Peripheral Nervous System and Autonomic Division (PNS overview)

Vocabulary flashcards covering key terms from the peripheral nervous system lecture.

Peripheral nervous system (PNS)

The portion of the nervous system outside the brain and spinal cord, consisting of sensory (afferent) and motor (efferent) divisions that carry impulses to and from the body.

Afferent (sensory) division

The sensory component of the PNS that transmits impulses toward the CNS; includes somatosensory and visceral sensory pathways.

Efferent (motor) division

The motor component of the PNS that transmits impulses away from the CNS to effectors; includes somatic and autonomic nervous systems.

Somatic sensory (somatosensory)

Sensation from the body surface and musculoskeletal system (touch, proprioception, pain, temperature).

Visceral sensory

Sensation from internal organs (e.g., stomach fullness, heart rate, gut stretch).

Autonomic nervous system (ANS)

The part of the motor division that controls involuntary functions of viscera; includes sympathetic and parasympathetic divisions.

Sympathetic nervous system

Division of the ANS that prepares for 'fight or flight'; typically involves short preganglionic fibers that synapse in the sympathetic chain with longer postganglionic fibers to targets.

Parasympathetic nervous system

Division of the ANS promoting 'rest and digest'; long preganglionic fibers that synapse near or on the target organ with short postganglionic fibers.

Two-neuron autonomic pathway

The typical arrangement of autonomic innervation: a preganglionic neuron from the CNS to a ganglion, then a postganglionic neuron to the target organ.

Preganglionic fiber

Autonomic neuron fiber that travels from the CNS to the autonomic ganglion; long in parasympathetic, short in sympathetic.

Postganglionic fiber

Autonomic neuron fiber from the autonomic ganglion to the target organ; often unmyelinated or lightly myelinated.

Sympathetic trunk (sympathetic chain)

Vertical chain of sympathetic ganglia alongside the spinal column where most sympathetic synapses occur; connects via rami communicantes.

Dorsal root ganglion

Sensory neuron cell bodies located on the dorsal root of a spinal nerve; site of first-order sensory neurons.

White ramus communicante

Myelinated preganglionic sympathetic fiber entering the sympathetic ganglion.

Gray ramus communicante

Postganglionic sympathetic fiber exiting the ganglion to join a spinal or peripheral nerve.

Brachial plexus

Network of nerves from C5–T1 that innervates the upper limb; gives rise to median, radial, and ulnar nerves; organized into roots, trunks, divisions, and cords.

Median nerve

Major nerve of the arm formed from contributions of the lateral and medial cords; travels through the carpal tunnel and controls many hand movements; implicated in carpal tunnel syndrome.

Dermatomes

Skin regions innervated by a single spinal nerve; used to map sensory loss and locate lesions.