Spinal Cord.
a tract is a bundle or group of nerve fibers located within the brain or spinal cord
It is a bundle of nerve fibers that carry electrical impulses to the brain from the retina.
The thick bundle of nerve fibers through which the brain communicates with the body is the spinal cord.
Each bundle of nerve fibers is surrounded by connective tissue called the perineurium. This protective layer helps to support and protect the bundle of nerve fibers as they travel throughout the body.
VASICLES
The bundle of the nerve fibers is a collection of the threadlike extension of the nerve cell that consists of the myelin sheath and axon in the nervous system. There are nerve fibers in the peripheral nervous system and the central nervous system.
A mixed nerve, such as the trigeminal nerve, contains both sensory and motor fibers that can send and receive messages. These nerves are responsible for carrying both sensory information from the body to the brain and motor commands from the brain to the muscles.
I also think that you may be thinking of how one half (or one side) of the brain carries messages to the other side. That is done with a wide, flat bundle of neural fibers called the corpus callosum.
This bridge is a large bundle of nerve fibers called the corpus collosum.Corpus Callosum
the corpus callosum
The corpus callosum is the bundle of nerve fibers that connects the two hemispheres of the brain, allowing communication between them.
A cable-like bundle of fibers or axons is called a nerve. Nerves carry electrical impulses between the brain, spinal cord, and other parts of the body to coordinate various functions such as movement, sensation, and organ control.