Chapter 14 The Brain and Cranial Nerves

Vocabulary-style flashcards covering the anatomy of the brain, protective layers, functional regions, and cranial nerves as described in the Chapter 14 lecture notes.

Gray matter

The component of the brain containing nerve cell bodies, dendrites, and terminals.

Cortex

The superficial layer of gray matter found in the cerebrum and cerebellum.

Nuclei

Deep masses of gray matter that are surrounded by white matter.

White matter

Composed of tracts, which are bundles of nerve fibers (axons) that connect different parts of the brain and the spinal cord.

Meninges

The three protective layers of the brain consisting of the dura mater, arachnoid mater, and pia mater.

Dura mater

The tough, outermost layer of the meninges located directly under the cranial bones, consisting of an outer periosteal layer and an inner meningeal layer.

Arachnoid mater

The middle layer of the meninges characterized by spiderweb-like extensions.

Pia mater

The innermost, delicate layer of the meninges that tightly clings to the brain, follows its contours, and contains blood vessels.

Cerebrospinal fluid (CSF)

A clear, colorless liquid that provides buoyancy, reduces the weight of the brain by $97\%$, protects the CNS from trauma, and nourishes the brain.

Ventricles

Chambers within the brain (lateral, third, and fourth) that produce and contain cerebrospinal fluid.

Choroid plexus

Specialized capillaries found in each ventricle that filter blood to produce cerebrospinal fluid.

Ependymal cells

Cells that line the ventricles to modify and move cerebrospinal fluid.

Brainstem

The region connecting the brain to the spinal cord, divided into the medulla oblongata, pons, and midbrain; it regulates vital functions like breathing and heart rate.

Medulla oblongata

The autonomic reflex center of the brainstem that regulates cardiac, vasomotor, and respiratory functions, as well as reflexes like sneezing and swallowing.

Decussation of the pyramids

The area in the medulla oblongata where nerve fibers cross to the opposite side, explaining why hemispheres control the opposite side of the body.

Pons

A brainstem region meaning 'bridge' that relays signals between the cerebrum, cerebellum, and medulla, and is involved in sleep-wake cycles and breathing.

Midbrain

Region located between the diencephalon and pons containing the cerebral peduncles and corpora quadrigemina.

Corpora quadrigemina

A midbrain structure consisting of the superior colliculus (visual reflex centers) and the inferior colliculus (auditory relay centers).

Cerebellum

The second-largest part of the brain, responsible for coordination, balance, and contains a branching white matter structure called the arbor vitae.

Diencephalon

A brain region enclosing the third ventricle and consisting of three paired gray matter structures: the thalamus, hypothalamus, and epithalamus.

Thalamus

Bilateral egg-shaped nuclei making up $80\%$ of the diencephalon that act as the main relay station for information going into the cerebral cortex.

Hypothalamus

The main control center for body homeostasis, regulating the autonomic nervous system, body temperature, hunger, thirst, and the endocrine system via the pituitary gland.

Mammillary bodies

Paired nuclei within the hypothalamus that act as olfactory relay stations.

Epithalamus

The region of the diencephalon containing the pineal gland, which secretes melatonin to regulate sleep-wake cycles.

Cerebrum

The largest part of the human brain, serving as the seat of sensory perception, memory, thought, and voluntary motor actions.

Corpus callosum

The structure that connects the right and left hemispheres of the cerebrum.

Gyri

The ridges on the surface of the cerebrum that increase the amount of cortex available for information-processing.

Sulci

The shallow grooves found on the surface of the cerebrum.

Longitudinal fissure

The deep groove that separates the two hemispheres of the cerebrum.

Frontal lobe

The lobe responsible for voluntary motor functions, foresight, planning, memory, and personality.

Insula

The cerebral lobe involved in understanding spoken language and taste.

Primary Somatosensory Cortex

Located in the postcentral gyrus of the parietal lobe; the site where sensory input is first received and consciously perceived.

Primary Motor Cortex

Located in the precentral gyrus of the frontal lobe; the site where motor signals are initiated.

Projection tracts

Bundles of white matter that connect the cerebral hemispheres with lower brain regions or the spinal cord.

Cerebral cortex

A $2-3\,mm$ thick layer of gray matter covering the surface of the hemispheres, constituting about $40\%$ of brain mass.

Basal Nuclei

Clusters of gray matter deep within white matter that influence motor control; their degeneration is associated with Parkinson’s and Huntington’s diseases.

Limbic System

A functional brain center for emotion and memory, including the cingulate gyrus, hippocampus, and amygdala.

Reticular formation

A loose web of nuclei in the brainstem that maintains consciousness and alertness by filtering out irrelevant sensory information.

Olfactory Nerve (CN I)

A purely sensory cranial nerve responsible for the sense of smell.

Optic Nerve (CN II)

A purely sensory cranial nerve that carries visual signals from the retina to the brain.

Vestibulocochlear Nerve (CN VIII)

A predominantly sensory nerve involved in hearing and equilibrium.

Vagus Nerve (CN X)

A mixed cranial nerve and the only one to innervate organs of the thorax and abdomen; it handles swallowing, speech, and heart deceleration.