Nervous System Anatomy and Physiology

Comprehensive vocabulary flashcards covering the structural divisions, embryology, lobes, functional areas, tracts, meninges, fluid circulation, peripheral nerves, and clinical correlations of the human nervous system.

Nervous System

A group of tissues composed of highly specialized cells possessing the characteristics of excitability and conductivity.

Somatic Efferent Division

The functional division of the nervous system innervating somatic structures such as skeletal muscles and skin.

Visceral Efferent Division

The autonomic nervous system division innervating visceral or involuntary structures including smooth muscles, cardiac muscles, and glands.

Neurons

The active conducting elements and basic units of the nervous system that conduct electrical impulses from one part of the body to another.

Neuroglia

The supporting elements (glial cells) of the nervous system, consisting of astrocytes, oligodendrocytes, microglia, and ependymal cells.

Synapse

The point of functional connection between neurons.

Myelin Sheath

An insulating material covering axons in the central and peripheral nervous system.

Saltatory Conduction

The mode of nerve impulse transmission where the electrical impulse jumps from node to node in the myelin sheath rather than traveling continuously along the nerve fiber.

Gray Matter

Gross division of the central nervous system characterized by a preponderance of nerve cell bodies and true dendrites.

White Matter

Gross division of the central nervous system composed chiefly of myelinated nerve fibers and essential for conducting nerve signals.

Brain

The part of the central nervous system contained within the skull; average weight in adults is approximately $1380\,\text{g}$ in males and $1250\,\text{g}$ in females.

Prosencephalon

The embryological forebrain, which subdivides into the telencephalon (cerebrum) and diencephalon (thalamus, hypothalamus, epithalamus, and subthalamus).

Mesencephalon

The embryological midbrain, consisting of the corpora quadrigemina (tectum), cerebral peduncles, and cerebral aqueduct of Sylvius.

Rhombencephalon

The embryological hindbrain, which subdivides into the metencephalon (cerebellum, pons) and myelencephalon (medulla oblongata).

Longitudinal Fissure

The deep groove dividing the cerebrum into right and left cerebral hemispheres, which remain connected at the midline by the corpus callosum.

Lateral Sylvian Fissure

The sulcus located between the frontal and parietal lobes superiorly and the temporal lobe inferiorly.

Central Sulcus (Rolandic Fissure)

The sulcus separating the frontal lobe from the parietal lobe.

Transverse Fissure

The fissure separating the cerebrum from the cerebellum.

Parieto-occipital Fissure

The groove located between the parietal and occipital lobes.

Calcarine Fissure

A fissure found in the occipital lobe that serves as the visual center (calcarine area).

Frontal Lobe

The cerebral cortex region anterior to the central sulcus and superior to the lateral sulcus; serves as the center for motor functions and personality.

Parietal Lobe

The cerebral cortex region lying posterior to the central sulcus and superior to the lateral Sylvian fissure; serves as the center for sensory functions.

Temporal Lobe

The cerebral cortex region lying beneath the lateral sulcus of Sylvius; serves as the center for hearing and olfaction.

Occipital Lobe

The cerebral cortex region occupying the posterior extremity behind the parieto-occipital fissure; serves as the visual center.

Insula (Island of Reil)

The cortical structure exposed when the lips of the lateral Sylvian fissure are drawn apart.

Primary Motor Area (Pre-central Gyrus)

Brodmann's area $4$, located in the frontal lobe anterior to the central sulcus, responsible for voluntary movements on the opposite side of the body.

Pre-motor Area

Cortical area situated in front of the primary motor area that exerts a controlling influence to ensure an orderly series of movements.

Pre-frontal Area

Cortical area concerned with behavior, character, emotional state, foresight, good judgment, and abstract thinking.

Primary Sensory / Somesthetic Area (Post-central Gyrus)

Brodmann's area $3, 1, 2$, located in the parietal lobe behind the central sulcus; receives and interprets sensations of pain, temperature, pressure, touch, and position/movement from the opposite side of the body.

Broca's Area (Motor Speech Area)

Brodmann's area $44, 45$, located in the inferior frontal gyrus of the dominant hemisphere; responsible for speech production.

Wernicke's Area (Sensory Speech Area)

Brodmann's area $22$, located in the temporal lobe posterior to the auditory area of the dominant hemisphere; responsible for language comprehension.

Transverse Gyri of Heschl (Auditory Area)

Brodmann's area $41$ and $42$, located below the lateral sulcus within the temporal lobe; functions as the center for hearing.

Visual Area

Brodmann's area $17$, located around the calcarine fissure and encompassing the greater part of the occipital lobe.

Hypothalamus

Diencephalic brain structure involved in the regulation of body temperature, feeding activities, biorhythm, and emotion.

Cerebral Peduncles

A pair of cylindrical bodies on the anterior aspect of the midbrain made up of nerve fiber tracts connecting the forebrain with the hindbrain.

Corpora Quadrigemina

Four colliculi on the posterior midbrain tectum; composed of two superior colliculi (visual reflexes) and two inferior colliculi (auditory reflexes).

Vermis

The constricted central portion of the cerebellum connecting the lateral cerebellar hemispheres.

Flocculonodular Lobe

A cerebellar lobe specifically concerned with the regulation of equilibrium, posture, and balance.

Pons

A bridge-like structure consisting almost entirely of white matter linking various parts of the brain, situated anterior to the cerebellum and between the midbrain and medulla.

Medulla Oblongata

The brainstem structure continuous with the spinal cord inferiorly and pons superiorly, containing vital centers for the circulatory system, breathing, swallowing, vomiting, coughing, and sneezing.

Pachymeninx

The thick, tough outer protective layer of the meninges, consisting of the dura mater.

Leptomeninges

The thin, delicate inner layers of the meninges, comprising the arachnoid mater and pia mater.

Cerebrospinal Fluid (CSF)

A colorless fluid resembling lymph with an approximate volume of $150\,\text{ml}$, produced by the choroid plexus to act as a protective water cushion for the brain and spinal cord.

Conus Medullaris

The tapered, conical lower termination of the spinal cord occurring at the level of the first lumbar vertebra in adults.

Filum Terminale

A thread-like fibrous prolongation extending downward from the conus medullaris.

Cauda Equina

The bundle of lumbar and sacral spinal nerve roots that descends along the filum terminale inside the lower vertebral canal.

Cervical Plexus

A nerve network formed by the ventral rami of $C_1$ to $C_4$ spinal nerves; innervates the head and neck and gives origin to the phrenic nerve.

Brachial Plexus

A nerve network formed by the lower four cervical nerves ($C_5$ to $C_8$) and the first thoracic nerve ($T_1$); innervates the skin and muscles of the upper limb.

Sciatic Nerve

The largest nerve in the body, arising from the sacral plexus ($L_4, L_5, S_1, S_2, S_3$) and dividing into the tibial and common peroneal nerves.

Thoracolumbar Division

The sympathetic division of the autonomic nervous system, arising from all thoracic segments and the first three lumbar segments of the spinal cord.

Craniosacral Division

The parasympathetic division of the autonomic nervous system, arising from cranial nerves $III, VII, IX, X$ and sacral segments $S_2, S_3, S_4$ of the spinal cord.

Cerebrovascular Accident (CVA)

Brain injury resulting from an interruption of blood flow caused by an occluding clot or a compressing tumor; commonly known as stroke.

Hydrocephalus

A condition characterized by an abnormal increase in cerebrospinal fluid pressure, usually resulting from obstruction of the CSF pathway.

Plegia

The complete loss of voluntary motor function resulting from dysfunction within the nervous system.

Paresis

Weakness or partial loss of voluntary muscle activity.

Infantile Paralysis (Poliomyelitis)

Condition caused by a viral infection that damages the anterior horn cells of the spinal cord and the motor nuclei of the cranial nerves.