spinal nerves and their distribution (week 10)

Question 1

what is the lumbar cistern and where does it extend from?

Answer 1

the area of subarachnoid space that surrounds the cauda equine. Extends from disc between L1 and L2 and end at the lower border of S2

Question 2

where is the needle inserted for a lumbar puncture?

Answer 2

between L3 and L4 or L4 and L5

Question 3

if a line is drawn from the top of the iliac crests which vertebrae does it reach?

Answer 3

crosses the L4 spinous processes

Question 4

which type of mesoderm do the somites develop from?

Answer 4

paraxial mesoderm

Question 5

where do the cell bodies of the somatic motor neurones lie in the neural tube in embryology?

Answer 5

anteriorly within the neural tube

Question 6

what are dermatomyotomes?

Answer 6

developed from somites and will become dermatomes and myotomes

Question 7

what is the best definition of a myotome?

Answer 7

a section of muscle(s) with similar functions supplied by motor neurons from the SAME spinal segments of the spinal cord.

Question 8

what do the dorsal root ganglia develop from?

Answer 8

neural crest cells

Question 9

where do sensory neurone cell bodies lie?

Answer 9

in the dorsal root ganglia

Question 10

what is a dermatome?

Answer 10

an area of skin innervated by sensory neurones from a specific region of spinal cord. (e.g. skin on lateral side of forearm develops adjacent from the C6 somite

Question 11

which infection can show rash patterns to specific dermatomes?

Answer 11

shingles (caused by varicella zoster virus lying dormant in a dorsal root ganglion)

Question 12

how many pairs of spinal nerves are there?

Answer 12

31 pairs

Question 13

how many cervical spinal nerves are there and how many vertebrae?

Answer 13

8 cervical spinal nerves and 7 vertebrae.

Question 14

do cervical spinal nerves emerge above or below the corresponding vertebrae?

Answer 14

above

Question 15

do thoracic spinal nerves arise above or below the corresponding vertebrae?

Answer 15

below (via the intervertebral foramen)

Question 16

where do the somatic motor nerves arise from that supply the intrinsic back muscles (the erector spinae muscles)?

Answer 16

the posterior ramus

Question 17

what do the sympathetic neurones do?

Answer 17

control structure in the body wall which control temperature (blood vessels, sweat glands etc)

Question 18

what are the three main components of the mixed nerves that make up the dorsal rami of the thoracic spinal nerves?

Answer 18

motor neurones which control the erector spinae muscles; sensory neurones from the skin of the back and from vertebral joints; sympathetic neurones to blood vessels and sweat glands of the skin

Question 19

what are the three main components of the mixed nerves which make up the ventral rami of the thoracic spinal nerves?

Answer 19

motor neurons which control the intercostal muscles (muscles between the ribs involved in breathing); sensory neurones from thoracic skin and pleura and vertebral joints; sympathetic neurones which control blood vessels and sweat glands of the skin

Question 20

what is the six step process of the reflex arc?

Answer 20

receptor, sensory neurone, integration centre, motor neurone and effector

Question 21

where do motor neurone cell bodies lie in the spinal cord?

Answer 21

in the anterior horn of the gray matter of spinal cord (axon travels in ventral root

Question 22

where do the cell bodies of sensory neurons lie and what shape of neurone are they?

Answer 22

in the dorsal root ganglion (of the dorsal root); pseudo unipolar shape of neurone

Question 23

what is the efferent nervous system?

Answer 23

motor neurones

Question 24

what is the afferent nervous system?

Answer 24

sensory neurones

Question 25

in which region are sympathetic cell bodies located?

Answer 25

in the lateral horns of T1-L2

Question 26

what is paraesthesia?

Answer 26

altered sensation in a region (usually caused by damage to spinal nerves)