Shier, Butler, and Lewis:  Hole’s Human Anatomy and Physiology, 10th ed.                                     

Chapter 11:  Nervous System II

I.  Introduction

A.  Introduction
1.  The central nervous system consists of the brain and spinal cord.
2.  The brain is the largest and most complex part of the nervous system
3.  The brain includes two cerebral hemispheres, the diencephalon, the brainstem, and the cerebellum.
4.  The brainstem connects the brain and spinal cord and allows two-way communication between them.
5.  The spinal cord provides two-way communication between the central nervous system and the peripheral nervous system.
6.  The brain lies within the cranial cavity of the skull and the spinal cord occupies the vertebral canal.
7.  Meninges are located between the bone and the soft tissues of the nervous system and protect the brain and spinal cord.

II.  Meninges

A.  The meninges have three layers.
B.  The outermost layer is the dura mater and is composed of tough, white, dense connective tissue.
C.  Dural sinuses are channels in dura mater.
D.  Denticulate ligaments are bands of pia mater that attach spinal cord to dura mater.
E.  The epidural space is between the dural sheath and the bony walls and contains blood vessels.
F.  The arachnoid mater is thin, weblike membrane that lacks blood vessels and is located between the dura and pia maters.
G.  The subarachnoid space is between the arachnoid and pia maters and contains a fluid called cerebrospinal fluid.
H.  The pia mater is very thin and contains many nerves and blood vessels.
I.  The pia matter is attached to the surfaces of the brain and spinal cord.

III.  Ventricles and Cerebrospinal Fluid

A.  Introduction
1.  Ventricles are interconnected cavities and are located within the cerebral hemispheres and brain stem.
2.  The ventricles are continuous with the central canal of the spinal cord
and are filled with cerebrospinal fluid.
3.  The largest ventricles are the lateral ventricles which are located in the cerebral hemispheres.
4.  The third ventricle is located in the midline of the brain beneath the corpus callosum.
5.  The fourth ventricle is located in the brainstem just in front of the cerebellum.
6.  The cerebral aqueduct is a connection between the third and fourth ventricles.
7.  The choroids plexus is specialized mass of capillaries and functions to secrete cerebrospinal fluid.
8.  Most of the cerebrospinal fluid arises in the lateral ventricles
and circulates into the third ventricle, fourth ventricle, the central canal of the spinal cord, and the subarachnoid space.
9.  Cerebrospinal fluid is continuously absorbed into the blood.
10.  Arachnoid granulations are tiny, fingerlike structures that project from the subarachnoid space into the dural sinuses.
11.  Cerebrospinal fluid is different from blood in that it contains a greater concentration of sodium and lesser concentrations of glucose and potassium.
12.  The functions of cerebrospinal fluid are to help maintain a stable ionic concentration in the CNS, and provides a pathway to the blood for wastes.
13.  Because cerebrospinal fluid completely surrounds the brain and spinal cord, it protects them by absorbing forces that might otherwise jar and damage them.

IV.  Spinal Cord

A.  Introduction
1.  The spinal cord is continuous with the brain and extends through downward through the vertebral canal.
2.  The spinal cord begins at the level of the foramen magnum and terminates near the intervertebral disc that separates the first and second lumbar vertebrae.
B.  Structure of the Spinal Cord
1.  The spinal cord consists of thirty-one segments, each of which gives rise to a pair of spinal nerves.
2.  The two enlargements of the spinal cord are the cervical enlargement and the lumbar enlargement.
3.  The cervical enlargement supplies nerves to the upper limbs.
4.  The lumbar enlargement supplies nerves to the lower limbs.
5.  The conus medullaris is the tapered end of the spinal cord.
6.  The filum terminale is a thin cord of connective tissue that anchors the spinal cord to the upper surface of the coccyx.
7.  The cauda equina is a group of spinal nerves below the conus medullaris.
8.  Two grooves that extend the length of the spinal cord are the anterior median fissure and a posterior median sulcus.
9.  In a cross section of the spinal cord, white matter surrounds gray matter.
10.  Each side of the gray matter is divided into the following three horns: posterior horn, anterior horn, and lateral horn.
11.  Motor neurons are located in the anterior horns.
12.  The gray commissure is a horizontal bar of gray matter in the middle of the spinal cord.
13.  The central canal is a canal running through the center of the gray commissure down the entire length of the spinal cord.
14.  Three regions of the white matter are posterior funiculi, anterior funiculi, and lateral funiculi.
15.  Nerve tracts are groups of myelinated nerve fibers in the CNS.
C.  Functions of the Spinal Cord
1.  Reflex Arcs
a.  Reflex arcs carry out reflexes.
b.  A reflex arc begins with a receptor at the end of the dendrites of a sensory neuron.
c.  The sensory neuron leads to several interneurons which serve as a processing center.
d.  The interneurons communicate with motor neurons whose fibers pass to effectors.
e.  Spinal reflexes are reflexes whose arcs pass through the spinal cord.
2.  Reflex Behavior
a.  Reflexes are automatic, subconscious responses to changes within or outside the body.
b.  Reflexes function to maintain homeostasis by controlling many involuntary processes such as heart rate, breathing rate, etc.
c.  The knee-jerk reflex is an example of a simple monosynaptic reflex because it only uses two neurons.
d.  The knee-jerk reflex is initiated by striking the patellar tendon.
e.  When the tendon is struck, the quadriceps muscle is pulled.
f.  When the muscle is pulled, stretch receptors are stimulated.
g.  The receptors generate a nervous impulse that enters the spinal cord on an axon; the axon synapses with a motor neuron.
h.  The axon of the motor neuron synapses with the quadriceps muscle and the muscle responds by contracting.
i.  The knee-jerk reflex helps maintain posture.
j.  The withdrawal reflex occurs when a person touches something painful.
k.  In the withdrawal reflex, muscles on the affected side contract and the flexor muscles on the unaffected side are inhibited.
l.  The extensor muscles on the unaffected side contract, helping to support the body weight that has been shifted.
m.  A crossed extensor reflex is due to interneuron pathways within the reflex center of the spinal cord that allow sensory impulses arriving on one side of the cord to pass across to the other side and produce an opposite effect.
n.  A withdrawal reflex protects because it prevents or limits tissue damage when a body part touches something potentially harmful.
3.  Ascending and Descending Tracts
a.  Ascending tracts conduct sensory impulses to the brain.
b.  Descending tracts conduct motor impulses away from the brain.
c.  The names that identify nerve tracts often reflect the origin and termination of the tract.
d.  Four major ascending tracts of the spinal cord are fasciculus gracilis, fasciculus cuneatus, spinothalamic tracts, and spinocerebellar tracts.
e.  The fasciculus gracilis and fasciculus cuneatus are located in posterior funiculi.
f.  The fibers of fasciculus gracilis and fasciculus cuneatus conduct sensory impulses associated with the senses of touch, pressure, and body movement from skin, muscles, tendons, and joints to the brain.
g.  The spinothalamic tracts are located in lateral and anterior funiculi.
h.  The lateral spinothalamic tracts conduct impulses from various body regions to the brain and five rise to sensation of pain and temperature.
i.  The anterior spinothalamic tracts impulses are interpreted as touch and pressure.
j.  Spinocerebellar tracts are located in lateral funiculi.
k.  Impulses on the spinocerebellar tracts originate in the muscles of the lower limbs and trunk and travel to the cerebellum.
l.  Three major descending tracts of the spinal cord are corticospinal tracts, reticulospinal tracts, and reubrospinal tracts.
m.  Corticospinal tracts are located in lateral and anterior funiculi.
n.  The corticospinal tracts conduct motor impulses associated with voluntary movements from the brain to skeletal muscles.
o.  The pyramidal tracts are the corticospinal tracts and the extrapyramidal tracts are all other descending spinal tracts.
p.  Reticulospinal tracts are located in lateral and anterior funiculi.
q.  Motor impulses of the reticulospinal tracts control muscular tone and activity of sweat glands.
r.  Rubrospinal tracts are located in lateral funiculi.
s.  Rubrospinal tracts carry motor impulses that coordinate muscles and control posture.
V.  Brain
A.  Introduction
1.  The brain contains nerve centers associated with sensory functions.
and is responsible for sensations and perceptions.
2.  The other functions of the brain include control of motor functions and higher mental functions such as memory; it also provides characteristics such as personality.
B.  Brain Development
1.  The brain begins as a neural tube.
2.  The portion of the neural tube that becomes the brain has the following three major cavities:  forebrain, midbrain, and hidbrain.
3.  The forebrain divides into the telencephalon and the diencephalon.
4.  The hindbrain partially divides into the metencephalon and myelencephalon.
5.  The wall of the anterior potion of the forebrain gives rise to the cerebrum and basal nuclei.
6.  The posterior portion of the forebrain gives rise to the diencephalon.
7.  The midbrain is called midbrain in the adult and the hindbrain gives rise to the cerebellum, pons, and medulla oblongata.
C. Structure of the Cerebrum
1.  The cerebrum is the largest part of the adult brain.
2.  The cerebrum consists of two hemispheres.
3.  The corpus callosum is a bridge of nerve fibers that connects the two cerebral hemispheres.
4.  Convolutions are ridges.
5.  Sulci are grooves between ridges.
6.  A fissure is a deep groove.
7.  The longitudinal fissure separates the left and right cerebral hemispheres.
8.  The transverse fissure separates the cerebrum from the cerebellum.
9.  The 5 lobes of the cerebral hemispheres are frontal, parietal, occipital, temporal and insular.
10.  The most anterior lobe is the frontal.
11.  The frontal lobe is bordered posteriorly by the central sulcus and inferiorly by a lateral sulcus.
12.  The parietal lobe is separated from the frontal lobe by the central sulcus.
13.  The temporal lobe lies inferior to the frontal and parietal lobes and is separated from them by the lateral sulcus.
14.  The most posterior lobe is the occipital lobe.
15.  The tentorium cerebelli is an extension of the dura mater between the occipital lobe and cerebellum.
16.  The insula is located deep within the lateral fissure.
17.  The cerebral cortex is an outer, thin layer of gray matter and contains nearly 75% of all the neuron cell bodies in the nervous system
18.  Just beneath the cerebral cortex is white matter.
D.  Functions of the Cerebrum
1.  Functional Regions of the Cortex
a.  The cerebral cortex is divided into the following three major sections:  motor, sensory, and association areas.
2.  Motor Areas
a.  The primary motor areas are located in the frontal lobes just in front of the central sulcus and in the anterior wall of this sulcus.
b.  Impulses transmitted from the primary motor are responsible for fine movements in skeletal muscles.
c.  Broca’s area is located just anterior to the primary motor cortex and superior to the lateral sulcus and is responsible for coordinating complex muscular movements of the mouth, tongue, and larynx for speech.
d.  Broca’s area is usually found in the left hemisphere.
e.  The frontal eye field is located above Broca’s area and is responsible for controlling voluntary movements of the eyes and eyelids.
3.  Sensory Areas
a.  Sensory areas interpret impulses from sensory receptors.
b.  Sensations on the skin are interpreted in the anterior portions of the parietal lobes along the central sulcus.
c.  Visual sensations are interpreted in the occipital lobe.
d.  Auditory sensations are interpreted in the temporal lobe.
e.  Taste sensations are interpreted in the bases of the central sulci along the lateral sulci.
f.  Like motor fibers, sensory fibers cross over in the spinal cord or brainstem.
4.  Association Areas
a.  Association areas are regions of the cerebral cortex that are not primarily sensory or motor in function.
b.  Association areas analyze and interpret sensory experiences and help provide memory, reasoning, verbalizing, judgment, and emotions.
c.  The association areas of the frontal lobe provide higher intellectual processes.
d.  The prefrontal areas control emotional behavior and produce awareness of the possible consequences of behavior.
e.  The parietal lobes have association areas that help interpret sensory information and aid in understanding speech and choosing word to express thoughts and feeling.
f.  The association areas of the temporal lobes interpret complex sensory experiences, such as those needed to understand speech and to read.
g.  The association areas of the occipital lobes are important for analyzing visual patterns and combining visual images with other sensory experiences.
h.  The general interpretative area is located where the parietal, temporal, and occipital association areas join and functions to make it possible for a person to recognize words and arrange them to express a thought, and to read and understand ideas presented in writing.
5.  Hemisphere Dominance
a.  In over 90% of the population, the left hemisphere is dominant.
b.  The dominant hemisphere controls language-related activities of speech, writing, and reading.  Is also controls complex intellectual functions requiring verbal, analytical, and computational skills.
c.  The nondominant hemisphere controls nonverbal functions, such as motor tasks that require orientation of the body in space, understanding and interpreting musical patterns and visual experiences.  It also controls emotional intuitive through processes.
d.  Nerve fibers of the corpus callosum enable the dominant hemisphere to control the motor cortex of the nondominant hemisphere.
6.  Memory
a.  Memory is the consequence of learning.
b.  Two types of memory are short-term and long-term.
c.  Short-term memories are electrical in nature.
d.  When the electrical impulse of a short-term memory ceases, the memory goes away.
e.  Long-term memory changes the structure or function of neurons in ways that enhance synaptic transmission.
f.  Memory consolidation is the way the brain encodes memories and how short-term memories are converted to long-term memories.
E.  Basal Nuclei
1.  The basal nuclei are masses of gray matter located deep within the cerebral hemispheres and are called caudate nucleus, the putamen, and globus pallidus.
2.  The basal nuclei relay motor impulses originating in the cerebral cortex and passing into the brainstem and spinal cord.
3.  The basal nuclei produce most of the dopamine in the nervous system.
4.  Impulses from the basal nuclei function to control muscular activities.
F.  Diencephalon
1.  The diencephalon is located between the cerebral hemispheres and above the brainstem.
2.  The various parts of the diencephalon are thalamus, hypothalamus, optic tracts, the infundibulum, posterior pituitary bland, mammillary bodies and the pineal gland.
3.  The thalamus is a selective gateway for sensory impulses ascending from other parts of the nervous system to the cerebral cortex.
4.  The thalamus receives most sensory impulses and channels them to appropriate parts of the cortex for interpretation.
5.  The hypothalamus regulates heart rate, arterial blood pressure, body temperature, water and electrolyte balance, control of hunger and body weight, control of movements and glandular secretions of the stomach and intestine, produces hormones, and controls sleep and wakefulness.
6.  The limbic system consists of portions of the cerebral cortex, thalamus, hypothalamus, basal nuclei, and other deep nuclei and controls emotional experience and expression and can modify the way a person acts.
G.  Brain Stem
1.  Introduction
a.  The brain stem connects the brain and spinal cord.
b.  The brain stem consists of the midbrain, pons, and medulla oblongata.
c.  Nuclei of the brain stem are masses of gray matter.
2.  Midbrain
a.  The midbrain is between the diencephalon and the pons.
b.  The cerebral aqueduct is a connection between the third ventricle and fourth ventricle.
c.  Corpora quadrigemina are two pairs of rounded knobs on the superior surface of the midbrain.
d.  The superior colliculi contain centers for visual reflexes.
e.  The inferior colliculi contain centers for auditory reflexes.
f.  The red nucleus is at the center of the midbrain and is important for controlling reflexes that maintain posture.
3.  Pons
a.  The pons is located on the underside of the brainstem between the midbrain and medulla oblongata.
b.  The dorsal portion of the pons largely consists of fibers that relay impulses to and from the medulla oblongata and the cerebrum.
c.  The ventral portion consists of fibers that relay impulses from the cerebrum to centers within the cerebellum.
d.  Several nuclei of the pons relay sensory information to higher brain centers.
e.  The pons also regulates rate and depth of breathing.
4.  Medulla Oblongata
a.  The medulla oblongata is located between the spinal cord and pons.
b.  The olive of the medulla oblongata is a bulge where bundles of fibers originate and pass to the cerebellum.
c.  The visceral activities controlled by the medulla oblongata are heart rate, vasoconstriction, vasodilation, and breathing.
d.  Nonvital reflexes regulated by the medulla oblongata are coughing, sneezing, swallowing, and vomiting.
5.  Reticular Formation
a.  The reticular formation is a complex network of fibers that extend throughout the brainstem and diencephalon and connects with centers of the hypothalamus, cerebrum, cerebellum, and basal nuclei.
b.  The reticular formation activates the cerebral cortex into a state of wakefulness.
c.  Decreased activity of the reticular formation results in sleep.
d.  The reticular formation also filters incoming sensory impulses.
e.  The reticular formation also regulates motor activities so that various skeletal muscles move together evenly, and it inhibits or enhances certain spinal reflexes.
6.  Types of Sleep
a.  The two types of sleep are slow wave and rapid eye movement.
b.  Slow-wave sleep occurs when a person is very tired and it reflects decreasing activity of the reticular formation.
c.  Slow-wave sleep is accompanied by reduced blood pressure and respiratory rate.
d.  REM sleep is the type of sleep in which dreaming occurs and heart rate and respiratory rates are irregular.
H.  Cerebellum
1.  The cerebellum is located inferior to the occipital lobes of the cerebrum and posterior to the pons and medulla oblongata.
2.  The falx cerebelli is a layer of dura mater that partially separates the cerebellar hemispheres.
3.  The vermis is a structure that connects the cerebellar hemispheres at the midline.
4.  The cerebellar cortex is an outer, thin layer of gray matter.
5.  The arbor vitae is a treelike pattern of white matter in the cerebellum.
6.  The largest and most important nucleus of the cerebellum is the dentate nucleus.
7.  Cerebellar peduncles are nerve tracts.
8.  Inferior peduncles bring sensory information concerning the actual position of body parts such as limbs and joints to the cerebellum.
9.  The middle peduncles transmit impulses from the cerebral cortex about the desired position of body parts to the cerebellum.
10.  The superior peduncles sends correcting impulses to the midbrain.
11.  Overall, the cerebellum functions to integrate sensory information concerning the position of body parts and coordinated skeletal muscle activity and maintains posture

VII.  Peripheral Nervous System

A.  Introduction
1.  The peripheral nervous system consists of nerves that branch from the central nervous system.
2.  The somatic nervous system consists of the cranial and spinal nerve fibers that connect the DNS to the skin and skeletal muscles.
3.  The autonomic nervous system consists of fibers that connect the CNS to viscera and various glands
B.  Structure of Peripheral Nerves
1.  A peripheral nerve consists of connective tissue surrounding bundles of nerve fibers.
2.  Epineurium is the outermost layer of connective tissue of a nerve.
3.  Perineurium is a sleeve of connective tissue that surrounds a nerve fascicle.
4.  Endoneurium is loose connective tissue that surrounds individual nerve fibers.
C.  Nerve Fiber Classification
1.  Sensory nerves are nerves that conduct impulses into the brain or spinal cord.
2.  Motor nerves are nerves that conduct impulses to muscles or glands
3.  Mixed nerves are nerves that include both sensory fibers and motor fibers.
4.  Cranial nerves are nerves that originate from the brain.
5.  Spinal nerves are nerves that originate from the spinal cord.
6.  General somatic efferent fibers carry motor impulses outward from the brain or spinal cord to skeletal muscles and stimulate them to contract.
7.  General visceral efferent fibers carry motor impulses outward from the brain or spinal cord to various smooth muscles and glands associated with internal organs, causing certain muscles to contract or glands to secrete.
8.  General somatic afferent fibers carry sensory impulses inward to the brain or spinal cord from receptors in the skin and skeletal muscles.
9.  General visceral afferent fibers carry sensory impulses to the central nervous system from blood vessels and internal organs.
10.  Special somatic efferent fibers carry motor impulses outward from the brain to the muscles used in chewing, swallowing, speaking, and forming facial expressions.
11.  Special visceral afferent fibers carry sensory impulses inward to the brain from the olfactory and taste receptors.
12.  Special somatic afferent fibers carry sensory impulses inward to the brain from the receptors of sight, hearing, and equilibrium.
D.  Cranial Nerves
1.  Cranial nerves arise from the underside of the brain.
2.  Cranial nerves are designated by roman numerals or names.
3.  The olfactory nerve functions to transmit sensory impulses associated with smell.
4.  The optic nerve functions to transmit sensory impulses associated with sight.
5.  The oculomotor nerve functions to transmit impulses to muscles that arise the eyelids, move the eyes, and adjust the amount of light entering the eyes, and focus the lenses.  It also transmits sensory impulses associated with proprioceptors.
6.  The trochlear nerve functions to transmit impulses to muscles that move the eyes.  It also transmits sensory impulses associated with proprioceptors.
7.  The three divisions of the trigeminal nerve are ophthalmic, maxillary, and mandibular.
8.  The ophthalmic division functions to transmit sensory impulses from the surface of the eyes, tear glands, scalp, forehead, and upper eyelids. 
9.  The maxillary division functions to transmit impulses from the upper teeth, upper gum, upper lip, lining of the palate, and skin of the face.
10.  The mandibular division functions to transmit sensory impulse from the scalp, skin of the jaw, lower teeth, lower gum, and lower lip.  It al transmits motor impulses to muscles of mastication and to muscles in the floor of the mouth.
11.  The abducens nerve functions to transmit motor impulses to muscles that move the eyes.  It also transmits sensory impulses associated with proprioceptors.
12.  The facial nerve functions to transmit sensory impulses associated with taste receptors of the anterior tongue.   It also transmits motor impulse to muscles of facial expression, tear gland, and salivary glands.
13.  The two branches of the vestibulocochlear nerve are the vestibular branch and the cochlear branch.
14.  The vestibular branch functions to transmit sensory impulses associated with the sense of equilibrium.
15.  The cochlear branch functions to transmit sensory impulses associated with hearing.
16.  The glossopharyngeal nerve functions to transmit sensory impulses for the pharynx, tonsils, posterior tongue, and carotid arteries.  It also transmits motor impulses to salivary glands and to muscles of the pharynx used in swallowing.
17.  The vagus nerve functions to transmit motor impulses to muscles associated with speech and swallowing, and to viscera of the thorax and abdomen.  It also transmits sensory impulses from the pharynx, larynx, esophagus, and viscera of the thorax and abdomen.
18.  The branches of the accessory nerve are the cranial branch and spinal branch.
19.  The cranial branch functions to transmit motor impulses to muscles of the soft palate, pharynx, and larynx. 
20.  The spinal branch functions to transmit motor impulses to muscles of the neck and back.
21.  The hypoglossal nerve functions to transmit motor impulses to muscles that move the tongue.
E.  Spinal Nerves
1.  Introduction
a.  There are thirty-one pairs of spinal nerves.
b.  All spinal nerves are mixed nerves and they provide two –way communication between the spinal cord and parts of the upper and lower limbs, neck and trunk.
c.  There are 8 pairs of cervical nerves.
d.  There are 12 pairs of thoracic nerves.
e.  There are 5 pairs of lumbar nerves.
f.  There are 5 pairs of sacral nerves.
g.  There is 1 pair of coccygeal nerves.
h.  The adult spinal cord ends at the level of the first or second lumbar vertebrae.
i.  The cauda equina is a collection of spinal nerves at the end of the spinal cord.
j.  Each spinal nerve emerges from the cord by roots.
k.  The dorsal root ganglion contains the cell bodies of the sensory neurons whose dendrites conduct impulses from the peripheral body parts.
l.  The axons of neurons in dorsal root ganglia extend through the dorsal root.
m. A dermatome is an area of skin that the sensory nerve fibers of a particular spinal nerve innervate.
n.  The ventral root consists of axons from the motor neurons whose cell bodies are located within the gray matter of the cord.
o.  A ventral root and dorsal root unite to form a spinal nerve.
p.  A meningeal branch of a spinal nerve supplies the meninges and blood vessels of the spinal cord, as well as the intervertebral ligaments and the vertebrae.
q.  A posterior branch of a spinal nerve supplies the muscles and skin of the back.
r.  An anterior branch of a spinal nerve supplies muscles and skin on the front and sides of the trunk and limbs.
s.  A visceral branch of a spinal nerve supplies viscera.
t.  A plexus is a complex network of anterior branches of spinal nerves.
u.  In a plexus, fibers of various spinal nerves are sorted and recombined, so fibers associated with a particular peripheral body part reach it in the same nerve, even though the fibers originate from different spinal nerves.
2.  Cervical Plexuses
a.  The cervical plexus is located deep in the neck on either side.
b.  The cervical plexus is formed by the anterior branches of the first four cervical nerves.
c.  Fibers from the cervical plexus supply the muscles and skin of the neck and contribute to the phrenic nerve.
d.  The phrenic nerve conducts impulses to the diaphragm.
3.  Brachial Plexuses
a.  The brachial plexus is located deep within the shoulders between the neck and axillae.
b.  The brachial plexus is formed by the anterior branches of the lower four cervical nerves and the first thoracic nerve.
c.  The major branches emerging from the brachial plexus are the musculocutaneous, ulnar, median, radial, and axillary.
d.  The musculocutaneous nerves supply muscles of the arms on the anterior sides and the skin of the forearms.
e.  The ulnar nerves supply muscles of the forearms and hands and the skin of the hands.
f.  The radial nerves supply muscles of the arms on the posterior sides and the skin of the forearms and hands.
g.  The median nerves supply muscles of the forearms and muscles and skin of the hands.
h.  The axillary nerves supply muscles and skin of the superior, lateral, and posterior regions of the arm.
4.  Lumbosacral Plexuses
a.  The lumbosacral plexus is located in the lumbar and pelvic regions.
b.  The lumbosacral plexus is formed by anterior branches of the last thoracic nerve and lumbar, sacral , and coccygeal nerves.
c.  The major branches of the lumbosacral plexus are obturator, femoral, and sciatic nerves.
d.  The obturator nerves supply the adductor muscles of the thighs.
e.  The femoral nerves supply motor impulses to muscles of the thighs and legs and receive sensory impulses from the skin of the thighs and legs.
f.  The sciatic nerves supply muscles and skin the thighs, legs, and feet.
g.  The common peroneal nerves supply muscles and skin of the thighs, legs, and feet.
h.  The anterior branches of thoracic spinal nerves do not form plexuses; instead these branches become intercostal nerves that supply motor impulses to the intercostal muscles and the upper abdominal wall muscles.
VIII.  Autonomic Nervous System
A.  Introduction
1.  The autonomic nervous system controls visceral activities by regulating the actions of smooth muscles, cardiac muscles, and various glands.
2.  The autonomic nervous system functions without conscious effort.
B.  General Characteristics
1.  The two divisions of the autonomic nervous system are sympathetic and parasympathetic.
2.  The sympathetic division prepares the body for energy-expending, stressful, or emergency situations.
3.  The parasympathetic division is most active during ordinary, restful conditions.
C.  Autonomic Nerve Fibers
1.  All nerve fibers of the autonomic nervous system are motor fibers.
2.  In the autonomic system, motor pathways include two neurons.
3.  A preganglionic fiber is an axon of a preganglionic neuron.
4.  A postganglionic fiber is an axon of a postganglionic neuron.
5.  A preganglionic fiber synapses with a postganglionic neuron.
6.  A postganglionic fiber synapses with an effector, such as a gland.
D.  Sympathetic Division
1.  In the sympathetic division, the preganglionic fibers originate from neurons within the lateral horns of the spinal cord.  These neurons are in the thoracic and lumbar regions of the spinal cord.
2.  In the sympathetic division, the preganglionic fibers leave the spinal nerves through white rami and enter sympathetic ganglia.
3.  Paravertebral ganglia are located in chains along the sides of the vertebral column.
4.  The sympathetic trunks are Paravertebral ganglia and the fibers that connect the ganglia.
5.  The collateral ganglia are located within the abdomen, closely associated with certain large blood vessels.
6.  Typically a preganglionic axon of the sympathetic nervous system will synapse with several other neurons within a sympathetic ganglion.
7.  In the sympathetic division, the postganglionic fibers extend out from the sympathetic ganglia to visceral effectors.
8.  Gray rami are branches that contain unmyelinated postganglionic axons.
E.  Parasympathetic Division
1.  The preganglionic fibers of the parasympathetic division arise from neurons in the midbrain, pons, medulla oblongata, and sacral region of the spinal cord.
2.  The preganglionic fibers of the parasympathetic division lead to ganglia that are located near or within various organs.
3.  The short postganlionic fibers of the parasympathetic division lead to specific muscles or glands within visceral organs.
4.  Parasympathetic preganglionic fibers are usually myelinated and the postganglionic fibers are usually unmyelinated.
F.  Autonomic Neurotransmitters
1.  The preganglionic fibers of the sympathetic and parasympathetic divisions secrete acetylcholine and are called cholinergic.
2.  The parasympathetic postganglionic fibers are cholinergic fibers.
3.  Most sympathetic postganglionic fibers secrete norepinephrine and are called adrenergic.
4.  The different postganglionic neurotransmitters are responsible for the different effects that the sympathetic and parasympathetic divisions have on organs.
5.  Sympathetic tone is a state of constant partial contraction of smooth muscles in the wall of blood vessels caused by sympathetic innervation.
G.  Actions of Autonomic Neurotransmitters
1.  The actions of autonomic neurotransmitters result from their binding to protein receptors in the membrane of effector cells.
2.  Two types of cholinergic receptors are muscarinic and nicotinic.
3.  Muscarinic receptors are located in the membranes of effector cells at the ends of all postganglionic parasympathetic nerve fibers and at the ends of the cholinergic sympathetic fibers.
4.  Nicotinic receptors are located in the synapses between the preganglionic and postganglionic neurons of the parasympathetic and sympathetic pathways.
5.  Responses from muscarinic receptors are excitatory and slow.
6.  Responses from nicotinic receptors are excitatory and rapid.
7.  The two major types of adrenergic receptors are alpha and beta receptors.
8.  Acetylcholinesterase decomposes acetylcholine.
H.  Control of Autonomic Activity
1.  The autonomic nervous system is largely controlled by the brain and spinal cord.
2.  The limbic system and cerebral cortex control the autonomic nervous system during emotional stress.
IX.  Life-Span Changes
A.  Apoptosis is a form of programmed cell death and first occurs during development.
B.  By age thirty, the die-off of neurons accelerates.
C.  Over an average lifetime, the brain shrinks by about 10%.
D.  With aging, the numbers of dendritic branches and amounts of neurotransmitters decrease.
E.  Noticeable signs of a normally aging nervous system include fading memory and slowed responses and reflexes.
F.  Decline in function of the sympathetic nervous system may cause transient drops in blood pressure.
G.  Changes in sleep patterns reflect the functioning of the reticular activating system.

Chapter 11
Nervous System II: Divisions of the Nervous System
11.1 Introduction
1.  Explain the general function of the brain, spinal cord, and brainstem, and their interrelationship. (p. 384)
The brain oversees many aspects of physiology, including sensation and perception, movement, and thinking.  The brainstem connects the brain and spinal cord and allows two-way communication between them.  The spinal cord provides two-way communication between the CNS and the PNS.

11.2 Meninges
2.  Name the layers of the meninges, and explain their functions. (p. 384)
The layers of the meninges surround the brain and spinal cord. They are, from the outermost to the innermost layers:
Dura mater—the dura mater is a tough, fibrous connective tissue layer containing many blood vessels and nerves. It functions as a protective layer, surrounding the brain and spinal cord.
Arachnoid mater—the arachnoid mater is a thin web-like membrane that lacks blood vessels and nerves. It is attached to the pia mater by thin strands.
Pia mater—the pia mater is a thin membrane containing many nerves and blood vessels that provide nourishment to the underlying brain cells and spinal cord. It is attached directly to the surface of the brain and spinal cord.

11.3 Ventricles and Cerebrospinal Fluid
3.  Describe the relationship among the cerebrospinal fluid, the ventricles, the choroid plexuses, and arachnoid granulations. (p. 385)
Tiny masses of specialized capillaries, called choroid plexuses, secrete CSF.  These structures project into the cavities of the ventricles.  CSF is continuously reabsorbed into the blood through tiny, fingerlike structures called arachnoid granulations that project from the subarachnoid space into the blood-filled dural sinuses.

4.  List the functions of cerebrospinal fluid. (p. 386)
Explain how cerebrospinal fluid is produced and how it functions.
Cerebrospinal fluid (CSF) is secreted by tiny reddish cauliflower-like masses of specialized capillaries in the pia mater called choroid plexuses that project into the ventricles. CSF is important in the protection and support of the CNS by absorbing the forces of impact, maintaining a stable ion concentration, and providing a route for waste products to be removed.  Humans secrete nearly 500 milliliters of CSF daily.  However, only about 140 milliliters are in the nervous system at any time.

11.4 Spinal Cord
5. Describe the structure of the spinal cord. (p. 387)
The spinal cord is a long slender column of nerve fibers that begins at the foramen magnum of the skull and extends downward to a point near the first and second lumbar vertebrae. The cord is actually a group of thirty-one segments that give rise to pairs of spinal nerves. These nerves connect all of the body to the CNS.
A thickening in the neck region, called the cervical enlargement, supplies the nerves to the arms and a similar thickening, the lumbar enlargement, supplies the nerves to the legs. Inferior to the lumbar enlargement, the spinal cord tapers into a structure (conus medullaris) that is connected to the coccyx by a thin cord of connective tissue (filum terminale).
Along the length of the cord are two grooves, the anterior median fissure and posterior median sulcus, which divide the cord into left and right halves. A cross section of the cord shows a gray matter core surrounded by white matter. The gray matter resembles a butterfly. The upper wings are called the posterior horns and the lower wings are called the anterior horns. Between these horns is a small protuberance called the lateral horn.
A horizontal bar of gray matter surrounds the central canal and connects the wings on both sides. The white matter is divided on each side into three regions, the anterior, lateral, and posterior funiculi.

6. Explain the two main functions of the spinal cord. (p. 387)
The two main functions of the spinal cord include serving as a center for spinal reflexes and serving as a conduit for nerve impulses to and from the brain.

7. Distinguish between a reflex arc and a reflex. (p. 389)
A reflex arc is the simplest response to a stimulus. It begins with a receptor at the end of sensor nerve fibers. It travels to a reflex center in the CNS and an impulse is sent to an effector along a motor nerve fiber.  A reflex is an automatic, subconscious response to stimuli inside or outside the body.

8.  Which of the choices is the correct sequence of events in a reflex arc? (p. 389)
b. sensory receptor to CNS to interneurons to motor neurons to effectors.

9.  Describe a withdrawal reflex. (p. 390)
When a person touches something painful, receptors in the skin send impulses to interneurons in a reflex center in the spinal cord. The reflex center sends impulses to the flexor muscles of the affected part causing the part to be moved away. At the same time this is happening, impulses to the extensor muscles of the affected part are inhibited, so that the flexors can work more effectively. A phenomenon, called a crossed extensor reflex, occurs simultaneously with the initial reflex that causes the extensors of the opposite limb to contract.

10.  Indicate whether each nerve tract is ascending or descending: (p. 393)
a. Rubrospinal—descending
b. Corticospinal—descending
c. Spinothalamic—ascending
d. Fasciculus gracilis—ascending
e. Reticulospinal—descending
f. Spinocerebellar—ascending

11.  Explain the consequences of nerve fibers crossing over. (p. 394)
Crossing over causes the impulses from one side of the body to be received and controlled by the opposite side of the brain.

11.5 Brain
12.  Describe the events of brain development. (p. 398)
During embryonic development, the brain begins as a neural tube that gives rise to the CNS. At one end there are three major cavities or vesicles: the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon). The forebrain divides into the anterior (telencephalon) and posterior (diencephalon) portions. The hindbrain partially divides into the metencephalon and myelencephalon. These five cavities in the mature brain become the ventricles and the tubes that connect them. The tissue of the telencephalon becomes the cerebrum and basal ganglia while the diencephalon remains unchanged. The midbrain continues to mature and is still called the midbrain in the adult structure. The hindbrain matures into the cerebella, pons, and medulla oblongata. The brain stem is comprised of the midbrain, pons, and medulla oblongata and connects the brain to the spinal cord.

13. Which choice lists the parts of the brainstem? (p. 398)
a. midbrain, pons, and medulla oblongata

14. Describe the structure of the cerebrum. (p. 398)
The cerebrum consists of two cerebral hemispheres separated by a layer of dura mater called the falx cerebri and connected deeply by a nerve fiber bundle called the corpus callosum. The hemispheres are marked by many convolutions separated by shallow grooves called sulci (sing. sulcus) and deep grooves called fissures.
These grooves form distinct patterns. For instance, the longitudinal fissure separates left and right hemispheres, and the transverse fissure separates the cerebrum from the cerebellum.
Various sulci divide each hemisphere into lobes named after the skull bones they underlie. They are:
Frontal lobe—the frontal lobe forms the anterior portion of each cerebral hemisphere, and lies in front of the central sulcus (fissure of Rolando) and above the lateral sulcus (fissure of Sylvius).
Parietal lobe—the parietal lobe lies behind the central sulcus and frontal lobe.
Temporal lobe—the temporal lobe lies below the frontal and parietal lobes, separated by the lateral sulcus.
Occipital lobe—the occipital lobe is the posterior portion of each hemisphere separated from the cerebellum by the tentorium cerebelli. There is no clear boundary between the temporal, parietal, and occipital lobes.
Insula—the insula (island of Reil) is found deep in the lateral sulcus and is separated from the frontal, parietal, and temporal lobes by a circular sulcus.

15.  Define cerebral cortex. (p. 400)
The cerebral cortex is the outermost layer of the cerebrum and is a layer of gray matter that contains 75 percent of all neuron bodies in the nervous system.

16.  Describe the location and function of the sensory areas of the cortex. (p. 401)
The sensory areas for temperature, touch, pressure, and pain in the skin are found in the anterior portion of the parietal lobes along the central sulcus. Vision sensory areas are found in the posterior portion of the occipital lobes. The sensory areas for hearing are found in the dorsal posterior portion of the temporal lobes. The sensory areas for taste are found near the base of the central sulci along the lateral sulci and the sense of smell arises from deep in the cerebrum.

17.  Explain the function of the association areas of the lobes of the cerebrum. (p. 402)
The association areas are found in the anterior frontal lobes, and in the lateral areas of the parietal, temporal, and occipital lobes. These function to analyze and interpret sensory experiences involving memory, reasoning, verbalizing, judgment, and emotions. The association areas of the frontal lobes deal with concentration, planning, problem solving, and judging the consequences of behavior. The areas of the parietal lobes deal with understanding speech and word choice for thought expression. The areas of the temporal lobes deal with complex sensory interpretation, such as reading, music, and memories of visual scenes. The areas of the occipital lobes deal with visual pattern analysis and combining these images with other sensory experiences.

18.  Describe the location and function of the motor areas of the cortex. (p. 402)
The primary motor areas of the cerebral cortex lie in the frontal lobes along the anterior wall of the central gyrus. Large pyramidal cells are responsible for nerve impulses sent through the corticospinal tracts to voluntary muscles. Impulses from the upper parts of the motor areas control muscles in the legs and thighs; the middle portion control muscles in the shoulders and arms; and the lower portions control the muscles of the head, face, and tongue.

19.  Broca’s area controls _________. (p. 402)
d. movements used in speaking

20.  Explain hemisphere dominance. (p. 403)
Although both hemispheres participate in basic functions, in most people, one hemisphere is dominant over the other. For instance, in over 90 percent of the population, the left hemisphere controls language activities such as reading, speech, and writing as well as complex intellectual functions requiring verbal, analytical, and computational skills. The non-dominant hemisphere seems to be more in control of the nonverbal activities such as spatial orientation, interpreting musical patterns, visual experiences, and emotional and intuitive thought.

21. Distinguish between short-term and long-term memory. (p. 404)
Short-term memories are thought to be electrical in nature such that the neurons are connected in a circuit so that the last in the series stimulates the first. As long as the stimulation continues, the thought is remembered. When it ceases, so does the memory, unless it enters long-term memory.
Long-term memories appear to change the structure or function of certain neurons that enhance synaptic transmission. The synaptic patterns must meet two requirements of long-term memory. First, there must be enough synapses to encode an almost infinite number of memories. Second, the pattern of synapses can remain unchanged for years.

22. Explain the conversion of short-term to long-term memory. (p. 404)
Understanding how neurons in different parts of the brain encode memories and how short-term memories are converted to long-term memories is at the forefront of research into the functioning of the human brain.  This process is referred to as memory consolidation.  Some theorists believe this conversion is explained by near simultaneous repeated stimulation of the same neurons.

23. The ________ transmits sensory information from other parts of the nervous system to the cerebral cortex. (p. 407)
thalamus

24.  List the parts of the limbic system, and explain its functions. (p. 407)
The limbic system controls emotional experience and expression. It produces feelings of fear, anger, pleasure, and sorrow. It apparently recognizes upsets in a person’s physical or psychological condition that could be life threatening. By relating pleasant or unpleasant feelings about experiences, it guides behaviors that may increase the chance of survival. It also interprets sensory impulses from the olfactory receptors.

25.  Name the functions of the midbrain, pons, and medulla oblongata. (p. 407)
The midbrain joins the lower parts of the brain stem and spinal cord with the higher parts of the brain. It also contains certain reflex centers. Two bundles of nerve fibers called the cerebral peduncles lie on the underside of the midbrain and form the corticospinal tracts, which are the main motor pathways between the cerebrum and lower parts of the nervous system. Two pairs of rounded knobs called the corporal quadrigemina provide centers for certain visual reflexes and the auditory reflex centers. In the center of the midbrain is a mass of gray matter called the red nucleus, which provides posture-maintaining reflexes.
The pons is a rounded bulge on the inferior side of the brain stem where it separates the midbrain from the medulla oblongata. The dorsal portion of the pons relays impulses between the medulla oblongata and the cerebrum. The ventral portion relays impulses from the cerebrum to the cerebellum. The pons also relays impulses from the peripheral nerves to higher brain centers. It also works with the medulla oblongata to regulate rate and depth of breathing.
The medulla oblongata is an enlarged continuation of the spinal cord at its superior end. It extends from the foramen magnum to the pons. Because of its location, all ascending and descending nerve fibers connecting the brain and the spinal cord must pass through it. Some of the nuclei in the gray matter relay ascending impulses to the other side of the brain stem and higher brain centers. Other nuclei control vital visceral activities and are called the cardiac center, the vasomotor center, and the respiratory center.

26.  Describe the location and function of the reticular formation. (p. 409)
The reticular formation is scattered throughout the medulla oblongata, pons, and midbrain as a complex network of nerve fibers associating with small islands of gray matter. It extends from the superior portion of the spinal cord through to the diencephalon and connects the hypothalamus, basal ganglia, cerebellum, and cerebrum with fibers in all the major ascending and descending tracts. Because the cerebral cortex is totally dependent on sensory impulses for its awareness of the external environment, the reticular formation is responsible for activating it into a state of wakefulness. Decreased activity in the reticular formation causes sleep. The reticular formation also filters incoming sensory impulses to prevent the cortex from being constantly bombarded by sensory stimulation, and allows it to concentrate on the significant information. The cerebra cortex can also activate the reticular formation during intense cerebral activities, keeping a person awake.

27.  Distinguish between normal and paradoxical sleep. (p. 409)
Normal sleep (slow wave or non-REM) occurs when a person is very tired and is caused by decreased activity of the reticular formation. It is restful, dreamless, and accompanied by reduced blood pressure and respiratory rate. Paradoxical sleep (REM sleep) is so named because some areas of the brain are active. It is identified by dreaming, rapid eye movement beneath the eyelids, and irregular respiratory and heart rates.

28.  The cerebellum _________. (p. 410)
d. does all of the above

11.6 Peripheral Nervous System
29.  Distinguish between the somatic and autonomic nervous systems. (p. 411)
The somatic nervous system is a division of the peripheral nervous system (PNS) and consists of cranial and spinal nerves that oversee conscious activities. The autonomic nervous system is the other division of the PNS and includes the fibers that connect the central nervous system (CNS) to the viscera. It controls unconscious activities.

30.  Describe the connective tissue and nervous tissue making up a peripheral nerve. (p. 412)
Describe the structure of a peripheral nerve.
A peripheral nerve consists of nerve fiber bundles surrounded by connective tissue. Each bundle of nerve fibers (fascicle) is encased in a sleeve of connective tissue called the perineurium, which is in turn, enclosed by dense collagenous fibers called the epineurium. The individual nerve fibers are surrounded by loose connective tissue called the endoneurium within the perineurium.

31.  Which of the following carry sensory impulses to the CNS from receptors in muscle or skin? (p. 412)
b. general somatic afferent fibers

32.  Draw the underside of a brain and label the cranial nerves. (p. 414)
See textbook figure
Olfactory nerves (I)— this pair serves as olfactory receptor nerve fibers which pass through the cribiform places as olfactory tracts to cerebral centers for interpretation as sensations of smell.
Optic nerves (II)—these lead from the eyes to the brain and are associated with the sense of sight.
Oculomotor nerves (III)—these arise from the midbrain and pass into the orbits of the eyes. These function to raise the eyelid, innervate muscles that move the eye, and allow the eye to adjust the amount of light entering the eyes and allow the lens to focus.
Trochlear nerves (IV)—these arise from the midbrain and carry motor impulses to certain voluntary muscles that move the eyes but are not supplied by the oculomotor nerves.
Trigeminal nerves (V)—these are the largest and arise from the pons. These are mixed nerves that have three major branches:
Opthalmic division—brings sensory impulses to the brain from the surface of the eyes, the tear glands, and the skin of the anterior scalp, forehead, and upper eyelids.
Maxillary division—carries sensory impulses from the upper teeth, upper gum, and upper lip, as well as from the mucous lining of the palate and the skin of the face.
Mandibular division—transmits impulses from the scalp behind the ears, the skin of the jaw, the lower teeth, the lower gum, and the lower lip. It has motor branches that supply the muscles of mastication, and certain muscles in the floor of the mouth.
Abducens nerve (VI)—these originate from the pons and enter the orbits of the eyes and supply motor impulses to a pair of muscles that move the eyes.
Facial nerves (VII)—these arise from the lower part of the pons and emerge on the sides of the face. The sensory branches are associated with taste receptors on the tongue. The motor fibers transmit impulses to the muscles of facial expression while others function in the autonomic nervous system and stimulate secretions from the tear glands and salivary glands.
Vestibulocochlear nerves (VIII)—sensory nerves that arise from the medulla oblongata. There are two distinct parts:
Vestibular branch—located in the ganglia associated with the parts of the inner ear and serve to help to maintain equilibrium.
Cochlear branch—located in parts of the inner ear that house the hearing receptors. Impulses from this branch pass through the pons and medulla oblongata on their way to the temporal lobes for interpretation.
Glossopharyngeal nerves (IX)—these arise from the medulla oblongata and are associated with the tongue and pharynx. These are mixed nerves but are predominantly sensory. They carry impulses from the linings of the pharynx, tonsils and posterior third of the tongue to the brain. The motor portion innervates muscles of the pharynx that function in swallowing.
Vagus nerves (X)—these originate in the medulla oblongata and extend downward into the chest and abdomen. These are mixed nerves containing both autonomic and somatic branches. The autonomic are the
predominate ones, associated with speech, swallowing, and motor activity of the smooth muscles and glands in the thorax and abdomen.
Accessory nerves (XI)—these originate in the medulla oblongata and the spinal cord. The cranial branch joins a vagus nerve and carries impulses to muscles of the soft palate, pharynx and larynx.
Hypoglossal nerves (XII)—these arise from the medulla oblongata and pass into the tongue. These work on tongue muscles that function in speaking, chewing, and swallowing.

33. Match the cranial nerve with its function. Functions may be used more than once.  (p. 414)
(1) olfactory nerve - I                                          
(2) optic nerve - K                                                 
(3) oculomotor nerve - H                                     
(4) trochlear nerve - C                                           
(5) trigeminal nerve – H, E, J                                        
(6) abducens nerve - C                                          
(7) facial nerve – B, E                                                
(8) vestibulocochlear nerve -G                            
(9) glossopharyngeal nerve – A, B, F                             
(10) vagus nerve – A, B, D, F                                                
(11) accessory nerve – A, F                                        
(12) hypoglossal nerve – A, B, F

34. Explain how the spinal nerves are grouped and numbered. (p. 417)
They are grouped according to the level from which they arise, and each nerve is numbered in sequence. There are eight pairs of cervical spinal nerves, twelve pairs of thoracic spinal nerves, five pairs of sacral spinal  nerves, and one pair of coccygeal nerves.

35. Define cauda equina. (p. 419)
The cauda equina is so named because in the adult, the spinal cord ends between the first and second lumbar vertebrae. Because of this the lumbar, sacral, and coccygeal nerves must descend down the spinal column to the exit points resembling a horse’s tail.

36. Describe the parts and their functions of a spinal nerve. (p. 419)
Each spinal nerve emerges from the spinal cord by two short branches that lie within the vertebral column.
The dorsal root is also called the posterior or sensory root. It can be identified by the dorsal root ganglion. This root conducts sensory impulses inward from the peripheral body parts. The ventral root is also called the anterior or motor root. It consists of axons from the motor neurons. The roots unite to form a spinal nerve, which extends outward from the vertebral canal through an intervertebral foramen. Each spinal nerve splits into three parts called the meningeal, posterior, and anterior branches. Spinal nerves in the thoracic and lumbar regions have a fourth or visceral branch, which supplies the autonomic nerve fibers.

37. Define plexus, and locate the major plexuses of the spinal nerves. (p. 420)
A plexus is the main portion of the spinal nerves that have combined to form complex networks. Except in the thoracic region, anterior branches of the spinal nerves provide the network for the plexus. In a plexus, the fibers of various spinal nerves are sorted and recombined so that the fibers associated with a particular peripheral body part reach it in the same nerve, even though the fibers originate from different spinal nerves.
There are three main plexuses:
Cervical plexuses—supply the muscles of the skin and neck and the phrenic nerves innervate the diaphragm.
Brachial plexuses—supply the muscles and skin of the arm, forearm, and hand.
Lumbosacral plexuses—give rise to motor and sensory fibers associated with the muscles and skin of the lower abdominal wall, external genitalia, buttocks, thighs, legs, and feet.

11.7 Autonomic Nervous System
38. The autonomic portion of the PNS functions _________. (p. 424)
are varied.   The general functions of the autonomic system are to bring in sensory signals from the visceral organs and skin, interpret them, and send out the appropriate motor response.  The autonomic nervous system includes two interacting divisions, the sympathetic and parasympathetic divisions.

39. Contrast the sympathetic and parasympathetic divisions of the autonomic nervous system. (p. 424)
The sympathetic division of the autonomic nervous system is concerned primarily with preparing the body for energy-expending, stressful, or emergency situations. The parasympathetic division is active under ordinary, restful conditions. It counterbalances the effects of the sympathetic division and restores the body to a resting state following a stressful experience.

40. Distinguish between a preganglionic fiber and a postganglionic fiber. (p. 424)
The preganglionic fiber is the axon of the first neuron in the two neuron autonomic system. Its cell body is located in the CNS and forms a synapse with one or more nerve fibers whose cell bodies are housed within an autonomic ganglion. The axon of the second neuron is called the postganglionic fiber, because it extends from the ganglia to a visceral effector

41. Define paravertebral ganglion. (p. 425)
Paravertebral ganglia are two groups of ganglia whose preganglionic fibers split from the spinal nerves of the thoracolumbar division at branches called white rami. They are located as chains along the sides of the vertebral column and comprise part of the sympathetic trunks.

42. Trace a sympathetic nerve pathway through a ganglion to an effector. (p. 425)
The pathway begins with the neuron in the lateral horn of the spinal cord. Its preganglionic fiber exits through the ventral roots of spinal nerves. It branches off in segments called white rami and enters the paravertebral ganglia (forming sympathetic trunks). Some fibers synapse with these ganglia while others pass through to other paravertebral ganglia or on to, or beyond, the collateral ganglia. The postganglionic fibers extend out to the visceral effectors. The fibers leaving the paravertebral ganglia usually pass through gray rami and return to a spinal nerve before synapsing with an effector.

43. Trace a parasympathetic nerve pathway. (p. 426)
These fibers arise from neurons in the midbrain, pons, and medulla oblongata of the brainstem and from part of the sacral region of the spinal cord.  From there, they lead outward on cranial or sacral nerves to ganglia near or in various organs.  Some continue on to specific muscles or glands in these organs.

44. Distinguish between cholinergic and adrenergic nerve fibers. (p. 428)
With a few exceptions, the preganglionic fibers of both the sympathetic and parasympathetic divisions, and the postganglionic fibers of the parasympathetic division, secrete acetylcholine, and are thus called cholinergic fibers. The postganglionic sympathetic fibers secrete norepinephrine (noradrenalin), and are thus called adrenergic fibers.

45. Define sympathetic tone. (p. 429)
Sympathetic tone is a maintained state of partial contraction of muscles stimulated by only the sympathetic division.

46. Explain how autonomic neurotransmitters influence the actions of effector cells. (p. 429)
Autonomic transmitters act by binding to protein receptors of effector cell membranes. This receptor
binding alters the membrane in certain ways to produce the desired effect. Muscarinic receptors are found in the membranes of all effector cells at the end of postganglionic parasympathetic and cholinergic sympathetic nerve fibers. Nicotinic receptors are found in the synapses between the pre- and postganglionic neurons of the postganglionic neurons of the sympathetic and parasympathetic pathways.

47.  Distinguish between alpha adrenergic and beta adrenergic receptors. (p. 430)
Alpha adrenergic receptors are responsible for smooth muscle contraction causing vasoconstriction.
Stimulation of the beta receptors, however, will cause smooth muscle relaxation leading to bronchodilation in the lungs. In essence, stimulation of alpha receptors is constrictive in nature, which stimulation of beta receptors will cause dilation.

11.8 Life-Span Changes
48. Explain the effects of apoptosis on the developing brain. (p. 431)
Apoptosis begins before birth as a form of programmed cell death.  This process helps to carve out the structures that will remain in the brain.  When brain apoptosis fails, disease results.

49. List three ways that the nervous system changes as we age. (p. 431)
!. Neuron death accelerates to a certain degree.
2. Decreased levels of neurotransmitters.
3. Fading memory and slower reflexes.

50. Describe sleep problems that may accompany aging. (p. 431)
Problems may include transient difficulty in getting to sleep and staying asleep, more frequent movements while sleeping, insomnia, diminished REM sleep, and daytime sleepiness.