Peripheral Nervous System Overview

Peripheral Nervous System Overview

• The peripheral nervous system (PNS) includes 12 pairs of cranial nerves and 31 pairs of spinal nerves.
• Cranial nerves (CN1-CN12) are associated with the brain, specifically the skull.

Spinal Nerves

• Spinal nerves branch from segments of the spinal cord.
• Specific spinal nerve pairs exist for the different segments:
  • 8 pairs of cervical nerves
  • 12 pairs of thoracic nerves
  • 5 pairs of lumbar nerves
  • 5 pairs of sacral nerves
  • 1 pair of coccygeal nerves

Cranial Nerve Functions (Illustrative Examples)

• This section focuses on the general functions, illustrative examples regarding the functionality of specific cranial nerves are shown from the figure.

• Olfactory (I): Smell

• Optic (II): Vision

• Oculomotor (III), Trochlear (IV), Abducens (VI): Eye movement.

• Trigeminal (V): Facial sensation and chewing.

• Facial (VII): Facial expressions and taste.

• Vestibulocochlear (VIII): Hearing and balance.

• Glossopharyngeal (IX): Taste and swallowing.

• Vagus (X): Extensive functions, including digestive organs, heart rate.

• Accessory (XI): Neck and shoulder movement.

• Hypoglossal (XII): Tongue movement.

Spinal Nerve Functions (Illustrative Examples)

• This section focuses on general functions (illustrative examples regarding the functionality of specific spinal nerves have been shown from the figure).

• Cervical nerves (C1-C8): Control neck, shoulder, and upper limb movements.

• Thoracic nerves (T1-T12): Involved in functions throughout the trunk and contribute to sympathetic tone (e.g., temperature regulation).

• Lumbar nerves (L1-L5): Control lower limb movements.

• Sacral nerves (S1-S5): Involved in bowel and bladder function, and sexual function.

• Coccygeal nerve (CO): Innervates muscles and skin around the coccyx.