1. 9 12
10
11
You don't have to flee any longer
Body’s Digest

2. STRUCTURE AND FUNCTION
The cerebral cortex is a thin layer of secondary, tertiary. (1) (399)
gray matter made up of neuron dendrites
and cell bodies that compose the surface
Somatic motor pathways in the
CNS: For the cerebral cortex to per-
of the cerebrum. Consists of 2 halves a
form its motor functions, impulses
right and left half. It controls sensory,
are conducted from its motor areas
motor, consciousness, language, emotions
to skeletal muscles by somatic mo-
and memory. (1) (393)
tor pathways. Consists of motor neu-
Somatic Sensory pathways in the CNS: rons that conduct impulses from the
For the cerebral cortex to perform its CNS to skeletal muscles.(1) (400)
sensory functions, impulses must first
be conducted to the sensory pathways.
Sensory paths to the cerebral cortex
are crossed. There are three main pools
of sensory neurons there are primary,

3. 8
Make it work sista and fight!
With the Sensory and motor pathways you are now fully aware of your
brains messaging throughout nerve impulses and the power with in your-
self. You’re practically a superhero!

4. Peripheral Nervous Sys.
There are thirty-one pairs of spinal root ganglion, or spinal ganglion.
nerves that are connected to the spi- (1)
nal cord, although they don’t have Plexuses:
special names they are numbered ac-
cording to the level of the vertebral
The ventral rami of most spinal
column at which they emerge from nerves subdivide to form complex
the spinal cavity. (1) networks called plexuses. There
are four major types of plexuses,
Structure of the Spinal Nerves:
and they are the cervical plexus,
The structure of the spinal nerves the brachial plexus, the lumbar
is separated into two sections, which plexus and the sacral plexus. (1)
are attached to the spinal cord in Cervical Plexus is found deep with-
terms of roots. These roots are the in the neck, the parts supplied
ventral and dorsal. The dorsal root with this are the sensory to the
of each spinal nerve is easily recog- back of the head, front of the neck,
nized by a swelling called the dorsal and upper part of the shoulder; mo

5. Peripheral Nervous Sys.
tor to numerous neck muscles. (1) Dermatomes & Myotomes:
Brachial Plexus is found deep Dermatomes- regions of skin surface ar-
within the shoulder. Lumbar Plex-
ea supplied by afferent (sensory) fibers of
us, which is formed by the inter-
a given spinal nerve. (1)
mingling of fibers from first four
lumbar nerves. This network of Myotomes- skeletal muscles supplied by
nerves is located in the lumbar efferent (motor) fibers of a given spinal
nerve. (1)
region of the back near the soas
muscle. Sacral Plexus are the fi- Cranial Nerves:
bers from the fourth and fifth
lumbar nerves and the first four
There are twelve pairs of cranial nerves
that connect to the brain, mostly to the
sacral nerves. It lies in the pelvic
brainstem. They are also made up of
cavity on the anterior surface of
bundles of axons, which are the mixed
the piriformis muscle.
cranial nerve where axons of sensory and

6. Peripheral Nervous Sys.
motor neurons. Sensory cranial 10) Vagus Nerve
nerve- axons of sensory neu- 11) Accessory Nerve
rons only. Motor cranial nerve- 12) Hypoglossal Nerve
mainly axons of motor neurons Afferent & Efferent Nerves:
and a small number of sensory
fibers (proprioceptors). There are two functional divi-
1) Olfactory Nerve sions of the peripheral nervous
2) Optic Nerve system which are the afferent
3) Oculomotor Nerve (sensory) division and the effer-
4) Trochlear Nerve ent (motor) division. The effer-
5) Trigeminal Nerve ent division is divided further
6) Abducens Nerve into the somatic motor nervous
7) Facial Nerve system and the efferent portions
8) Vestibulocochlear Nerve of the autonomic nervous sys-
9) Glossopharyngeal Nerve tem. (1)

7. Peripheral Nervous Sys.
Autonomic Nervous System: 1) Preganglionic neuron- conducts
impulses from the central nervous
Structure:: each pathway is up system to an autonomic ganglion.
of autonomic nerves, ganglia,
2) Postganglionic neuron- efferent
and plexuses, which are made of
neuron with which a preganglion-
efferent autonomic neurons. All
ic neuron synapses with autonom-
autonomic neurons function in
ic ganglion
the reflex arcs. Efferent auto-
Function:: the autonomic nervous sys-
nomic regulation ultimately de-
tem functions to regulate visceral
pends on the feedback from sen-
effectors in ways that tend to main-
sory receptors. Relay of two ef-
tain or quickly restore homeostasis.
ferent autonomic neurons con-
Sympathetic and Parasympathetic
ducts information from central
divisions are tonically active, often
nervous system to autonomic ef-
exerting antagonistic influences on
fectors:
visceral effectors.

8. Peripheral Nervous Sys.
Doubly innervated effectors con- maintain normal tone of the smooth
tinually receive both sympathet- muscle in blood vessel walls. The ma-
ic and parasympathetic impuls- jor function of this system is that it
es, and the summation of the serves as an “emergency” system-
two determine the controlling the “fight-or-flight” reaction. (1)
effect. Parasympathetic Nervous System:
Sympathetic Nervous System:
The purpose of the parasympathetic
The purpose of the sympathetic nervous system is the dominant con-
nervous system is that under troller of most autonomic effectors
resting conditions, the sympa- most of the time. This includes Ace-
thetic division can act to main- tylcholine which slows the heartbeat
tain the normal functioning of and acts to promote digestion and
doubly innervated autonomic ef- elimination. (1)
fectors. As a result the sympa-
thetic impulses function to

9. The Brainstem
Three divisions of the brain The pons, like the medulla, is also
make up the brainstem, the me- composed of white matter and retic-
dulla oblongata, the pons, and ular formation. Fibers that run
the midbrain. (1) transversely across the pons and
The medulla oblongata is the through the middle cerebellar pe-
part of the brain that attaches duncles into the cerebellum make up
to the spinal cord, it is about an the external white matter of the
inch in length and is separated pons and give it its arching appear-
from the pons above by a hori- ance. (1)
zontal groove. It is composed of
white matter (projection tracts)
and a network called the reticu-
lar formation. In this reticular
formation there are various nu-
clei, or clusters of neuron cell
bodies. (1) 8

10. The Cerebellum
The midbrain lies below the The cerebellum is the second larg-
pons and above the cerebrum. est part of the brain. A transverse
Both white matter and reticular fissure separates the cerebrum from
formation compose the mid- the cerebellum. The cerebellum is
brain. Extending divergently full of white matter much like the
through it are two ropelike cerebrum, it also has sulci and gyri
masses of white matter named along its surface. The cerebellum is
cerebral peduncles. Tracts in composed of two larger lateral
the peduncles conduct impulses masses the cerebral hemisphere and
between the midbrain and cere- the Vermis. (1)
brum. (1)
The internal white matter of the
The function of the brainstem cerebellum is composed of some
is similar to the spinal cord. It short and some long tracts. The
performs sensory, motor and re- shorter tracts conduct impulses
flex functions from neuron cell bodies located in

11. The Cerebellum
the cerebellar cortex to neurons -tate nuclei, one of which lies in each
whose dendrites and cell bodies hemisphere. Tracts connect these
compose nuclei located in the nuclei with the thalamus and with
interior of the cerebellum. The motor areas of cerebral cortex. By
longer tracts conduct impulses means of these tracts cerebellar im-
to and from the cerebellum. fi- pulses are able to influence the mo-
bers of the longer tracts con- tor cortex and vice versa. (1)
duct impulses to and from the
cerebellum. Fibers of the longer
tracts enter or leave the cere-
bellum by way of its three pairs
of peduncles, inferior cerebellar
8
peduncles, middle cerebellar pe-
duncles, and superior cerebellar
peduncles. An important pair of
cerebellar nuclei are the den-

12. The Diencephalon
The functions of the cerebel- matter made up of many nuclei.;two
lum all have to do with the con- in which are the geniculate bodies,
trol of skeletal muscles. The located in the posterior region of
cerebellum acts with the cere- each lateral mass. The geniculate
bral cortex to produce skilled bodies play a role in processing audi-
movements by coordinating the tory and visual input. Large numbers
activities of groups of muscles. of axons conduct impulses into the
The cerebellum also helps to thalamus from all parts of the brain.
control posture and maintain These axons terminate the thalamic
balance. (1) nuclei, where they synapse with neu-
rons whose axons conduct impulses
The Diencephalon is made up of out of the thalamus to all areas of
several structures. The two the cerebral cortex. Thus the thala-
main structures are the thala- mus is a relay station for sensory im-
mus and hypothalamus. (1) pulses on their way to the cerebral
cortex. (1)
The thalamus is a mass of gray

13. The Diencephalon
vival and the enjoyment of life. It
The thalamus’ functions are functions as a link between the mind
taking impulses from appropri-
and the body. And also links to the
ate receptors and produce a
nervous and endocrine system. The
conscious recognition of less
hypothalamus serves as a regulator
critical sensations of pain like
and coordinator of autonomic activi-
temperature and touch. Plays
ties and provides a crucial role in the
part in emotions/ association,
route by which emotions can express
the thalamus also plays a part
themselves in changed bodily func-
in arousal and producing com-
tions. It also plays a vital role in wa-
plex reflex movements. (1)
ter balance, waking state, appetite,
The hypothalamus consists of and body temp. (1)
several structures that are un-
der the thalamus. It is small
but extremely important., be-
cause it contributes to both sur- 8

14. The Meninges
Three meninges: dura mater, Function of CSF (cerebrospinal flu-
arachnoid membrane, pia mater id)
(2) • Provides supportive, protective
Inflammation of meninges: cushion (2)
• Reservoir of circulating fluid,
meningitis (2)
which is monitored by the brain to
Dura mater: made of strong detect changes in internal environ-
white fibrous material, outside ment (2)
of brain (2) Found within subarachnoid space
around the brain, spinal cord & sur-
Arachnoid membrane: delicate, rounding cavities, and canals of the
cob like membrane, lies between
dura and pia mater(2) brain and spine. (2)
Pia mater: transparent matter Spinal cord
that adheres to the outer sur-
face if the brain and spinal cord, • Within spinal cavity and extends
contains blood vessels (2) from the foramen magnum to the
lower border of the first lumbar ver-

15. The Meninges
-tebrae (2)
• Oval shaped cylinder that ta-
pers slightly from above down-
ward with bulges in cervical re-
gion & lumbar region (2)
Nerve Roots
• Carry sensory and motor info
into spinal canal (fibers of dor-
sal nerve root and central nerve
root) (2)