Neuroanatomy and Neurophysiology Review

Comprehensive vocabulary flashcards covering anatomical divisions of the nervous system, meninges, ventricles, cranial nerves, cellular neurophysiology, and pituitary functioning.

Pia mater

The innermost layer of the meninges closest to the brain and spinal cord, known as the gentle or swaddling mother, which hugs the brain and shields it from potentially harmful blood.

Arachnoid membrane

The middle, spider-like, soft, and spongy protective layer of the meninges featuring arachnoid trabeculae.

Subarachnoid space

The region situated between the arachnoid membrane and the pia mater that contains cerebrospinal fluid (CSF).

Dura mater

The tough, durable outermost layer of the meninges underneath the skull, referred to as the tough mother.

Arachnoid granulation

Structures protruding into the superior sagittal sinus within the longitudinal fissure that absorb cerebrospinal fluid (CSF) and return it to the bloodstream for eventual filtering by the kidneys.

Choroid plexus

Small pieces of blood-rich tissue located throughout the ventricular system (predominantly in the lateral ventricles) that produce cerebrospinal fluid (CSF).

Circle of Willis

A circulatory anastomosis providing blood to the brain; receives input from the internal carotid arteries and the basilar artery (formed by fused vertebral arteries) and includes communicating and cerebral arteries.

Spinal cord divisions

The anatomical regions of the spinal cord, organized superior to inferior as cervical, thoracic, lumbar, and sacral.

Dorsal roots

Spinal nerve roots that carry incoming sensory information into the spinal cord.

Ventral roots

Spinal nerve roots that carry outgoing motor signals and information outside of the spinal cord.

Dorsal ramus

A branch of a spinal nerve that innervates the back of the body.

Ventral ramus

A branch of a spinal nerve that innervates the front of the body.

Ganglion

A cluster of neuronal cell bodies located outside the central nervous system (CNS).

Dorsal root ganglion

A cluster of cell bodies situated outside the spinal nerve root that connects to the dorsal root leading into the spinal cord/CNS.

Nuclei

Clusters of neuronal cell bodies located inside the central nervous system (CNS).

Tract

A collection or bundle of nerve fibers located inside the central nervous system (CNS).

Nerve

A bundle of nerve fibers located outside the central nervous system (CNS).

Afferent pathways

Sensory pathways carrying arriving information from the periphery into the central nervous system (CNS).

Efferent pathways

Motor pathways carrying exiting signals and commands from the central nervous system (CNS) out to the periphery.

Gray matter vs. White matter organization

In the spinal cord, gray matter (cell bodies) is on the inside and white matter (axons) is on the outside; in the brain, white matter is on the inside and gray matter is on the outside.

Sulcus (or Fissure)

A line, groove, or indentation on the surface of the cerebral cortex.

Gyrus

A raised fold, ridge, or bump on the surface of the cerebral cortex.

Corpus callosum

A large white matter tract connecting the two cerebral hemispheres, composed of three main parts: the genu, body, and splenium.

Cranial Nerve I (Olfactory)

A sensory cranial nerve responsible for smell.

Cranial Nerve II (Optic)

A sensory cranial nerve responsible for vision.

Cranial Nerve III (Oculomotor)

A motor cranial nerve responsible for eye movement.

Cranial Nerve IV (Trochlear)

A motor cranial nerve controlling eye movement; it is characterized as the thinnest and shortest cranial nerve.

Cranial Nerve V (Trigeminal)

Both a sensory and motor cranial nerve, known as the thickest cranial nerve; responsible for masticatory movements and facial sensation.

Cranial Nerve VI (Abducens)

A motor cranial nerve responsible for eye movement.

Cranial Nerve VII (Facial)

Both a sensory and motor cranial nerve responsible for facial movement and taste sensation.

Cranial Nerve VIII (Auditory vestibular)

A sensory cranial nerve responsible for hearing and balance.

Cranial Nerve IX (Glossopharyngeal)

Both a sensory and motor cranial nerve responsible for movement and sensation of the tongue and pharynx.

Cranial Nerve X (Vagus)

Both a sensory and motor cranial nerve, noted as the longest cranial nerve; provides parasympathetic control to the heart, blood vessels, viscera, larynx, and pharynx.

Cranial Nerve XI (Spinal Accessory)

A motor cranial nerve responsible for neck movement.

Cranial Nerve XII (Hypoglossal)

A motor cranial nerve responsible for tongue movement.

Cations

Positively charged ions involved in neuronal signaling, such as sodium ($\text{Na}^+$) and potassium ($\text{K}^+$).

Anions

Negatively charged ions, such as chloride ($\text{Cl}^-$) and large intracellular protein molecules ($\text{A}^-$).

Concentration gradient

The diffusion force that drives ions to move from an area of higher concentration to an area of lower concentration to achieve equal distribution.

Voltage gradient

The electrical force that directs the movement of ions based on charge, repelling like charges and attracting opposite charges to balance electrical potential.

Sodium-potassium pump

A specialized membrane protein that maintains resting membrane potential by actively pumping $3\,\text{Na}^+$ out of the intracellular fluid while bringing $2\,\text{K}^+$ in.

Driving force

The net electrochemical force acting on an ion, calculated as membrane potential minus equilibrium potential ($V_m - E_{\text{ion}}$), where negative values favor movement into the cell and positive values favor movement out.

Inhibitory postsynaptic potential (IPSP)

A hyperpolarization that increases the negative voltage inside the neuron (such as through chloride entry or potassium exit), making the cell less likely to fire an action potential.

Excitatory postsynaptic potential (EPSP)

A depolarization that makes the inside of the cell membrane more positive (typically through sodium influx), increasing the likelihood of reaching threshold.

Temporal summation

The integration of postsynaptic potentials (EPSPs or IPSPs) occurring closely together in time at the same synapse to reach threshold before dissipating.

Spatial summation

The addition of simultaneous postsynaptic potentials produced at different locations across a neuron, combining into a larger potential when close together.

Absolute refractory period

The phase immediately following an action potential during which a neuron cannot fire another action potential under any circumstances due to inactivated voltage-gated sodium channels.

Relative refractory period

The phase following the absolute period in which an action potential can only be triggered by an unusually strong stimulus that is larger than normal.

Saltatory conduction

The mode of action potential propagation combining passive conduction along myelinated segments with active regeneration of potentials at each node of Ranvier.

Myelin

A fatty substance wrapping around axons to increase action potential speed, produced by oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS).

Multiple sclerosis

An autoimmune disorder in which the immune system attacks myelin in the central nervous system, and oligodendrocytes do not allow it to recover.

Tetrodotoxin (TTX)

A pharmacological neurotoxin that blocks voltage-gated sodium channels, thereby eliminating the depolarization phase of an action potential.

Anterior pituitary (Adenohypophysis)

A non-neural, endocrine structure composed of glandular tissue that synthesizes its own hormones after receiving hormonal stimulation from the hypothalamus.

Posterior pituitary (Neurohypophysis)

A structure directly connected to the hypothalamus via axons that does not synthesize hormones itself, but rather stores and releases hypothalamic hormones transported down to axon terminals.

Telencephalon

The forebrain region encompassing the neocortex, basal ganglia (motor control), and limbic system structures including the hippocampus (memory), amygdala (emotion), and fornix.

Diencephalon

The subcortical brain division containing the thalamus (relay station and sensory filter), hypothalamus (hormone synthesis and homeostasis), and pituitary gland.

Mesencephalon

The midbrain division responsible for integrating sensory and motor information, consisting of the tectum (superior/inferior colliculi), tegmentum, red nucleus, and substantia nigra.

Metencephalon

The hindbrain division consisting of the cerebellum (balance, equilibrium) and pons (sleep, arousal, and cortical-cerebellar relay).

Myelencephalon

The most caudal brain division consisting of the medulla oblongata, which contains the olive, trapezoid body, and motor pyramids.