Anatomy of the back, nerves and vessels Flashcards
What does the spinal cord lie in?
Vertebral canal/foramen
Where does the spinal cord end?
Ends at conus medullaris at L1/L2 (adult); L3 (child)
What lie in the intervertebral foramen?
Spinal cord nerve roots
What nerves are found in the cauda equina?
`L2-5, S1-5 and Co
Where are lumbar punctures performed?
Lumbar puncture at L3/4 or L4/5 in children
Where are there enlargements in the spinal cord and why?
Cervical and Lumbar enlargements for brachial and lumbar plexus nerves respectively
To which vertebral level does the dura matter and the arachnoid matter descend?
S2
What does the lateral horn contain?
The lateral horn contains the cell bodies of the sympathetic neurons
Where is the lateral horn present?
The lateral horn is present:
o Between levels T1-L2/3 vertebrae (thoracolumbar/sympathetic outflow) – sympathetic
o Between levels S2-S4 vertebrae (sacral/parasympathetic outflow) – parasympathetic
What vertebral levels show sympathetic outflow?
T1-L2/3
What vertebral levels show parasympathetic outflow?
S2-4 plus cervical (facial) nerves
Describe the sympathetic signalling pathway to the spinal cord
- In sympathetic signalling, the signal leaves the lateral horn, through the white myelinated ramus communicans to a sympathetic ganglion in the sympathetic chain where it synapses to receive another NT, before re-entering the ventral rami and dorsal rami after traveling through the grey unmyelinated ramus communicans
- Nerves can exit below and above where it originates by travelling up or down the sympathetic chain
If sympathetic fibres only originate between T1-L2(3), how do parts of the body above and below these levels receive sympathetic innervation?
Can travel up and down the sympathetic chain/trunk to other sites
What are splanchnic nerves?
The splanchnic nerves are paired visceral nerves (nerves that contribute to the innervation of the internal organs), carrying fibers of the autonomic nervous system (visceral efferent fibers) as well as sensory fibers from the organs (visceral afferent fibers).
Describe the autonomic signalling to the thoracic viscera
Sympathetic preganglionic fibres to the thoracic viscera (heart, lungs) also synapse in the chain, then go to the cardiopulmonary plexus to the prevertebral ganglion, and then on to the heart and lungs.
Describe the autonomic signalling to the abdominal viscera
Sympathetic fibres to abdominal viscera do not synapse in the chain – the merely pass through it with out synapsing there and synapse instead on prevertebral/preaortic ganglia in the abdomen and then on to the abdominal viscera.
Define the parasympathetic nerves
Parasympathetic nerve fibres arise from the CNS with the S2, S3, and S4 spinal nerves and from the 3rd, 7th, 9th and 10th (10th = vagus) cranial nerves - craniosacral outflow.
Define the origin of the pelvic parasympathetic splanchnic nerves
- The S2, S3, and S4 spinal nerves are commonly referred to as the pelvic splanchnic nerves – i.e. they supply pelvic organs.
- The pelvic splanchnic nerve cell bodies reside in the lateral grey horn of the spinal cord at the T12-L2(3) vertebral levels (just like the sympathetic nerve cell bodies) and run down the sympathetic chain to S2-4
What is a sentinel lymph node?
The sentinel lymph node is the hypothetical first lymph node or group of nodes draining a cancer. Common ones are the axillary lymph nodes and breast cancer
What does the thoracic duct drain?
Thoracic Duct - drains lymph from whole body except right upper quadrant (3/4 body)
What does the right lymphatic duct drain?
Right Lymphatic Duct - drains only the lymph of the right upper quadrant of the body
