BIOL 221 Chapter 12: The Central Nervous System

Vocabulary flashcards covering the Central Nervous System including embryonic development, adult brain anatomy, functional cortical areas, pathways, and clinical conditions based on Chapter 12 lecture notes.

Prosencephalon

A primary brain vesicle known as the forebrain that appears during the 4th week of development.

Mesencephalon

A brain vesicle known as the midbrain; it is both a primary and a secondary brain vesicle.

Rhombencephalon

A primary brain vesicle known as the hindbrain.

Telencephalon

A secondary brain vesicle derived from the prosencephalon which develops into the adult cerebrum, including the cerebral hemispheres and basal nuclei.

Diencephalon

A secondary brain vesicle derived from the prosencephalon which develops into the adult thalamus, hypothalamus, and epithalamus.

Metencephalon

A secondary brain vesicle derived from the rhombencephalon which develops into the adult pons and cerebellum.

Myelencephalon

A secondary brain vesicle derived from the rhombencephalon which develops into the adult medulla oblongata.

Cerebrospinal fluid (CSF)

A clear, colorless fluid that cushions and protects the CNS; it reduces the effective weight of a $1400\,g$ brain to approximately $50\,g$.

Gyrus

A raised ridge on the cerebral cortex that serves to increase surface area.

Sulcus

A shallow groove that separates gyri on the cerebral cortex.

Fissure

A deep groove that separates large regions of the brain, such as the longitudinal and transverse fissures.

Frontal Lobe

Anterior cerebral lobe responsible for voluntary movement, planning, personality, and speech production.

Parietal Lobe

Posterior cerebral lobe involved in touch, pain, temperature, pressure, and spatial awareness.

Temporal Lobe

Inferior cerebral lobe responsible for hearing, memory, smell, and language comprehension.

Occipital Lobe

Cerebral lobe located at the posterior of the brain responsible for vision.

Insula

A lobe deep within the lateral sulcus responsible for taste, visceral sensation, self-awareness, and emotional processing.

Contralateral control

The physiological generalization that each cerebral hemisphere controls the opposite side of the body.

Corpus Callosum

The largest commissural fiber tract that connects and allows communication between the left and right hemispheres.

Plasticity

The ability of the brain to reorganize after injury, which is especially strong in children.

Primary Motor Cortex

Located in the precentral gyrus of the frontal lobe, it controls voluntary skeletal muscle movement.

Motor Homunculus

A cortical map where large areas represent body parts requiring fine control, such as the fingers, face, and tongue.

Premotor Cortex

Region located immediately anterior to the primary motor cortex that plans movements and stores learned motor skills.

Apraxia

A condition caused by damage to the premotor cortex where a patient maintains strength but cannot perform familiar, learned movements.

Broca’s Area

A region, usually in the left frontal lobe, responsible for speech production; damage causes slow, broken speech but intact comprehension.

Frontal Eye Fields

Area in the frontal lobe that controls voluntary eye movements such as tracking objects or reading.

Primary Somatosensory Cortex

Located in the postcentral gyrus, it receives information regarding touch, pain, temperature, pressure, and vibration.

Astereognosis

The inability to identify an object by touch, shape, or weight without looking, despite having physical sensation; caused by damage to the somatosensory association cortex.

Visual agnosia

A condition results from damage to the visual association area where a patient can see an object but cannot recognize what it is.

Wernicke’s aphasia

Condition caused by damage to the auditory association area where speech is fluent but meaningless, and the patient cannot understand language.

Prefrontal Cortex

The most anterior part of the frontal lobe responsible for executive functions like judgment, decision-making, and emotional control.

Association Fibers

White matter fibers that connect different cortical areas within the same hemisphere.

Commissural Fibers

White matter fibers that connect the left and right hemispheres.

Projection Fibers

White matter fibers that connect the cerebral cortex with lower CNS structures such as the brainstem, thalamus, or spinal cord.

Basal Nuclei

Deep structures including the caudate nucleus, putamen, and globus pallidus that smooth movements and filter out unwanted movements.

Thalamus

The major relay station of the brain where almost all sensory signals, except for smell, pass before reaching the cortex.

Supraoptic nucleus

A hypothalamic nucleus that produces ADH (antidiuretic hormone) to help the body conserve water.

Paraventricular nucleus

A hypothalamic nucleus that produces oxytocin, which stimulates uterine contractions and milk ejection.

Suprachiasmatic nucleus

Known as the body's biological clock, it regulates circadian rhythms via input from the retina.

Superior Colliculi

Midbrain structures responsible for visual reflexes, such as turning the head toward a flash of light.

Inferior Colliculi

Midbrain structures responsible for auditory reflexes, such as turning the head toward a loud noise.

Substantia Nigra

A midbrain structure containing dopamine-producing neurons; its degeneration is the hallmark of Parkinson disease.

Pyramidal Decussation

The crossing of motor fibers at the inferior medulla, resulting in contralateral control of the body.

Arbor vitae

The white matter within the cerebellum that resembles a tree in cross-section.

Ataxia

A condition resulting from cerebellar damage characterized by poor balance, coordination, and a wide-based gait.

Hippocampus

A limbic system structure vital for memory formation and converting short-term memory into long-term memory.

Amygdala

A limbic system structure responsible for fear, aggression, and emotional memory.

Reticular Activating System (RAS)

A network of neurons in the brainstem that maintains consciousness, wakefulness, and alertness.

Beta Waves

Brain waves observed on an EEG when an individual is awake, alert, and active in thinking or problem-solving.

Delta Waves

The slowest brain waves, which are typically observed during deep sleep or in infants.

REM Sleep

A stage of sleep characterized by rapid eye movement, dreaming, and temporary skeletal muscle paralysis.

Dura Mater

The thickest and toughest of the meninges, made of dense irregular connective tissue.

Arachnoid Villi

Granulations that project into dural venous sinuses to return CSF to the bloodstream.

Choroid Plexus

A structure within each ventricle, composed of capillaries and ependymal cells, that produces CSF.

Blood-Brain Barrier (BBB)

A protective barrier formed by capillary tight junctions, a basement membrane, and astrocyte end-feet to maintain a stable neural environment.

Area postrema

A leaky region of the blood-brain barrier which detects toxins and can trigger vomiting.

Dorsal Column–Medial Lemniscal Pathway

An ascending sensory pathway for fine touch, vibration, and proprioception that crosses in the medulla.

Spinothalamic Tract

An ascending sensory pathway for pain, temperature, and crude touch that crosses immediately in the spinal cord.

Corticospinal Tract

The direct descending motor pathway originating in the primary motor cortex responsible for precise voluntary movements.

Quadriplegia

Paralysis of all four limbs resulting from a spinal cord injury in the cervical region.

Paraplegia

Paralysis of the lower limbs resulting from a spinal cord injury in the thoracic or lumbar region.