Spinal Cord 2

Question 0

Where do cervical spinal nerves exit?

Answer 0

Above their vertebra

Question 1

How many spiral nerves are there? Be specific.

Answer 1

31 pairs

• 8 cervical
• 12 thoracic
• 5 lumbar
• 5 sacral
• 1 coccygeal

Question 2

Where do thoracic and lower spinal nerves exit?

Answer 2

Below their vertebrae

Question 3

What are the 2 spinal cord enlargements and where are they?

Why are these areas enlarged?

Answer 3

1. Cervical: C4-T1
2. Lumbar: L2-S3
   Increased neuronal density create the enlargements. They supply the upper and lower limbs/perineum via the brachial and lumbosacral plexuses.

Question 4

Where does the spinal cord bluntly terminate and what is this structure called?

Answer 4

It terminates at L2 and its called the conus medullaris

Question 5

What is the area of the spinal cord below the conus medullaris? And what is the structure that descends with it? Where does it anchor?

Answer 5

Cauda equina
The filum terminale (thin filament of pia mater off the surface of the spinal cord) descends with the CE. It anchors to the coccyx.

Question 6

What are the 3 layers that surround the brain and spinal cord?

Answer 6

3 meninges: dura mater, arachnoid and pia mater

Question 7

Where is the epidural space and what does it contain?

Answer 7

It is superficial to the dura mater. It contains fat and venous anastomoses.

Question 8

What is the arachnoid space filled with? What else lies in this layer?

Answer 8

CSF

Also, superficial arteries and veins of the spinal cord.

Question 9

What forms the denticulate ligament? What is its function?

Answer 9

The pia mater extends off of the lateral edges of the spinal cord and attaches to the dura.
It functions to fix the spinal cord in place.

Question 10

What ligaments run vertically along the tips of the spinous processes and which ones run in between the bases?

Answer 10

Supraspinous ligaments

Interspinous ligaments

Question 11

Which ligaments run between the transverse processes? Which ones extend between lamina (on a cross section)?

Answer 11

Intertransverse ligaments

Ligamentum flava

Question 12

Where do the rootlets emanate from?

Answer 12

Lateral sulci

Question 13

Which root is considered the inflow pathway to the CNS? Outflow pathway?

Answer 13

Afferent stimuli is carried to the CNS via the posterior/dorsal root and the sensory ganglion. Efferent stimuli is carried from the CNS via the anterior/ventral root.

Question 14

How do you define the true spinal nerve?

Answer 14

When the dorsal and ventral roots combine and exit thru the intervertebral foramen and before it splits into post/ant rami.

Question 15

The __________ rami remains segmented throughout the length of the spinal cord. It innervates _____________.

Answer 15

Posterior

The skin, muscles and vasculature of the back

Question 16

The __________ rami may either be segmental or anastomose throughout the length of the spinal cord. It innervates ______________.

Answer 16

Anterior

Muscles and blood vessels of lateral and anterior body wall of the abdomen

Question 17

The ____________ rami is capable of forming plexuses.

Answer 17

Anterior

Question 18

Describe the vasculature of the spinal cord. How many arteries? Where? Where do they arise from? What do they supply?

Answer 18

On the posterior side, there are two posterior spinal arteries that lie over the posterior intermediate sulci. These arteries arise from the posterior inferior cerebellum arteries (off the vertebral a.). They supply the posterior 1/3 of the spinal cord.
On the anterior side,nthe anterior spinal artery lies over the anterior median fissure. It arises from the vertebral artery. It supplies the anterior 2/3.

Question 19

What does the anterior/ventral ramus innervate?

Answer 19

It innervates the blood vessels and muscles of the anterior and lateral abdominal wall.

Question 20

What does the posterior ramus innervate?

Answer 20

The blood vessels, skin and muscles of the back.

Question 21

Which branches off the post./ant. rami are responsible for distributing the cutaneous innervation?

Answer 21

The lateral and anterior cutaneous branches from the anterior ramus, coupled with the branches of the dorsal rami, innervate a dermatome.

Question 22

What is a dermatome?

Answer 22

A band of skin/muscles and blood vessels of the body wall.

Question 23

Where is the first point where a nerve becomes mixed?

Answer 23

At the true spinal nerve when the dorsal and ventral roots combine.

Question 24

What vertebral levels exhibit typical (segmental) spinal nerve?

Answer 24

T2-T12

Question 25

Describe a typical spinal nerve.

Answer 25

One whose ventral rami do not form a plexus and remained segmental

Question 26

For complete cutaneous sensory loss, how many spinal nerves would have to be lesioned? Why?

Answer 26

3 because there is some overlap (collateral branches) from each spinal nerve into the dermatome above and below it.

Question 27

Describe the modality of the ventral and dorsal roots.

Answer 27

Dorsal-sensory and postganglionic

Ventral- motor and preganglionic

Question 28

How does the structural organization between the motor/sensory and ANS differ?

Answer 28

Motor/sensory: utilize single neuron to link CNS and effector organ in PNS
ANS: utilizes 2 neurons

Question 29

What does the PNS contain to facilitate the difference between somatic and ANS systems?

Answer 29

The PNS contains ANS ganglia as a site of synapse between the two neurons.