0312 - Spinal cord and peripheral nerves - EG

Question 1

What is a spinal segment?

Answer 1

A section of spinal cord that carries sensory information from, and motor information to, a predictable and discrete body region.

Question 2

What are the two major sensory pathways within the spinal column and what type of information does each convey?

Answer 2

dorsal column - fine touch and proprioception; spinothalamic tract - pain and temperature

Question 3

What are the two major motor pathways within the spinal column and what type of information does each convey?

Answer 3

lateral corticospinal tract - contralateral information; ventral corticospinal tract - ipsilateral information.

Question 4

What is a sensory territory also known as?

Answer 4

a dermatome. dorsal rami of C1 does not have a cutaneous representation.

Question 5

What is a motor territory also known as?

Answer 5

a myotome. Segments from upper part of a plexus innervate proximal muscle groups and segments from lower parts of a plexus innervate distal muscle groups.

Question 6

Does the ventral primary ramus contain sensory, motor, or mixed nerves?

Answer 6

mixed nerves.

Question 7

Does the ventral root contain sensory, motor, or mixed nerves?

Answer 7

motor nerves

Question 8

Does the dorsal root contain sensory, motor, or mixed nerves?

Answer 8

sensory nerves

Question 9

Describe the numbering of spinal nerves to vertebrae

Answer 9

C1-C7 n’s exit at the vertebral level above corresponding vertebrae, C8 n exits below C7 vertebrae, T1-S5 exit below pedicles of corresponding vertebrae.

Question 10

What cervical n does the radial n derive from?

Answer 10

C6

Question 11

What cervical n does the median n derive from?

Answer 11

C7

Question 12

What cervical n does the ulnar n derive from?

Answer 12

C8

Question 13

The brachial plexus is comprised of which nerves?

Answer 13

ventral primary rami of C5 to T1

Question 14

At what vertebral level down the spinal cord end in an adult? What is the end of the spinal cord known as? What is below this level?

Answer 14

L1, end called conus medullaris, post which is cauda equina

Question 15

What helps anchor the spinal cord within the spinal column?

Answer 15

The denticulate ligaments and the phylum terminale, both extensions of the pia mater that anchor to the lateral and inferior respectively.

Question 16

Describe the cross-sectional appearance of a cervical, thoracic, lumbrosacral spinal cord section.

Answer 16

Cervical: large ventral horn with cell bodies of motor neurons supplying upper limb and large proportion of white matter; thoracic: prominent lateral horn of sympathetic neurons; lumbosacral: large ventral horn for motor neurons supplying lower limb, minimal white matter.

Question 17

Describe the simple reflex arc in the withdrawal reflex from a pinprick in a finger.

Answer 17

sensory dermatome (thumb C6, index-ring C7, little finger C8), pinprick sensation sent via sensory nerve into dorsal root, enters spinal cord to interneuron - initiates motor reflex to cause movement of the wrist (C6,7) and fingers (C7,8) away from insulting object.