The nervous system is broadly categorized into two main types of nerves based on their function and direction of signal transmission:
1. Sensory Nerves (Afferent):
Sensory nerves carry information from the body's tissues and organs to the central nervous system (CNS), which includes the brain and spinal cord. They relay signals about sensations like touch, temperature, pain, and pressure. Think of them as the system's "incoming" lines.
- Examples: Nerves that detect a hot stove's heat and send a signal to your brain to pull your hand away; or nerves in your eyes sending visual information to your brain.
2. Motor Nerves (Efferent):
Motor nerves transmit signals from the CNS to muscles and glands, causing actions like muscle contractions or gland secretions. These are the system's "outgoing" lines, dictating movement and other bodily functions.
- Examples: Nerves instructing your hand to move, or those activating your salivary glands when you smell delicious food.
The peripheral nervous system (PNS), which contains these nerves outside the CNS, is further divided into the somatic and autonomic nervous systems. However, both the somatic and autonomic nervous systems utilize both sensory and motor nerves. The distinction lies in what they control (voluntary vs. involuntary actions).
The provided references mention both sensory and motor nerves, clarifying their roles in transmitting information to and from the central nervous system. The reference also notes that the peripheral nervous system (PNS) is further divided into the somatic and autonomic nervous systems. While this adds to the complexity of the nervous system, the fundamental division within the nerves themselves remains sensory and motor.
