Spinal Nerves and their Distribution

Question 1

What could you inject into the vertebral canal via lumbar puncture?

Answer 1

Anaesthetics, antibiotics and chemotherapeutic agents.

Question 2

What is coning?

Answer 2

Herniation of the brain.

Question 3

When should you not do a lumbar puncture?

Answer 3

When a patient has raised intracranial pressure.

Question 4

Why might you need to access the vertebral canal?

Answer 4

Sample CSF for blood or organisms and measure pressure of CSF.

Question 5

Why is access safest in the lumbar region?

Answer 5

Spinal cord ends at L1/L2 so cauda equina unlikely to be damaged.

Question 6

Which way do hypaxial muscles form?

Answer 6

Ventrally.

Question 7

Which way do epaxial muscles form?

Answer 7

Dorsally.

Question 8

Where does the subarachnoid space extend to?

Answer 8

S2.

Question 9

Where does the lumbar cistern extend?

Answer 9

From disc between L1 and L2 to the lower border of S2.

Question 10

What surrounds the cauda equina?

Answer 10

The lumbar cistern.

Question 11

How should the patient lie when doing a lumbar puncture?

Answer 11

In the fetal position to space the spinous processes.

Question 12

Where is the needle inserted in a lumbar puncture?

Answer 12

Between L3 and L4 or L4 and L5.

Question 13

What are somites?

Answer 13

Paired aggregations of paraxial mesoderm.

Question 14

How are somites arranged?

Answer 14

Sequentially along each side of the neural tube.

Question 15

What part of the somite gives rise to musculoskeletal elements?

Answer 15

Dermatomyotome

Question 16

Where are cell bodies of neurons located?

Answer 16

Anteriorly in the neural tube.

Question 17

What is the function of somatic motor efferents?

Answer 17

Carry impulses from the CNS to skeletal muscle and stimulate muscle contraction.

Question 18

What does the dermatomyotome of each somite give rise to?

Answer 18

Individual skeletal muscle.

Question 19

What follows the development of the skeletal muscle from the dermatomyotome?

Answer 19

Spinal nerves from adjacent somites.

Question 20

How does the skeletal muscle correspond to the somatic motor fibres?

Answer 20

The muscle receives the fibre from the spinal cord segment adjacent to their somite.

Question 21

Where do the cell bodies lie?

Answer 21

In the dorsal root ganglia.

Question 22

Where do the dorsal root ganglia develop from?

Answer 22

The neural crest.

Question 23

What does the dermis send?

Answer 23

Somatic sensory fibres to the spinal cord segment adjacent to its corresponding somite.

Question 24

What gives rise to the dermis of skin?

Answer 24

The dermatomyotome.

Question 25

What is a dermatome?

Answer 25

An area of skin innervated by a single spinal segment.

Question 26

What causes shingles?

Answer 26

Varicella zoster virus.

Question 27

Where does chickenpox go after initial infection?

Answer 27

The virus lies dormant in a dorsal root ganglion.

Question 28

How is shingles related to the spinal nerves?

Answer 28

The rash develops in the skin area supplied by the spinal nerve affected.

Question 29

What are the horns of the gray matter?

Answer 29

Dorsal horn, lateral horn and ventral horn.

Question 30

What are the columns of the white matter?

Answer 30

Dorsal column, lateral column and anterior column.

Question 31

What does a pair of spinal nerves consist of?

Answer 31

Axons of: motor neurons, sensory neurons and sympathetic neurons.

Question 32

What are the function of motor neurons in the spinal nerves?

Answer 32

They innervate a group of muscles arising from the same somite (myotome).

Question 33

What are the functions of sensory neurons in the spinal nerves?

Answer 33

They innervate a defined area of skin (dermatome).

Question 34

What are the functions of the sympathetic neurons of the in the spinal nerves?

Answer 34

They go to structures on the body wall that control body temperature.

Question 35

What is the end of the spinal cord called?

Answer 35

Conus medullaris.

Question 36

What happens when the cells of the neural crest invaginate?

Answer 36

They form the neural groove.

Question 37

What are epaxial muscles supplied by?

Answer 37

Dorsal rami.

Question 38

What are the hypaxial muscles supplied by?

Answer 38

Ventral rami.

Question 39

What type of neuron emerges from the anterior horn of the spinal cord?

Answer 39

Afferent motor neuron.

Question 40

What type of neuron develops out of the lateral horn of the spinal cord?

Answer 40

Efferent sympathetic neuron.

Question 41

What happens to the sympathetic neuron in the ganglion?

Answer 41

They synapse onto a postganglionic neuron.

Question 42

What develops from the neural crest cells?

Answer 42

Sensory nerve cell bodies.

Question 43

Which part of the rami are used for communicating?

Answer 43

Ramis communicans.

Question 44

Where do dorsal rami of the thoracic spinal nerves carry motor neurones?

Answer 44

To erector spinae muscles.

Question 45

Where do dorsal rami of the thoracic spinal nerves carry sensory neurones?

Answer 45

From the skin of the back and from vertebral joints.

Question 46

Where do dorsal rami of the thoracic spinal nerves carry sympathetic neurones?

Answer 46

To blood vessels and sweat glands of the skin.

Question 47

Where do the ventral rami of the thoracic spinal nerves carry motor neurones?

Answer 47

To intercostal muscles.

Question 48

Where do the ventral rami of the thoracic spinal nerves carry sensory neurones?

Answer 48

From thoracic skin and pleura and vertebral joints.

Question 49

Where do the ventral rami of the thoracic spinal nerves carry sympathetic neurones?

Answer 49

To blood vessels and sweat glands of the skin.

Question 50

What is involved in a reflex arc?

Answer 50

Receptor, sensory neuron, integration centre, motor neuron and effector.

Question 51

What is a reflex?

Answer 51

A rapid, involuntary motor response to a stimulus.

Question 52

What is a spinal reflex?

Answer 52

Somatic spinal reflexes provides information on integrity of the reflex pathway and degree of excitability.

Question 53

Where does the axon of the motor neuron lie?

Answer 53

In the ventral root.

Question 54

Where does the axon of the sensory neuron lie?

Answer 54

In the dorsal root.

Question 55

Which spinal vertebrae have lateral horns?

Answer 55

T1-L2.

Question 56

What is altered sensation called?

Answer 56

Paraesthesia.

Question 57

What is a symptom of paraesthesia?

Answer 57

Nerve irritation can cause pins and needles.

Question 58

What does nerve compression cause?

Answer 58

Muscle weakness, loss of sensation and reflexes.