spinal cord anatomy

Question 1

between where does the spinal cord run

Answer 1

the brainstem down to the L1/L2 level

Question 2

whats the end of the brain stem called

Answer 2

the conus medullaris

Question 3

where do we see the enlargements and why

Answer 3

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.

Question 4

conus medullaris is attached to what and whats the attachment do

Answer 4

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

Question 5

whats the clincal significant of the epidural fat

Answer 5

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

Question 6

what are the two extensions of the pia mater called

Answer 6

the filum terminale and the denticulate ligaments - these stabilise the spinal cord laterally

Question 7

whats the deep fascia of the spinal cord called

Answer 7

thoracolumbar fascia

Question 8

whats the arterial supply to the spinal cord, what areas

Answer 8

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

Question 9

where do the two posterior spinal arteries and the anterior spinal artery stem from

Answer 9

from the vertebral artery

Question 10

whats the venous drainage of the spinal cord

Answer 10

three anterior and three posterior spinal veins coming together to form an Anastamosing plexus along the surface of the spinal cord

Question 11

what spinal cord levels is the lateral horn present in

Answer 11

T1-L2 segments of the spinal cord

Question 12

what is the paravertebral sympathetic chain ganglion

Answer 12

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

Question 13

what are the pre-vertebral sympathetic chain ganglia

Answer 13

these are sympathetic chain ganglia present only in front of the abdominal aorta.

Question 14

where do the white rami communicans exist

Answer 14

only exist at the T1-L2 levels but gray exists up the whole chain

Question 15

what are the 4 types of sympathetic outflow

Answer 15

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)

Question 16

describe the path of sympathetic innervation at the level of origin of the preganglionic fibre

Answer 16

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.

Question 17

describe the path of sympathetic innervation above or below the level of innervation of the preganglionic fibre

Answer 17

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.

Question 18

describe the path of sympathetic innervation for the thoracic and cervical viscera

Answer 18

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.

Question 19

which type of sympathetic innervation uses the paravertebral ganglia

Answer 19

when there is innervation of the pelvis or abdomen

Question 20

describe the path of innervation for the pelvis or abdomen

Answer 20

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.

Question 21

what makes the splanchnic nerves

Answer 21

the exit of pre-ganglionic neurons from the para-vertebral ganglia toward the pre-vertebral ganglia

Question 22

what are the names of the 4 splanchnic nerves

Answer 22

greater, lesser, least and lumbar

Question 23

whats the case for adrenal medulla sympathetic innervation

Answer 23

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