Week 4 Nervous System Quick Review

Vocabulary flashcards covering key terms and concepts from the nervous system notes.

Central Nervous System (CNS)

Brain and spinal cord; the site for intelligence, memory, learning, and processing of sensory input and motor output.

Peripheral Nervous System (PNS)

Nerves outside the CNS, including cranial and spinal nerves; divided into sensory (afferent) and motor (efferent) divisions.

Sensory (Afferent) Division

Carries sensory information to the CNS; subdivides into Sensory Visceral and Sensory Somatic.

Motor (Efferent) Division

Carries motor commands from the CNS to muscles and glands; subdivides into Motor Somatic and Motor Visceral.

Autonomic Nervous System (ANS)

Visceral motor division of the PNS; divided into Sympathetic (fight or flight) and Parasympathetic (rest and digest) divisions.

Preganglionic Neuron

Axon that synapses with autonomic ganglia.

Postganglionic Neuron

Axon connecting autonomic ganglia to peripheral effectors.

Dura Mater

Outer covering of the brain and spinal cord.

Arachnoid Mater

Middle meninx; contains arachnoid trabeculae extending to the pia.

Pia Mater

Innermost meninx; tightly adheres to brain and spinal cord.

Arachnoid Trabeculae

Bundles of fibers connecting arachnoid to pia mater.

Cerebrospinal Fluid (CSF)

Fluid in the subarachnoid space that cushions the CNS and is regulated/produced by ependymal cells.

Neuron

Basic functional and structural unit of nervous tissue; excitable and conductive; composed of soma, dendrites, and axon.

Soma (Cell Body)

Main metabolic center of the neuron.

Dendrites

Branching extensions that receive impulses and conduct them toward the cell body.

Axon

Long process that conducts impulses away from the cell body.

Neuroglial Cells

Supporting cells of nervous tissue; include CNS types (astrocytes, microglia, oligodendrocytes, ependymal) and PNS types (Schwann and Satellite cells).

Astrocytes

Star-shaped glial cells; anchor blood vessels to neurons and support the blood–brain barrier; provide nutrients.

Microglia

Small glial cells that act as phagocytes.

Oligodendrocytes

Glial cells that form myelin sheaths around CNS axons.

Ependymal Cells

Line the brain ventricles and spinal central canal; regulate and produce CSF.

Schwann Cells

PNS glial cells that form myelin sheaths around peripheral axons.

Satellite Cells

PNS glial cells surrounding dorsal root and autonomic ganglia.

Nodes of Ranvier

Gaps in the myelin sheath where axonal membrane is exposed; facilitate rapid conduction.

Ganglia

Clusters of neuron cell bodies in the PNS.

Spinal Cord Segments

31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.

Conus Medullaris

Tapered end of the spinal cord below the lumbar enlargement.

Cauda Equina

Bundle of spinal nerves and roots beyond the conus medullaris; resembles a horse’s tail.

Filum Terminale

Filamentous tissue that anchors the spinal cord to the coccyx.

White Matter

Outer region of the spinal cord composed of myelinated axons; organized into columns; conveys signals up and down.

Gray Matter

Inner region of the spinal cord shaped like an H; contains neuron cell bodies and unmyelinated fibers; has dorsal, ventral, and lateral horns.

Dorsal (Posterior) Horn

Contains cell bodies of sensory neurons and interneurons; visceral sensory nuclei present.

Ventral (Anterior) Horn

Contains somatic motor nuclei.

Lateral Horns

Contain autonomic (visceral) motor neuron cell bodies.

Nerves

Bundles of peripheral axons and tracts of central axons.

Second-Order Neuron

A neuron with cell body in the posterior horn that ascends to the brain.

Spinothalamic Tract

Ascending sensory pathway carrying pain and temperature to the primary somatosensory cortex.

Posterior (Dorsal) Column

Ascending tract composed of fasciculus cuneatus and fasciculus gracilis; carries fine touch, proprioception, and vibration.

Fasciculus Cuneatus

Part of the dorsal column carrying upper body proprioception and fine touch.

Fasciculus Gracilis

Part of the dorsal column carrying lower body proprioception and fine touch.

Receptors (Somatic vs Visceral)

Classified by location: somatic receptors in body walls/skeletal muscles; visceral in internal organs.

Proprioceptors

Receptors that monitor position and movement of muscles and joints.

Effectors

Muscle cells, gland cells, and other cells that respond to neural stimuli.

Spinocerebellar Tracts

Ascending pathways that carry proprioceptive information to the cerebellum for coordination and balance.

Corticospinal Tract

Major descending motor pathway from the cerebral cortex to the spinal cord; controls voluntary movement and fine motor skills.

Nerve Coverings (Layers)

Endoneurium surrounds individual nerve fibers; Perineurium surrounds a fascicle; Epineurium surrounds the whole nerve.

Spinal Nerves

31 pairs; formed by the joining of dorsal and ventral roots; mixed nerves with motor and sensory fibers.

Ventral Root

Contains axons of motor neurons.

Dorsal Root

Contains axons of sensory neurons.

Mixed Spinal Nerves

Spinal nerves contain both motor and sensory fibers because dorsal and ventral roots join to form them.

Ventral and Dorsal Rami

Branches of spinal nerves; ventral rami form major plexuses.

Plexuses

Networks of nerves: cervical, brachial, lumbar, lumbosacral, coccygeal.

Major Plexus Nerves

Phrenic, radial, median, ulnar, femoral, sciatic—arise from plexuses and innervate limbs.

Sciatic Nerve

Largest nerve in the body; arises from L4–S3 segments.