Download Outline 10

Outline 10
The Brain
Overview of the Brain
 Major landmarks
o Cerebrum – largest and most superior part of the brain, divided into two
hemispheres separated by a longitudinal ________________
o Cerebellum – second largest part of the brain, inferior to the cerebrum
o Brainstem – all of the brain _______________ the cerebrum and
cerebellum
 Major components include the medulla oblongata, pons, midbrain,
and diencephalon
 Grey and White Matter
o Grey matter lacks myelin and forms a surface layer called a
_________________ over the cerebrum and cerebellum
o Grey matter also forms deeper masses called nuclei surrounded by white
matter
o White matter contains __________________ and lies deep to the cortical
gray matter in most of the brain (opposite the pattern of grey and white
matter in the spinal cord)
 Meninges
o Dura mater – different from the dura mater in the spinal cord in that there
are two _________________ of dura mater
 The periosteal layer adheres to the inside of the cranium
 The meningeal layer lies within and continues into the vertebral
canal
 There is no epidural space in the _________________
o Arachnoid – transparent membrane over the brain surface between the
dura mater and pia mater
o Pia mater – thin delicate membrane that closely follows all the contours of
the brain surface, even dipping into the grooves (sulci)
 Ventricles and Cerebrospinal Fluid
o The brain has 4 fluid-filled chambers
 There are two lateral ventricles, each of which forms an
_____________ in a cerebral hemisphere
 There is a third ventricle near the center of the cerebrum
 There is a fourth ventricle ____________ to the cerebellum
o On the floor or wall of each ventricle there is a choroid plexus
 The choroid plexus is a spongy mass of blood capillaries
 The choroid plexus produces some cerebrospinal fluid; the rest of
the fluid comes from the lining of the ___________________ or
from the subarachnoid space
o Cerebrospinal fluid is a clear, colorless liquid that fills the ventricles and
canals of the CNS and bathes its external surface
 It is formed by filtration of blood plasma

Ependymal cells chemically modify the filtrate as it passes
through them into the ventricles and subarachnoid space
 Functions:
 Buoyancy – because the brain and CSF are similar in
_______________, the brain neither sinks nor floats
 Protection – CSF protects the brain from striking the
cranium when the head is jolted
 Chemical stability – the flow of CSF rinses metabolic
wastes from nervous tissue and regulates its
_________________ environment
 Blood supply and the brain barrier system
o Blood is of critical importance to the brain, but blood is also a source of
bacterial toxins and other agents that can _____________ brain tissue
o The blood-brain barrier strictly regulates which substances get from the
bloodstream into the tissue fluid of the brain
o Anything passing from the blood into the tissue fluid has to pass through
the endothelial _________________ themselves, which are more selective
than gaps between cells
The hindbrain and the midbrain
 The medulla oblongata
o The most caudal part of the brainstem, immediately superior to the
foramen magnum of the skull
o It connects the spinal cord to the rest of the brain
o It regulates the rate and force of the ______________________
o It regulates blood pressure and flow
o It regulates the rate and depth of _____________________
 The pons
o The section of the brainstem between the midbrain and medulla oblongata
o It is the source of most nerve fibers carrying signals from the brainstem to
the cerebellum
o Nerves from the pons control _________________ movements, facial
expression, chewing, and swallowing, and they receive sensory signals
including taste, hearing, equilibrium, touch, and pain
 The cerebellum
o Large portion of the brain dorsal to the brainstem and inferior to the
cerebrum
o Two hemispheres are connected by a narrow bridge called the vermis
o In sagittal section, the inner white matter, called the arbor vitae, looks like
a branching ______________
o The cerebellum smooths muscle contractions, maintains muscle tone and
posture, coordinates the motions of different joints with each other,
coordinates eye and body movements, and serves in learning and storing
________________ skills
 The midbrain
o Short section of the brainstem that connects the hindbrain and forebrain
o Contains the corpora quadrigemina (2 superior and 2 inferior colliculi)

Superior colliculi – functions in _____________ attention, such as
turning the eyes and head in response to a visual stimulus
 Inferior colliculi – receives and processes ___________________
input from lower levels of the brainstem and relays it to other parts
of the brain
o Contains the substantia nigra
 Center that improves motor performance by suppressing
_________________ muscle contractions
 The reticular formation
o Loosely organized web of gray matter that runs vertically through all
levels of brainstem and to many areas of the cerebrum
o Plays roles in somatic muscle control, cardiovascular control, __________
modulation, consciousness, and habituation
The forebrain
 The diencephalon – includes __________________, hypothalamus, and
epithalamus
o Thalamus – oval mass of gray matter underlying each cerebral hemisphere
 Gateway to the cerebral cortex – signals going to and from the
cerebrum pass through this region
o Hypothalamus – sits ___________________ the thalamus and connects to
the pituitary gland
 Involved in:
 hormone secretion,
 autonomic effects
 thermoregulation
 food and water intake
 sleep and circadian rhythms
 emotional responses
 memory
o Epithalamus – consists mostly of the __________________ gland, which
produces melatonin which helps regulate our sleep-wake cycle
 The cerebrum – largest and most superior portion of the brain
o Is marked by gyri (thick folds) and _________________ (depressed
grooves)
o The two hemispheres are separated by a longitudinal fissure
 At the bottom of this fissure, the hemispheres are connected by a
thick “C” shaped bundle of nerve fibers called the
______________ callosum
o Lobes:
 Frontal lobe – behind frontal bone, concerned with cognition,
___________________, and motor control
 Parietal lobe – under parietal bones, concerned with receiving and
interpreting general senses as well as taste
 Occipital lobe – at the rear of the head, concerned with
______________


Temporal lobe – lateral and horizontal lobe, concerned with
hearing, smell, learning, memory, and some aspects of vision and
emotion
______________ – deep lobe (normally covered), plays some roles
in taste, hearing, and visceral sensation
The cranial nerves
 Olfactory
o Composition: Sensory
o Function: _______________
o Origin: Olfactory mucosa in nasal cavity
o Termination: olfactory bulb
o Cranial passage: Cribiform plate of the ethmoid bone
 Optic
o Composition: Sensory
o Function: Vision
o Origin: ____________________
o Termination: thalamus
o Cranial passage: Optic foramen
 Oculomotor
o Composition: Motor with some proprioceptor fibers
o Function: Eye movement, opening of eyelid, constriction of pupil,
focusing
o Origin: Midbrain
o Termination: superior, medial, and inferior rectus; and inferior oblique eye
muscles, constrictor of iris and ciliary muscles of lens
o Cranial passage: superior _________________ fissure
 Trochlear
o Composition: Motor with some proprioceptor fibers
o Function: Eye movements
o Origin: Midbrain
o Termination: Superior _____________________ eye muscle
o Cranial passage: Superior orbital fissure
 Trigeminal
o Opthalmic division
 Composition: Sensory
 Function: touch, temperature, and pain sensation in
_________________ face
 Origin: superior region of face
 Termination: pons
 Cranial passage: superior orbital fissure
o Maxillary division
 Composition: sensory
 Function: touch, temperature, and pain sensation in
_____________ face
 Origin: middle region of face
 Termination: pons





 Cranial passage: foramen rotundum
o Mandibular division
 Composition: sensory and motor
 Function: touch, temperature, and pain sensation in lower
________, mastication
 Sensory Origin: inferior region of face
 Sensory Termination: pons
 Motor Origin: Pons
 Motor Termination: muscles of mastication
 Cranial passage: Foramen ovale
Abducens
o Composition: Motor with some proprioceptor fibers
o Function: eye movements
o Origin: inferior pons
o Termination: lateral ______________ eye muscle
o Cranial passage: superior orbital fissure
Facial
o Composition: Mixed
o Function: motor nerve of facial expression, control of salivary glands,
sensation of taste on anterior two-thirds of tongue
o Sensory Origin: Taste buds on ___________________ two-thirds of
tongue
o Sensory Termination: thalamus
o Motor Origin: pons
o Motor Termination: muscle of facial expression, salivary glands
o Cranial passage: mastoid foramen
Vestibulocochlear
o Composition: sensory
o Function: hearing and equilibrium
o Origin: inner ear
o Termination: pons and medulla oblongata
o Cranial passage: internal auditory meatus
Glossopharyngeal
o Composition: mixed
o Function: swallowing, regulation of blood pressure and respiration, taste
sensations on the ______________________ one-third of the tongue
o Sensory Origin: Pharynx, posterior one-third of tongue, internal carotid
arteries
o Sensory Termination: medulla oblongata
o Motor Origin: Medulla oblongata
o Motor Termination: salivary glands, muscles of swallowing
o Cranial passage: jugular foramen
Vagus
o Composition: Mixed
o Function: cardiovascular and gastrointestinal regulation; sensations of
________________, fullness, and intestinal discomfort


o Sensory Origin: thoracic and abdominal viscera
o Sensory Termination: medulla oblongata
o Motor Origin: medulla oblongata
o Motor Termination: thoracic and abdominal viscera
o Cranial passage: jugular foramen
Accessory
o Composition: Motor with some proprioceptive fibers
o Function: swallowing; head, neck, and shoulder movements
o Origin: medulla oblongata and segments of C1-C5
o Termination: Palate, pharynx, sternocleidomastoid and
________________
o Cranial passage: jugular foramen
Hypoglossal
o Composition: Motor with some proprioceptive fibers
o Function: ___________________ manipulation, swallowing, speech
o Origin: medulla oblongata
o Termination: muscles of the tongue
o Cranial passage: hypoglossal canal