The Cerebrum is a large, folded mass of nervous tissue that makes up most of the human brain. Many ridges of cerebral tissue, called gyri (singular: gyrus), extend from the surface of the Cerebrum and are bordered by grooves in the Cerebrum.

In the Cerebellum, there are parallel grooves that conceal that it is a continuous thin layer of tissue (the cerebellar cortex), tightly folded in an accordion style. This thin layer contains several types of neurons with a highly regular arrangement, most importantly Purkinje cells and granule cells.

A Spinal Ganglion is a cluster of nerve bodies positioned along the spinal cord at the dorsal and ventral roots of a spinal nerve.

References:
Nervous Tissue. (n.d.). National Cancer Institute. Retrieved from https://training.seer.cancer.gov/anatomy/cells_tissues_membranes/tissues/nervous.html

Spinal ganglion. (n.d.). Britannica. Retrieved from https://www.britannica.com/science/spinal-ganglion

Taylor, T. (2017 October 16). Cerebrum. Innerbody Research. Retrieved from https://www.innerbody.com/image_nerv02/nerv41-new.html

The Cerebellum. (n.d.). Boundless Anatomy and Physiology. Retrieved from https://courses.lumenlearning.com/boundless-ap/chapter/the-cerebellum/