Peripheral Nervous System and Central Nervous System Architecture

Comprehensive vocabulary flashcards covering the subdivisions, efferent pathways, neurotransmitters, ganglia, pharmacology, embryological development, protective structures, functional brain regions, and cranial nerves of the peripheral and central nervous systems based on the lecture notes.

Somatic Nervous System

A subdivision of the peripheral nervous system consisting of sensory neurons related to touch, pain, temperature, proprioception, and special senses, as well as motor neurons under voluntary control that innervate skeletal muscles.

Autonomic Nervous System (ANS)

A subdivision of the peripheral nervous system responsible for involuntary motor innervation of smooth muscle, cardiac muscle, and glands, as well as receiving sensory input from organs and blood vessels.

Preganglionic Neuron

The first motor neuron in an autonomic two-neuron chain, with its cell body located in the brain or spinal cord and a lightly myelinated axon extending to an autonomic ganglion or the adrenal medulla.

Postganglionic Neuron

The second motor neuron in an autonomic two-neuron chain, whose cell body resides in an autonomic ganglion and whose unmyelinated axon extends directly to an effector organ.

Sympathetic Nervous System

The fight-or-flight division of the autonomic nervous system that mobilizes the body during activity by raising alertness, cellular metabolic rate, heart rate, and tissue activity.

Parasympathetic Nervous System

The rest-and-digest division of the autonomic nervous system that counteracts sympathetic stimulation by slowing down most body activities and conserving energy.

Dual Innervation

The arrangement in which visceral organs are served by both sympathetic and parasympathetic divisions, exerting dynamic antagonism to sustain homeostatic balance.

Thoracolumbar Division

Another term for the sympathetic nervous system, referring to the location of its preganglionic cell bodies in the lateral horns of spinal cord segments T1–T12 and L1–L2/3.

White Rami Communicantes

Structures containing lightly myelinated preganglionic sympathetic axons that leave the anterior root of a spinal nerve to enter a sympathetic trunk ganglion.

Gray Rami Communicantes

Structures containing unmyelinated postganglionic sympathetic axons that exit a sympathetic trunk ganglion to merge with the anterior ramus of a spinal nerve.

Splanchnic Nerves

Nerves composed of preganglionic sympathetic axons that pass through the sympathetic trunk without synapsing, extending to synapse in paravertebral (prevertebral) ganglia or the adrenal medulla.

Chromaffin Cells

Specialized cells within the adrenal medulla that act functionally as modified sympathetic postganglionic neurons, secreting epinephrine and norepinephrine into the bloodstream when stimulated.

Terminal Ganglia

Parasympathetic ganglia located near target visceral organs or situated directly within the walls of the organs themselves.

Cholinergic Neurons

Neurons that release acetylcholine (ACh) from their axon terminals, encompassing all autonomic preganglionic neurons, parasympathetic postganglionic neurons, and sympathetic postganglionic neurons to sweat glands.

Adrenergic Neurons

Neurons that release norepinephrine (NE) from their axon terminals, comprising most sympathetic postganglionic neurons.

Nicotinic Receptors

A type of cholinergic receptor present on all postganglionic neurons that produces an excitatory response whenever bound by acetylcholine.

Muscarinic Receptors

Cholinergic receptors found on parasympathetic target effectors and sweat glands that trigger either excitatory or inhibitory responses depending on the host cell.

Sympathomimetic Drugs

Pharmacological agents, such as phenylephrine, that bind to adrenergic receptors and mimic the actions of norepinephrine in the sympathetic efferent pathway.

Sympatholytic Drugs

Medications, such as β-blockers, that act as antagonists to adrenergic receptors and block or diminish sympathetic activity.

Neural Tube

A fluid-filled structure formed by the folding of the embryonic outer layer that gives rise to the ventricles, brain, and spinal cord.

Dural Folds

Inward extensions of the meningeal dura mater—comprising the falx cerebri, falx cerebelli, and tentorium cerebelli—that separate and support brain structures.

Cerebrospinal Fluid (CSF)

A clear fluid composed of water, glucose, electrolytes, proteins, and lymphocytes that nourishes, protects, and provides buoyancy to the brain and spinal cord.

Choroid Plexuses

Structures located within the ventricles of the brain that are covered by ependymal cells to filter blood plasma and produce cerebrospinal fluid.

Blood-Brain Barrier

A protective barrier formed by capillary endothelial cells connected by tight junctions, basal laminae, and astrocyte processes that prevents pathogens and large polar molecules from entering brain extracellular fluid.

Primary Motor Cortex

A functional area located in the precentral gyrus of the frontal lobe that contains upper motor neurons responsible for consciously planning and controlling voluntary motor output.

Primary Somatosensory Cortex

A sensory area located in the postcentral gyrus of the parietal lobe that receives impulses for touch, pressure, pain, temperature, vibration, tickle, itch, and proprioception.

Broca's Area

A motor area in the frontal lobe, typically located on the left hemisphere, that coordinates muscle movements necessary for speech production.

Thalamus

A superior diencephalic region containing grouped nuclei that acts as the primary relay station for all incoming sensory information to the cerebral cortex, with the exception of olfaction.

Hypothalamus

An essential region of the diencephalon situated inferior to the thalamus that serves as the major link between the nervous and endocrine systems and regulates autonomic functions, body temperature, hunger, thirst, and circadian rhythms.

Pineal Gland

An endocrine structure located in the epithalamus that secretes melatonin to assist in establishing the body's sleep/wake cycle.

Medulla Oblongata

The most inferior segment of the brainstem, continuous with the spinal cord, containing medullary pyramids, cardiac and respiratory centers, and cranial nerve nuclei for CN VIII through CN XII.

Pons

A brainstem region superior to the medulla oblongata that functions as a bridge connecting the cerebrum to the cerebellum and contains nuclei for CN V, VI, VII, and VIII.

Corpora Quadrigemina

Four elevated reflex centers on the tectum of the midbrain, consisting of two superior colliculi for visual reflexes and two inferior colliculi for auditory reflexes.

Arbor Vitae

The tree-like branching arrangement of inner white matter inside the cerebellum.

Hippocampus

A core structure of the limbic system essential for forming long-term memories and storing information.

Amygdaloid Body

A limbic system structure heavily involved in processing emotional states, particularly fear.

Olfactory Nerve (CN I)

A pure sensory cranial nerve originating in the nasal epithelium that passes through the cribriform plate to the olfactory bulb to convey the sense of smell.

Optic Nerve (CN II)

A sensory cranial nerve formed by retinal ganglion cell axons that passes through the optic canal to transmit visual impulses to the lateral geniculate nucleus and visual cortex.

Oculomotor Nerve (CN III)

A motor cranial nerve originating in the midbrain that innervates most extraocular muscles, as well as providing parasympathetic input for pupil constriction and lens accommodation.

Trochlear Nerve (CN IV)

A motor cranial nerve arising from the posterior midbrain that innervates the superior oblique muscle to depress and intort the eyeball.

Trigeminal Nerve (CN V)

The largest cranial nerve, divided into ophthalmic (V1), maxillary (V2), and mandibular (V3) branches, providing general facial sensation and motor innervation for mastication.

Abducens Nerve (CN VI)

A motor cranial nerve emerging from the pons that innervates the lateral rectus muscle to abduct the eyeball.

Facial Nerve (CN VII)

A mixed cranial nerve responsible for facial expression muscles, taste from the anterior two-thirds of the tongue, and parasympathetic innervation of lacrimal, submandibular, and sublingual glands.

Vestibulocochlear Nerve (CN VIII)

A pure sensory cranial nerve composed of a vestibular branch for balance and a cochlear branch for hearing.

Glossopharyngeal Nerve (CN IX)

A mixed cranial nerve that provides taste and sensation from the posterior one-third of the tongue, monitors blood pressure and gases, controls swallowing muscles, and innervates the parotid gland.

Vagus Nerve (CN X)

A mixed cranial nerve carrying approximately 90% of parasympathetic fibers to thoracic and abdominal organs, regulating heart rate, airway diameter, and GI motility.

Accessory Nerve (CN XI)

A motor cranial nerve arising from the spinal cord and medulla that innervates the sternocleidomastoid and trapezius muscles to coordinate head, neck, and shoulder movements.

Hypoglossal Nerve (CN XII)

A motor cranial nerve originating from the medulla oblongata that innervates intrinsic and extrinsic tongue muscles required for speech, mastication, and swallowing.