathetic ganglia)
Nerve heading towards heart is called splanchnic nerve and heads towards relevant organs e.g heart to increase force of contraction
It can ascend or descend in the sympathetic chain to get where it needs to be
