Central Nervous System

The nervous system enables the body to respond to

continuous changes in its external and internal environment

CNS consists of

brain, spinal cord

Cerebellum

motor coordination

Brainstem

basic life functions (HR, breathing, etc)

Cerebrum

responsible for the integration of complex sensory and neural functions and the initiation and coordination of voluntary activity in the body

Gray Matter

outer covering or cortex

White Matter

inner core

contains only axons of nerve cells and the associated glial cells and blood vessels

Cerebral cortex

outermost layer of the brain

contains nerve cell bodies, axons, dendrites

PNS consists of

peripheral nerves, ganglia

Planes of the Body

Coronal Plane (Frontal Plane)

A vertical plane running from side to side; divides the body or any of its parts into anterior and posterior portions

Sagittal Plane (Lateral Plane)

A vertical plane running from front to back; divides the body or any of its parts into right and left sides

Axial Plane (Transverse Plane)

A horizontal plane; divides the body or any of its parts into upper and lower parts

CNS Anatomy

Central sulcus divides

frontal and parietal lobes

Precentral gyrus

motor cortex/ motor strip

Postcentral gyrus

sensory cortex/ sensory strip

Frontal Lobe

Planning, decision-making, problem-solving

Motor control: Voluntary movement via the motor cortex.

Speech production: Broca’s area (usually in the left hemisphere).

Personality and behavior: Emotional regulation, impulse control

Parietal Lobe

Sensory processing: Touch, temperature, pain, and proprioception.

Spatial awareness: Navigation and understanding spatial relationships.

Mathematical and analytical thinking

Temporal Lobe

Auditory processing: Hearing and interpreting sounds.

Language comprehension: Wernicke’s area (usually in the left hemisphere).

Memory formation: Especially in the hippocampus.

Emotional responses: Involvement of the amygdala

Occipital Lobe

Visual processing: Interpreting visual information like color, shape, and

motion

Telencephalon contains what?

Cerebral hemisphere and main lobes of cerebrum

• Limbic system

• Corpus striatum

• Olfactory Bulb

• Internal gray matter subcortical structures

The Subcortical Structures contain…

Basal Ganglia

• Caudate nucleus, putamen, globus pallidus

Hippocampus

Amygdala

Dicephalon

Thalamus, Hypothalamus, pineal gland

Brain stem

midbrain, pons, medulla

Ventricles

cavities in the brain that produce and circulate CSF

How many ventricles are there?

4 total:

• 2 lateral ventricles

• 3rd ventricle

• 4th ventricle

Spinal Cord Anatomy

Spinal Cord Anatomy

CNS Development

During the first 2 weeks of development, the embryo is typically

not susceptible to

teratogens

**Dark blue denote highly sensitive stages; light blue denote stages that

are less sensitive to teratogens

Teratogens

A substance either damages all or most of the cells of the embryo, resulting in its death, or it damages only a few cells, allowing the embryo to recover without developing defects

The neural plate folds during neurulation to form the

neural tube and neural crest

Four Stages of Development

A. Early in embryogenesis three germ cell layers—the

ectoderm, mesoderm, and endoderm—lie close

together.

B. The neural plate buckles at its midline to form the

neural groove and elevates the neural folds.

C. Closure of the dorsal neural folds forms the neural

tube, which gives rise to the CNS.

D. The neural tube lies over the notochord and is

flanked by somites, an ovoid group of mesodermal cells

that give rise to muscle and cartilage.

Ectoderm

nervous system, epidermis (skin)

Endoderm

internal organs (GI tract, lungs, other internal organs)

Mesoderm

muscles, bone, cartilage

Early development of the neural tube produces the three primary vesicles called the

forebrain (prosencephalon), midbrain (metencephalon), and hindbrain (rhombencephalon)

Differentiation of each of the five vesicles produced the major

brain structures

Nerve tissues consists of two types of cells

neurons and supporting cells (glial)

Supporting structures

meninges, blood-brain-barrier

Neuron is the ____ ___ of the nervous system

functional unit

Cell body

contains the nucleus and several processes of varying length

Nerve cells are specialized to

receive stimuli from other cells and to conduct electrical impulses to other parts of the system via their processes

Specialized contacts exist between neurons to provide

transmission of information from one neuron to the next are called synapses

Gray Matter Cells

Neuropil

meshwork of axonal, dendritic, and glial processes associated with the gray matter

The organization of the neuropil is not demonstrable in

H&E stained sections; cell type specific markers and immunostaining to visualize cell types

The inner core of the entire brain is called the

parenchyma

The parenchyma is the

function part of the brain and it does not include the outer coverings (meninges) of the brain

Brain Histology

Mostly the nuclei of glial cells are seen in routine histologic preparations of the CNS

Glia Cells

Astrocytes

morphologically heterogeneous cells that provide physical and

metabolic support for neurons of the CNS

Oligodendrocytes

are small cells that are active in the formation and

maintenance of myelin in the CNS

Microglia

are resident immune cells with small, dark, elongated nuclei that possess phagocytotic properties

Ependymal cells

are columnar cells that line the ventricles of the brain and the

central canal of the spinal cord

Meninges

three sequential connective tissue membranes cover the brain and spinal cord

Dura Mater

the outermost thickest and toughest layer (“tough mother”)

Arachnoid layer

lies beneath the dura; Contains CSF cushion

Pia Mater

delicate layer resting directly on the surface of the brain and spinal cord (“tender mother”)

Blood Brain Barrier protects the CNS from

fluctuating levels of electrolytes, hormones, and tissue metabolites circulating in the blood vessels

The barrier is created mostly by the ___ ___ between the ___ ___.

tight junctions between the endothelial cells

The tight junctions between the endothelial cells forms

continuous-type capillaries, pericyte (smooth muscle cell) and

association of astrocytes and their end foot processes

with the endothelial basal lamina

tight junctions eliminate gaps between

endothelial cells and prevent simple diffusion of solutes and fluid into the neural tissue