What type of nerve is described as carrying messages from tissue cells to the brain?

The correct answer is the type of nerve known as an afferent nerve. Afferent nerves, also referred to as sensory nerves, are responsible for transmitting sensory information from tissue cells and sensory receptors throughout the body to the central nervous system, which includes the brain and spinal cord. This transmission process allows the brain to interpret various stimuli, such as pain, temperature, and touch, facilitating an appropriate response.

While sensory and afferent nerves are closely related, "afferent" specifically denotes the direction of the information flow—toward the brain—whereas “sensory” generally describes the function of perceiving sensory input. Efferent nerves, in contrast, carry messages away from the brain and spinal cord to the muscles and glands, often resulting in a motor response. Motor nerves are a subset of efferent nerves dedicated to controlling muscles, not conveying sensory information. Understanding these distinctions is key in the study of neuroanatomy and physiology, as they delineate how the nervous system integrates sensory feedback and motor responses.