Question 1

Except for T2-T12, all anterior (ventral) rami form nerve plexuses.

Accepted Answer

The anterior (ventral) rami of all spinal nerves except for T2-T12 form nerve plexuses, such as the cervical, brachial, lumbar, and sacral plexuses. The thoracic nerves (T2-T12) do not form plexuses and instead directly innervate the intercostal spaces as intercostal nerves.

Question 2

Name the four plexuses and give the general distribution of each.

Accepted Answer

The answer of Name the four plexuses and give the...

Question 3

Sketch and label a cross (transverse) section of a spinal cord segment showing the attachments of a spinal nerve and the features of the cord.

Accepted Answer

The answer of Sketch and label a cross (transverse) section...

Question 4

The femoral nerve is a branch of the sciatic nerve.

Accepted Answer

The femoral nerve is not a branch of the sciatic nerve; it originates from the lumbar plexus, specifically from the nerve roots L2 to L4.

Question 5

All segments of the spinal cord contain lateral, posterior (dorsal), and anterior (ventral) gray horns.

Accepted Answer

Only the thoracic and lumbar segments of the spinal cord contain lateral gray horns, which are associated with the autonomic nervous system. The cervical and sacral segments do not have lateral gray horns. All segments do contain posterior (dorsal) and anterior (ventral) gray horns.

Question 6

From which plexus does the superior gluteal nerve arise?

Accepted Answer

The superior gluteal nerve arises from the sacral plexus.

Question 7

The denticulate ligaments and the filum terminale are both structures that help to anchor the spinal cord and protect it against sudden displacement.

Accepted Answer

The denticulate ligaments are lateral extensions of the pia mater that attach to the dura mater and help to anchor the spinal cord within the vertebral column, while the filum terminale is an extension of the pia mater that extends downward from the apex of the conus medullaris to attach to the coccyx, also helping to anchor the spinal cord.

Question 8

The anterior median fissure of the spinal cord is shallower and narrower than the posterior median sulcus.

Accepted Answer

The anterior median fissure of the spinal cord is deeper and wider than the posterior median sulcus, which is shallower and narrower.

Question 9

From which plexus does the ulnar nerve arise?

Accepted Answer

The ulnar nerve arises from the brachial plexus, which is responsible for the innervation of the upper limb.

Question 10

The adult spinal cord extends from the _____ of the brain inferiorly to the superior border of the _____ lumbar vertebra.

Accepted Answer

The adult spinal cord starts from the medulla oblongata at the base of the brain and extends down to the superior border of the second lumbar vertebra.

Question 11

The thin transparent spinal meninx called pia mater separates the spinal cord from the surrounding cerebrospinal fluid.

Accepted Answer

The pia mater is the innermost layer of the meninges, closely enveloping the spinal cord and brain, and it separates them from the cerebrospinal fluid in the subarachnoid space.

Question 12

Describe, in order, from superficial (outermost) to deep (innermost), the structures, tissues, and fluids that provide protection for the spinal cord.

Accepted Answer

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Question 13

Cell bodies of motor neurons that supply smooth muscle, cardiac muscle, or glands via the autonomic nervous system can be found in the lateral gray horns of the spinal cord.

Accepted Answer

The cell bodies of motor neurons that innervate smooth muscle, cardiac muscle, or glands through the autonomic nervous system are indeed located in the lateral gray horns of the spinal cord, specifically in the thoracic and upper lumbar (T1-L2) regions, which comprise the sympathetic division of the autonomic nervous system.

Question 14

Describe the anatomy of a spinal nerve from the point where it is attached to the spinal cord to where it divides into branches. Name the roots and branches and describe in general the regions served by each branch.

Accepted Answer

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Question 15

From which plexus does the axillary nerve arise?

Accepted Answer

The axillary nerve arises from the brachial plexus, specifically from the posterior cord.

Question 16

From which plexus does the iliohypogastric nerve arise?

Accepted Answer

The iliohypogastric nerve arises from the lumbar plexus, specifically from the L1 nerve root.

Question 17

Complete anesthesia of a dermatome typically requires blocking of only one pair of spinal nerves because there is never overlap between neighboring dermatomes.

Accepted Answer

There is considerable overlap between neighboring dermatomes, so blocking a single pair of spinal nerves is often insufficient for complete anesthesia of a dermatome.

Question 18

The epidural space found between the dura mater and the wall of the vertebral canal contains a protective cushion of fat and connective tissue.

Accepted Answer

The epidural space is indeed located between the dura mater and the wall of the vertebral canal, and it contains a protective cushion of fat and connective tissue that helps cushion the spinal cord.

Question 19

From which plexus does the pudendal nerve arise?

Accepted Answer

The pudendal nerve arises from the sacral plexus, specifically from the ventral rami of the S2-S4 spinal nerves.

Question 20

Complete paralysis of the diaphragm occurs if the spinal cord is crushed or destroyed just below the C5 region.

Accepted Answer

The phrenic nerve, which controls the diaphragm, originates from the cervical spinal cord segments C3, C4, and C5. Damage below C5 would not typically result in complete paralysis of the diaphragm.

Quiz 17: The Spinal Cord and the Spinal Nerves