Lecture 9.2 Central Nervous System: Brain Anatomy, Protection, and Development

Dura Mater

The outermost and strongest layer of the meninges, composed of a two-layered sheet of dense fibrous connective tissue.

Periosteal Layer

The outer layer of the cranial dura mater that attaches directly to the inner surface of the skull bones.

Meningeal Layer

The inner layer of the cranial dura mater that directly covers the brain.

Dural Sinuses

Blood-filled spaces formed where the outer periosteal and inner meningeal layers of dura mater separate, serving to collect de-oxygenated blood from the brain.

Falx Cerebri

A curving fold of dura mater located along the longitudinal fissure that divides the cerebral hemispheres, attaching anteriorly to the crista galli and posteriorly to the tentorium cerebelli.

Tentorium Cerebelli

A fold of dura mater that separates the cerebrum from the cerebellum.

Arachnoid Mater

The middle layer of the meninges, characterized by a thin, web-like membrane.

Subdural Space

The narrow space located between the dura mater and the arachnoid mater containing a thin film of fluid.

Subarachnoid Space

The wide space deep to the arachnoid mater filled with cerebrospinal fluid and the brain's largest blood vessels, anchored to the pia mater by web-like threads.

Pia Mater

The delicate, innermost meningeal layer of connective tissue, richly vascularized with fine blood vessels to nourish the brain and spinal cord.

Cerebrospinal Fluid (CSF)

A watery fluid derived from blood plasma containing more $\text{Na}^+$ and $\text{Cl}^-$ and fewer proteins, which cushions, suspends, nourishes, and clears waste from the central nervous system.

Choroid Plexus

Specialized vascular areas of pia mater located around the brain's four ventricles where blood plasma filters through ependymal cells to produce cerebrospinal fluid.

Arachnoid Granulations

Finger-like projections through which cerebrospinal fluid exits the subarachnoid space and enters the dural venous sinuses into the bloodstream.

Meningitis

A bacterial or viral infection characterized by inflammation of the meninges caused by microbes in the CSF, which can cause encephalitis and death.

Blood-Brain Barrier

A protective barrier formed by brain capillary endothelial cells joined by tight junctions, preventing toxins like urea and bacteria from entering brain tissue while permitting lipid-soluble molecules.

Astrocytes

The most abundant neuroglial cells of the CNS, which secrete regulatory chemicals that restrict the permeability of brain capillaries.

Prosencephalon

The primary brain vesicle of the 3-week embryo (forebrain) that divides into the telencephalon and diencephalon.

Mesencephalon

The primary and secondary embryonic brain vesicle (midbrain) that develops into the adult midbrain, enclosing the cerebral aqueduct.

Rhombencephalon

The primary brain vesicle of the 3-week embryo (hindbrain) that divides into the metencephalon and myelencephalon.

Telencephalon

The secondary brain vesicle of the 6-week embryo that develops into the cerebrum and encloses the lateral ventricles.

Metencephalon

The secondary brain vesicle of the 6-week embryo that develops into the cerebellum and pons, associated with the fourth ventricle.

Myelencephalon

The secondary brain vesicle of the 6-week embryo that develops into the medulla oblongata, associated with the fourth ventricle.

Cerebrum

The largest brain division, making up $83\%$ of the brain, responsible for conscious thought processes, intellectual functions, memory storage, and regulation of skeletal muscle contractions.

Gyrus

An elevated ridge on the surface of the cerebral cortex.

Sulcus

A shallow groove on the cerebral surface separating adjacent gyri.

Fissure

A deep groove on the brain surface, such as the longitudinal fissure dividing the two cerebral hemispheres.

Nuclei

Clusters of neuron cell bodies with similar functions located within the gray matter of the central nervous system.

Frontal Lobe

The anterior cerebral lobe bordered by the central and lateral sulci, responsible for motor eye movements, speech production, thinking, planning, decision-making, and short-term memory.

Parietal Lobe

The cerebral lobe situated deep to the parietal bones, involved in the conscious perception of touch, pressure, vibration, and pain.

Occipital Lobe

The posterior lobe of the cerebral hemisphere containing the visual cortex.

Temporal Lobe

The lateral cerebral lobe separated by the lateral sulcus, housing the auditory cortex and olfactory cortex.

Insula

A deep cerebral lobe located internal to the lateral sulcus, involved in taste and visceral sensations.

Thalamus

A paired diencephalic structure containing roughly a dozen major nuclei that processes and relays sensory information to the cerebrum or brain stem.

Hypothalamus

The diencephalic center that controls autonomic visceral functions, emotions, thirst, body temperature, and endocrine hormone production.

Pineal Gland

An endocrine structure in the epithalamus/diencephalon that secretes melatonin to regulate day-night cycles.

Cerebellum

The posterior brain structure that smooths and coordinates complex voluntary motor movements, maintains balance and posture, and stores motor memories.

Folia

The slender, parallel fold-like ridges across the surface of the cerebellar cortex.

Vermis

The narrow, midline region of cortex that connects the right and left cerebellar hemispheres.

Corpora Quadrigemina

Four prominent nuclei located on the dorsal midbrain (mesencephalon) involved in processing visual and auditory information and initiating reflexive motor responses.

Pons

A prominent bulge of the brain stem located inferior to the midbrain that relays sensory information to the cerebellum and thalamus, and helps regulate respiration.

Medulla Oblongata

The most inferior segment of the brain stem connecting directly to the spinal cord, containing ascending/descending tracts and vital visceral regulatory centers.

Cardiovascular Centers

Autonomic centers located in the medulla oblongata that adjust heart rate, contraction force, and peripheral vascular smooth muscle tone.

Respiratory Rhythmicity Centers

Autonomic centers located in the medulla oblongata that set the basic pace for breathing using regulatory input from the pons.