1 The Spinal Cord, Reflexes, and Plexuses

What are the two main divisions of the nervous system?

Central nervous system
Peripheral nervous system

What structures make up the central nervous system (CNS)?

Brain and spinal cord

What structures make up the peripheral nervous system (PNS)?

All nerves and ganglia outside the brain and spinal cord.

Between which vertebral landmarks does the spinal cord extend?

From the foramen magnum to the 2nd lumbar vertebra

What protects the spinal cord?

Vertebral column

What allows movement through connections with the spinal cord?

Spinal nerves

What can occur if the spinal cord is damaged?

Paralysis

Where is gray matter located in the spinal cord?

In the center of the spinal cord.

What shape does gray matter have in the spinal cord?

H-shaped with horns or butterfly-shaped.

Where is white matter located in the spinal cord?

Outside the spinal cord.

What type of fibers does white matter contain?

Myelinated fibers

What are the three columns found in CNS white matter?

Dorsal, ventral, and lateral columns.

What do the three columns of CNS white matter contain?

Ascending and descending tracts

Which tracts conduct action potentials toward the brain?

Ascending tracts

Which tracts conduct action potentials away from the brain?

Descending tracts

What do the posterior horns of gray matter contain?

Axons that synapse with interneurons.

What type of neurons are found in the anterior horns of gray matter?

Somatic neurons

What type of neurons are found in the lateral horns of gray matter?

Autonomic neurons

It is the fluid-filled space in the center of the spinal cord.

Central canal

What type of reaction is a reflex?

An involuntary reaction

What initiates a reflex reaction?

A stimulus applied to the periphery

Where is the peripheral stimulus transmitted during a reflex?

To the CNS