15. Back and Nervous System

Question 1

What do the sclerotomes form?

Answer 1

The sclerotome forms the vertebrae and the rib cartilage and part of the occipital bone.

Question 2

What do the myotome form?

Answer 2

The myotome forms the musculature of the back, the ribs and the limbs.

Question 3

What do the syndetome form?

Answer 3

The syndetome forms the tendons.

Question 4

What do the dermatome form?

Answer 4

The dermatome forms the skin on the back.

Question 5

Where does the nucleus pulposus derive from?

Answer 5

From the notochord.

Question 6

How many cervical vertebrae are there? How many of them are atypical?

Answer 6

Seven cervival vertebrae and the first 2 are atypical.

Question 7

What passes throught the transverse foramina?

Answer 7

Vertebral artery and vein.

Question 8

Describe the Atlas.

Answer 8

It is the first cervical vertebra (C1). It has no body and leaves a space to accommodate the dens of the second cervical vertebra.

Question 9

Describe the Axis.

Answer 9

It is the second vertebra (C2). It has a tooth-shaped process, the dens (odontoid process), which articulates with the atlas as a pivot joint. Movement at this joint allows lateral rotation of the head.

Question 10

How many thoracic vertebrae are there?

Answer 10

There are 12.

Question 11

How many lumbar vertebrae are there?

Answer 11

5 of them L1 to L5.

Question 12

How many sacral vertebrae are there?

Answer 12

5 of them S1 to S5 which are fused together.

Question 13

What is the most common route of a herniation ?

Answer 13

It is almost always in a posterolateral direction, passing through a rupture of the anulus fibrosus. The herniated nucleus often comes to lie in the intervertebral formaen where it may compress a spinal nerve.

Question 14

Describe an intervetebral disk.

Answer 14

Each disk has an outer portion called the anulus fibrosus, which is composed of fibrocartilage and fibrous connective tissue, and an inner portion, the nucleus pulposus, which is semigelatinous fluid with very few, if any, cells.

Question 15

Which ligament reinforces the intervertebral disk anteriorly and anterolaterally?

Answer 15

The anterior longitudinal ligament.

Question 16

Which ligament reinforces the intervertebral disk posteriorly?

Answer 16

The posterior longitudinal ligament. There is no reinforcement of the posterolateral side.

Question 17

What passes through the intervertebral foramen?

Answer 17

The spinal nerve.

Question 18

What type of nerves does the dorsal root contain?

Answer 18

It contains sensory nerve fibers with their cell bodies in the dorsal root ganglion.

Question 19

What type of nerves does the ventral root contain?

Answer 19

It contains motor nerve fibers with their cell bodies in the gray matter of the spinal cord.

Question 20

What does the dorsal ramus innervate?

Answer 20

The skin of the back, the deep back muscles, and the zygopohyseal joints.

Question 21

What does the ventral ramus innervate?

Answer 21

The anterior and lateral portions of the body wall and the limbs.

Question 22

At what level is lumbar puncture typically performed and what anatomical structure can we use to guide?

Answer 22

It is performed at the L4-L5 interspace. The top of the iliac crest marks the level of the L4 vertebra.

Question 23

What are all the layers that the needle passes through in a lumbar puncture?

Answer 23

10 layers: Skin, Superficial fascia, Deep fascia, Supraspinous ligament, Interspinous ligament, Interlaminar space, Epidural space, Dura, Arachnoid, Subarachnoid.

Question 24

Which space contains the cerebrospinal fluid?

Answer 24

The subarachnoid space.

Question 25

How can a subdural space be created when normally there isn’t?

Answer 25

Through bleeding.

Question 26

What is the inferior limit of the dural sac and the subarachnoid space?

Answer 26

Vertebral level S2.

Question 27

What are the 2 divisions of the autonomic nervous system (ANS)?

Answer 27

Sympathetic and parasympathetic.

Question 28

Where do preganglionic neurons of the ANS have their cell bodies?

Answer 28

The cell bodies are in the CNS.

Question 29

Where do postganglionic neurons of the ANS have their cell bodies?

Answer 29

The cell bodies are in motor ganglia in PNS.

Question 30

Where exactly are the parasympathetic preganglionic neuron cell bodies located at?

Answer 30

In the brain stem nuclei of cranial nerves 3,7,9,10 or in the gray matter of the spinal cord segments S2-S4 (pelvic splanchinics).

Question 31

Parasympathetics to the head originate from which cranial nerves?

Answer 31

3, 7, 9.

Question 32

Parasympathetics to the thorax, foregut, and midgut originate from which cranial nerves?

Answer 32

10

Question 33

Parasympathetics to the hindgut and pelvic viscera from which cranial nerves?

Answer 33

S2-S4.

Question 34

Where are sypathetic preganglionic cell bodies found?

Answer 34

In the lateral horn of the gray matter of spinal cord segments T1-L2.

Question 35

Where do sympathetics to the body wall, head, and thoracic viscera synapse to?

Answer 35

To the chain ganglia (paravertebral).

Question 36

Where do sympathetics to the foregut and midgut and to the hindgut and pelvic viscera synapse to?

Answer 36

To the collateral (prevertebral) ganglia.

Question 37

Which are the pelvic splanchnics nerves?

Answer 37

S2-S4.

Question 38

Which are the lumbar splanchnics nerves?

Answer 38

L1-L2.

Question 39

Which are the thoracic splanchnics nerves?

Answer 39

T5-T12.