Nervous System: Brain, Spinal Cord, and Peripheral Pathways

Comprehensive vocabulary flashcards covering the structural divisions, functional areas, tracts, meninges, reflexes, and autonomic divisions of the central and peripheral nervous system.

Cerebrum

The large rounded portion of the brain divided into left and right hemispheres that processes voluntary motor functions, general and special senses, and higher-level cognitive processes.

Gyri

The numerous outward folds, ridges, or rounded masses located all around the surface of the cerebrum.

Sulci

The grooves, lines, or divots situated between the gyri of the cerebrum.

Central sulcus

The groove extending from the top of the cerebrum down to the lateral fissure that anatomically separates the frontal lobe from the parietal lobe.

Frontal lobe

The anterior lobe of the cerebrum responsible for voluntary motor functions, higher-level thinking, reasoning, personality, mood, aggression, and motivation.

Parietal lobe

The cerebral lobe situated posterior to the central sulcus that receives and perceives general sensory inputs such as touch, pressure, pain, temperature, and balance.

Temporal lobe

The inferior lobe of the cerebrum responsible for processing olfactory (smell) and auditory (hearing) sensations, as well as functions in memory.

Occipital lobe

The posterior lobe of the brain containing the visual cortex, responsible for receiving and perceiving visual information.

Corpus callosum

A large, rounded white matter structure that connects the left and right cerebral hemispheres to allow communication between them.

Thalamus

A paired diencephalon structure that serves as the gatekeeper of all sensory and motor neurons, relaying incoming sensations to the brain and outgoing motor plans to the periphery.

Hypothalamus

The diencephalon structure located below the thalamus that regulates homeostasis, autonomic functions, body temperature, hunger, thirst, and directly stimulates the pituitary gland.

Decussation

The crossing over of sensory and motor nerve tracts to the opposite side of the body, which occurs in the medulla oblongata.

Cerebellum

The inferior, posterior brain structure responsible for fine motor control, coordination of movements, posture, muscle tone, balance, and motor learning of new tasks.

Amygdala

A limbic system structure that processes emotions and becomes especially active during states of aggression, fear, and anxiety.

Hippocampus

A limbic system structure located in the temporal lobe that serves as the primary processing center for short-term and long-term memory acquisition.

Basal ganglia

Deep movement-processing structures of the brain that plan, organize, and coordinate motor movements by either stimulating voluntary movement or inhibiting muscle activity.

Dura mater

The thickest, most durable, and most superficial connective tissue layer of the meninges wrapping the brain, brainstem, and spinal cord.

Arachnoid mater

The intermediate meningeal layer named for its distinct spider-web-like appearance.

Pia mater

The deepest meningeal layer that adheres tightly to the surface of the brain, brainstem, and spinal cord.

Subarachnoid space

The fluid-filled space situated between the arachnoid mater and the pia mater through which cerebrospinal fluid circulates.

Conus medullaris

The tapered, cone-shaped inferior termination of the spinal cord located approximately at the $L_2$ vertebral level.

Filum terminale

A thin string-like extension of the pia mater extending inferiorly from the conus medullaris to anchor the spinal cord to the coccyx.

Cauda equina

The collection of nerve roots extending inferiorly from the spinal cord below the $L_2$ level, named for its resemblance to a horse's tail.

Dorsal root ganglion

A swelling on the dorsal root containing the pseudounipolar cell bodies of sensory neurons in the peripheral nervous system.

Epineurium

The tough, outermost connective tissue sheath surrounding an entire peripheral nerve, which is continuous with the dura mater.

Perineurium

The layer of connective tissue that surrounds an individual bundle of axons known as a nerve fascicle.

Endoneurium

The innermost layer of connective tissue wrapping around a single, individual axon within a nerve fascicle.

Reflex arc

The basic functional unit of the nervous system, mediating an involuntary, subconscious response from a sensory receptor to an effector.

Stretch reflex

The simplest reflex where a muscle involuntarily contracts in response to a stretching force detected by muscle spindles, such as the patellar or knee-jerk reflex.

Withdrawal reflex

A protective flexor reflex stimulated by pain that contracts muscles to pull a limb away from a harmful stimulus.

Dermatome

An area of skin supplied with sensory innervation by a single pair of spinal nerves.

Myotome

An area or collection of muscles innervated by motor fibers from a single spinal nerve.

Dorsal column system

An ascending sensory tract that conveys information regarding proprioception, touch, deep pressure, and vibration to the brain.

Spinothalamic tract

An ascending sensory pathway that originates in the spinal cord and travels to the thalamus to transmit sensations of pain and temperature.

Corticospinal tract

The primary descending motor tract carrying impulses from the cerebral cortex to the spinal cord to control voluntary muscle contraction and tone.

Sympathetic nervous system

The fight-or-flight branch of the autonomic nervous system originating between $T_1$ and $L_2$, characterized by short preganglionic neurons and long postganglionic neurons.

Parasympathetic nervous system

The rest-and-digest branch of the autonomic nervous system originating in the cranial nerves and sacral spinal cord, characterized by long preganglionic neurons and short postganglionic neurons.