Central Nervous System
A&P Spring, 2012-13
General Organization of the Brain
Cerebrum: highly folded, largest volume, problem solving, memory, personality,
sensory interpretation, initiates motor activity
Cerebellum: posterior, inferior, coordination of body movements, motor memory
Brain Stem: homeostasis (HR, RR, control of hormone secretions), primitive emotions
Basic Landmarks of the Cerebrum
Gyrus: ridge on the cerebrum (increases surface area and provides more space for neurons)
Sulcus: groove in between the gyri.
Fissure: a deep sulcus
Central Sulcus
Parietal Lobe
Frontal Lobe
Lateral Fissure
Temporal Lobe
Occipital Lobe
Transverse Fissure
Frontal Lobe
personality
problem solving
motor aspects of speech
initiation of movements
(pre-central gyrus – somatomotor area)
Temporal Lobe
hearing
interpretation of vision and hearing
Parietal Lobe
experience and interpretation of touch
(post-central gyrus – somatosensory area)
association of hearing, touch, vision
Occipital Lobe
Vision – perception and
interpretation
Corpus Callosum
Contains commisural fibers
Thalamus
primarily a relay
of sensory info
to the cerebrum
(projection fibers)
Hypothalamus
control of pituitary gland
body temperature
weight, hunger and thirst
regulation of reproduction
Midbrain
motor pathways from
cerebrum to spinal cord
coordinates visual and
auditory reflexes
Pons
feeds info in and out
of cerebellum
Medulla Oblongata
Cardiac Control Center
Respiratory Control Center
Decussation of Ascending Pathways
Part of RAS
Part of Reticular
Activating System
(RAS)
Basal Nuclei
Below Cerebrum
and surrounding the
thalamus
Important for fine control
of body movements
(Parkinson’s Disease)
Caudate nucleus, putamen, globus pallidus, substantia nigra, red nucleus
Brain Stem
Thalamus
Pineal Gland
Superior colliculus
Inferior colliculus
Pons
Medulla
The Limbic System
Cingulate gyrus
Hippocampus
Amygdala
Hypothalamus
Basic, emotional responses
to the environment
The Four “F’s”
feeding
fighting
fear
reproduction
Sensory Mapping of the
Somatosensory Area
For each touch receptor on
the body, there is a coresponding
neuron in the brain. Areas of the
skin with higher densities of
receptors will require more
neurons on the somatosensory
area.
Homunculus
Coronal Section
Showing PostCentral Gyrus
Location of spinal cord inside
canal of vertebra
White matter
Ventral root
Dorsal root ganglion
Gray matter
Dorsal root
Organization of the Spinal
Cord
dorsal root
Sensory neuron
cell body
Dorsal root
ganglion
sensory
Spinal nerve
Ventral
root
motor
Motor neuron
cell body
Simple Knee Jerk Reflex Coordinated by the Spinal Cord
Dorsal root
Dorsal root ganglion
Sensory neuron
Quadriceps muscle
Motor neuron
Ventral root
Withdrawal Reflex
interneuron
Quickie Review
C
Quickie Review
B
D
A
E
F
H
G
B
C
A
E
D
1. What do the Basal Nuclei do?
2. What does the limbic system do?
3. What does the Reticular Activating System do?
4. What is the difference between a knee jerk reflex and a withdrawal
reflex?
Peripheral Nervous System
Cranial Nerves: provide sensory and motor control to the head, senses, facial
expressions, control of the tongue.
Olfactory nerve
Optic nerve
Oculomotor nerve
Trochlear nerve
Trigeminal nerve
Abducens
Facial
Vestibulocochlear
Glossopharengeal
Vagus
Accesory
Hypoglossal
Spinal Nerves and
Nerve Plexes
C1-C5 = cervical
T1-T12 = thoracic
L1-L5 = Lumbar
S1-S6 = Sacral
A “plexus” is a gathering
of spinal nerves in a
specific area of the body.
Here the nerves are
reorganized and form the
major nerves leading to
the arms and legs.
cervical
brachial
lumbar
sacral
QUICKIE REVIEW
1.
2.
3.
4.
5.
6.
7.
In general, what are the functions of the cranial nerves?
Which cranial nerve descends into the thoracic and abdominal cavities?
If a person injured their L-2 spinal nerve, where is it located (precisely)?
What does it mean to say that a cranial or spinal nerve is a “mixed” nerve?
What is the name of the largest plexus leading to the arm?
Which region of the spinal cord doesn’t give rise to plexes?
What are four specific changes that occur when the sympathetic nervous
system becomes stimulated?
8. Which division of the autonomic nervous system has its ganglia on or near
the target organ?
9. Which division of the autonomic nervous system uses norepinephrine as it’s
post-ganglionic neurotransmitter?
10. If a motor activity for the foot is initiated in the pre-central gyrus, all of the
following will become active except (more than one answer)
thalamus
midbrain
medulla
descending tract
dorsal root
ventral root
lumbar or sacral plexus
thoracic plexus