NEUROANATOMY: ORGANIZATION OF THE NERVOUS SYSTEM | Science

Central Nervous System Brain1. Brain2. Spinal Cord

Major Divisions of the Central and Peripheral Nervous Systems

1. Forebrain- cerebrum- diencephalon (between brain)2. Midbrain3. Hindbrain- medulla oblongata- pons- cerebellum

Divisions of the Brain

- cervical segment- thoracic segment- lumbar segment- sacral segment- coccygeal segment

Divisions of the Spinal Cord

CN 1 - olfactoryCN 2 - opticCN 3 - oculomotorCN 4 - trochlearCN 5 - trigeminal CN 6 - abducensCN 7 - facial CN 8 - vestibulocochlearCN 9 - glossopharyngeal CN 10 - vagusCN 11 - spinal accessory CN 12 - hypoglossal

Cranial nerves and their ganglia

128CN 1 - olfactoryCN 2 - opticCN 8 - vestibulocochlear

nerves that are entirely sensory

34 6 11 12CN 3 - oculomotorCN 4 - trochlearCN 6 - abducensCN 11 - spinal accessory CN 12 - hypoglossal

nerves that are entirely motor

57 910CN 5 - trigeminal CN 7 - facial CN 9 - glossopharyngeal CN 10 - vagus

are both sensory and motor nerves (mixed)

foramina

Cranial nerves and their ganglia exit the skull through the __

Folfactory, optic, and vestibulocochlear - SENSORY

(T or F) The olfactory and optic nerves are ENTIRELY SENSORY

foramina

openings in bones that allow nerves and blood vessels to enter or leave the bone

Foculomotor, trochlear, abducent, accessory, and hypoglossal - MOTOR

(T or F) The olfactory, oculomotor, trochlear, abducent, accessory, and hypoglossal nerves are ENTIRELY MOTOR

cranial nerves

have central motor and/or sensory nuclei within the brain and peripheral nerve fibers that emerge from the brain and exit from the skull to reach their effector or sensory organs

FCranial nerves

(T or F) Peripheral nerves have central motor and/or sensory nuclei within the brain and peripheral nerve fibers that emerge from the brain and exit from the skull to reach their effector or sensory organs

intervertebral foramina

Spinal nerves and their ganglia exit the vertebral column through the __.

F31

(T or F) The spinal nerves have a total of 33 pairs of ganglia.

8 - cervical12 - thoracic5 - lumbar5 - sacral1 - coccygeal

Spinal nerves and their ganglia:

situated within the vertebral canal of the vertebral column

Where is the spinal cord located?

1. dura mater2. arachnoid mater3. pia mater

The spinal cord is surrounded by 3 meninges:

cerebrospinal fluid

What protects the spinal cord?

subarachnoid space

The protection of spinal cord is provided by the cerebrospinal fluid, which surrounds the spinal cord in the __ space.

Fsuperiorly at the foramen magnum in the skull

(T or F) The spinal cord is roughly cylindrical and begins inferiorly at the foramen magnum in the skull, where it is continuous with the medulla oblongata of the brain

Fapex of which a prolongation of the pia mater

(T or F) The spinal cord terminates inferiorly in the lumbar region. Below, the spinal cord tapers off into the conus medullaris, from the base of which a prolongation of the pia mater, the filum terminale, descends to attach to the back of the coccyx

conus medullarisfilum terminale

Below, the spinal cord tapers off into the __, from the apex of which a prolongation of the pia mater, the __, descends to attach to the back of the coccyx

anterior or motorposterior or sensory

Along the entire length of the spinal cord are attached 31 pairs of spinal nerves by the anterior or __ and the __ or sensory roots

T

(T or F) In the CNS, each root is attached to the cord by a series of rootlets, which extend the whole length of the corresponding segment of the cord

posterior root ganglion

Each posterior nerve root possesses a __, the cells of which give rise to peripheral and central nerve fibers

Finner - grayouter - white

(T or F) The spinal cord is composed of an inner core of white matter, which is surrounded by an outer covering of gray matter

gray matter

Structure of the Spinal Cord__ is seen on cross-section as an H-shaped pillar with anterior and posterior columns, or horns, united by a thin gray commissure containing the small central canal

white matter

Structure of the Spinal Cord___, for purposes of description, may be divided into anterior, lateral, and posterior columns

Fanterior, lateral, posterior

(T or F) White matter is divided into anterior and posterior columns.

FH-shaped pillar

(T or F) Gray is seen on cross-section as an G-shaped pillar with anterior and posterior columns, or horns, united by a thin gray commissure containing the small central canal

Fforamen magnum

(T or F) The brain lies in the cranial cavity and is continuous with the spinal cord through the foramina

T

(T or F) The brain is surrounded by three meninges : the dura mater, the arachnoid mater, and the pia mater; these are continuous with the corresponding meninges of the spinal cord

cerebrospinal fluid

fluid that surrounds the brain in the subarachnoid space

- hindbrain- midbrain- forebrain

3 major divisions of the brain (in ascending order from the spinal cord):

- medulla oblongata- pons- cerebellum

the hindbrain is subdivided into:

- diencephalon- cerebrum

the forebrain is subdivided into:

diencephalon

the central part of the forebrain

brainstem

a collective term for the medulla oblongata, pons, and midbrain

brainstem

part of the brain that remains after the cerebral hemispheres and cerebellum are removed

conical

The medulla oblongata is __ in shape and connects the pons superiorly to the spinal cord inferiorly

Fconnects the pons superiorly to the spinal cord inferiorly.

(T or F) The medulla oblongata is conical in shape and connects the pons inferiorly to the spinal cord superiorly.

medulla oblongata

is conical in shape and connects the pons superiorly to the spinal cord inferiorly.

Medulla oblongata

contains many collections of neurons, called nuclei, and serves as a conduit for ascending and descending nerve fibers.

Fanterior of cerebelluminferior to midbrainsuperior to medulla oblongata

(T or F) The pons is situated on the posterior surface of the cerebellum, inferior to the midbrain and superior to the medulla oblongata.

Pons

is situated on the anterior surface of the cerebellum, inferior to the midbrain and superior to the medulla oblongata.

pons or bridge

derives its name from the large number of transverse fibers on its anterior aspect connecting the two cerebellar hemispheres.

T

(T or F) The pons also contains many nuclei and ascending and descending nerve fibers

Fanterior

(T or F) The pons, or bridge, derives its name from the large number of transverse fibers on its posterior aspect connecting the two cerebellar hemispheres.

cerebellum

lies within the posterior cranial fossa of the skull , posterior to the pons and the medulla oblongata

Fposterior cranial fossaposterior to pons and med oblongata

(T or F) The cerebellum lies within the posterior cranial fossa of the skull , anterior to the pons and the medulla oblongata.

Cerebellum

It consists of two laterally placed hemispheres connected by a median portion

vermis

Cerebellum consists of two laterally placed hemispheres connected by a median portion, __

midbrain - superior cerebellar pedunclespons - middle cerebellar pedunclesmedulla - inferior cerebellar peduncles

The cerebellum is connected to the midbrain by the __, to the __ by the middle cerebellar peduncles, and to the medulla by the __cerebellar peduncles.

peduncles

are composed of large bundles of nerve fibers connecting the cerebellum to the remainder of the nervous system

cortexgray matter

The surface layer of each cerebellar hemisphere is called the __ and is composed of __

cerebellar cortex

is thrown into folds, or folia, separated by closely set transverse fissures

dentate nucleus

Certain masses of gray matter are found in the interior of the cerebellum, embedded in the white matter; the largest of these is known as the __

Finterior

(T or F) Certain masses of gray matter are found in the exterior of the cerebellum, embedded in the white matter

fourth ventricle

The medulla oblongata, the pons, and the cerebellum surround a cavity filled with cerebrospinal fluid, called the __

cerebral aqueduct

CerebellumThis is connected superiorly to the third ventricle by the __; inferiorly, it is continuous with the central canal of the spinal cord.

T

(T or F) Cerebellum - It communicates with the subarachnoid space through three openings in the inferior part of the roof. It is through these openings that the cerebrospinal fluid within the central nervous system can enter the subarachnoid space.

midbrain

is the narrow part of the brain that connects the forebrain to the hindbrain

cerebral aqueduct

The narrow cavity of the midbrain is the __, which connects the third and fourth ventricles.

T

(T or F) The Midbrain contains many nuclei and bundles of ascending and descending nerve fibers.

Diencephalon

is almost completely hidden from the surface of the brain

Fdorsal thalamusventral hypothalamus

(T or F) The diencephalon consists of a ventral thalamus and a dorsal hypothalamus.

thalamus

is a large, egg-shaped mass of gray matter that lies on either side of the third ventricle.

Fthird ventricle

(T or F) The thalamus is a large, egg-shaped mass of gray matter that lies on either side of the fifth ventricle.

Fthalamus

(T or F) The anterior end of the hypothalamus forms the posterior boundary of the interventricular foramen, the opening between the third and lateral ventricles.

hypothalamus

forms the lower part of the lateral wall and floor of the third ventricle.

Fhypothalamus

(T or F) The thalamus forms the lower part of the lateral wall and floor of the third ventricle.

...

the largest part of the brain

corpus callosum.

consists of two cerebral hemispheres, which are connected by a mass of white matter called the __

Fwhite matter

(T or F) The cerebrum consists of two cerebral hemispheres, which are connected by a mass of gray matter called the corpus callosum

...

Note:Cerebrum:each hemisphere extends from the frontal to the occipital bones in the skull, superior to the anterior and middle cranial fossae; posteriorly, the cerebrum lies above the tentorium cerebelli .

the longitudinal fissure

The hemispheres of the cerebrum are separated by a deep cleft, __, into which projects the falx cerebri

...

(T or F) The hemispheres of the cerebrum are separated by a deep cleft, longitudinal fissure, into which projects the falx cerebri

T

(T or F) The brain is composed of an inner core of white matter, which is surrounded by an outer covering of gray matter.

Fbrain

(T or F) The spinal cord is composed of an inner core of white matter, which is surrounded by an outer covering of gray matter.

T

(T or F) The peripheral nervous system consists of the cranial and spinal nerves and their associated ganglia

T

(T or F) There are 12 pairs of cranial nerves, which leave the brain and pass through foramina in the skull.

T

(T or F) The cranial and spinal nerves are made up of bundles of nerve fibers supported by connective tissue.

...

Note:There are 31 pairs of spinal nerves, which leave the spinal cord and pass through intervertebral foramina in the vertebral column. The spinal nerves are named according to the regions of the vertebral column with which they are associated: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.

F8 cervical nerves7 cervical vertebrae

(T or F) There are 8 cervical nerves and only 5 cervical vertebrae

F1 coccygeal nerve4 coccygeal vertebrae

(T or F) There is 1 coccygeal nerve and there are 2 coccygeal vertebrae

anterior root

consists of bundles of nerve fibers carrying nerve impulses away from the central nervous system

efferent fibers (anterior root)

nerve fibers carrying nerve impulses away from the central nervous system

motor fiber

Those efferent fibers that go to skeletal muscles and cause them to contract are called __

Fmotor - anterior gray horn

(T or F) The sensory fibers' cells of origin lie in the anterior gray horn of the spinal cord.

afferent

The posterior root consists of bundles of nerve fibers, called __ fibers, that carry nervous impulses to the central nervous system

afferent fibers / sensory fibers

these fibers are concerned with conveying information about sensations of touch, pain, temperature, and vibration

T

(T or F) The cell bodies of sensory nerve fibers are situated in a swelling on the posterior root called the posterior root ganglion

spinal nerve

is made up of a mixture of motor and sensory fibers

Note:The spinal nerve roots pass from the spinal cord to the level of their respective intervertebral foramina, where they unite to form a spinal nerve. Here, the motor and sensory fibers become mixed together; thus, a spinal nerve is made up of a mixture of motor and sensory fibers.Because of the disproportionate growth in length of the vertebral column during development, compared with that of the spinal cord, the length of the roots increases progressively from above downward

T

(t or F) The length of the roots increases progressively from above downward

cauda equina

In the upper cervical region, the spinal nerve roots are short and run almost horizontally, but the roots of the lumbar and sacral nerves below the level of the termination of the cord (lower border of the first lumbar vertebra in the adult) form a vertical leash of nerves around the filum terminale. Together, these lower nerve roots are called the __

filum terminale.

In the upper cervical region, the spinal nerve roots are short and run almost horizontally, but the roots of the lumbar and sacral nerves below the level of the termination of the cord form a vertical leash of nerves around the __

Fupper cervical - short, run horizontally

(T or F) In the upper cervical region, the spinal nerve roots are short and run almost vertically.

T

(T or F) The roots of the lumbar and sacral nerves below the level of the termination of the cord form a vertical leash of nerves around the filum terminale

T

(T or F) After emerging from the intervertebral foramen, each spinal nerve immediately divides into a large anterior ramus and a smaller posterior ramus, each containing both motor and sensory fibers.

posterior ramus

The __ passes posteriorly around the vertebral column to supply the muscles and skin of the back.

anterior ramus

The __ continues anteriorly to supply the muscles and skin over the anterolateral body wall and all the muscles and skin of the limbs.

Fanterior ramus

(T or F) The posterior ramus continues anteriorly to supply the muscles and skin over the anterolateral body wall and all the muscles and skin of the limbs.

Fanterior rami

(T or F) The posterior rami join one another at the root of the limbs to form complicated nerve plexuses.

Fcervical and brachial - upperlumbar and sacral - lower

(T or F) The cervical and brachial plexuses are found at the root of the lower limbs, and the lumbar and sacral plexuses are found at the root of the upper limbs