Topic 4: Anatomy of the Nervous System A

Vocabulary flashcards covering CNS vs PNS, neuron structure and function, glial cells, nerves, trunks like spinal nerves, plexuses, peripheral nerves, motor units, and autonomic/somatic divisions as described in the notes.

Central Nervous System (CNS)

The brain and spinal cord.

Peripheral Nervous System (PNS)

Everything outside the CNS; includes nerves, plexuses, and peripheral nerves.

Neuron

A nerve cell; the basic functional unit of the nervous system that transmits and receives impulses.

Soma (cell body)

The main body of a neuron that contains the nucleus and major organelles.

Axon

A single long process that conducts nerve impulses away from the soma; may branch to contact multiple targets.

Dendrite

Branched processes that receive input from other neurons.

Synapse

A junction where a neuron communicates with another cell via neurotransmitters.

Synaptic End Bulb

Enlarged end of an axon terminal at the synapse.

Neuroglia/Glial Cells

Supportive cells in nervous tissue that help neurons function; provide framework and other roles.

Nerve

A bundle of axons in the PNS; can be sensory, motor, or mixed, containing hundreds to thousands of neurons.

Tract

A bundle of axons in the CNS (the equivalent of a nerve in the CNS).

Intervertebral Foramen

The opening through which a spinal nerve exits the vertebral column.

Spinal Nerve

Nerve that exits the spinal cord at a specific level; named by spinal level (e.g., C1–C8).

31 Spinal Nerves

Eight cervical (C1–C8), twelve thoracic (T1–T12), five lumbar (L1–L5), five sacral (S1–S5), and one coccygeal nerve.

Cervical Plexus

Plexus supplying nerves to the posterior head/neck and diaphragm.

Brachial Plexus

Plexus supplying nerves to the arm.

Lumbar Plexus

Plexus supplying nerves to the anterior thigh.

Sacral Plexus

Plexus supplying nerves to the posterior leg.

Musculoskeletal Nerve (e.g., Musculocutaneous Nerve)

A peripheral nerve that innervates muscles (and sometimes skin); example: musculocutaneous nerve innervates the biceps brachii.

Motor Unit

One motor neuron and all the muscle fibers it innervates; recruitment of multiple motor units increases contraction strength.

Upper Motor Neuron

A neuron located in the CNS that synapses onto lower motor neurons.

Lower Motor Neuron

A neuron that directly innervates skeletal muscle; located in the spinal cord or brainstem.

Somatic Nervous System (SNS)

Voluntary nervous system; innervation of skeletal muscles; includes reflexes and learned motor skills.

Autonomic Nervous System (ANS)

Involuntary nervous system; regulates glands, smooth muscle, and cardiac muscle to maintain homeostasis.

Parasympathetic Nervous System

Subdivision of the ANS associated with rest and digest activities.

Sympathetic Nervous System

Subdivision of the ANS associated with fight or flight responses.

Integration/Association Areas

Brain regions that integrate sensory input with memory, emotion, and learning to produce responses.

Nerve vs. Tract

Nerve: bundle of neurons/axons in the PNS; Tract: bundle of axons in the CNS.

Peripheral Nerve Innervation

Peripheral nerves can innervate multiple muscles and skin areas; a single neuron may contribute to several targets.