Anat Ch. 9 Part 4

The third cranial nerve (oculomotor nerve) conducts impulses from the brain to muscles in the eye, where they

cause contractions that move the eye.

RESEARCH, ISSUES, AND TRENDS: Parkinson disease (PD) is a chronic, progressive nervous disorder resulting from a deficiency of the neurotransmitter dopamine in the basal nuclei of the cerebrum. The group of signs associated with this disorder is a syndrome called

parkinsonism.

Create and study figure 9-17 WS

(do it)

(#)__ pairs of nerves are attached to the spinal cord in the following descending anatomical order: (omitted)

31

Thirty-one pairs of nerves are attached to the spinal cord in the following descending anatomical order:

8 pairs are attached to the cervical segments, 12 pairs are attached to the thoracic segments, 5 pairs are attached to the lumbar segments, 5 pairs are attached to the sacral segments, and 1 pair is attached to the coccygeal segment (seeFigure 9-12).

Main Function(s) Of Cranial Nerve: Abducens

Eye movements

Main Function(s) Of Cranial Nerve: Oculomotor

Eye movements

Main Function(s) Of Cranial Nerve: Trochlear

Eye movements

Name of cranial nerve VII

Facial

Cranial Nerve conduct Impulses: Optic

From eye to brain

Name of cranial nerve XII

Hypoglossal

# of Cranial Nerve: Glossopharyngeal

IX

Cranial Nerve conduct Impulses: Accessory

From brain to certain shoulder and neck muscles

Cranial Nerve conduct Impulses: Abducens

From brain to external eye muscles

Cranial Nerve conduct Impulses: Trochlear

From brain to external eye muscles

Cranial Nerve conduct Impulses: Oculomotor

From brain to eye muscles

Cranial Nerve conduct Impulses: Hypoglossal

From brain to muscles of tonugue

Cranial Nerve conduct Impulses: Vestibulocochlear

From ear to brain

Cranial Nerve conduct Impulses: Olfactory

From nose to brain

Cranial Nerve conduct Impulses: Trigeminal

From skin and mucous membrane of head and from teeth to brain; also from brain to chewing muscles

Cranial Nerve conduct Impulses: Facial

From taste buds of tongue to brain; from brain to face muscles

Cranial Nerve conduct Impulses: Glossopharyngeal

From throat and taste buds of tongue to brain; also from brain to throat muscles and salivary glands

Cranial Nerve conduct Impulses: Vagus

From throat, larynx, and organs in thoracic and abdominal cavities to brain; also from brain to muscles of throat and to organs in thoracic and abdominal cavities

Name of cranial nerve IX

Glossopharyngeal

Main Function(s) Of Cranial Nerve: Vestibulocochlear

Hearing; sense of balance

# of Cranial Nerve: Vagus

X

CLINICAL APPLICATION: The meninges, the fluid-containing membranes surrounding the brain and spinal cord, extend beyond the spinal cord, an anatomical fact that allows physicians to

perform lumbar punctures without putting the spinal cord at risk of injury. A lumbar puncture, or "spinal tap," is the withdrawal of some cerebrospinal fluid (CSF) from the

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion. In the autonomic ganglia, the axon endings of preganglionic neurons synapse with the dendrites or cell bodies of

postganglionic neurons. Postganglionic neurons, as their name suggests, conduct impulses from a ganglion to cardiac muscle, smooth muscle, or glandular epithelial tissue.

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called

preganglionic neurons because they conduct impulses between the spinal cord and a ganglion.

Conduction paths to visceral and somatic effectors from the CNS (spinal cord or brainstem) differ somewhat. Autonomic paths to visceral effectors, as the right side of Figure 9-20 shows, consist of two- neuron relays. Impulses travel over __ from the spinal cord or brainstem to __. There they are relayed across synapses to __, which then conduct the impulses from the ganglia to visceral effectors.

preganglionic neurons; autonomic ganglia; postganglionic neurons

Spinal nerves conduct impulses between the spinal cord and the parts of the body not supplied by cranial nerves. The spinal nerves shown inFigure 9-12 contain, as do all spinal nerves, sensory and motor fibers. Spinal nerves therefore function to make possible

sensations and movements. A disease or injury that prevents conduction by a spinal nerve thus results in a loss of feeling and a loss of movement in the part supplied by that nerve.

Spinal nerves conduct impulses between the spinal cord and the parts of the body not supplied by cranial nerves. The spinal nerves shown inFigure 9-12 contain, as do all spinal nerves, (2)

sensory and motor fibers.

The autonomic nervous system (ANS) consists of certain motor neurons that conduct impulses from the spinal cord or brainstem to the following kinds of tissues: 1. Cardiac muscle tissue2. Smooth muscle tissue3. Glandular epithelial tissue The ANS includes the parts of the nervous system that regulate involuntary functions (for example, the heartbeat, contractions of the stomach and intestines, and secretions by glands). On the other hand, motor nerves that control the voluntary actions of skeletal muscles are sometimes called the

somatic nervous system.

Name of cranial nerve III

Oculomotor

Cranial nerves with main functions of Eye movements:

Oculomotor, Trochlear, Abducens

Name of cranial nerve V

Trigeminal

CLINICAL APPLICATION: A lumbar puncture, or "__,"

spinal tap

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion. In the autonomic ganglia, the axon endings of preganglionic neurons synapse with the dendrites or cell bodies of postganglionic neurons. Postganglionic neurons, as their name suggests, conduct impulses from a ganglion to cardiac muscle, smooth muscle, or glandular epithelial tissue. Autonomic or visceral effectors are

the tissues to which autonomic neurons conduct impulses. Specifically, visceral effectors are cardiac muscle that makes up the wall of the heart, smooth muscle that partially makes up the walls of blood vessels and other hollow internal organs, and glandular epithelial tissue that makes up the secreting part of a gland.

Twelve pairs of cranial nerves are attached to

the undersurface of the brain.

CLINICAL APPLICATION: A lumbar puncture, or "spinal tap," is

the withdrawal of some cerebrospinal fluid (CSF) from the subarachnoid space in the lumbar region of the spinal cord.

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because

they conduct impulses between the spinal cord and a ganglion.

Main Function(s) Of Cranial Nerve: Accessory

Shoulder movements; turning movements of head

The autonomic nervous system (ANS) consists of certain motor neurons that conduct impulses from the spinal cord or brainstem to the following kinds of tissues: (3)

1. Cardiac muscle tissue 2. Smooth muscle tissue 3. Glandular epithelial tissue

Conduction paths to visceral and somatic effectors from the CNS (spinal cord or brainstem) differ somewhat. Autonomic paths to visceral effectors, as the right side of Figure 9-20 shows, consist of two- neuron relays. Impulses travel over preganglionic neurons from the spinal cord or brainstem to autonomic ganglia. There they are relayed across synapses to postganglionic neurons, which then conduct the impulses from the ganglia to visceral effectors. Compare the autonomic conduction path with the somatic conduction path illustrated on the left side of Figure 9-20. (describe somatic conduction path)

A single somatic motor neuron, like the ones shown in the figure, conducts impulses all the way from the spinal cord or brainstem to somatic effectors with no intervening synapses.

Name of cranial nerve VI

Abducens

Name of cranial nerve XI

Accessory

__ are the motor neurons that make up the ANS.

Autonomic neurons

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion. In the autonomic ganglia, the axon endings of preganglionic neurons synapse with the dendrites or cell bodies of postganglionic neurons. Postganglionic neurons, as their name suggests, conduct impulses from a ganglion to cardiac muscle, smooth muscle, or glandular epithelial tissue. __ or __ are the tissues to which autonomic neurons conduct impulses. Specifically, visceral effectors are cardiac muscle that makes up the wall of the heart, smooth muscle that partially makes up the walls of blood vessels and other hollow internal organs, and glandular epithelial tissue that makes up the secreting part of a gland.

Autonomic; visceral effectors

CLINICAL APPLICATION: Lumbar punctures are often performed when (2) (or)

CSF is needed for analysis or when it is necessary to reduce pressure caused by swelling of the brain or spinal cord after injury or disease. The normal sample of CSF from a lumbar puncture shown here is slightly yellowish and clear, but the red color in the abnormal sample indicates bleeding (in this case, a hemorrhage in the subarachnoid space).

# of Cranial Nerve: Olfactory

I

Identify the name and number of all 12 cranial nerves:

I Olfactory, II Optic, III Oculomotor, IV Trochlear, V Trigeminal, VI Abducens, VII Facial, VIII Vestibulocochlear, IX Glossopharyngeal, X Vagus, XI Accessory, XII Hypoglossal

# of Cranial Nerve: Optic

II

# of Cranial Nerve: Oculomotor

III

# of Cranial Nerve: Trochlear

IV

Name of cranial nerve I

Olfactory

*The first letters of the words in the following sentence are the first letters of the names of the cranial nerves, in the correct order. Many anatomy students find that using this sentence, or one like it, helps in memorizing the names and numbers of the cranial nerves. It is "__ ."

On Old Olympus' Tiny Tops, A Friendly Viking Grew Vines And Hops

Name of cranial nerve II

Optic

PD stands for

Parkinson disease (PD)

Main Function(s) Of Cranial Nerve: Trigeminal

Sensations of face, scalp, and teeth; chewing movements

Main Function(s) Of Cranial Nerve: Vagus (6)

Sensations of throat and larynx and of thoracic and abdominal organs; swallowing, voice production, slowing of heartbeat, acceleration of peristalsis (gut movements)

Main Function(s) Of Cranial Nerve: Glossopharyngeal (4)

Sensations of throat, taste, swallowing movements, secretion of saliva

Main Function(s) Of Cranial Nerve: Olfactory

Sense of smell

Main Function(s) Of Cranial Nerve: Facial

Sense of taste; contraction of muscles of facial expression

Main Function(s) Of Cranial Nerve: Hypoglossal

Tongue movements

Name of cranial nerve IV

Trochlear

(#)__ pairs of cranial nerves are attached to the undersurface of the brain.

Twelve

# of Cranial Nerve: Trigeminal

V

# of Cranial Nerve: Abducens

VI

# of Cranial Nerve: Facial

VII

# of Cranial Nerve: Vestibulocochlear

VIII

Name of cranial nerve X

Vagus

Name of cranial nerve VIII

Vestibulocochlear

Main Function(s) Of Cranial Nerve: Optic

Vision

# of Cranial Nerve: Accessory

XI

# of Cranial Nerve: Hypoglossal

XII

RESEARCH, ISSUES, AND TRENDS: Parkinson disease (PD) is a chronic, progressive nervous disorder resulting from

a deficiency of the neurotransmitter dopamine in the basal nuclei of the cerebrum.

Unlike cranial nerves, spinal nerves have no special names; instead,

a letter and number identify each one. C1, for example, indicates the pair of spinal nerves attached to the first segment of the cervical part of the spinal cord, and T8 indicates nerves attached to the eighth segment of the thoracic part of the spinal cord.

Spinal nerves conduct impulses between the spinal cord and the parts of the body not supplied by cranial nerves. The spinal nerves shown inFigure 9-12 contain, as do all spinal nerves, sensory and motor fibers. Spinal nerves therefore function to make possible sensations and movements. A disease or injury that prevents conduction by a spinal nerve thus results in a loss of feeling and a loss of movement in the part supplied by that nerve. Detailed mapping of the skin's surface reveals a close relationship between the source on the spinal cord of each spinal nerve and the part of the body that it innervates. Knowledge of the segmental arrangement of spinal nerves is useful to physicians. For instance,

a neurologist can identify the site of a spinal cord or nerve abnormality by noting the area of the body that is insensitive to a pinprick. Skin surface areas that are supplied by a single spinal nerve are calleddermatomes. A dermatome "map" of the body is shown in Figure 9- 18.

In Figure 9-12 the cervical area of the spine has been dissected to show the emerging spinal nerves in that area. After spinal nerves exit from the spinal cord, they branch to form the many peripheral nerves of the trunk and limbs. Sometimes, nerve fibers from several spinal nerves are reorganized to form a single peripheral nerve. This reorganization can be seen as a network of intersecting or "braided" branches called

a plexus.

ANS stands for

autonomic nervous system (ANS)

Autonomic or visceral effectors are the tissues to which autonomic neurons conduct impulses. Specifically, visceral effectors are (3)

cardiac muscle that makes up the wall of the heart, smooth muscle that partially makes up the walls of blood vessels and other hollow internal organs, and glandular epithelial tissue that makes up the secreting part of a gland.

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion. In the autonomic ganglia, the axon endings of preganglionic neurons synapse with the dendrites or cell bodies of postganglionic neurons. Postganglionic neurons, as their name suggests, conduct impulses from a ganglion to (3)(or)

cardiac muscle, smooth muscle, or glandular epithelial tissue.

The autonomic nervous system (ANS) consists of

certain motor neurons that conduct impulses from the spinal cord or brainstem to the following kinds of tissues: 1. Cardiac muscle tissue2. Smooth muscle tissue3. Glandular epithelial tissue

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion. In the autonomic ganglia, the axon endings of preganglionic neurons synapse with the dendrites or cell bodies of postganglionic neurons. Postganglionic neurons, as their name suggests,

conduct impulses from a ganglion to cardiac muscle, smooth muscle, or glandular epithelial tissue.

Detailed mapping of the skin's surface reveals a close relationship between the source on the spinal cord of each spinal nerve and the part of the body that it innervates. Knowledge of the segmental arrangement of spinal nerves is useful to physicians. For instance, a neurologist can identify the site of a spinal cord or nerve abnormality by noting the area of the body that is insensitive to a pinprick. Skin surface areas that are supplied by a single spinal nerve are called

dermatomes. A dermatome "map" of the body is shown in Figure 9- 18.

RESEARCH, ISSUES, AND TRENDS: Parkinson disease (PD) is a chronic, progressive nervous disorder resulting from a deficiency of the neurotransmitter dopamine in the basal nuclei of the cerebrum. The group of signs associated with this disorder is a syndrome called parkinsonism. Parkinsonism is characterized by rigidity and trembling of the head and extremities, a forward tilt of the trunk, and shuffling manner of walking, as you can see in the figure. You may have noticed these characteristics in former boxing champion Muhammad Ali, the actor Michael J. Fox, or others you may know with PD. All of these characteristics result from a lack of dopamine, leading to misinformation in the part of the brain that normally prevents the skeletal muscles from being overstimulated. Dopamine injection into the blood and dopamine pills are not effective treatments because

dopamine cannot cross the BBB. A breakthrough in the treatment of PD came when the drug levodopa, orl-dopa, was found to increase the dopamine levels in afflicted patients. Neurons use l-dopa, which can cross the BBB, to make dopamine. For some reason, l-dopa does not always have the desired effects in individual patients, so a number of alternatives have been developed. One option that has had some success is the surgical grafting of normal dopamine-secreting cells into the brains of individuals with PD. Another experimental option is an artificial implant that gives electrical stimulation to the basal nuclei, causing them to produce more dopamine.

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons

extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion.

In Figure 9-12 the cervical area of the spine has been dissected to show the emerging spinal nerves in that area. After spinal nerves exit from the spinal cord, they branch to form the many peripheral nerves of the trunk and limbs. Sometimes, nerve fibers from several spinal nerves are reorganized to

form a single peripheral nerve. This reorganization can be seen as a network of intersecting or "braided" branches called a plexus.

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called

ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion.

Unlike cranial nerves, spinal nerves

have no special names; instead, a letter and number identify each one. C1, for example, indicates the pair of spinal nerves attached to the first segment of the cervical part of the spinal cord, and T8 indicates nerves attached to the eighth segment of the thoracic part of the spinal cord.

Twelve pairs of cranial nerves are attached to the undersurface of the brain. Figure 9-17 shows the attachments of these nerves to the brainstem and diencephalon. Their fibers conduct impulses between the brain and structures in the __ and __ and in the __ and __ cavities.

head; neck; thoracic; abdominal

The tenth cranial nerve (vagus nerve) conducts impulses between the __ and structures in the neck and thoracic and abdominal cavities.

medulla oblongata

Autonomic neurons are the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion. In the autonomic ganglia,

the axon endings of preganglionic neurons synapse with the dendrites or cell bodies of postganglionic neurons. Postganglionic neurons, as their name suggests, conduct impulses from a ganglion to cardiac muscle, smooth muscle, or glandular epithelial tissue.

Autonomic neurons are

the motor neurons that make up the ANS. The dendrites and cell bodies of some autonomic neurons are located in the gray matter of the spinal cord or brainstem. Their axons extend from these structures and terminate in peripheral "junction boxes" called ganglia. These autonomic neurons are called preganglionic neurons because they conduct impulses between the spinal cord and a ganglion.

Unlike cranial nerves, spinal nerves have no special names; instead, a letter and number identify each one. C1, for example, indicates

the pair of spinal nerves attached to the first segment of the cervical part of the spinal cord, and T8 indicates nerves attached to the eighth segment of the thoracic part of the spinal cord.

Spinal nerves conduct impulses between the spinal cord and

the parts of the body not supplied by cranial nerves.

The autonomic nervous system (ANS) consists of certain motor neurons that conduct impulses from the spinal cord or brainstem to the following kinds of tissues: 1. Cardiac muscle tissue2. Smooth muscle tissue3. Glandular epithelial tissue The ANS includes

the parts of the nervous system that regulate involuntary functions (for example, the heartbeat, contractions of the stomach and intestines, and secretions by glands).

The ANS consists of two divisions called

the sympathetic division and the parasympathetic division (Figure 9-19).