chapter 7 : the nervous system central nervous system, anatomy

Chapter 7 : The Nervous System

Central Nervous System,

Anatomy

Regions of the BrainRegions of the Brain

Figure 7.12

Central Nervous System: Central Nervous System: AnatomyAnatomy

Protection of the Central Nervous Protection of the Central Nervous System:System:

Scalp and skin

Skull and vertebral column

Meninges

Cerebrospinal fluid

Blood brain barrier

Figure 7.16a


MeningesMeninges Dura mater

Double-layered external covering

Periosteum – attached to surface of the skull

Meningeal layer – outer covering of the brain

Folds inward in several areas


MeningesMeninges Arachnoid

layer

Middle layer

Web-like

Pia mater

Internal layer

Clings to the surface of the brain


Cerebral AnatomyCerebral Anatomy The surface

is made of ridges (gyri) and grooves (sulci)

Deep sulci are called fissures

Figure 7.13a


Gray matter

Outer layer

Composed mostly of neuron cell bodies

Basal nuclei – internal islands of gray matter

Figure 7.13a


Cerebral AnatomyCerebral Anatomy

White matter

Fiber tracts inside the gray matter

Example: corpus callosum connects hemispheres


Cerebral AnatomyCerebral Anatomy

Cerebral Hemispheres (Cerebrum)Cerebral Hemispheres (Cerebrum) Paired (left

and right) superior parts of the brain

Include more than half of the brain mass

Central Nervous System: Central Nervous System: Cerebral AnatomyCerebral Anatomy

Lobes of the CerebrumLobes of the Cerebrum Fissures (deep grooves) divide the

cerebrum into lobes

Surface lobes of the cerebrum

Frontal lobe

Parietal lobe

Occipital lobe

Temporal lobe

Central Nervous System: Central Nervous System: Cerebral AnatomyCerebral Anatomy

CerebellumCerebellum Two hemispheres with convoluted

surfaces

Provides involuntary coordination

of body movements

Central Nervous System: Central Nervous System: Cerebellar AnatomyCerebellar Anatomy

DiencephalonDiencephalon Sits on top of the brain stem

Enclosed by the cerebral hemispheres

Made of three parts Thalamus

Hypothalamus

Epithalamus


Thalamus - Surrounds the third ventricle

Hypothalamus - Under the thalamus

• The pituitary gland is attached to the hypothalamus

Epithalamus – Upon the thalamus

• Forms the roof of the third ventricle

• Houses the pineal body (an endocrine gland)

• Includes the choroid plexus – forms cerebrospinal fluid

Central Nervous System: Central Nervous System: DiencephalonDiencephalon

Brain StemBrain Stem Attaches to the spinal cord

Parts of the brain stem Midbrain

Pons

Medulla oblongata


MidbrainMidbrain Mostly composed of tracts of nerve fibers

Has two bulging fiber tracts – cerebral peduncles

Has four rounded protrusions – corpora quadrigemina

Central Nervous System: Central Nervous System: Brain StemBrain Stem

PonsPons The bulging center part of the brain stem

Mostly composed of fiber tracts

Includes nuclei involved in the control of breathing

Medulla OblongataMedulla Oblongata The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts

Figure 7.15a


Ventricles and Location of the Ventricles and Location of the Cerebrospinal FluidCerebrospinal Fluid


Figure 7.17b

Central Nervous System: Central Nervous System: Ventricles and Cerebrospinal FluidVentricles and Cerebrospinal Fluid

Cerebrospinal Fluid Similar to blood plasma

composition

Formed by the choroid plexus

Forms a watery cushion to protect the brain

Circulated in arachnoid space, ventricles, and central canal of the spinal cord

Central Nervous System: Central Nervous System: Ventricles and Cerebrospinal FluidVentricles and Cerebrospinal Fluid

Nervous Tissue: Supporting Cells Nervous Tissue: Supporting Cells (Neuroglia, or simply Glia)(Neuroglia, or simply Glia)

Astrocytes Abundant, star-shaped cells

Anchor neurons

Form barrier between capillaries and neurons

Control the chemical environment of the brain Figure 7.3a

Central Nervous System: Central Nervous System: NeurogliaNeuroglia

Microglia Spider-like phagocytes

Dispose of debris

Ependymal cells Line cavities of the

brain and spinal cord

Circulate cerebrospinal fluid with beating cilia

Figure 7.3b, c


Oligodendrocytes

• Produce myelin sheath around nerve fibers in the CNS

Figure 7.3d


• Function like Schwann cells in the PNS

Spinal CordSpinal Cord Extends from the

medulla oblongata to the region of T12

Below T12 is the cauda equina (a collection of spinal nerves)

Enlargements occur in the cervical and lumbar regions

Figure 7.18

Central Nervous System: Central Nervous System: Spinal CordSpinal Cord

Spinal Cord AnatomySpinal Cord Anatomy Meninges cover the spinal cord

Nerves leave at the level of each vertebrae

• Dorsal root

• Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system

• Ventral root


Exterior white mater – conduction tracts

Figure 7.19


Central canal filled with cerebrospinal fluid

Internal gray matter - mostly cell bodies

• Dorsal (posterior) horns

• Anterior (ventral) horns

Figure 7.19


Michelangelo’s “The Creation of Adam” from his fresco in the Sistine Chapel.

Does the red cloth look familiar?

chapter 7 : the nervous system central nervous system, anatomy

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