Exam 1 Spinal Cord

Question 1

Spinal Cord- segmental levels cervical

Answer 1

8

Question 2

Spinal Cord- segmental levels thoracic

Answer 2

12

Question 3

Spinal Cord- segmental level lumbar

Answer 3

5

Question 4

Spinal Cord- segmental level sacral

Answer 4

5

Question 5

Spinal Cord- segmental level coccygeal

Answer 5

1

Question 6

Where does the spinal cord end?

Answer 6

extend form foramen magnum to L1-L2 vertebra

Question 7

What are the paired spinal nerves formed from?

Answer 7

a dorsal and ventral root

Question 8

Dorsal root ganglion are composed of

Answer 8

sensory neuron cell bodies for spinal primary afferent sensory axons

Question 9

What is the overall size of the spinal cord?

Answer 9

7-8mm dorsal-ventral and ~12mm lateral axis at largest segment

Question 10

Where is the spinal cord located?

Answer 10

within the vertebral column

Question 11

Where do the spinal nerves exit?

Answer 11

~C1-7 above similar # vertebra
~C8 below C7 vertebra
~T1-L5 below similar vertebra
~Sacral- in the sacral foramina
~coccygeal- below the sacrum

Question 12

External features of the spinal cord

Answer 12

a number of longitudinal "furrows" on the surface
~Posterior or dorsal median sulcus
~Anterior or ventral median fissure
~Dorsolateral sulcus
~Ventrolateral sulcus

Question 13

Posterior or dorsal median sulcus on the spinal cord

Answer 13

marking the dorsal surface

Question 14

Anterior or ventral median fissure on the spinal cord

Answer 14

marking the ventral surfaces

Question 15

Dorsolateral sulcus

Answer 15

entry point of dorsal root

Question 16

Ventrolateral sulcus

Answer 16

exit for ventral root

Question 17

Why is there a cervical enlargement in the spinal cord?

Answer 17

~gives rise to the brachial plexus
~innervating upper extremity, which has a high innervation density (that is a large number of neurons innervating a relatively small muscle mass)
~gives rise to the fine motor control muscles of the hand

Question 18

Where is the cervical enlargement in the spinal cord?

Answer 18

C4-T1

Question 19

Comparison of the innervation of the back musculature versus the innervation of hand musculature

Answer 19

~ low innervation density of the back musculature versus the high innervation density of hand musculature
~Smaller number of neurons in the ventral horn of the spinal cord segments which innervate a larger muscle mass in the trunk and proximal limbs.
~each neuron there innervates a large number of number of muscle fibers.
~low innervation density but a larger Motor Unit (# muscle fibers innervated by a single neuron by its single axon in the back and proximal limbs.
~larger number of neurons in the ventral horn of the spinal cord segments which innervate a smaller muscle mass in the distal limbs.
~each neuron innervates a large number of number of muscle fibers.
~high innervation density but a smaller Motor Units in the distal extremities.
~gives more power to the trunk and proximal limb muscles but more fine motor control to the distal limb muscles

Question 20

Why is T2-L1 more narrow?

Answer 20

~these spinal segments innervate the trunk

Question 21

Comparison of sensory density of skin on the back versus sensory density of skin on the hand

Answer 21

~there are few receptors cover large areas of skin of the back
~sensory density of skin of the distal extremities where there are a very large number of receptors in small areas of skin
~the back has a low sensory innervation density while the distal extremity has a very high innervation density

Question 22

Where is the lumbosacral enlargement?

Answer 22

L5-S2

Question 23

Why is there a lumbosacral enlargement?

Answer 23

~gives rise to lumbosacral plexus, which innervates lower extremity
~higher innervation but not as high as cervical enlargement

Question 24

Conus medularis

Answer 24

the spinal cord tapers to form the medullaris (S3-Co1)

Question 25

Cauda equina

Answer 25

the descending nerves form the cauda equine after the spinal cord as ended

Question 26

Filum Terminale

Answer 26

connective tissue layers of the spinal cord form the filum terminale which attaches to the sacrum to stabilize the spinal cord within the spinal canal

Question 27

Dermatome

Answer 27

segmented area of skin innervated by each of the spinal nerve (spinal segment)

Question 28

Myotome

Answer 28

segmented pattern of muscle innervation by each of the spinal nerve

Question 29

Myotome and Function for diaphargm

Answer 29

root C3,4,5

~respiration

Question 30

Myotome and Function for deltiod

Answer 30

C5

~abduction of arm

Question 31

Myotome and Function for biceps

Answer 31

C5

~flexion of forearm

Question 32

Myotome and Function for brachioradialis

Answer 32

C6

~flexion of forearm

Question 33

Myotome and Function for triceps

Answer 33

C7

~extension of forearm

Question 34

Myotome and Function for quadriceps femoris

Answer 34

L3,4

~extension of the knee

Question 35

Myotome and Function for extensor halluces longus

Answer 35

L5

~dorsiflexion of great toe

Question 36

Myotome and Function for gastrocnemius

Answer 36

S1

~plantar flexion

Question 37

Internal organization of spinal cord- Gray matter

Answer 37

~contains cell bodies and their dendritic fields
~a central H or butterfly shaped with features such as dorsal horn, ventral horn, and intermediate gray region with a lateral horn
~has a rich capillary network

Question 38

where is there a lateral horn in the gray matter?

Answer 38

thoracic and upper spinal cord

Question 39

Internal organization of spinal cord- White matter

Answer 39

~densely packed, longitudinally running myelinated axons

~divided into dorsal, lateral, and ventral white columns (funiculi)

Question 40

Internal organization of spinal cord- Commissures

Answer 40

~Gray-made up of the unmyelinated axons of interneurons, which functionally connect one side to the other
~White- decussating myelinated fibers of ascending spinal pathways

Question 41

How does the white matter change through the spinal cord?

Answer 41

~progressive increase in white matter as it moves rostrally

Question 42

How does the dorsal and ventral horns change though the spinal cord?

Answer 42

~there is an increase of the size of dorsal and ventral horns in cervical and lumbosacral enlargements because of the innervation density of the upper and lower limbs compared to the trunk and upper cervical spine
~the gray matter increases in relation to the richness of peripheral innervation of upper and lower extremities