Nerves: Types, Function & Anatomy

Overview

What are nerves?

• Nerves are like cables carrying electrical impulses between the brain and the body.
• These impulses help feel sensations and move muscles; they support autonomic functions like breathing, sweating, and digestion.
• Nerve cells, or neurons, are found throughout the body, especially in the brain and spinal cord.
• Nerves, along with the brain and spinal cord, compose the nervous system.
• Peripheral nervous system refers to nerves outside the brain and spinal cord.

Types of Nerves

• Sensory Nerves: Carry signals to the brain for touch, taste, smell, and sight.
• Motor Nerves: Send signals to muscles/glands for movement and function.

Groups of Nerves

• Cranial Nerves:
  • 12 pairs originate in the brain, extending through face, head, and neck.
  • Functions: sensory, motor, or both (e.g., facial expressions, eye movement).
• Spinal Nerves:
  • 31 pairs from the spinal cord, providing sensory/motor functions.
  • Control reflexes, e.g., pulling away from a hot stove.

Function

Purpose of Nerves

• Nerves send electrical signals controlling:
  • Voluntary movement.
  • Senses (touch, pain, temperature, vibration, hearing, balance, taste, smell, sight).
  • Blood pressure, breathing, digestion, heart rate, stress response.

Interaction with Nervous System

• Peripheral Nervous System: Network transmitting signals to the spinal cord.
• Central Nervous System: Brain and spinal cord, receives/interprets signals.
  • Brain processes inputs for movement, sensation, behavior, thought.
  • Reflexive actions occur subconsciously.

Nerve Signal Transmission

1. Signal travels down axon.
2. Converts to chemical signal at axon hillock.
3. Releases neurotransmitters into synapses.
4. Neurotransmitter binds to receptor, converting back to electrical signal.
5. Signal continues until reaching target.

Anatomy

Location of Nerves

• Originate in spinal cord/brain, extending to:
  • Arms: Ulnar, median, radial, axillary nerves.
  • Chest/Abdomen: Vagus, phrenic nerves.
  • Face: Facial, trigeminal, optic nerves.
  • Legs: Sciatic, femoral, tibial, obturator, sural nerves.
  • Pelvis: Pudendal nerve.

Structure of Nerves

• Axons: Central fibers.
• Dendrites: Branches carrying impulses.
• Endoneurium: Connective tissue surrounding axons.
• Perineurium: Surrounds axon groups (fascicles).
• Epineurium: Outer connective tissue layer.
• Myelin sheath (oligodendrocytes in brain, Schwann cells outside CNS) insulates axons.

Conditions and Disorders

Affecting Nerves

• Peripheral Neuropathy: Damage to peripheral nerves.
• Sciatica: Pain affecting lower back nerve roots, sciatic nerve.

Care

Keeping Nerves Healthy

• Avoid tobacco, limit alcohol.
• Eat nutritious diet, manage diabetes.
• Reduce stress through meditation/exercise.
• Ensure adequate sleep and hydration.

Doctor Consultation

• Identifying nerve pain and causes.
• Available tests and treatments for nerve health.
• Strategies for preventing nerve issues.

Note from Cleveland Clinic

• Nerves enable movement, sensation, and control of automatic functions.
• Healthy habits support nervous system health.
• Cleveland Clinic offers expert guidance for neurological conditions.

Medically Reviewed: 03/22/2022