Nerves are a collection of nerve fibres in the central nervous system. Nerves are an enclosed bundle of peripheral axons. They are cable-like in appearance and they provide the pathway for nerve impulses that are transmitted along the axons. Nerves are found in the peripheral nervous system. All nerves have a cordlike structure and contain many axons. Each of these axons are surrounded the endoneurium, these are layers of connective tissues. The axons, in turn, are bundled together to form fascicles, these fascicles are wrapped in another layer of connective tissue called the perineurium. Nerves are again wrapped in another set of connective tissues called epineurium.
There are three categorizations for nerves: Afferent nerves, efferent nerves and mixed nerves.
Afferent Nerves main purpose is to conduct signals from the sensory neurons to the central nervous system while Efferent Nerves essentially conducts signals from the central nervous system. Mixed Nerves are a combination of these two; they conduct both incoming and outgoing impulses to and from the central nervous system.
Nerves can be further categorized based on where they are connected. The two categories are: Spinal nerves that are connected through the spinal column to the spinal cord and Cranial nerves that are directly connected to the brainstem. Spinal nerves are given letter and number designations whereas cranial nerves are assigned roman numerals from 1 to 12.
Nerves transmit information through electrochemical impulses or what is known as nerve impulses. These are carried out by individual neurons that make up the nerve. Nerve impulses can travel really fast at speeds of 120 m/s. The impulses travel through the synapse. There are two categorizations of nerves based on their function: sensory nerves, which convey information from receptors to the central nervous system and motor nerves, which convey information from the central nervous system to the muscles. These two are similar to afferent and efferent nerves.
Nerves are an essential part of our anatomy. The peripheral nervous system contains more than 100 billion nerve cells. The peripheral nervous system has two parts:
The Somatic Nervous System, which contains nerves that are connected to the brain and spinal cord through muscles that you control consciously, these are called voluntary or skeletal muscles. It also has receptors in the skin that detect information inside and around the body.
The Autonomic Nervous System is the one responsible for connecting the brain stem and spinal cord with the internal organs. This part regulates the processes in our body that does not require any conscious effort to operate, such as, blood pressure, breathing, heart contractions and the speed the food is digested, among others.
As an important part of the body, any damage to the nerves may have severe consequences. These damages can be caused by a number of different things such as, physical injury, autoimmune diseases, diabetes, infection, swelling, paralysis, weakness and numbness. People who have damaged nerves may experience the pain in other parts of their body far from the actual site of damage. This is called referred pain, this occurs when the nerves is damaged. Any damage to the nerves, no matter how small, should be referred to a neurologist. The neurologist will then find out what is wrong through a physical examination.