Chapter 7: The Peripheral Nervous System

Vocabulary practice flashcards covering the components, structure, and functions of the peripheral nervous system, including cranial nerves, spinal nerves, nerve plexuses, and the autonomic division.

Peripheral Nervous System (PNS)

The nervous system division consisting of sensory receptors, nerves that link sensory receptors with the central nervous system (CNS), and nerves that link the CNS with effectors (muscles and glands).

Somatic Division

The division of the PNS that keeps the body in adjustment with the external environment; consists of sensory receptors and nerves.

Cranial Nerves

Twelve pairs of nerves that link the brain directly with sensory receptors and effectors.

Spinal Nerves

Thirty-one pairs of nerves that link the spinal cord with sensory receptors and effectors, divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal pairs.

Dorsal Root

The spinal root consisting of sensory fibers that transmits sensory impulses into the spinal cord.

Ventral Root

The spinal root consisting of motor fibers that carries motor impulses away from the spinal cord.

Spinal Ganglion

An enlargement visible on the dorsal root just before it joins the spinal cord, containing the cell bodies of sensory neurons.

Dorsal Branch

The branch of a spinal nerve that supplies the skin and muscles of the dorsal part of the body.

Ventral Branch

The branch of a spinal nerve that supplies the ventral and lateral regions of the body trunk.

Plexus

A complex network formed by the joining of the ventral branches of several spinal nerves.

Cervical Plexus

The nerve plexus that serves the head, neck, and shoulders (derived from C1-C4).

Brachial Plexus

The nerve plexus that supplies the shoulder, arm, and hand (derived from C5-T1).

Lumbar Plexus

The nerve plexus that supplies the lower abdominal wall, buttocks, and genitals (derived from L1-L4).

Sacral Plexus

The nerve plexus that supplies the thigh, leg, and foot (derived from L5-S3).

Autonomic Division

The division of the PNS that works to maintain a steady state within the internal environment; divided into sympathetic and parasympathetic systems.

Autonomic Reflex Pathway

A visceral reflex pathway consisting of an afferent neuron, an interneuron in the spinal cord, and a two-neuron efferent chain (preganglionic and postganglionic neurons synapsing in a ganglion) leading to an effector organ.

Sympathetic Nervous System

The efferent autonomic system emerging from the thoracic and lumbar regions of the spinal cord that mobilizes energy and prepares the body for action during stress.

Parasympathetic Nervous System

The efferent autonomic system emerging from the brain and the sacral region of the spinal cord that works to conserve and restore energy during periods of relaxation.

Sympathetic Preganglionic Neuron

The first efferent neuron of the sympathetic pathway; it emerges from the spinal cord, ends in a sympathetic chain ganglion or collateral ganglion, is cholinergic, and releases acetylcholine.

Sympathetic Postganglionic Neuron

The second efferent neuron of the sympathetic pathway; it innervates smooth muscle or sweat glands, is adrenergic, and releases norepinephrine.

Terminal Ganglia

Parasympathetic ganglia located near or directly within the walls of the organs they innervate, where preganglionic neurons synapse with postganglionic neurons.

Dual Innervation

The supply of an organ by both sympathetic and parasympathetic nerves, typically producing opposing physiological responses such as accelerating or slowing heart rate.