Lab 12: Nervous System Histology

What are the main structures of a neuron that you need to identify?

Cell body, nucleus, and cell processes (axons and dendrites).

What is neuroglia?

Supporting cells of nervous tissue that are associated with and support neurons.

What is the cell body of a neuron?

The main portion of the neuron that contains the nucleus.

What are the two major types of neuronal cell processes?

Axons and dendrites.

Can you distinguish axons from dendrites in the ox spinal cord preparation?

No. The preparation does not allow you to reliably distinguish axons from dendrites.

What is a nerve fiber?

A neuronal process, such as an axon, associated with its supporting structures.

What are nerve fiber bundles?

Groups of nerve fibers bundled together within a nerve.

What is a Schwann cell?

A cell associated with peripheral nerve fibers that forms the myelin sheath around axons.

What is the myelin sheath?

An insulating covering surrounding many axons.

What is the functional significance of myelination?

Myelination allows nerve impulses to travel more rapidly along an axon.

What is a node of Ranvier?

A gap between adjacent sections of the myelin sheath along an axon.

What is the functional significance of nodes of Ranvier?

They allow rapid transmission of nerve impulses along myelinated axons.

What is the endoneurium?

The connective tissue surrounding an individual nerve fiber.

What is the perineurium?

The connective tissue surrounding a bundle of nerve fibers.

What is the epineurium?

The connective tissue surrounding the entire nerve.

What is the order of connective tissue organization in a nerve?

Endoneurium → perineurium → epineurium

How is the organization of a nerve similar to the organization of a muscle organ?

Both are organized into smaller units surrounded by connective tissue coverings.

What structures should you identify in the motor nerve ending preparation?

Axons, motor end plates, myelin sheath, nodes of Ranvier, and muscle fibers.

What is a motor end plate?

The specialized region where a motor neuron communicates with a muscle fiber.

What is a motor unit?

A motor neuron and all of the muscle fibers it innervates.

What is the functional significance of motor unit size?

Motor unit size affects how precisely a muscle can be controlled; smaller units allow finer control.

What major structures should you identify in a spinal cord preparation?

Anterior and posterior surfaces, central canal, white matter, gray matter, gray matter horns, white matter columns, spinal roots, dorsal root ganglion, and meninges.

What is the anterior (ventral) median fissure?

A prominent groove on the anterior surface of the spinal cord.

What is the posterior (dorsal) median sulcus?

A groove on the posterior surface of the spinal cord.

Where is the central canal located?

In the center of the spinal cord.

What is white matter of the spinal cord?

The region containing nerve fibers organized into white columns (funiculi).

What are the three white columns of the spinal cord?

Posterior white column, lateral white column, and anterior white column.

What is gray matter of the spinal cord?

The region containing neuron cell bodies and other neural tissue.

What are the three horns of spinal cord gray matter?

Anterior (ventral) horn, lateral horn, and posterior (dorsal) horn.

What is found in the anterior (ventral) horn of the spinal cord?

The cell bodies of somatic motor neurons.