Chapter 13: Anatomy & Physiology - The Brain and Cranial Nerves

Comprehensive vocabulary flashcards covering the developmental anatomy, meninges, ventricles, brain regions, pathways, disorders, electrophysiology, and twelve cranial nerves from Chapter 13.

Neurulation

The process of nervous tissue formation beginning in the 3rd week of embryonic development, wherein the notochord induces the overlying ectodermal neural plate to invaginate and form the neural tube, which gives rise to the CNS.

Primary Brain Vesicles

The three fluid-filled bulges that form from the embryonic neural tube by 4 weeks of development: prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain).

Secondary Brain Vesicles

The five brain vesicles present at 5 weeks of embryonic development: telencephalon and diencephalon (from prosencephalon), mesencephalon, and metencephalon and myelencephalon (from rhombencephalon).

Dura Mater

The tough, outer cranial meningeal layer composed of two sublayers: an outer periosteal layer adjacent to the cranial bone and an inner meningeal layer.

Arachnoid Mater

The middle cranial meninge located deep to the subdural space, featuring delicate web-like arachnoid trabeculae spanning across the subarachnoid space.

Pia Mater

The innermost, delicate cranial meningeal layer of connective tissue that directly adheres to the contours, sulci, and gyri of the brain surface.

Epidural Hematoma

A pool of blood collecting within the epidural space of the skull, typically caused by a severe blow to the head that ruptures vessels and compresses adjacent brain tissue.

Subdural Hematoma

A hemorrhage in the subdural space, typically resulting from ruptured veins during fast rotational head trauma, which compresses brain tissue more slowly than an epidural hematoma.

Meningitis

An inflammation of the meninges typically caused by viral or bacterial infection, characterized by fever, headache, vomiting, and stiff neck, with bacterial forms being more severe.

Encephalitis

An acute inflammation of the brain tissue, most frequently caused by viral infections, presenting with symptoms including drowsiness, fever, headache, and neck pain.

Choroid Plexus

A specialized network of ependymal cells and capillaries situated within each brain ventricle that filters blood plasma to produce cerebrospinal fluid (CSF).

Hydrocephalus

A pathological accumulation of excessive cerebrospinal fluid (CSF) caused by impaired drainage at the arachnoid villi or an obstruction in the ventricles, often treated with surgical shunts.

Blood-Brain Barrier (BBB)

A selective physiological barrier separating blood circulation from brain parenchyma, formed by continuous capillary endothelial cells with tight junctions, a continuous basement membrane, and astrocyte perivascular feet.

Frontal Lobe

The anterior lobe of the cerebrum bounded posteriorly by the central sulcus and inferiorly by the lateral sulcus, governing voluntary motor control, verbal communication, decision-making, planning, concentration, and personality.

Parietal Lobe

The cerebral lobe situated between the central sulcus anteriorly, the parieto-occipital sulcus posteriorly, and lateral sulcus laterally, dedicated to processing general sensory input like shape and texture.

Temporal Lobe

The cerebral lobe positioned inferior to the lateral sulcus and internal to the temporal bone, primarily involved in hearing and smell.

Occipital Lobe

The posterior portion of each cerebral hemisphere that processes incoming visual information and stores visual memories.

Insula

A small cerebral lobe located deep to the lateral sulcus, observable upon pulling away the temporal lobe, involved in memory and the sense of taste.

Primary Motor Cortex

Cortical area localized in the precentral gyrus of the frontal lobe (somatic motor area) that initiates contralateral voluntary skeletal muscle activity.

Motor Homunculus

A distorted anatomical diagram along the primary motor cortex depicting the relative proportion of cortical surface area dedicated to regulating specific bodily regions.

Motor Speech Area (Broca Area)

A specialized functional region located in the inferolateral frontal lobe responsible for regulating the complex skeletal muscle movements required for vocalization.

Primary Somatosensory Cortex

Cortical area residing in the postcentral gyrus of the parietal lobe that receives and processes somatic sensory signals from proprioceptors, touch, pressure, pain, and temperature receptors.

Somatosensory Association Area

An association area located immediately posterior to the postcentral gyrus in the parietal lobe that integrates touch data to allow identification of objects by feel.

Wernicke Area

A multi-association area typically located in the left cerebral hemisphere involved in recognizing, understanding, and comprehending written and spoken language.

Prefrontal Cortex

The anterior-most region of the frontal lobe rostral to the premotor cortex that mediates higher intellectual functions, judgment, complex planning, and personality.

Association Tracts

Bundles of white matter axons, including arcuate fibers and longitudinal fasciculi, that connect different cortical regions within the same cerebral hemisphere.

Commissural Tracts

White matter pathways, such as the corpus callosum and anterior commissure, extending between the cerebral hemispheres to allow interhemispheric communication.

Projection Tracts

Axon bundles linking the cerebral cortex to inferior brain structures, the brainstem, and the spinal cord, converging through the internal capsule.

Cerebral Lateralization

The functional specialization of the left and right cerebral hemispheres for distinct cognitive tasks, typically developing before $5\text{ to }6$ years of age.

Cerebral Nuclei

Internal paired masses of gray matter buried deep within cerebral white matter, consisting of the caudate nucleus, putamen, globus pallidus, claustrum, and amygdaloid body.

Parkinson Disease

A neurodegenerative disease marked by stiff posture, slow voluntary movements, and resting tremors, resulting from decreased dopamine release by the substantia nigra.

Huntington Disease

A fatal, hereditary progressive disorder affecting the cerebral nuclei that causes rapid, jerky, involuntary chorea-like movements and progressive intellectual deterioration.

Epithalamus

The posterior-superior division of the diencephalon containing the pineal gland (secreting melatonin) and the habenular nucleus.

Thalamus

Paired oval gray-matter masses flanking the third ventricle that act as the principal sensory filter and relay station for incoming signals directed to the cerebral cortex.

Hypothalamus

The anteroinferior region of the diencephalon containing nuclei that control autonomic functions, endocrine hormone secretion, body temperature, emotional behavior, and food and water intake.

Tectal Plate

The posterior midbrain roof composed of two pairs of sensory nuclei: the superior colliculi (visual reflex centers) and inferior colliculi (auditory reflex centers).

Substantia Nigra

A pair of midbrain nuclei containing melanin-pigmented neurons producing dopamine, involved in regulating movement output from the basal nuclei.

Decussation of the Pyramids

The anatomical crossing over of descending corticospinal motor tracts located on the anterior inferior surface of the medulla oblongata.

Vermis

A narrow, midline band of cerebellar cortex connecting the cerebellar hemispheres that receives and processes sensory signals regarding torso position and balance.

Arbor Vitae

The branching, tree-like pattern of internal white matter observable in a sagittal cross-section of the cerebellum.

Reticular Activating System (RAS)

The sensory component of the reticular formation that processes visual, auditory, and somatosensory input to maintain consciousness and project alerting signals to the cerebrum.

Beta Waves

High-frequency brain waves oscillating at $14\text{--}30\,\text{Hz}$ on an electroencephalogram (EEG), characteristic of an awake state with active mental concentration.

Alpha Waves

Rhythmic brain waves oscillating at $8\text{--}13\,\text{Hz}$ on an EEG, typically present in awake, resting individuals with closed eyes.

Theta Waves

Brain waves with frequencies between $4\,\text{Hz}$ and $7\,\text{Hz}$ recorded on an EEG, normal in children and present during early sleep stages in adults.

Delta Waves

Low-frequency brain waves oscillating at $<3.5\,\text{Hz}$ on an EEG, characteristic of deep sleep in healthy adults.

Sensory Memory

The initial, briefest form of memory storage that holds incoming perceptual input for a duration lasting from a millisecond to $1\,\text{second}$.

Short-Term Memory (STM)

A limited-capacity memory stage holding information for a brief duration of $<1\,\text{minute}$ unless maintained by active rehearsal or repetition.

Long-Term Memory (LTM)

The permanent or semi-permanent storage of encoded knowledge, facts, and experiences that can persist for days, months, or years.

Alzheimer Disease

The leading cause of dementia in the developed world, presenting after age $65$ with progressive cognitive impairment, emotional changes, memory loss, and beta-amyloid plaques and tau tangles.

Olfactory Nerve (CN I)

A sensory cranial nerve dedicated to conveying smell (olfaction) sensations from the nasal cavity to the brain.

Optic Nerve (CN II)

A sensory cranial nerve that transmits visual signals from the retina of the eye through the optic canal to the optic chiasm and primary visual cortex.

Oculomotor Nerve (CN III)

A motor cranial nerve innervating four extrinsic eye muscles, the levator palpebrae superioris, and intrinsic pupillary and ciliary smooth muscles.

Trochlear Nerve (CN IV)

A motor cranial nerve innervating the superior oblique extrinsic eye muscle that loops through a pulley-like loop of tissue (trochlea).

Trigeminal Nerve (CN V)

A mixed cranial nerve composed of ophthalmic ($\text{V}_1$), maxillary ($\text{V}_2$), and mandibular ($\text{V}_3$) branches, receiving facial sensory input and innervating muscles of mastication.

Abducens Nerve (CN VI)

A motor cranial nerve supplying the lateral rectus extrinsic eye muscle to abduct the eyeball laterally.

Facial Nerve (CN VII)

A mixed cranial nerve responsible for innervating the muscles of facial expression and carrying taste sensation from the anterior two-thirds of the tongue.

Vestibulocochlear Nerve (CN VIII)

A sensory cranial nerve with vestibular and cochlear branches that conducts equilibrium and auditory (hearing) sensory signals from the inner ear.

Glossopharyngeal Nerve (CN IX)

A mixed cranial nerve that transmits taste and general touch sensations from the tongue and provides motor innervation to a pharyngeal muscle.

Vagus Nerve (CN X)

A major mixed cranial nerve providing extensive parasympathetic motor innervation to thoracic and abdominal organs, as well as somatic motor control to pharyngeal and laryngeal muscles.

Accessory Nerve (CN XI)

A motor cranial nerve that controls skeletal muscles in the neck (such as the trapezius and sternocleidomastoid) and muscles of the pharynx.

Hypoglossal Nerve (CN XII)

A motor cranial nerve providing innervation to the intrinsic and extrinsic muscles of the tongue for tongue movement.