Question

Give a brief account of peripheral nervous system.

Answer 1

The PNS comprises all neural structures located outside the central nervous system (brain and spinal cord), connecting the central nervous system to the rest of the body. It is divided into two primary divisions:

1. Somatic Nervous System:

• Cranial Nerves: They consists of 12 pairs of nerves emerging directly from the brain, such as the olfactory, optic, and auditory nerves.
• Spinal Nerves: They consists of 31 pairs of mixed nerves emerging from the spinal cord (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal). Each spinal nerve branches into a dorsal root of sensory fibres and a ventral root of motor fibres.

2. Autonomic Nervous System (ANS):

• Nature of ANS: It operates without conscious control to manage internal activities and respond to stress. It consists of two complementary, antagonistic systems.
• Sympathetic System: It arises from the spinal cord, prepares the body for 'fight or flight' during emergencies or stress, and controls adrenaline release.
• Parasympathetic System: It arises from the brain and exits via cranial nerves, counteracting sympathetic actions and restoring calm and normal functioning.