Chapter 15 - Brain and Cranial Nerves

CN VI (6)

ABDUCENS NERVE Innervates lateral rectus eye muscle, which abducts the eye ("pulls away laterally") somatic motor function- innervates one extrinsic eye muscle (lateral rectus) for eye ebduction Conditions caused by nerve damage Paralysis of lateral rectus limits lateral movement of eye; diplopia (double vision)

The subdivision of the brain that does not initiate somatic motor movements, but rather coordinates and fine-tunes those movements is the

CEREBELLUM

Tract

CNS axon bundle in which the axons have a similar function and share a common origin and destination

Lobes of the Cerebrum

Each cerebral hemisphere is divided into five anatomically and functionally distinct lobes: frontal lobe, parietal lobe, temporal lobe, occipital lobe, and insula

Cerebral hemisphere

Either of two symmetrical halves of the cerebrum, separated by the longitudinal fissure

Gray matter

Houses motor neuron and interneuron cell bodies, dendrites, telodendria, and unmyelinated axons.

The frontal eye field

Is on the superior surface of the middle frontal gyrus, which is immediately anterior to the premotor cortex in the frontal lobe. These cortical areas control and regulate the eye movements needed for reading and coordinating binocular vision

Functional Areas of the Cerebrum

Three categories of functional areas are recognized: - motor areas: control voluntary motor functions; - sensory areas: provide conscious awareness of sensation - association areas: primarily integrate and store information.

Brainstem

Three regions form the brainstem: the superiorly placed mesencephalon, the pons, and the inferiorly placed medulla oblongata The brainstem is a bidirectional passageway for all tracts extending between the cerebrum and the spinal cord. It also contains many autonomic centers and reflex centers required for our survival, and it houses nuclei of many of the cranial nerves.

amygdaloid body

It connect to the hippocampus. The amygdaloid body is involved in several aspects of emotion, especially fear. It can also help store and code memories based on how a person emotionally perceives them—for example, as related to fear, extreme happiness, or sadness.

Which os the following statements is false about the choroid plexus?

It forms the blood-brain barrier

What is the fissures?

It is a shalow sulci or deeper grooves

Cingulate gyrus

It receives input from the other components of the limbic system. It focuses attention on emotionally significant events and appears to bring them into consciousness.

parahippocampal gyrus

Its function is associated with the hippocampus

Arcuate nucleus?

Regulates appetite, release of gonadotropin- releasing hormone, release of growth hormone- releasing hormone, and release of prolactin-inhibiting hormone

suprachiasmatic nucleus

Regulates sleep-wake( circadian) ryhtm

Cerebrum

The two large hemispheres on the superior aspect of the brain. It is the center of your intelligence, reasoning, sensory perception, thought, memory, and judgment, as well as your voluntary motor, visual, and auditory activities. -it is formed from the telencephalon

What is arbor vitae?

The white matter of the cerebellum is called the arbor bitae because its distribution patteren resembles the branches of a tree

CN X (10)

VAGUS NERVE Innervates structures in the head and neck and in the thoracic and abdominal cavities somatic motor function- innervates most pharynx muscles and larynx muscles Parasympathetic motor function- innervates visceral smooth muscle, cardiac muscle, and glands of heart, lungs, pharynx, larynx, trachea, and most abdominal organs Conditions caused by nerve damage: Paralysis leads to a variety of larynx problems, including hoarseness, monotone voice, or complete loss of voice. Other lesions may cause diffi culty in swallowing or impaired gastrointestinal system mobility

innervates lateral recuts

abducents nerve

Cerebral Nuclei

also called the basal nuclei; and sometimes erroneously referred to as basal ganglia are paired, irregular masses of gray matter buried deep within the central white matter in the basal region of the cerebral hemispheres inferior to the floor of the lateral ventricle

What is the arachnoid granulations?

collections of arachnoid villi

What is corpus callosum?

connects the two hemispheres

What is the substantia nigra?

consists of bilaterally symmetrical nuclei within the midbrain -houses clusters of neuons that produce the neurotramitter dopamine

-preoptic area?

"Thermostat" (regulates body temp)

Anterior nucleus?

"thirst center" (stimulates fluid intake); autonomic control center

what are functions of lateral group?

Controls sensory fl ow to parietal lobes and emotional information to cingulate gyrus

The primary visual cortex

located in the occipital lobe, receives and processes incoming visual information.

The primary auditory cortex

located in the temporal lobe, receives and processes auditory information.

The primary olfactory cortex

located in the temporal lobe, provides conscious awareness of smells.

Brain size

- Average volume of 1200-1500 cc - Average weight of 1.35-1.4 kilograms.

Cranial Nerves

Cranial nerves are part of the peripheral nervous system and originate on the inferior surface of the brain. There are 12 pairs of cranial nerves.

CSF Circulation

- CSF flows from the lateral ventricles and third ventricle through the cerebral aqueduct into the fourth ventricle. - Most of the CSF in the fourth ventricle flows into the subarachnoid space by passing through openings in the roof of the fourth ventricle. These ventricular openings are the paired lateral apertures and the single median aperture. CSF also fills the central canal of the spinal cord. - As it travels through the subarachnoid space, CSF removes waste products and provides buoyancy for the brain and spinal cord. - Excess CSF flows into the arachnoid villi, then drains into the dural venous sinuses. Pressure allows the CSF to be released into the blood without permitting any venous blood to enter the subarachnoid space. The greater pressure on the CSF in the subarachnoid space ensures that CSF moves into the venous sinuses.

What are the following components cerebral nuclei?

- The C-shaped caudate nucleus has an enlarged head and a slender, arching tail that parallels the swinging curve of the lateral ventricle. When a person begins to walk, the neurons in this nucleus stimulate the appropriate muscles to produce the pattern and rhythm of arm and leg movement associated with walking -The amygdaloid body is an expanded region at the tail of the caudate nuscleus. It particpates in the expression of emotions control of behavioral activities, and development of moods -The putamen and the globus pallidus are two masses of grey matter positioned between the bulging external surface of the insula and the lateral wall of the diencephalon. The putmen and the globus pallidus combine to form a larger body, the lentiform nucleus, which is usually a compact almost rounded mass. -The claustrum is a thin silver of gray matter formed by a layer of neurons located immediately internal to the cortex of the insula and derived from that cortex. It processes visual information at a subconscious level

four ventricles in the brain

- Two lateral ventricles are in the cerebrum, separated by a thin medial partition called the septum pellucidum -Within the diencephalon is a smaller ventricle called the third ventricle. Each lateral ventricle communicates with the third ventricle through an opening called the interventricular foramen (formerly called the foramen of Munro). - fourth ventricle is located between the pons/medulla and the cerebellum. The fourth ventricle narrows at its inferior end before it merges with the slender central canal in the spinal cord. All of the ventricles contain cerebrospinal fluid.

What are the four ventricles?

- two lateral ventricles (are in the cerebrum, seperated by a thin medial partial called the septum pellucidium) -third ventricle- within the diencephalon is a smaller ventricle- each lateral ventricle communicates with the third ventricle through the interventricular foramen -fourth ventricle= is loated between the pons/medulla and the cerebellum- it narrows at its inferior end before before megering with the lender central canal in the spinal cord

What are the nucleus or hypothalmic region?

-Anterior nucleus -Arcuate nucleus -mammillary body -paraventricular nucleus -preoptic area -suprachiasmatic nucleus -supraoptic nucleus -ventromedial nucleus

Medulla Oblongata

-Connects the brain to the spinal cord - All communication between the brain and spinal cord involves tracts that ascend or descend through the medulla oblongata -is formed by the myelencephalon

Explain the tentorium cerebelli dural septa

-is a horizontally oriented fold of dura mater that separates the occipital and temporal lobes of the cerebrum from the cerebellum -forms a dural tent over the cerebellum -tansverse sinuses

What is the subdural space?

-potential space -where subdural hematoma can form because the space if filled with blood or fluid

When viewed superiorly, the cerebrum is divided into:

2 halves: the left and the right hemispheres Each hemispheres are subdivided into 4 functional areas called LOBES

What are cranial meninges and their functions?

3 connective tissue layers that: - separate the soft tissue of the brain from the bones of the cranium - enclose and protect blood vessels that supply the brain, and - contain and circulate cerebrospinal fluid. - In addition, some parts of the cranial meninges form some of the veins that drain blood from the brain. - From deep (closest to the brain) to superficial (farthest away from the brain), the cranial meninges are the pia mater, the arachnoid mater, and the dura mater

CN XI (11)

ACCESSORY NERVE Innervates trapezius, sternocleidomastoid, and some pharynx muscles; formerly called the "spinal accessory nerve" somatic motor function- cranial root: travels with CNX fibers to pharynx spinal root- innervates trapezius and sternocleidomastoid Conditions caused by nerve damage Paralysis of trapezius and sternocleidomastoid, resulting in diffi culty in elevating shoulder (trapezius function) or turning head to opposite site (sternocleidomastoid function)

vermis

Along the midline, a narrow band of cortex in the cerebellum Functions: - separates the left and right cerebellar hemispheres -receives sensory input reporting torso position and balance. Its output to the vestibular nucleus helps maintain balance.

What determines intelligence?

Although modern humans display variability in brain size, it isn't the size of the brain that determines intelligence, but the number of active synapses among neurons.

Functions Controlled by Thalamic Nuclei

Anterior group Lateral group Medial group Posterior group Ventral group

Nerve

Axon bundle extending through the PNS

Temporal lobe

Consists of: - Primary auditory cortex - Primary olfactory cortex - Auditory association area - Olfactory association area - Part of Wernicke area - Part of gnostic area Functions: Interpretation of auditory and olfactory sensations; storage of auditory and olfactory experiences; understanding speech

Parietal lobe

Consists of: - Primary somatosensory cortex (located within postcentral gyrus) - Somatosensory association area - Part of Wernicke area - Part of gnostic area Functions: Sensory interpretation of textures and shapes; understanding speech and formulating words to express thoughts and emotions

Occipital lobe

Consists of: - Primary visual cortex - Visual association areas Functions: Conscious perception of visual stimuli; integration of eye-focusing movements; correlation of visual images with previous visual experiences

Nucleus

Center in the CNS that displays discrete anatomic boundaries

Pathway

Centers and tracts that connect the CNS with body organs and systems

The ___ are descending motor tracts on the anterolateral surface of the midbrain

Cerebral Peduncles

The ___ are the isolated, innermost, gray matter areas near the base of the cerebrum, inferior to the lateral ventricles

Cerebral nuclei

CSF Formation

Cerebrospinal fluid is formed by the choroid plexusin each ventricle. The choroid plexus is composed of a layer of ependymal cells and the capillaries that lie within the pia mater. CSF is produced by secretion of a fluid from the ependymal cells that originates from the blood plasma. CSF is somewhat similar to blood plasma, although certain ion concentrations differ between the two types of fluid.

what are functions of anterior group?

Changes motor cortex excitability and modifi es mood

Cerebrospinal Fluid (CSF)

Clear, colorless liquid that circulates in the ventricles and subarachnoid space. CSF bathes the exposed surfaces of the central nervous system and completely surrounds the brain and spinal cord.

Ganglion

Cluster of neuron cell bodies within the PNS

Projection tracts

Connect cerebral cortex to the diencephalon, brainstem, cerebellum, and spinal cord Corticospinal tracts (motor axons traveling from cerebral cortex to spinal cord; sensory axons traveling from spinal cord to cerebrum)

Commissural tracts

Connect corresponding lobes of the right and left hemispheres Corpus callosum, anterior commissure, posterior commissure

Longitudinal fasciculi

Connect gyri between different cerebral lobes of the same hemisphere Tracts connecting Wernicke area (parietal/temporal lobes) and motor speech area (frontal lobe)

Arcuate fibers

Connect neighboring gyri within a single cerebral lobe Tracts connecting primary motor cortex (frontal lobe) to motor association area (frontal lobe)

Association tracts

Connect separate cortical areas within the same hemisphere Arcuate fibers longitidinal fasciculi

Insula

Consists of: Primary gustatory cortex Functions: Interpretation of taste; memory

Frontal lobe

Consists of: - Primary motor cortex (located within precentral gyrus) - Premotor cortex, Motor speech area (Broca area) (usually found only on the left frontal lobe) - Frontal eye fields Functions: Higher intellectual functions (concentration, decision making, planning); personality; verbal communication; voluntary motor control of skeletal muscles

White matter

Derives its color from the myelin in the myelinated axons.

CN VII (7)

FACIAL NERVE Innervates muscles of facial expression, lacrimal (tear) gland, and most salivary glands; conducts taste sensations from anterior two-thirds of tongue somatic motor function- the 5 major motor branches (temporal, zygomatic, buccal, mandibular, and cervical) innervate the muscles of facial expression, the posterior belly of the digastric muscle, and the stylohoid and stapedius muscles Parasympatetic motor function- increases secretions of the lacrimal gland of the eye as the submandiubular and sublingual salivary glands Conditions caused by nerve damage: Decreased tearing (dry eye) and decreased salivation (dry mouth); loss of taste sensation to anterior two-thirds of tongue and/or facial nerve palsy (sometimes called Bell palsy) characterized by paralyzed facial muscles, lack of obicularis oculi contraction, sagging at corner of mouth

What is the arachnoid villi?

Fingerlike extensions of the arachnoid mater project through the dura mater into the dural venous sinuses

Secondary brain vesicles

Formed by the fifth week of development ■ The telencephalon arises from the prosencephalon and eventually forms the cerebrum. ■ The diencephalon arises from the prosencephalon and eventually forms the thalamus, hypothalamus, and epithalamus. ■ The mesencephalon is the only primary vesicle that does not form a new secondary vesicle. ■ The metencephalon arises from the rhombencephalon and eventually forms the pons and cerebellum. ■ The myelencephalon also derives from the rhombencephalon, and it eventually forms the medulla oblongata.

Primary brain vesicles

Formed by the late fourth week of development - Prosencephalon (the forebrain) - Mesencephalon (the midbrain) - Rhombencephalon (the hindbrain)

CN IX (9)

GLOSSOPHARYNGEAL NERVE Receives taste and touch sensations from posterior tongue, innervates one pharynx muscle and the parotid salivary gland somatic motor function- innervates stylopharyngeus (phaync muscle) parasympathtic motor function- increases secretion of parotid salivary gland Conditions caused by nerve damage: Reduced salivary secretion (dry mouth); loss of taste sensations to posterior one-third of tongue

Center

Group of CNS neuron cell bodies with a common function

Funiculus

Group of tracts in a specifi c area of the spinal cord

CN XII (12)

HYPOGLOSSAL NERVE Innervates intrinsic and extrinsic tongue muscles; name means "under the tongue" somatic innervates intrinsic and extrinsic tongue muscles Conditions caused by nerve damage Swallowing and speech diffi culties due to impaired tongue movement; if a single hypoglossal nerve (either left or right) is paralyzed, a protruded (stuck out) tongue deviates to the side of the damaged nerve

The primary somatosensory cortex

Is housed within the postcentral gyrus of the parietal lobes. Neurons in this cortex receive general somatic sensory information from touch, pressure, pain, and temperature receptors.

Posterior group

Lateral geniculate nuclei: Relay visual information from optic tract to visual cortex and midbrain Medial geniculate nuclei: Relay auditory information from inner ear to auditory cortex Pulvinar nuclei: Integrate and relay sensory information for projection to association areas of cerebral cortex

The primary motor cortex (somatic motor area)

Located within the precentral gyrus of the frontal lobe. Neurons there control voluntary skeletal muscle activity. The axons of these neurons project contralaterally (to the opposite side) to the brainstem and spinal cord. Thus, the left primary motor cortex controls the right-side voluntary muscles, and vice versa.

Nerve plexus

Network of nerves in PNS

CN III

OCULOMOTOR NERVE Innervates upper eyelid muscle and four of the six extrinsic eye muscles Somatic motor function-supplies 4 extrisic eye muscles(superior rectus, inferior rectus, medial rectus, inferior oblique) that move eye......supplies levator palebrae superioris muscle to elevate eyelin parasympathetic motor function-innervates sphincter pupillae muscle of iris to make pupil constrict...... contracts cillary mucles to make lens of eye more spherical (as needed for near vision) Conditions caused by nerve damage: Ptosis (upper eyelid droop); paralysis of most eye muscles, leading to strabismus (eyes not in parallel/deviated improperly), diplopia (double vision), focusing diffi culty

CN I

OLFACTORY NERVE Conducts olfactory (smell) sensations to brain; only type of nervous tissue to regenerate. -Travels through the cribriform foramina of ethmoid bone and synapses in the olfactory bulbs, which are located in the anterior cranial fossa. Within the olfactory bulb, the axons synapse with a smaller # of neurons, the axons of which form the olfacotry tract and project to olfacotry cortex Conditions caused by nerve damage: Anosmia (partial or total loss of smell)

CN II

OPTIC NERVE Special sensory nerve of vision that is an outgrowth of the brain; more appropriately called a brain tract -origin- retina of the eye pathway- enters cranium via optic canal of sphenoid bone; left and right optic nerves unite at optic chaism; optic tract travels to lateral geniculate nucleus of thalamus; finally, info is fowerded to the occipital lobe Conditions caused by nerve damage: Anopsia (visual defects)

Cortex

Outer layer of gray matter in cerebrum and cerebellum; consists of densely packed neuron cell bodies

Which cerebral lobe is located immediately posterior the central sulcus and superior to the lateral sulcus

Parietal lobe

The primary motor cortex is located in which cerebral structure?

Pre central gyrus

ventromedial nucleus

Satiety center- produces hunger sensations

Medial group

Sends signals about conscious awareness of emotional states to frontal lobes

Sulci (sulcus)

Shallow depressions between folds (gyrus)

CN V (5)

TRIGEMINAL NERVE This nerve consists of three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3); receives sensory impulses from face, oral cavity, nasal cavity, and anterior scalp, and innervates muscles of mastication somatic motor function- innervates muscles of mastication (temporalis, masseter, lateral and medial pterygoids), mylohoid, anterior belly of digastric, tenor tympani muscle, and tensor veli palatina Conditions caused by nerve damage: Trigeminal neuralgia (tic douloureux) is caused by infl ammation of the sensory components of the trigeminal nerve and results in intense, pulsating pain lasting from minutes to several hours

CN IV (4)

TROCHLEAR NERVE Innervates one extrinsic eye muscle (superior oblique) that loops through a pulley-shaped ligament somatic motor function- supplies one extrinsic eye muscle (superior oblique) to move eye inferioly and laterally Conditions caused by nerve damage: Paralysis of superior oblique, leading to strabismus (eyes not in parallel/deviated improperly), diplopia (double vision)

Cerebral Hemispheres

The cerebrum is composed of two halves, called the left and right cerebral hemispheres The paired cerebral hemispheres are separated by a deep longitudinal fissure that extends along the midsagittal plane.

What are the brain's four major regions?

The cerebrum, the diencephalon, the brainstem, and the cerebellum

Motor Areas

The cortical areas that control motor functions are housed within the frontal lobes.

Sensory Areas

The cortical areas within the parietal, temporal, and occipital lobes typically are involved with conscious awareness of sensation.

Corpus callosum

The largest of these white matter tracts It provides the main communications link between these hemispheres.

Limbic System

The limbic system is composed of multiple cerebral and diencephalic structures that collaboratively process and experience emotions. It is a collective name for the human brain structures that are involved in motivation, emotion, and memory with an emotional association. The limbic system affects memory formation by integrating past memories of physical sensations with emotional states.

Gyri (gyrus)

The outer surface of an adult brain exhibits folds

Blood-brain barrier (BBB)

The perivascular feet of the astrocytes (when they completely cover the capillary) and the tight endothelial junctions of the capillaries work together to prevent harmful materials in the bloodstream from reaching the brain.

Association Areas

The primary motor and sensory cortical regions are connected to adjacent association areas that either process and interpret incoming data or coordinate a motor response Association areas integrate new sensory inputs with memories of past experiences.

Cerebellar Peduncles

Three thick tracts that link the cerebellum with the brainstem are called Peduncles - The superior cerebellar peduncles connect the cerebellum to the mesencephalon. - The middle cerebellar peduncles connect the pons to the cerebellum. - The inferior cerebellar peduncles connect the cerebellum to the medulla oblongata. - It is these extensive communications that enable the cerebellum to "fine-tune" skeletal muscle movements and interpret all body proprioceptive movement.

True or false- The folds of the cerebellar cortex are called folia

True

True or false- all the ventricle contain CSF

True

True or false- the medulla oblongta contains the paired nucleus cuneatus and the nucleus gracilis, which relay somatic sensory information to the thalamus?

True

True or false; the CSF is formed by the choroid plexus

True -The choroid plexus is composed of layer of ependymal cells and the capillaries that lie within the pia mater

CN VIII (8)

VESTIBULOCOCHLEAR NERVE Conducts equilibrium and auditory sensations to brain; formerly called the auditory nerve or acoustic nerve sensory function- vestibular conducts impulses for equilbrium, whereas cochlear branch conducts impulses for hearing Conditions caused by nerve damage: Lesions in vestibular branch produce loss of balance, nausea, vomiting, and dizziness; lesions in cochlear branch result in deafness (loss of hearing)

what is the postcentral gyrus?

a mass of nervous tissue immediately posterior to the central sulcus

What are the ventricles?

are cavities or expansions within the brain that are derived from lumen of the embryonic neural tube

Brain Ventricles

are cavities or expansions within the brain that are derived from the lumen (opening) of the embryonic neural tube.

What is the cerebral peduncles

are motor tracts located on the anteriolateral surfaces of the mesencephalon

olfactory bulbs, olfactory tracts, and olfactory cortex

are part of the limbic system as well, since particular odors can provoke certain emotions or be associated with certain memories.

What is the cerebellar peduncles?

are transverse groups of fibers that connect the pons to the cerebellum

What is cranial dural septa?

double layers of dura mater -seperate specfic parts of the brain and provide additional stabilization and support to the entire brain

responsible for involuntary arm swinging

cerebral nuclei

What is an epidural space?

contain arteries and veins that nourish the meninges and bones of the cranium

Motor homunculus

diagram of the innervation of the primary motor cortex to various body parts.

Cerebral nuclei

discrete internal clusters of gray matter, which are oval, spherical, or sometimes irregular shaped clusters of neuron cell bodies

What is the thalamic nuclei?

each part of the thalamus is a gray matter mass composed of about a dozen major thalamic nuclei that are organized into groups; axons from these nuclei project to particular regions of the cerebral cortex

What is the cerebral aqueduct?

extending through the midbrain is the cerebral aqueduct connecting the third and fourth ventricle; it surrounds the periaquductal gray matter

dura mater fold between cerebral hemispheres

fall cerebri

What are the four cranial dural septa?

falx cerebri, tentorium cerebelli, falx cerebelli, and diaphragma

contains the motor speech area

frontal lobe

What is the tentorial notch?

has a gap opening called the tentorial notch which allows for the passage of the brainstem -in the tentorium cerebelli

hormone melatonin

help regulate day-night cycles known as the body's circadian rhythm.

What is an olive?

immediately lateral to each pyramid is a distinct bulge, called olive, which contains a large fold of gray matter the inferior olivary nucleus

Which of the following is not a function of the hypothalamus?

initiates voluntary skeletal muscle movement

The primary gustatory cortex

is in the insula and is involved in processing taste information

Pons

is a bulge on the ventral side of the hindbrain that contains nerve tracts, nuclei, and part of the reticular formation. Housed within the pons are sensory and motor tracts that connect to the brain and spinal cord In addition, the middle cerebellar peduncles are transverse groups of fibers that connect the pons to the cerebellum. The pons also houses two autonomic respiratory centers: the pneumotaxic center and the apneustic center. These centers regulate the rate and depth of breathing, and both of them influence and modify the activity of the respiratory center in the medulla oblongata. The pons houses sensory and motor cranial nerve nuclei for the trigeminal (CN V), abducens (CN VI), and facial (CN VII) cranial nerves. Some of the nuclei for the vestibulocochlear cranial nerve (CN VIII) are located there. Additionally, nuclei called the superior olivary complex are located in the inferior pons. This nuclear complex receives auditory input and is involved in the pathway for sound localization.

What is the precentral gyrus?

is a mass of nervous tissue immediately anterior to the central sulcus

hippocampus

is a nucleus located superior to the parahippocampal gyrus that connects to the diencephalon via a structure called the fornix. As its name implies, this nucleus is shaped like a seahorse. Both the hippocampus and the parahippocampal gyrus are essential in storing memories and forming longterm memory.

Diencephalon

is a part of the prosencephalon sandwiched between the inferior regions of the cerebral hemispheres. This region is often referred to as the "in-between brain." The components of the diencephalon include the epithalamus, the thalamus, and the hypothalamus The diencephalon provides the relay and switching centers for some sensory and motor pathways and for control of visceral activities.

What is the interthalamic adhesion?

is a small midline mass of gray matter that connects the right and left thakamic bodies

Fornix

is a thin tract of white matter that connects the hippocampus with other diencephalon limbic system structures

The motor speech area

is also called the Broca area, and located in most individuals within the inferolateral portion of the left frontal lobe. This region is responsible for controlling the muscular movements necessary for vocalization.

What is the pineal gland?

is an endocrine gland, it secretes the hormone melatonin

Dura Mater

is an external tough, dense irregular connective tissue layer composed of two fibrous layers: - Periosteal layer-most superfical, forms peristeum on the internal surface of the cranial bones - Meningeal layer- lies deep

Gnostic area

is composed of regions of the parietal, occipital, and temporal lobes. This region integrates all sensory, visual, and auditory information being processed by the association areas within these lobes. Thus it provides comprehensive understanding of a current activity. For example, suppose you awaken from a daytime nap: The hands on the clock indicate that it is 12:30, you smell food cooking, and you hear your friends talking about being hungry. The gnostic area then interprets this information to mean that it is lunchtime.

The premotor cortex (the somatic motor association area)

is located in the frontal lobe, immediately anterior to the precentral gyrus. It permits us to process motor information and is primarily responsible for coordinating learned, skilled motor activities, such as moving the eyes in a coordinated fashion when reading a book or playing the piano. An individual who has sustained trauma to this area would still be able to understand written letters and words, but would have difficulty reading because his or her eyes couldn't follow the lines on a printed page.

The visual association area

is located in the occipital lobe and surrounds the primary visual area. It enables us to process visual information by analyzing color, movement, and form, and to use this information to identify the things we see. For example, when we look at a face, the primary visual cortex receives bits of visual information, but the visual association area is responsible for integrating all of this information into a recognizable picture of a face.

The somatosensory association area

is located in the parietal lobe and lies immediately posterior to the primary somatosensory cortex. It interprets sensory information and is responsible for integrating and interpreting sensations to determine the texture, temperature, pressure, and shape of objects. The somatosensory association area allows us to identify objects while our eyes are closed. For example, we can tell the difference between the coarse feel of a handful of dirt, the smooth, round shape of a marble, and the thin, flat, rounded surface of a coin because those textures have already been stored in the somatosensory association area.

The auditory association area

is located within the temporal lobe, posteroinferior to the primary auditory cortex. Within this area, the cortical neurons interpret the characteristics of sound and store memories of sounds heard in the past.

What is the tegmentum?

is sandwiched between the substantia nigra and the periaqueductal gray matter -the tegmentum contains the pigmented red nuclei and the reticular formations it integrates information from the cerebrum and cerebullum and issues involuntary motor commands to the erector spinae muscles of the back to help maintain posture while standing, bending at the waist, or walking

Hypothalamus

is the anteroinferior region of the diencephalon. A thin, stalklike infundibulum extends inferiorly from the hypothalamus to attach to the pituitary gland

Pia Mater

is the innermost of the cranial meninges. It is a thin layerof delicate areolar connective tissue that is highly vascularized and tightly adheres to the brain.

Explain the falx cerebri dural septa

is the largest of the four dural septa -located in the midsagittal plane, projects into the longitudinal fissure between the left and right cerebral hemispheres -superior sagittal sinus -inferior sagitatal sinus

What is the tectum?

is the posterior region of the midbrain dorsal to the cerebral aqueduct

Cerebellum

is the second largest part of the brain, and it develops from the metencephalon. Functions: - coordinates and "fine-tunes" skeletal muscle movements and ensures that skeletal muscle contraction follows the correct pattern leading to smooth, coordinated movements. - The cerebellum stores memories of previously learned movement patterns. - In addition, the cerebellum has several other functions. It adjusts skeletal muscle activity to maintain equilibrium and posture. - It also receives proprioceptive (sensory) information from the muscles and joints and uses this information to regulate the body's position. For example, you are able to balance on one foot because the cerebellum takes the proprioceptive information from the body joints and "maps out" a muscle tone plan to keep the body upright. - Finally, because proprioceptive information from the body's muscles and joints is sent to the cerebellum, the cerebrum knows the position of each body joint and its muscle tone, even if the personis not looking at the joint. For example, if you close your eyes, you are still aware of which body joints are flexed and which are extended because the cerebrum gives you this awareness.

What is the midbrain?

is the superior portion of the brainstem

Wernicke area

is typically located only within the left hemisphere, where it overlaps the parietal and temporal lobes. The Wernicke area is involved in recognizing, understanding, and comprehending spoken or written language. As you may expect, the Wernicke area and the motor speech area must work together in order for fluent communication to occur.

What is the arachnoid tubeculae?

it is composed of delicate web of collagen and elastic fibers

What is the diaphragma sellar of the dura septa?

it is the smallest -which forms a roof over the sella turcic of the sphenoid bone -allots for the passage of a thin stalk, called infundibulum, that attaches the pituitary gland to the base of the hypothalamus

What is the dural venous sinuses?

large veins that drain blood from the blood from the brain transport this blood to the internal jugular veins that help drain circulation of the head

Central White Matter

lies deep to the gray matter of the cerebral cortex and is composed primarily of myelinated axons. Most of these axons are grouped into bundles called tracts, which are classified as association tracts, commissural tracts, or projection tracts

Pia Mater

lies external to the pia mater - arachnoid trabeculae. - subarachnoid space - subdural space

What is arachnoid mater?

lies external to the pia mater -resembling a sipder web

What is sensory homunclulus?

may be traced on the postcentral gyrus surface

autonomic centers for heart rate and respiration

medulla oblongata

has nuclei for cn3 and cn4

midbrain

What is the falx cerebelli of the dural septa?

sickle-shaped vertical partition that divides the left and right cerebellar hemispheres -occipital sinus- runs in its posterior vertical border

Epithalamus

partially forms the posterior roof of the diencephalon and covers the third ventricle. The posterior portion of the epithalamus houses the pineal gland and the habenular nuclei. The pineal gland is an endocrine gland. It secretes the hormone melatonin, which appears to help regulate day-night cycles known as the body's circadian rhythm.

Which structure contains some autonomic centers involved in regulating respiration?

pons

mammillary body?

processes sensation related to smelling

supraoptic nucleus

produces oxytocin and antidiretic hormon(ADH)

paraventricular nucleus ?

produces oxytocin and antidiuretic hormone (ADH)

Thalamus

refers to paired oval masses of gray matter that lie on each side of the third ventricle The thalamus forms the superolateral walls of the third ventricle. The thalamus is the principal and final relay point for sensory information that will be processed and projected to the primary somatosensory cortex. Only a relatively small portion ofthe sensory information that arrives at the thalamus is forwarded to the cerebrum because the thalamus acts as an information filter.

Visual reflex centers

superior colliculi

The visual reflex center is housed within the

superior colliculus

contains the primary auditory cortex

temporal lobe

sensory information relay center

thalamus

What is the longitudinal fissure?

that extends along the midsagittal plane of the two hemispheres

What is the lateral sulcus?

that marks the boundary with the parietal lobes

cerebral cortex

the external layer of gray matter, covers most of the adult brain

What are the central sulcus?

the frontal lobe ends posteteriosly at a deep grove called central sulcus

Anterior thalamic nuclei, the habenular nuclei, the septal nuclei and the mammillary bodiies

they interconnect other parts of the limbic system and contribute to its overall function

Which cranial nerve has 3 divisions (ophthalmic, maxillary, and mandibular) ?

trigeminal (CNV)

innervates most thoracic/ abdominal cortex

vagus nerve

What are pyraminds?

which house the motor projection tracts called the corticospinal tracts -in the posterior region of the medulla most of these axons cross to the opposite side of the brain at a point called decussation of the pyramids

Functions of CSF

■ Buoyancy. The brain floats in the CSF, which thereby supports more than 95% of its weight and prevents it from being crushed under its own weight. Without CSF to support it, the heavy brain would sink through the foramen magnum. ■ Protection. CSF provides a liquid cushion to protect delicate neural structures from sudden movements. When you try to walk quickly in a swimming pool, your movements are slowed as the water acts as a "movement buffer." CSF likewise helps slow movements of the brain if the skull and/or body move suddenly and forcefully. ■ Environmental stability. CSF transports nutrients and chemicals to the brain and removes waste products from the brain. Additionally, CSF protects nervous tissue from chemical fluctuations that would disrupt neuron function. The waste products and excess CSF are eventually transported into the venous circulation, where they are filtered from the blood and secreted in urine in the urinary system.

Three aspects about cerebral Hemispheres

■ In most cases, it is difficult to assign a precise function to a specific region of the cerebral cortex. Considerable overlap and indistinct boundaries permit a single region of the cortex to exhibit several different functions. Additionally, some aspects of cortical function, such as memory or consciousness, cannot easily be assigned to any single region. ■ With few exceptions, both cerebral hemispheres receive their sensory information from and project motor commands to the opposite side of the body. The right cerebral hemisphere controls the left side of the body, and vice versa. ■ The two hemispheres appear as anatomic mirror images, but they display some functional differences, termed hemispheric lateralization. For example, the portions of the brain that are responsible for controlling speech and understanding verbalization are frequently located in the left hemisphere.

Functions of the Hypothalamus

■ Master control of the autonomic nervous system. The hypothalamus is a major autonomic integration center. In essence, it is the "president" of the corporation known as the autonomic nervous system. It projects descending axons to autonomic nuclei in the inferior brainstem that influence heart rate, blood pressure, digestive activities, and respiration. ■ Master control of the endocrine system. The hypothalamus is also "president" of another "corporation"—the endocrine system—overseeing most but not all of that system's functions. The hypothalamus secretes hormones that control secretory activities in the anterior pituitary gland. In turn, subsequent normal secretions from the pituitary gland control metabolism, growth, stress responses, and reproduction. Additionally,the hypothalamus produces two hormones that are transported through axons in the infundibulum and then stored and released in the posterior pituitary: Antidiuretic hormone reduces water loss at the kidneys, and oxytocin stimulates smooth muscle contractions in the uterus, mammary gland, and prostate gland. ■ Regulation of body temperature. The body's thermostat is located within the hypothalamus. Neurons in the preoptic area detect altered blood temperatures and signal other hypothalamic nuclei, which control the mechanisms that heat or cool the body (shivering and sweating, respectively). ■ Control of emotional behavior. The hypothalamus is located at the center of the limbic system, the part of the brain that controls emotional responses, such as pleasure, aggression, fear, rage, contentment, and the sex drive. ■ Control of food intake. Neurons within the ventromedial nucleus monitor levels of nutrients such as glucose and amino acids in the blood and produce sensations of hunger. ■ Control of water intake. Specific neurons within the anterior nucleus continuously monitor the blood solute (dissolved substances) concentration. High solute concentration stimulates both the intake of fluid and the production of antidiuretic hormone by neurons in the supraoptic nucleus and paraventricular nucleus. ■ Regulation of sleep-wake (circadian) rhythms. The suprachiasmatic nucleus directs the pineal gland when to secrete melatonin. Thus, both work to regulate circadian rhythms.

Medulla oblongata contains several autonomic nuclei, which regulate functions vital for life:

■ The cardiac center regulates both the heart's rate and its strength of contraction. ■ The vasomotor center controls blood pressure by regulating the contraction and relaxation of smooth muscle in the walls of the smallest arteries (called arterioles) to alter vessel diameter. Blood pressure increases when vessels are constricted and lowers when vessels are dilated. ■ The respiratory center regulates the respiratory rate. It is influenced by the apneustic and pneumotaxic centers of the pons. ■ Other nuclei in the medulla oblongata are involved in coughing, sneezing, salivating, swallowing, gagging, and vomiting.