spinal cord anatomy Flashcards
between where does the spinal cord run
the brainstem down to the L1/L2 level
whats the end of the brain stem called
the conus medullaris
where do we see the enlargements and why
there are two enlargements, one at the cervical region and another at the lumbar region.
lumbosacral and cervical enlargement
these enlargements are due to the increased amount if neurons in the grey matter of these areas. as these are regions which are primary contributors to the plexuses of the upper and lower limbs.
conus medullaris is attached to what and whats the attachment do
its attached to the filum terminale, this is a fine filament which anchors the spinal cord to the base of the spinal canal. doing so for stability of the distal spinal cord during movement
whats the clincal significant of the epidural fat
this is fat in the extra dural fat and it has protective function of the spinal cord. this is where epidural anaesthesia is given to people receiving a spinal tap
what are the two extensions of the pia mater called
the filum terminale and the denticulate ligaments - these stabilise the spinal cord laterally
whats the deep fascia of the spinal cord called
thoracolumbar fascia
whats the arterial supply to the spinal cord, what areas
there are 2 sets of posterior spinal arteries - from vertebral artery supply the posterior 1/3 of the spinal cord
one anterior spinal artery stems from vertebral artery and supplies anterior 2/3 of the spinal cord
where do the two posterior spinal arteries and the anterior spinal artery stem from
from the vertebral artery
whats the venous drainage of the spinal cord
three anterior and three posterior spinal veins coming together to form an Anastamosing plexus along the surface of the spinal cord
what spinal cord levels is the lateral horn present in
T1-L2 segments of the spinal cord
what is the paravertebral sympathetic chain ganglion
these are chain ganglia that are found on either side of the spinal cord anteriorly. connected to the ventral rami by the gray and white ramus communicans
what are the pre-vertebral sympathetic chain ganglia
these are sympathetic chain ganglia present only in front of the abdominal aorta.
where do the white rami communicans exist
only exist at the T1-L2 levels but gray exists up the whole chain
what are the 4 types of sympathetic outflow
1: peripheral sympathetic innervation at the level of origin of the preganglionic fibre
2: innervation at a level above or below the level of origin of the preganglionic fibre
3:sympathetic innervation of thoracic and cervical viscera
4: sympathetic innervation of the abdomen and pelvic region ( and adrenals)
describe the path of sympathetic innervation at the level of origin of the preganglionic fibre
The preganglionic neuron starts at the lateral horn and runs through the ventral horn, through the ventral root and entering the ventral rami. The neuron then runs through the white ramis communicans and into the paravertebral sympathetic ganglion on the same level. Here the pre ganglionic neuron synapses onto the post ganglionic neuron. The post ganglionic neuron then runs out of the paravertebral sympathetic ganglion via the gray ramus communicans and into the spinal nerve, then travelling to the desired target organ. This is same level.
describe the path of sympathetic innervation above or below the level of innervation of the preganglionic fibre
The preganglionic neuron starts at the lateral horn and runs through the ventral horn, through the ventral root and entering the ventral rami. The neuron then runs through the white ramis communicans and into the paravertebral sympathetic ganglion on the same level. Here the pre ganglionic synapses onto the post ganglionic neuron. The axon of the post ganglionic neuron then travels up or down the sympathetic chain ganglion depending on the site where the innervation is required. This neuron then travels out of the sympathetic chain via the gray rami communicans and into the spinal nerve.
describe the path of sympathetic innervation for the thoracic and cervical viscera
The preganglionic neuron starts at the lateral horn and runs through the ventral horn, through the ventral root and entering the ventral rami. The neuron then runs through the white ramis communicans and into the paravertebral sympathetic ganglion on the same level. Here the preganglionic neuron synapses onto the post ganglionic neuron. This time the axon of the post ganglionic neuron runs directly medially out of the sympathetic ganglion and attaches to an artery to the desired organ.
which type of sympathetic innervation uses the paravertebral ganglia
when there is innervation of the pelvis or abdomen
describe the path of innervation for the pelvis or abdomen
The preganglionic neuron starts at the lateral horn and runs through the ventral horn, through the ventral root and entering the ventral rami. The neuron then runs through the white ramis communicans and into the paravertebral sympathetic ganglion on the same level. This time the pre ganglionic fibres do not synapse onto anything. Instead the ganglionic fibres exit medially right out of the paravertebral ganglion and into the pre-vertebral ganglion. Here they synapse and the post ganglionic neurons then run out into the abdominal viscera.
what makes the splanchnic nerves
the exit of pre-ganglionic neurons from the para-vertebral ganglia toward the pre-vertebral ganglia
what are the names of the 4 splanchnic nerves
greater, lesser, least and lumbar
whats the case for adrenal medulla sympathetic innervation
the preganglionic fibres run out of the paravertebral ganglia but do not synapse in the pre-vertebral ganglion, instead the fibres go straight to the adrenal medulla
