Chapter 12 notes
State standards:
Describe the anatomy, histology, and physiology of the central and peripheral nervous systems and
name the major divisions of the nervous system.
Identify the major parts of a cross section through the spinal cord.
Identify the function for the major parts of the brain, including the meninges, medulla, pons,
midbrain, hypothalamus thalamus, cerebellum and cerebrum.
Human Brain characteristics
Pinkish grey, wrinkled, mass of tissue with the consistency of cold oatmeal. The average adult male’s
brain weighs about 3.5 lbs, and a woman’s brain is about 3.2 lbs.
Brain development –
The ectoderm thickens at the dorsal midline access in week 3 of gestation to form the neural plate. It
then creates a furrow and the superior edges fuse, creating the neural tube. After the neural tube
forms, it begins to expand and constrict to mark off the prosencephalon (forebrain), mesencephalon
(midbrain), and rhombencephalon (hindbrain) - 4th week of gestation.
The proscencephalon becomes the
a. Telencephalon
a. cerebrum
b. and dienchphalon
a. Thalamus
b. Hypothalamus
c. Epithalamus
d. Retina
The mesencephalon becomes the midbrain.
The rhombencephalon becomes the
a. metencephalon which becomes the
a. pons and cerebellum
b. myelencephalon becomes the
a. medulla oblongata
The ventricles arise from the lumen of the embryonic neural tube. They are hollow and filled with
cerebrospinal fluid. They are lined with ependymal cells.
The paired lateral ventricles are c-shaped and reflect the pattern of cerebral growth. All 4 of the brain’s
ventricles are connected together. Lateral ventricles are connected to the third ventricle, and the third
is connected to the 4th ventricle.
Cerebral hemispheres
 account for 83% of the total brain mass.
 Covered with elevated ridges called gyri, and furrows called sulci
 The deepest grooves that separate the large regions of the brain are called fissures.
o Longitudinal fissure
o Transverse cerebral fissure
 Several sulci divide each hemisphere into 5 lobes. (frontal, parietal, temporal, occipital, and
insula.
o
o
o
Central sulcus – divides the frontal lobe from the parietal lobe.
Parieto-occipital sulcus – divides the parietal and occipital lobes.
The fifth lobe, the insula, is deep to the other lobes.
Cerebral cortex
 Consists of the large part of the brain that we can see easily.
 Contains 3 functional areas:
o Motor
 Primary motor cortex located in the dorsal portion of the frontal lobe
 Somatotopy (mapping of the body in CNS structures) shows which areas
control which body parts.
 Anterior to the primary motor cortex is the pre-motor cortex.
 Controls patterned movements like typing or playing an instrument.
 Broca’s area -Located anterior and inferior to the pre-motor cortex.
o Directs the muscles involved with speech production, and
assists with planning to speak.
 Frontal eye field -Located superior and interior to Broca’s area
 Controls voluntary movements of the eye.
o Sensory
 Primary somatosensory cortex -Most anterior part of parietal lobe
 Special discrimination (being able to tell which body region is being
stimulated.
 Somatosensory association cortex -Posterior to the primary somatosensory
cortex.
 Integrates sensory inputs like temperature, pressure, etc. so you can
make sense of what you are touching. Like reaching into your pocket,
and recognizing that you have a coin vs. a key in your pocket.
 Primary visual cortex -Posterior section of the occipital lobe.
 Receives all the visual input from the retina of the eye.
 Visual association area surrounds the visual cortex, and relates the input
received to previous visual experiences to help you interpret what you
are seeing.
 Primary Auditory cortex - Superior margin of the temporal lobe
 Receives information from ear as pitch, loudness and location.
 Auditory association area -Posterior to the primary auditory cortex,
compares sounds heard to sounds previously heard.
 Olfactory cortex - Medial aspect of temporal lobe
 Conscious awareness of different odors.
 Gustatory cortex (taste)
 Located deep to the temporal lobe
 Visceral sensory areas ( internal organs)
 Located posteriorly to gustatory, and allows you to feel an upset
stomach, full bladder, etc.
 Vestibular cortex
 Balance, where your head is in space. Located in posterior portion of
insula.
o Association

Information flows from sensory receptors to the primary sensory cortex
(whichever one is appropriate), then to sensory association cortex then to the
multimodal association cortex.
 Multimodal association areas
 Anterior association area (frontal lobe aka prefrontal cortex)
o Involved in intellect, complex learning abilities, recall, memory,
and personality
 Posterior association area
o Recognizing patterns and faces, where we are located
o Also involved in understanding written and spoken language
 Limbic association area
o Part of the limbic system
o Adds emotional impact to a scene
General other tidbits of interesting stuff:
 Right side of brain controls the left side of the body and vice versa
 About 90% of the time, Left hemisphere has greater control over language abilities,
math and logic.
 The right side of the brain tends to be more free-spirited, better with visual spatial skills,
art, music, poetic and creative.
 The other 10% of cases display the roles of the hemispheres are switched.
 People who are able to use both hemispheres pretty equally are generally
ambidextrous.
 White matter is composed of myelinated neurons (think fat is white, therefore neurons
with myelin are white)
 Corpus colossum connects the right and left hemispheres of the brain together.
Thalamus - from the Greek meaning “inner room”
 Deep inside the brain and forms the superolateral walls of the third ventricle.
o Serves as the relay station for information coming into the cerebral cortex.
o Information is sorted out and edited and sent to the correct portion of the cerebral
cortex.
Hypothalamus –(hypo=below)
 Below Thalamus, caps the brainstem, and forms the inferolateral walls of the third ventricle.
 Contains the :
o Mammillary bodies that relay information for the olfactory pathways (smell)
o Infundibulum (connects the pituitary to the base of the hypothalamus)
o Pituitary gland
 Main visceral control center of the body and maintains homeostasis
o Regulates the Autonomic Nervous System (ANS) by controlling the activity centers of the
brain stem and spinal cord.
 Influences blood pressure, heart rate, digestive tract motility, eye pupil size, etc.
o Heart of the limbic system (center for emotional part of the brain)
 Pleasure, fear, rage, and biological rhythms and drives
o Body temperature regulation
o Regulation of food intake
o
o
Regulation of water balance and thirst
Regulation of sleep/wake cycles
Brain Stem – maintains life functions. Filters out repeated stimuli.
Midbrain
 Located between diencephalon and pons
 Pathway between higher and lower brain centers. Houses visual and auditory reflex centers.
Pons
 Located between Pons and Medulla oblongata
 Relays info from the cerebrum to the cerebellum
 Controls respiration rate and depth
Medulla Oblongata
 Located between pons and spinal cord
 Controls heart rate, blood vessel diameter, respiratory rate, vomiting, coughing, etc.
Cerebellum
Second largest section of the brain.
 Provides the precise timing and appropriate patterns of skeletal muscle contraction for smooth,
coordinated movements and agility needed for daily living.
 Evaluates the body’s position in space and coordinates the cerebrum’s voluntary motor
response.
Special groupings / areas
Limbic System – Group of structures that encircle the upper part of the brain stem. It is responsible for
the emotions we have. Smells relate to memories (good or bad).
Amygdala – recognizes fear and angry facial expressions, recognizes danger and makes us feel
fear.
The reticular formation - distributes impulses to keep us awake, and filters out extraneous impulses.
This may be the reason that you can study while listening to music, or in a crowded, noisy room.
Broca’s area – speech
Wernicke’s area – understanding language
Meninges – connective tissue membranes that encase and protect the brain.
Cerebrospinal fluid – “floats” the brain so that it does not cause damage to itself under its own weight,
and protects it from trauma.
Diseases that affect this part of the CNS –
Cerebrovascular accidents – stroke / Ischemic attack (lack of blood to the brain)
Alzheimer’s disease – degradation of the brain typically in old age
Parkinson’s disease – degradation of one central area causes another to become overstimulated
resulting in shaking movements.
Huntington’s disease – mutant huntingtin protein accumulates and causes surrounding brain tissue to
die.
Spinal Cord - Runs from the brain stem through the spine to the first lumbar vertebrae, after that, the
remaining are nerves.
Parts – Central canal in the center
Grey matter in the middle area of spinal cord – Grey commissure, dorsal horn, ventral horn, lateral horn
White matter on the exterior – Dorsal funiculus, ventral funiculus, lateral cuniculus
Protruding from spinal cord, are the spinal nerves with ther dorsal and ventral root ganglions. The spinal
cord is covered with the meninges.
Diseases that affect this area of the CNS –
Spinal cord trauma – damage to the spinal cord that can result in paralysis
Polio myelitis – Broken down = Polio (grey matter) Myel (spinal cord) “itis” (Inflamation) Polio virus
causes inflammation of the grey matter of the spinal cord.
Post polio syndrome – survivors of the polio virus in essence relapse later in life due to additional loss of
neurons due to aging.
Amyotrophic lateral sclerosis – Lou Gehrig’s disease – progressive destruction of the ventral horn motor
neurons and fibers of pyramidal tracts. Patient usually dies within 5 years. Loss of ability to speak,
swallow and breathe.
Diseases or conditions that can happen during development
Cerebral Palsy – lack of oxygen to the brain during development or delivery.
Anencephaly – “an” without “encephaly” brain. Born without a brain.
Spina bifida – “forked spine” persons with this condition do not have the spinous processes on one or
more vertebrae. This lack of a dorsal wall for the spinal cord frequently results with some of the spinal
cord components usually meninges and cerebral spinal fluid protruding from the spine. Meningocele or
worse if it includes the spinal cord - (Myelomeningocele)