A&P Chapter 13 RE: Brain and Cranial Nerves

The Four Main Brain Regions are the?

• Cerebrum

• Diencephalon

• Brainstem

• Cerebellum

Whats the difference between a Gyri?, and Sulci?, and a Fissure?

• Gyri is a Ridge/Fold

• Sulci is a depression between the ridges/Gyri

• Fissures are deep sulci

Gray Matter is composed of?

Neuron cell bodies, Dendrites, and Unmyelinated Axons

A Cortex is a superficial layer of?

Grey Matter

What is a Nucleus?

A Cluster of Cell Bodies, aka Grey Matter located in the CNS/Brain

What is a Ganglia?

A Cluster of Cell Bodies, in the PNS

White Matter consists of?, and they will be organized in bundles called?

Consists of Myelinated Axons, organized into Tracts

• Nerves are bundles of axons, which can form a network called a Nerve Plexus
  Which matter is this?

White Matter in the PNS

There are three connective tissue layers in the brain called the Cranial Meninges, which will do what 3 functions?

• Separate and support soft tissue of brain

• Enclose and protect blood vessels supplying the brain

• Help contain and circulate cerebrospinal fluid

The Pia Mater is the?

Innermost layer of the meninges, ahdering to the brain surface

The Pia Mater is a thin layer of?

Areolar Connective Tissue

The Arachnoid Mater is between the Pia and Dura Mater, containing two structures being the Arachnoid Trabeculae, and Subarachnoid Space, which do what?

• Trabeculae will extend to pia mater through subarachnoid space
  Space will contain Cerebrospinal Fluid

The Arachnoid Mater will be made of?

A web of collagen and elastic fibers

The Subdural space, between the Dura Mater and Arachnoid Mater is a potential space that can fill with blood if a vein is ruptured

The Dura Mater is the tough, outer membrane made of?

Dense Irregular Tissue

The Dura Mater will contain two different layers being the?, which will come together to form the?

• Meningeal Layer and Periosteal Layer

• Form the Periosteum on the internal surface of cranial bones

The Epidural Space is a potential space between the Dura and Skull which will contain?

Arteries and Veins

The Cranial Dura Septa are sheets of dura mater which will do what?

Extend into cranial cavity to form partitions between brain areas providing support

The Falx Cerebri is the largest of the dural septa which will do what?

Located on the midline, projecting into a longitudinal fissure between the cerebral hemispheres, to seperate the left and right

The Falx Cerebri will contain a Superior and Inferior Sagittal Sinus

What does the Tentorium Cerebelli do?

Separate the Occipital and Temporal lobes from the Cerebellum

The Falx Cerebeli will do what?

Run vertically in midsagittal plane to separate the left and right cerebellar hemispheres

The Diaphragma Sellae is the smallest of the dural septa which will form the?

“roof” over sella turcica

The Dural Venous Sinuses are modified veins that are?

large, blood filled spaces that collect blood draining from brain

What will converge at the confluence of sinuses? (Hint: All Sinuses with different direction or orientations)

• Superior and Inferior Sagittal Sinuses

• Transverse sinuses

• Straight Sinus

• Occipital will be within in the posterior border of falx cerebelli

The Ventricles are cavities within the brain, lined with ependymal cells which will contain the Cerebrospinal Fluid

The Four Ventricles within the brain

CSF or Cerebrospinal Fluid is a clear, colorless liquid surrounding the CNS, circulating in ventricles and subarachnoid space to do what functions?

• Buoyancy which will reduce brain’s apparent weight by 95%

• Protection, providing a liquid cushion

• Environmental Stability, which will do a transport of nutrients/ wastes and protects against fluctuations

What is CSF formed by?, and what is that structure made of?

Choroid plexus in each ventricle

• Layer of ependymal cells and blood capillaries

CSF is continually formed and reabsorbed where excess CSF will flow into the?, and be drained into the?

Into the Arachnoid Villi, and drain into the dural venous sinuses

• An arachnoid granulation is a collection of these villi

The BBB or Blood-Brain Barrier will help regulate?

Which substances enter the Brain’s Interstitial Fluid

With the BBB regulating what enters, it helps prevent the neurons from?

Harmful substances, like drugs, and wastes

What is the BBB Composed of? (Hint: 4 things to note)

Specialized Capillaries
-Endothelial Cells are connected by tight junctions

-Walls have a thick basement membrane

-Wrapped in perivascular feet of astrocytes

What are two additional means of Water removal besides the CSF drain?

• Meningeal lymphatic vessels, which absorb and transport excess fluid in CSF

• Glymphatic systems

How does the Glymphatic System work?

Perivascular feet of astrocytes facilitate removal of waste

The Cerebrum is the origin of all complex intellectual functions, with two large cerebral hemispheres, being the center of?

• Intelligence and reasoning

• Thought, memory, and judgement

• Voluntary control of skeletal muscles

• Conscious perception of senses

The Longitudinal Fissure is a deep cleft separating the hemispheres, but then how do they communicate?

The largest white matter tract will provide connections between them called the Corpus Callosum

Each hemisphere interacts with the opposite side of the body, like for example, left hemisphere receives sensory signals from right side of body and sends motor signals to right side of body

For some higher-order functions, they will be primarily controlled by one side of the brain, that idea is called?

Cerebral lateralization

What is each function of the Five Lobes in the Hemisphere?

• Frontal Lobe = Varied Function, being motor control, concentration, verbal communication, decision making, planning, and personality

• Parietal Lobe = General Sensory Function

• Temporal Lobe = Hearing and Smelling

• Occipital Lobe = Vision and Visual memories

• Insula = Memory and sense of taste

What is the Location word related to each Lobe?

Frontal is Anterior Part of Cerebrum

• Posterior Border is deep central Sulcus

• Inferior portion of frontal is separated from temporal by Lateral Sulcus

Parietal Lobe

• Anterior border is central sulcus

• Posterior border is parieto-occipital sulcus

Temporal Lobe

• Located inferior to lateral sulcus

Occipital Lobe is posterior part of cerebrum

Insula is a small lobe that can only be observed after pulling away temporal (deep to lateral sulcus)

What does the Precentral gyrus control?

Voluntary movement

Motor Areas of the Brain are housed within the Frontal Lobes

The Primary motor cortex (somatic motor area) located in the precentral gyrus, will control the?

Skeletal muscle activity on opposite side of body

(Project contralaterally within brainstem or spinal cord)

This is the Motor Homonculus, what do we see here?

• Distorted proportions of the body reflect amount of cortex dedicated to each part

• Hand’s are large, because brain controls their precise movements

The Motor Speech Area, or Broca’s will control the?

Movements for vocalization

Where is the Broca’s located in?

In the Inferolateral portion of left frontal lobe

The Frontal Eye Field will regulate the?

Eye movements needed for reading and binocular vision

Where is the Frontal Eye Field located at?

The Superior surface of middle frontal gyrus

The Premotor Cortex which is located anterior to Primary Motor Cortex, will do what?

Coordinates learned, skilled activities

The Primary Somatosensory Cortex, located in the postcentral gyrus of the parietal lobes, will?

Receive somatic sensory information from proprioceptors, and touch, pressure, pain, and temperature receptors

This is the Sensory Homunculus, what do we see here?

• Distorted proprotion’s reflect the amount of sensory information collected from that region

• Large regions for lips, fingers, and genital regions

The Somatosensory Association Area is an area immediately posterior to the postcentral gyrus which helps with integration, being that it?

Integrates touch information allowing us to identify objects by feel

Where is the Primary Visual Cortex?

The Occipital Lobe

What does the Primary Visual Cortex do?

Receive, processes, stores visual information

The Visual Association Cortex surrounds the primary visual cortex to do what?

Integrate and interpret color, and also allow identification/recognition of things like faces

Where is the Primary Auditory Cortex?

Located within temporal lobe

Primary Auditory Cortex will do what?

Receive, processes, and store auditory information

The Auditory Association area located in the temporal lobe, will do what?

Integrate and interprets sounds

What does the Primary Olfactory Cortex do?, and where is it located in?

• Receives, processes, stores odor information

• Located within Temporal Lobe

What does the Primary Gustatory Cortex do?, and where is it located in?

• Receives, processes, stores taste information

• Located within insula

The Prefrontal Cortex will deal with? (Hint: 5 things)
Located rostral(front) to premotor cortex

• Complex thought

• Judgment

• Personality

• Planning

• Deciding

The Wernicke Area in the left hemisphere is involved in?, and it’s in what two lobes?

Language comprehension

• Overlaps parietal and temporal

The Central White Matter lies deep to gray cerebral cortex, composed of myelinated axons grouped into tracts

The Association Tracts will connect what?

Regions of cerebral cortex within same hemisphere

Arcuate Fibers are short tracts that will connect?

Neighboring Gyri

Longitudinal Fasciculi are longer tracts that will do what?

Connect gyri in different lobes

Commissural tracts will connect regions in?

Different hemispheres like corpus callosum

Cerebral White Matter Tracts

Projection tracts will link the cerebral cortex to the inferior brain regions and spinal cord

Quick: Cerebral Lateralization

The Cerebral Nuclei are paired masses of?

Gray matter located deep within central white matter

What do the Cerebral Nuclei do?

Help Regulate Motor Output

The Caudate Nucleus helps produce?

Pattern and rhythm of walking movements

The Lentiform Nucleus are composed of the Putamen and Globus Pallidus which do what?

• Putamen = Help control movement at subconscious level

• Globus Pallidus = Influence thalamus to adjust muscle tone

The Claustrum is an extensive connection to the cerebral areas which are involved in?

Consciousness

The Amygdaloid Body help with the function in?

Mood, and emotion

Coronal Cut View

• Cerebral Nuclei (General): Paired masses of gray matter located deep within the central white matter.

• Caudate Nucleus: Features an enlarged head and a slender tail that parallels the lateral ventricle.

• Lentiform Nucleus: A rounded mass positioned between the insula and the diencephalon (composed of the putamen and globus pallidus).

• Claustrum: A thin sliver of gray matter located immediately internal to the insula cortex.

• Amygdaloid Body (Amygdala): An expanded region located at the tail of the caudate nucleus.

• Corpus Striatum: Features a distinct striated (striped) appearance created by the internal capsule passing through it.

Dinecephalon

The Epithalamus forms the posterior part of the roof of the diencephalon, covering third ventricle

Pineal Gland is an Endocrine gland that will secrete?

Melatonin, which helps regulate circadian rhythm

The Habenular Nuclei will help do what?

Relay signals from limbic system to midbrain

The Habenular Nuclei is also involved in what two responses to odor?

Visceral and Emotional

The Thalamus are oval masses of gray matter on the lateral sides of third ventricle, which are involved with

Receiving signals from all conscious senses except olfaction, basically the relay center

• Will relay some signals to appropriate part of cortex and filters out other signals distracting from subject of attention

The Thalamus has an inter thalamic adhesion, which is a midline mass of?

Gray matter connecting left and right thalamus

The Thalamus are composed of about a dozen of thalamic nuclei, where axons from a given nucleus will?

Project to a particular region of the cortex

The Infundibulum is a stalk of the pituitary that extends from the hypothalamus

The Hypothalamus has control of Autonomic Nervous System and Endocrine System being?

• Autonomic = Influences heart rate, blood pressure, digestive activities, respiration

• Endocrine = Secretes hormones that control the anterior pituitary, antidiuretic hormones, and Oxytocin

The Hypothalamus will also monitor five other things being?

• Regulation of body temperature, with neurons in pre optic nucleus

• Food Intake, by stimulating feelings of hunger and satiety

• Water Intake, where anterior nucleus monitors concentration of dissolved substances in blood, regulating thirst

• Sleep-wake (circadian) rhythms by using suprachiasmatic nucleus directing pineal gland to secrete melatonin

• Emotional Behavior, part of limbic; controlling emotional responses

The Brain Stem will connect the?

Cerebrum, diencephalon, and cerebellum to spinal cord

What does the Brainstem contains?

• Ascending and Descending tracts

• Autonomic nuclei, nuclei of cranial nerves, and reflex centers

• Midbrain, pons, and medulla oblongata

What does the Brainstem control?

Many processes (sush as breathing) that keep the body alive

Components of Midbrain

The Cerebral Peduncles are motor tracts on the anterolateral surface of the midbrain which will do what?

Carry voluntary motor commands from primary motor cortex

The Medial Lemniscus has what tracts running through the brainstem?

Sensory

The Superior Cerebellar Peduncles will connect what two structures?

Cerebellum to Midbrain

The Substantia Nigra will house neurons that produce dopamine, where it is involved in?

• Movement

• Emotions

• Pleasure and Pain Responses

(It’s degeneration causes parkinsons)

The Tegmentum is involved in?, and will contain what two structures?

• Involved in postural motor control

• Contains red nuclei and reticular formation

The Cerebral aqueduct is a structure surrounded by periaqueductal gray matter, which will connect what two structures?

Connects the third and fourth ventricle

The Tectum contains four mounds making a tect plate being which two pairs?

• Pair of superior colliculi controlling visual reflexes and tracking

• Pair of Inferior colliculi controlling auditory reflexes