Neuroanatomy Lecture – Key Vocabulary

A comprehensive set of vocabulary flashcards covering major structures, developmental stages, and functional systems of the nervous system as presented in the lecture notes.

Cerebrospinal Fluid (CSF)

Clear liquid that fills brain ventricles, central canal, and subarachnoid space; provides buoyancy, protection, and chemical stability.

Blood–Brain Barrier (BBB)

Tight-junction seal between CNS capillaries, basement membrane, and astrocyte feet that restricts blood solutes from entering brain tissue.

Hypothalamus

Diencephalon region forming floor of third ventricle; regulates ANS, endocrine function, temperature, thirst, hunger, and circadian rhythms.

Limbic System

Interconnected cortical and subcortical structures (e.g., hippocampus, amygdala, cingulate gyrus) governing emotion, memory, and motivation.

Reticular Formation

Diffuse brainstem network of nuclei that controls posture, cardiovascular and pain modulation, sleep–wake states, and habituation.

Longitudinal Fissure

Deep groove that separates the right and left cerebral hemispheres.

Transverse Cerebral Fissure

Groove dividing cerebrum from cerebellum.

Falx Cerebri

Dural fold that descends into the longitudinal fissure to separate cerebral hemispheres.

Tentorium Cerebelli

Dural fold that separates cerebellum from occipital lobes.

Falx Cerebelli

Vertical dural fold that partially separates the cerebellar hemispheres.

Gray Matter

CNS tissue containing neuron cell bodies, dendrites, and synapses; site of information processing.

White Matter

CNS tissue composed of myelinated axons that transmit signals between regions.

Neural Plate

Thickened ectoderm that initiates nervous-system development around day 18 of gestation.

Neural Tube

Embryonic structure formed by fused neural folds; gives rise to CNS and ventricular system.

Primary Brain Vesicles

Three initial swellings of neural tube—forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon).

Prosencephalon (Forebrain)

Most rostral primary vesicle; later forms telencephalon and diencephalon.

Mesencephalon (Midbrain)

Middle primary vesicle that remains undivided; becomes the adult midbrain.

Rhombencephalon (Hindbrain)

Caudal primary vesicle that forms metencephalon and myelencephalon.

Secondary Brain Vesicles

Five divisions arising by week 5: telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon.

Telencephalon

Secondary vesicle that develops into the cerebral hemispheres (cerebrum).

Diencephalon

Secondary vesicle forming thalamus, hypothalamus, and epithalamus around the third ventricle.

Metencephalon

Secondary vesicle that becomes pons and cerebellum.

Myelencephalon

Secondary vesicle that develops into the medulla oblongata.

Cerebrum

Largest brain region; responsible for cognition, voluntary motor control, and conscious perception.

Thalamus

Paired diencephalic relay center—"gateway to the cortex" for nearly all sensory and motor signals.

Epithalamus

Dorsal diencephalon containing pineal gland and habenula; involved in circadian and limbic functions.

Midbrain

Mesencephalic portion of brainstem housing cerebral aqueduct, tectum, and cerebral peduncles.

Pons

Bulging metencephalic brainstem structure conveying signals between cerebrum, cerebellum, and medulla; aids respiration and sleep.

Medulla Oblongata

Myelencephalic brainstem segment controlling vital autonomic centers for heart rate, vasomotor tone, and respiration.

Cerebellum

Posterior brain region coordinating movement, posture, balance, and some cognitive processes.

Rostral

Directional term meaning toward the nose or forehead.

Caudal

Directional term meaning toward the tail or spinal cord.

Gyrus (Gyri)

Thick fold of cerebral cortex increasing surface area.

Sulcus (Sulci)

Shallow groove separating adjacent gyri.

Corpus Callosum

Large commissural fiber bundle connecting the two cerebral hemispheres.

Basal Nuclei (Basal Ganglia)

Subcortical gray matter group (caudate, putamen, globus pallidus) involved in motor control and habit learning.

Ventricles (Brain)

Four CSF-filled internal chambers: two lateral, third, and fourth ventricles.

Choroid Plexus

Capillary-ependymal network within ventricles that produces CSF.

Arachnoid Villi

Projections of arachnoid mater into dural sinuses that reabsorb CSF into venous blood.

Blood-CSF Barrier

Tight junctions between ependymal cells of choroid plexus limiting exchange between blood and CSF.

Circumventricular Organs (CVOs)

Third and fourth ventricular regions lacking BBB, allowing blood monitoring and hormone release.

Inferior Olivary Nucleus

Wavy gray matter in medulla that relays spinal and cerebral information to cerebellum.

Corticospinal Tract

Major descending pathway from cerebral cortex to spinal cord controlling voluntary skeletal muscle.

Cardiac Center

Medullary nucleus that regulates heart rate and contractility.

Vasomotor Center

Medullary nucleus adjusting blood vessel diameter to influence blood pressure.

Respiratory Centers

Medullary and pontine nuclei controlling rhythm and depth of breathing.

Cerebellar Peduncles

Three paired bundles (inferior, middle, superior) linking cerebellum to brainstem and carrying input/output fibers.

Purkinje Cells

Large, branched cerebellar cortex neurons that provide sole output from cerebellum to deep nuclei.

Substantia Nigra

Midbrain pigmented nucleus supplying inhibitory dopamine to basal nuclei; degeneration causes Parkinson’s tremors.

Red Nucleus

Highly vascular midbrain tegmental nucleus involved in motor coordination.

Superior Colliculi

Dorsal midbrain visual reflex centers for tracking and gaze shifts.

Inferior Colliculi

Dorsal midbrain auditory relay and startle reflex centers.

Reticulospinal Tracts

Descending fibers from reticular formation that modulate muscle tone and posture.

Central Pattern Generators

Reticular neuronal pools producing rhythmic motor outputs for breathing and swallowing.

Mammillary Bodies

Pair of hypothalamic nuclei relaying limbic memory signals to thalamus.

Fornix

C-shaped fiber tract connecting hippocampus to mammillary bodies.

Cingulate Gyrus

Limbic cortical fold arching over corpus callosum; involved in emotion and pain processing.

Association Tracts

White-matter fibers connecting regions within the same cerebral hemisphere.

Commissural Tracts

Fiber bundles, chiefly the corpus callosum, that cross between hemispheres.

Projection Tracts

Vertical fibers linking cortex with lower brain and spinal cord centers.

Neocortex

Six-layered, evolutionarily recent cerebral cortex covering 90 % of cortical surface.

Stellate Cells

Star-shaped cortical interneurons that receive and locally process sensory input.

Pineal Gland

Epithalamic endocrine organ secreting melatonin to regulate circadian rhythms.

Amygdala

Limbic nucleus critical for fear, aggression, and emotional memory processing.

Hippocampus

Medial temporal lobe structure essential for memory formation and spatial navigation.

Reticular Activating System (RAS)

Ascending reticular projections that maintain cortical alertness and consciousness.

Cranial Nerves

Twelve paired nerves (I–XII) arising mainly from brainstem that supply head and neck sensory, motor, and autonomic functions.

alpha waves

have a frequenct of 8 to 13 Hz and are recorded especially in the Pareto-occipital area

they dominate the EEG when a person is awake and relaxed, with the eyes closed and the mindd wandering

they are suppressed when a person opens the eyes, recieves sensory stimulation, or engages in a mental task such as reading or performing mathematical calculations. They are absent during deep sleep

beta waves

have a frequency of 14 to 30 Hz and occur in the frontal to parietal region. They are accentuated during mental activity and sensory stimulation

theta waves

have a frequency of 4 to 7 Hz. They are normal in children and in drowsy or sleeping adults, but a predominance of theta waves in awake adults suggest emotional stress or brain disorders

delta waves

are high amplitude “slow waves” with a frequency of less than 3.5 Hz. Infants exhibit delta waves when awake, and adults exhibit them in deep sleep.

autonomic nervous system (ANS

(AW-toe-NOM-ic) A motor division of the nervous system that innervates glands, smooth muscle, and cardiac muscle; consists of sympathetic and parasympathetic divisions and functions largely without voluntary control.

sympathetic divison

adapts the body in many ways for physical activity-it increases alertness, heart rate, blood pressure, pulmonary airflow, blood glucose, and blood flow to cardiac and skeletal muscle but at the same time it reduces blow flow to the skin and digestive tract. Cannon referred to extreme sympathetic responses as the fight or flight reaction because it comes into play when an animal must attack, defend or flee from danger

parasympathetic divison

has a calming effect on many body functions

it is associated with reduced energy expenditure and normaily body maintenance including such functions as digestion and waste elimination. this is often resting and digesting state

autonomic tone

they exhibit a background rate of activity both systems active

Acetylcholine

ACH is secreted by the pre-ganglionic Neurons in both divisions and the postganglionic nons of the parasympathetic division.

Any neuron that secrets ACh is called a

cholinergic neuron

muscarinic receptors

these are named for muscarine A mushroom talks and used in their discovery. All cardiac muscle, smooth muscle and gland cells with cholinergic inner action have muscarinic receptors. These are different subclasses of muscarinic receptors with different effects; thus ACh excites intestinal smooth muscle by binding to one type of muscarinic receptors and inhibits cardiac muscle by binding to a different type

Nicotinic receptors

These are named for another botanical toxin helpful to their discovery nicotine. They occur at all synopsis in the autonomic ganglia where the preganglionic fibers stimulate the postganglionic cells on cells of the adrenal medulla and at the neuromuscular junction of skeletal muscle fibers.the binding of ACh to a nicotinic receptor is always excitatory. Nicotinic receptors work by opening ligand- gated ion channels and producing an excitatory post synaptic potential in the target cell.

Norepinephrine

this neurotransmitter is secreted by nearly all sympathetic postganglionic fibers

neurons that secrete any are called

Adrenergic neurons

a-adrenergic receptors

These usually have excitatory effects. For example, the binding of any to a adrenergic receptor promotes labor contractions, stimulates piloerection, and constricts dermal blood vessels, yet it inhibits intestinal motility. These contrasting effects result from the different actions of the two subclasses of a-adrenergic receptors-a1 and a2

Receptors of the a1 type act through calcium ions as a second messenger whereas a2 receptors inhibit the synthesis of cyclic AMP

B adrenergic receptors

They are usually inhibitory. For example NE relaxes and dilates the bronchioles when it binds to B adrenergic receptors of the smooth muscle. Yet when it binds to the B adrenergic receptors of cardiac muscle it has an excitatory effect. Such contrasting effects- increased pulmonary airflow and a stronger faster heartbeat are obviously appropriate to a state of exercise.

Sympathetic postganglonic fibers

Mostly adrenergic a few cholinergic

Antagonistic effect

In effect in which two hormones, neurotransmitters or divisions of the nervous system, oppose each other and produce opposite effects on a target cell or Organ

Adrenal cortex

Outer rind Secretes steroid hormones

Adrenal medulla

Is essentially a sympathetic ganglion. It consists of modified postganglionic neurons without dendrites or axons. Sympathetic preganglionic fibers penetrate through the cortex and terminate on the cells. The sympathetic nervous system and adrena medulla are so closely related in the development and function that they are referred to collectively as the sympathoadrenal system.

there is some neural divergence in the parasympathetic division but much less than in the sympathetic the parasympathetic division has a ratio of fewer than five postganglionic neurons to every preganglionic neuron. Furthermore the preganglionic fibers reach their target organs before even this slight divergence occurs the parasympathetic division is therefore

Relatively selective in its stimulation of target organs

Each preganglionic neuron branches out to multiple postganglionic neurons thus showing

Neural divergence

Encapsulated nerve endings

Are nerve fibers wrapped in glue cells or connective tissue most of them are receptors for touch pressure and stretch the connective tissue either enhances the sensitivity of the nerve fiber, or makes it more selective with respect to which modality respond to. The principle encapsulated nerve endings are as follows.

Free nerve endings

Include warm receptors, which respond to rising temperature; Cold receptors, which respond to following temperature and nociceptors for pain. They are bare dendrites that have no special association with specific accessory cells or tissues. They’re most abundant in the skin and mucous membranes. You can locate some of your cold receptors by gently touching your skin with the point of a graphite pencil which conducts heat away from the skin

Tactile discs

Are tonic receptors for light touch thought two sense textures, edges and shapes. They are flat and nerve endings that terminate adjacent to specialized tactile cells in the basil layer of the epidermis. They respond to compression of the skin which releases a chemical from the tactile cell that excites the associated nerve fiber

each Postganglionic neuron may receive synapses from multiple preganglionic neurons thus exhibiting the principle of

Neural convergence

Hair receptors

are dendrites that coil around a hair follicle and respond to movements of the hair. They are stimulated when an ants walks across One skin, Bending one hair after another. However, they adapt quickly, so we aren’t constantly irritated by the feel of clothing against the skin. Hair receptors are particularly important in the eyelashes where the slightest touch evokes a protective blink reflex

encapsulated nerve endings

Are nerve fibers wrapped in glial cells or connective tissue. Most of them are mechanoreceptors for touch,pressure and stretch. The connective tissue either enhances the sensitivity of the nerve fiber or makes it more selective with respect to which modality it responds to

Tactile corpuscles

Or physic receptors for light touch and texture. They are tall avoid two pair shaped and consist of two or three nerve fibers meandering upward through a fluid filled capsule of flatten Schwann cells. They are mechanically linked to the edges of the dermal papillae of the skin. Tactile corpuscles are especially concentrated in sensitive hairless areas, such as the fingertips palms eyelids lips, nipples, and genitals. Drag your finger lightly across the back of your hand and then across your palm. The difference you perceive is due to the high concentration of tactile cord piles in the Palmar skin. Tactile corpuscles enable you to tell the difference between silk and sandpaper

Lamellar corpuscles

Phasic receptors, chiefly for vibration and pressure. They are large void receptors up to one to 2 mm long found in the period of bones in joint capsules in the pancreas and some visceral, deep in the dermis, especially on the hands feet breast and genitals they consist of a single dendrite running through the core of the organ encapsulated by multiple concentric layers of cell

End bulbs

Or functionally similar to tactile corpse, but instead of occurring in the skin, they are found in the mucous membranes of the lips and tongue in the conjunctiva on the interior surface of the eye, and in the epineurium of large nerves. They are obvious codies composed of a connective tissue sheath around a sensory nerve fiber

Bulbous corpuscles

Protonic receptors for heavy touch, pressure stretching of the skin deformation of the fingernails and joint movements. They aid in our perception of the shapes of objects held in the fingers. They are flattened elongated capsules containing a few myelinated axons in an incomplete fibrous capsule. They are located in the dermis, subcutaneous tissue and joint capsules.

They connect the subcutaneous tissues to skin folds in the joints and palms and beneath the fingernails

Lamellar corpuscles are phasic receptors that respond with one or two action potentials when pressure is applied to them and again when the pressure is taken away but not

In between