Spinal Cord - Chapter 14

Question 1

What are the four major functions of the spinal cord?

Answer 1

1. Conduction - sensory signals from body to brain, motor signals from brain to muscles/glands
2. Neural Integration - pools of neurons integrate signals from various sources and execute an appropriate output
3. Locomotion - pools of spinal neurons control movement
4. Reflexes - control posture, motor coordination, and protection from injury

Question 2

Where (specifically) is the spinal cord located?

Answer 2

From the Foramen Magnum (of the skull) to the 1st/2nd lumbar vertebrae
(Upper 2/3 of vertebral canal)

Question 3

How many pairs of spinal nerves are there?

Answer 3

31 pairs of MIXED spinal nerves

Question 4

Where is the spinal cord the widest? What are the four regions? What is considered a segment?

Answer 4

Widest at bottom (widens inferiorly)
Four regions: cervical, thoracic, lumbar, and sacral/coccygeal
A segment is a part of the spinal cord supplied by each pair of spinal nerves

Question 5

What are the longitudinal grooves on the anterior and posterior sides called?

Answer 5

1. anterior median fissure

2. posterior median sulcus

Question 6

What two areas of the cord are thicker than elsewhere? Why?

Answer 6

1. Cervical enlargement - supplies nerves to upper limb

2. Lumbar (lumbosacral) enlargement - supplies nerves to pelvic region and lower limbs

Question 7

What is the medullary cone?

Answer 7

Where the cord tapers to a point inferior to lumbar enlargement

Question 8

What is the cauda equina?

Answer 8

Bundle of nerve roots that occupy the vertebral canal from L2 to S5

Question 9

What is the filum terminale (hit: associated with the cauda equina)

Answer 9

A thin strand of Pia mater that attaches the conus medullar is to the coccyx

Question 10

What are the three spinal meninges?

Answer 10

1. Dura Mater (outermost)
2. Arachnoid mater (middle)
3. Pia mater (innermost)

Question 11

Describe the dura mater of the spinal cord and what it does

Answer 11

Dural sheath surrounding the spinal cord
Separated from vertebrae via periosteum (this is where they put epidermal anesthesia)
Provides the stability in the meningeal layers

Question 12

Describe the arachnoid mater of the spinal cord and what it does

Answer 12

Membrane adheres to dura

Separated from Pia by fibers in the subarachnoid space (filled with CSF, where you take a spinal tap from)

Question 13

Describe the Pia mater of the spinal cord and what it does

Answer 13

Delicate membrane, follows contours of CNS

Transparent, past medially cone - terminal filum

Question 14

Describe the grey matter of the spinal cord. Is it the stuff on the inside or outside?

Answer 14

Neuron cell bodies with little to no myelin
Neurosomas, dendrites, proximal axon
Site of information processing, synaptic integration
Stuff on the inside (butterfly/H-shaped)

Question 15

Describe the white matter of the spinal cord. Is it the stuff on the inside or outside?

Answer 15

Myelinated axons
Carry signals from one part of CNS to next
Stuff on the outside

Question 16

Describe the (4) different features/landmarks in the grey matter of the spinal cord

Answer 16

1. Posterior (dorsal) horns - receive sensory info, cell bodies of interneurons
2. Anterior (ventral) horns - somas of motor neurons
3. Gray commissure - connects right and left side, central canal lined with ependymal cells (filled with CSF)
4. Lateral horn - visible from T2 through L1, neurons of sympathies nervous system

Question 17

Describe the 3 funiculi/columns in the white matter of the spinal cord

Answer 17

Bundles of axons up and down the spinal cord
Communicate between levels fo the CNS
Surround grey matter
3 pairs of bundles:
1. Posterior column
2. Lateral column
3. Anterior column

Question 18

What are the subdivisions of the funiculi/columns in white matter of the spinal cord called?

Answer 18

Ascending tracts (take sensory info TO higher levels of cord and brain)
Descending tracts (take motor signals FROM brain to motor neurons that control muscles and glands)

Question 19

What is decussation?

Answer 19

Cross over from one side to the other

Ex: left side of brain controls right side of the body

Question 20

What’s the difference in contralateral and ipsilateral?

Answer 20

Contralateral - origin and destination on opposite side of body
Ipsilateral - origin and destination on same side of body