Anatomy and Physiology: Nervous System Comprehensive Review

Vocabulary flashcards covering nervous tissue, spinal cord anatomy, spinal nerves, sensory and motor tracts, brain regions, cranial nerves, and the autonomic nervous system based on human anatomy lecture materials.

Central Nervous System (CNS)

The anatomical division consisting of the brain and spinal cord, serving as the integrative and control centers of the nervous system.

Peripheral Nervous System (PNS)

All nervous tissue outside the central nervous system, including cranial nerves and spinal nerves, that serves as communication lines between the CNS and the rest of the body.

Sensory (Afferent) Division

The PNS division consisting of somatic and visceral sensory nerve fibers that conducts impulses from receptors to the CNS.

Motor (Efferent) Division

The PNS division consisting of motor nerve fibers that conducts impulses from the CNS to effectors (muscles and glands).

Somatic Nervous System

The voluntary motor division of the PNS that conducts impulses from the CNS to skeletal muscles.

Autonomic Nervous System (ANS)

The involuntary visceral motor division of the PNS that conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands.

Ependymal Cells

Ciliated CNS neuroglia that line cavities filled with cerebrospinal fluid and assist in CSF secretion and regulation.

Microglia

Phagocytic immune cells in the central nervous system that engulf microbes, waste products, and debris.

Astrocytes

Star-shaped CNS neuroglia that provide structural support, regulate interstitial fluid, maintain the blood-brain barrier, and repair damaged neural tissue.

Oligodendrocytes

CNS neuroglia that provide structural support and form myelin sheaths around segments of axons on multiple neurons.

Satellite Cells

PNS neuroglia that surround neuronal cell bodies in peripheral ganglia, isolating neurons and regulating nutrient and waste exchange with interstitial fluid.

Schwann Cells

PNS neuroglia that form myelin sheaths around segments of neuronal axons, with each cell covering a single internode.

Nodes of Ranvier

Small gaps that separate adjacent internodes along a myelinated axon.

Dendrites

Neuronal processes stimulated by other cells or the environment that convey electrical signals toward the cell body.

Axon

A neuronal process that conducts impulses away from the cell body toward axon terminals to release neurotransmitters.

Epineurium

The outermost dense connective tissue layer covering an entire peripheral nerve.

Perineurium

The connective tissue layer surrounding a single bundle of axons, called a fascicle, within a peripheral nerve.

Endoneurium

The delicate connective tissue layer surrounding an individual axon within a fascicle.

Anaxonic Neuron

A neuron with more than two processes where axons cannot be distinguished from dendrites.

Bipolar Neuron

A neuron having two distinct processes separated by the cell body.

Pseudounipolar Neuron

A neuron having a single elongate process with the cell body located off to one side.

Multipolar Neuron

A neuron with more than two processes, featuring a single axon and multiple dendrites.

Synapse

A functional junction that mediates information transfer between a neuron and another cell, such as another neuron, a muscle cell, or a gland cell.

Neuronal Pool

A group of interconnected neurons with one or more specific processing functions.

Divergence

A neural circuit pattern that spreads stimulation from one neuron to multiple neurons or neuronal pools in the CNS.

Convergence

A neural circuit pattern providing input to a single neuron from multiple sources.

Serial Processing

A neural circuit pattern in which neurons or pools work sequentially in a stepwise fashion.

Parallel Processing

A neural circuit pattern in which neurons or pools process the same information simultaneously.

Reverberation

A neural circuit pattern that functions via positive feedback to continually re-stimulate earlier neurons in the pathway.

Conus Medullaris

The tapered inferior extremity of the spinal cord located at the level of L1.

Filum Terminale

A fibrous strand within the coccygeal ligament anchoring the conus medullaris to the coccyx.

Cauda Equina

The collection of spinal nerve roots extending inferiorly beyond the conus medullaris.

Dura Mater

The superficial, tough, fibrous layer of the spinal and cranial meninges.

Arachnoid Mater

The middle meninx layer featuring a web-like network of collagen and elastic fibers, with a subarachnoid space filled with CSF.

Pia Mater

The deep meninx layer firmly bound to underlying neural tissue, containing supplying blood vessels.

White Ramus Communicans

A branch connecting T1–L2 spinal nerves to sympathetic ganglia containing myelinated preganglionic fibers.

Gray Ramus Communicans

A branch containing unmyelinated postganglionic fibers exiting a sympathetic chain ganglion to re-enter a spinal nerve.

Dermatome

A specific region of the body surface monitored by sensory fibers of a single pair of spinal nerves.

Phrenic Nerve

A major nerve originating from the cervical plexus ($C_3-C_5$) that innervates the diaphragm.

Reflex Arc

The complete neural pathway of a single reflex, including receptor, sensory neuron, CNS center, motor neuron, and effector.

Monosynaptic Reflex

A reflex circuit involving a single central synapse between a peripheral sensory neuron and a motor neuron.

Polysynaptic Reflex

A reflex circuit involving one or more interneurons between the sensory neuron and motor neurons.

Stretch Reflex

A monosynaptic spinal reflex initiated by muscle spindle stretching that results in reflexive contraction of the muscle.

Crossed Extensor Reflex

A polysynaptic reflex in which a flexion/withdrawal reflex in one limb induces extension in the opposite limb to maintain balance.

Sensory Modality Arrangement

The organization of sensory fibers in the spinal cord based on the specific type of sensory information carried.

Medial-Lateral Rule

The rule stating that sensory nerves entering the spinal cord at inferior levels travel more medially within a tract than nerves entering at superior levels.

Somatotopic Arrangement

The spatial arrangement of ascending sensory fibers within individual tracts according to their site of origin in the body.

Posterior Columns

Ascending sensory tracts carrying proprioception, fine touch, pressure, and vibration sensations to the primary somatosensory cortex.

Anterior Spinothalamic Tracts

Ascending sensory tracts carrying crude touch and pressure sensations to the thalamus.

Lateral Spinothalamic Tracts

Ascending sensory tracts carrying pain and temperature sensations to the thalamus.

Spinocerebellar Tracts

Ascending sensory tracts carrying proprioceptive information from muscles, tendons, and joints directly to the cerebellum.

Decussation

The crossing over of nerve fibers from one side of the CNS to the contralateral side.

Upper-Motor Neuron

A somatic motor neuron whose cell body lies in a CNS processing center and delivers commands to motor nuclei in the brainstem or spinal cord.

Lower-Motor Neuron

A somatic motor neuron whose cell body lies in a brainstem or spinal cord motor nucleus and relays commands directly to skeletal muscle fibers.

Corticospinal Tracts

Conscious motor tracts formed by upper-motor neuron axons descending from the primary motor cortex into the spinal cord.

Pyramids

Thick bands of corticospinal tract axons visible along the ventral surface of the medulla oblongata.

Primary Brain Vesicles

The three early embryonic brain expansions comprising the prosencephalon, mesencephalon, and rhombencephalon.

Secondary Brain Vesicles

The five embryonic brain subdivisions comprising the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.

Choroid Plexus

A specialized vascular structure in brain ventricles composed of permeable capillaries and ependymal cells that produces cerebrospinal fluid.

Arachnoid Granulations

Projections of the arachnoid mater through which cerebrospinal fluid drains into the dural sinuses.

Blood-Brain Barrier

A selective cellular barrier formed by capillary endothelial tight junctions and astrocyte processes that insulates neural tissue from general circulation.

Medulla Oblongata

The most inferior region of the brainstem containing vital autonomic centers that regulate cardiovascular, respiratory, and digestive functions.

Pons

The brainstem region relaying sensory information between the cerebellum and thalamus, containing respiratory control centers.

Corpora Quadrigemina

Four reflex centers on the tectum of the mesencephalon composed of the superior and inferior colliculi.

Superior Colliculi

Midbrain nuclei that integrate visual information and initiate somatic motor reflexes to visual stimuli.

Inferior Colliculi

Midbrain nuclei that integrate auditory information and initiate somatic motor reflexes to auditory stimuli.

Pineal Gland

An endocrine structure located in the epithalamus that secretes the hormone melatonin.

Thalamus

The principal relay and processing center in the diencephalon for sensory information heading to the cerebral cortex.

Hypothalamus

The diencephalic center controlling emotions, autonomic functions, hormone production, body temperature, and circadian rhythms.

Cerebellum

The posterior brain structure that coordinates complex somatic motor patterns and adjusts postural muscles for balance.

Arbor Vitae

The branching, tree-like layout of white matter visible in a sagittal section of the cerebellum.

Vermis

The narrow central band of tissue separating the left and right cerebellar hemispheres.

Gyri

Elevated ridges on the surface of the cerebral cortex that increase overall surface area.

Sulci

Shallow grooves separating adjacent gyri on the surface of the cerebral cortex.

Precentral Gyrus

The gyrus located immediately anterior to the central sulcus that contains the primary motor cortex.

Postcentral Gyrus

The gyrus located immediately posterior to the central sulcus that contains the primary somatosensory cortex.

Prefrontal Cortex

The anterior region of the frontal lobe responsible for higher intellectual functions, personality, abstract reasoning, and planning.

Corpus Callosum

A massive band of commissural fibers connecting the left and right cerebral hemispheres.

Association Fibers

Myelinated nerve fibers that connect different cortical regions within the same cerebral hemisphere.

Commissural Fibers

Myelinated nerve fibers that cross the midline to connect corresponding cortical regions between the two cerebral hemispheres.

Projection Fibers

Myelinated nerve fibers linking the cerebral cortex to lower regions of the brain and spinal cord.

Preganglionic Neuron

An autonomic visceral motor neuron whose cell body resides in the CNS and whose lightly myelinated axon extends to an autonomic ganglion.

Ganglionic Neuron

An autonomic visceral motor neuron whose cell body resides in an autonomic ganglion and whose unmyelinated postganglionic fiber extends to an effector.

Sympathetic Division

The thoracolumbar division of the ANS that mobilizes body systems during stress and emergency ('fight or flight').

Parasympathetic Division

The craniosacral division of the ANS that conserves energy and promotes rest and digestive functions ('rest and digest').

Sympathetic Chain Ganglia

Autonomic ganglia situated paired lateral to the vertebral column that innervate visceral organs and body wall structures.

Collateral Ganglia

Unpaired sympathetic ganglia situated anterior to the vertebral column that receive preganglionic fibers via splanchnic nerves.

Chromaffin Cells

Modified postganglionic neuroendocrine cells in the adrenal medulla that secrete epinephrine and norepinephrine into the blood.

Dual Innervation

The arrangement where a target organ receives nerve fibers from both the sympathetic and parasympathetic divisions of the ANS.