Chapter 13

Right Cerebral Hemisphere

-Analyzes sensory information and relates body to sensory environment. Ex: Recognizing faces, understanding 3D relationships. -Important in analyzing emotional context of conversation. -9% of population is left handed. This is controlled by the primary motor cortex of the right hemisphere. It is found in an unusually high percentage of musicians and artists--the primary motor cortex and association areas on right cerebral hemisphere are near spatial visualization and emotion association areas.

Left Cerebral Hemisphere

-Contains general interpretive and speech centers. -Is responsible for language-based skills such as reading, writing, speaking. -Premotor cortex controlling hand movements is larger for right-handed individuals. -Important in performing analytical tasks such as mathematics and logic.

Central Sulcus

A deep groove on each cerebral hemisphere that divides the anterior frontal lobe from the posterior parietal lobe.

Falx cerebri

A fold of dura mater between the cerebral hemispheres. Inferior portions attach anteriorly to the crista galli of the ethmoid bone and posteriorly to the internal occipital crest of the occipital bone. Location of superior and inferior dural sinuses.

Lateral Ventricle

A large chamber found in each cerebral hemisphere.

Reticular formation

A loosely organized mass of gray matter that contains embedded nuclei and centers that regulate vital autonomic functions. It extends from the medulla oblongata to the midbrain.

Interthalamic Adhesion

A projection of gray matter extending into the third ventricle from the left and right sides of the thalamus, although no fibers cross the midline. Absent in 1/5 of human brains.

Corpus Callosum

A thick tract of white matter that interconnects the two cerebral hemispheres.

Septum Pellucidum

A thin partition that separates the two lateral ventricles.

Arachnoid Mater (Cranial)

A weblike membrane that covers the brain, providing a smooth surface that does not follow the underlying folds. The subarachnoid space extends between this meninges and the pia mater. Fibrous strands of arachnoid trabeculae traverse the subarachnoid space.

Interventricular Foramen

Allows the lateral ventricles to communicate with the third ventricle.

Basal Nuclei of Cerebrum

Also known as basal ganglia. Masses of gray matter within each cerebral hemisphere deep to the floor of the lateral ventricle. Provide subconscious control of skeletal muscle tone and help coordinate learned movement patterns. Under normal conditions, they do not initiate particular movements, but once a movement is under way, the they provide the general pattern and rhythm, especially for movement of the trunk and proximal limb muscles. -Subconscious adjustment and modification of voluntary motor commands.

Choroid Plexus

An area found in each ventricle that is involved in producing and maintaining CSF. Each contains specialized ependymal cells with tight junctions and capillaries. Produce 500 mL/day of CSF.

Precentral gyrus

Anterior to the central sulcus, contains the primary motor cortex. Motor neurons control voluntary movements.

Tegmentum

Area anterior to the cerebral aqueduct in the midbrain.

Wernicke's Area

Associated with language comprehension. Analytical center receives information from the somatosensory association areas and plays an important role in personality by integrating sensory information and coordinating visual and auditory memories. Present in left cerebral hemisphere.

Broca's Area (motor speech area)

Associated with speech production. It regulates breathing and vocalization patterns needed for normal speech. A person with damage to this area can make sounds but not words.

Pia Mater (Cranial)

Astrocyte processes bind this meningeal layer to the surface of the brain. It extends into every fold and accompanies the branches of cerebral blood vessels as they penetrate the surface of the brain to reach internal structures.

Median aperture

CSF reaches the subarachnoid space through two lateral apertures and a single one of these in the roof of the fourth ventricle. The CSF then flows through the subarachnoid space surrounding the brain, spinal cord, and cauda equina.

Lateral Apertures

CSF reaches the subarachnoid space through two of these and a single median aperture in the roof of the fourth ventricle. The CSF then flows through the subarachnoid space surrounding the brain, spinal cord, and cauda equina.

Third Ventricle

Chamber located in the diencephalon.

Fourth Ventricle

Chamber that begins in the metencephalon and extends into the superior portion of the medulla oblongata. It then narrows and becomes the central canal of the spinal cord.

Ventricles

Chambers of the brain that are filled with cerebrospinal fluid and lined by ependymal cells.

Nuclei

Components of hypothalamus that are autonomic centers that control cardiovascular and vasomotor centers of the medulla oblongata.

Pons

Connects the cerebellum to the brainstem. In addition to tracts and relay centers, it also contains nuclei that function in somatic and visceral motor control. Links the cerebellum to the midbrain, diencephalon, cerebrum, medulla oblongata, and spinal cord. Contains four groups of structures: ascending, descending and transverse tracts that interconnect other portions of the CNS, nuclei involved with the control of respiration, sensory and motor nuclei of cranial nerves, and nuclei and tracts that process and relay information sent to and from the cerebellum. -Carry motor commands from higher centers of the brain to nuclei of cranial or spinal nerves. -Carry sensory information from brainstem nuclei to the thalamus. -Link pontine nuclei with cerebellum of opposite side. -Adjust activities of the respiratory rhythmicity centers in the medulla oblongata and itself. -Autonomic processing of incoming sensations and outgoing motor commands. -Nuclei of cranial nerves V, VI, VII, and VIII (in part): relay sensory information and issue somatic motor commands to face, jaw, and extrinsic eye muscles. -Relay sensory and motor information to the cerebellum.

Cerebellar Peduncles

Contain tracts that link the cerebellum with the brainstem, cerebrum, and spinal cord. Middle and inferior carry input to cerebellum and superior carries most of cerebellar output.

Midbrain

Contains nuclei that process visual and auditory information and control reflexes triggered by these stimuli. Contains centers that maintain consciousness. Most complex and integrative part of the brainstem. It can direct complex motor patterns at the subconscious level. It influences the level of activity in the entire nervous system. It contains the red nucleus, the substantia nigra, the cerebral peduncles, the reticular activating system, and the Corpora Quadrigemina. -Integrate visual information with other sensory inputs; initiates reflex responses to visual stimuli. -Relay auditory information to medial geniculate nuclei; initiate reflex responses to auditory stimuli. -Provides subconscious control of upper limb position and background muscle tone. -Regulates activity in the basal nuclei. -Processes incoming sensations and outgoing motor commands automatically; can initiate involuntary motor responses to stimuli; helps maintain consciousness. -Are associated with cranial nerves III and IV. -Connect primary motor cortex with motor neurons in brain and spinal cord; carry ascending sensory information to thalamus.

Frontal Eye Field

Controls learned eye movements, such as when scanning text.

Fissures

Deep grooves that subdivide each cerebral hemisphere.

Cerebrum

Divided into left and right cerebral hemispheres. Surfaces are highly folded and covered by a superficial layer of gray matter 1.5-4.5 mm thick, called the cerebral cortex. Functions include conscious thought, memory storage and processing, sensory processing, and regulating skeletal muscle contractions.

Lobes

Divisions of the cerebral hemispheres.

Arachnoid Granulations

Fingerlike extensions of the arachnoid membrane that penetrate the meningeal layer of the dura mater and extend into the superior sagittal sinus. These extensions are the sites where CSF is absorbed into venous circulation.

Hypothalamus

Floor of diencephalon. Contains centers involved with emotions, autonomic function, and hormone production. Contains important control and integrative centers. Centers can be stimulated by sensory information from the cerebrum, brainstem, and spinal cord; changes in composition of the CSF of interstitial fluid; or chemicals in the circulating blood that rapidly enter the region because this region lacks a blood brain barrier. Components include the infundibulum that connects to the pituitary gland; mamillary bodies that control feeding reflexes like liking and swallowing; and hormonal centers that secrete chemical messengers that control endocrine cells in the anterior pituitary and secrete two hormones released by the posterior pituitary; nuclei are automatic centers that control cardiovascular and vasomotor centers of the medulla oblongata (preoptic area regulates body temperature through adjustments in sweat gland activity and blood flow; suprachiasmic nucleus coordinates the day-night cycles of activity/inactivity). -Secretes oxytocin, stimulates smooth muscle contraction in uterus and mammary glands. -Regulates body temperature by control of autonomic centers in the medulla oblongata. -Produce inhibitory and releasing hormones that control endocrine cells of the anterior lobe of the pituitary gland (adenohypophysis). -Control feeding reflexes (liking, swallowing). -Regulates daily/circadian rhythms. -Secretes antidiuretic hormones, restricts water loss by kidneys.

Gyri

Folds in the cerebral hemisphere that increase surface area.

Folia

Folds of the cerebellar cortex. Not as prominent as folds in cerebral hemispheres.

Limbic System

Includes nuclei and tracts along the border between the cerebellum and the diencephalon. It is a functional grouping. It establishes emotional states; links the conscious, intellectual functions of the cerebral cortex to the unconscious and autonomic functions of the brain stem; facilitates memory storage and retrieval; and affects motivation. Emotional areas for rage, fear, pain, sexual arousal, and pleasure. Also includes areas that produce heightened alertness/generalized excitement, generalized lethargy, and sleep. These responses are caused by stimulation or inhibition of the reticular formation. Motivational system.

Brainstem

Includes the midbrain, pons, and medulla oblongata.

Dural Folds

Inner layer of the dura mater extends into the cranial cavity to form these. They stabilize and support the brain.

Prefrontal Cortex

Integrates information from sensory association areas and performs intellectual functions, such as predicting the consequences of possible responses.

Dural Venous Sinuses

Large collecting veins found within the dural folds.

Superior Sagittal Sinus

Largest dural sinus.

Anterior Commissure

Marks anterior side of diencephalon. A tract that interconnects the cerebral hemispheres, and the optic chasm, where the optic nerves (II) connect to the brain.

Insula

Medial to the lateral sulcus.

Vermis

Narrow band of cortex that separates the cerebellar hemispheres.

Cerebral peduncles

Nerve fiber bundles on the ventrolateral surfaces of the midbrain. They contain descending fibers that reach the cerebellum by way of the pons and descending fibers that carry voluntary motor commands issued by the cerebral hemispheres.

Sensory Cortex

Neurons in the primary somatosensory cortex receive somatic information from receptors for touch, pressure, pain, vibration, or temperature. The somatosensory cortex association area monitors activity in the primary somatosensory cortex.

Motor Cortex

Neurons of the primary motor cortex direct voluntary movement by controlling somatic motor neurons in the brainstem and spinal cord. Neurons are pyramidal cells because of their shape. The premotor cortex, or somatic motor association area, coordinates learned movements.

Thalamus

Part of diencephalon. Contains relay and processing centers for sensory information. Left and right sides are superior to the midbrain. It is the final relay point for ascending sensory information to be relayed or projected to the cerebral cortex. It acts as a filter, only passing a small portion of sensory information. It also has regions that contain nuclei/groups of nuclei that connect to specific regions of cerebral cortex. -Part of the limbic system. -Integrates sensory information for projection to the frontal lobes. -Projects sensory information to the primary sensory cortex; relays information from the cerebellum and basal nuclei to the motor area of the cerebral cortex. -Integrates sensory information for projection to association areas of the cerebral cortex. -Project visual information to the visual cortex . -Project auditory information to the auditory cortex. -Integrates sensory information and influences emotional states.

Suprachiasmatic Nucleus

Part of hypothalamus that coordinates the day-night cycles of activity/inactivity.

Preoptic area

Part of hypothalamus that regulates body temperature through adjustments in blood flow and sweat gland activity.

Hormonal centers

Part of hypothalamus that secrete chemical messengers that control endocrine cells in the anterior pituitary and secrete two hormones released by the posterior pituitary.

Mamillary Bodies

Part of the hypothalamus that controls feeding reflexes like licking and swallowing.

Gustatory Cortex

Part of the insula that receives information from taste receptors.

Substantia nigra

Part of the midbrain. Contains darkly pigmented cells that inhibit activity in the basal nuclei of the cerebrum. These cells are involved in motor control and are damaged in Parkinson's disease.

Red Nucleus

Part of the midbrain. Contains numerous blood vessels, giving it its color. Receives information from the cerebrum and cerebellum and issues subconscious motor commands that affect upper limb position and background muscle tone.

Reticular Activating System

Part of the midbrain. Specialized part of the reticular formation. Stimulation of this makes you more alert/attentive, while damage can produce unconsciousness.

Ataxia

Permanent damage to the cerebellum from trauma or stroke or temporarily affected by drugs like alcohol. Result is an inability to coordinate muscular movement. In severe cases, the person cannot stand or sit independently.

Infundibulum

Portion of the hypothalamus that connects to the pituitary gland.

Postcentral gyrus

Posterior to the central sulcus, contains the primary somatosensory cortex that receives sensory information that reaches our conscious awareness.

Language Areas

Primarily associated with left cerebral hemisphere.

Integrative Centers

Receive information from association areas and direct motor activities as well as performing analytical functions. They are located in the lobes and cortical areas of both cerebral hemispheres.

Superior Colliculus

Receive visual inputs from the thalamus and controls the reflex movements of the eyes, head, and neck in response to visual stimuli, like a bright light. Part of Corpora Quadrigemina.

Inferior Colliculus

Receives auditory input from nuclei in the medulla oblongata and pons and controls reflex movements of the head, neck, and trunk in response to auditory stimuli, such as a load noise. Part of Corpora Quadrigemina.

Olfactory Cortex

Receives sensory information from the olfactory receptors.

Hemispheric lateralization

Regional specialization; each of the two cerebral hemispheres is responsible for specific functions that are not ordinarily performed by the opposite hemisphere.

Association areas

Regions of the cerebral cortex that interpret incoming data or coordinate a motor response.

Medulla Oblongata

Relays sensory information to other portions of the brainstem and thalamus. Contains major centers that regular autonomic functions, such as heart rate and blood pressure. Contains autonomic reflex centers, relay stations, and ascending and descending tracts. All communications between the brain and the spinal cord travel along tracts that ascend or descend through this area. It is a center that coordinates complex autonomic reflexes and visceral functions. Descending tracts cover its anterior surface. It contains autonomic centers controlling vital functions and contains relay stations along sensory and motor pathways. -Relays information from the red nucleus, other midbrain centers, and the cerebral cortex to the cerebellum. -Regulate heart rate and force of contraction. -Set basic pace of respiratory movements. -Relay somatic sensory information to the thalamus. -Integrates and relays visceral sensory information to autonomic processing centers. -Regulate distribution of blood flow. -Contain sensory and motor nuclei of cranial nerves VIII, XI, X, XI (in part) and XII. -Relay ascending sensory information from the spinal cord to higher centers. -Link the brain with the spinal cord.

Tectum

Roof of midbrain. Posterior to cerebral aqueduct.

Epithalamus

Roof of the diencephalon superior and posterior to the third ventricle. Its anterior portion contains an extensive choroid plexus that extends through the interventricular foramina. Pineal gland found in posterior portion--responsible for secreting melatonin which is important in regulating day-night cycles.

Cerebellum

Second largest region of the brain. Partially hidden by cerebral hemispheres. Coordinates and modulates motor commands from cerebral cortex. Includes one-tenth of the brain's volume, but over half of the brain's neurons. Coordinates learned and reflexive patterns of muscular activity at the subconscious level. It is an autonomic processing center that monitors proprioceptive, visual, tactile, balance, and auditory sensations. Adjusting postural muscles of the body: Coordinates rapid, automatic adjustments that maintain balance and equilibrium. These adjustments are made by modifying the activities of the motor centers in the brainstem. Programming and fine-tuning movements controlled at the conscious and subconscious levels. It refines learned movement patterns like riding a bike or playing the piano. It does this indirectly by regulating activity along the motor pathways at the cerebral cortex, basal nuclei, and motor centers in the brainstem. It compares the motor commands with proprioceptive information and stimulates any adjustments needed to make the movement smooth. -Involuntary coordination and control of ongoing body movements. -Connects cerebellar cortex and nuclei with cerebellar peduncles. -Link the cerebellum with midbrain, diencephalon, and cerebrum. -Contain transverse fibers and carry communications between cerebrum and pons. -Link the cerebellum with the medulla oblongata and spinal cord. -Interconnect pontine nuclei with cerebellar hemisphere on the opposite side. -Monitors motor and sensory pathways and coordinates them.

Tentorium cerebelli

Separates the cerebral hemisphere from the cerebellum.

Lateral sulcus

Separates the frontal lobe from the temporal lobe.

Parieto-occipital sulcus

Separates the parietal lobe from the occipital lobe.

Falx cerebelli

Separates the two cerebellar hemispheres along the midsagittal line inferior to the tentorium cerebelli.

Sucli

Shallow grooves in the cerebral hemispheres that separate adjacent gyri.

Cerebral aqueduct

Slender canal within the midbrain that connects the third ventricle to the fourth ventricle.

Diencephalon

Structural and functional link between the cerebral hemispheres and the rest of the CNS. Includes the thalamus, hypothalamus, and epithalamus.

Cerebrospinal Fluid

Surrounds and bathes the exposed surfaces of the CNS. Functions in: Supporting the weight of the brain, cushioning the brain and spinal cord against physical trauma, and transporting nutrients, chemical messengers, and wastes. It circulates from the choroid plexuses through the ventricles and fills the central canal of the spinal cord. While circulating, materials diffuse between this and the interstitial fluid of the CNS across the ependymal cells. Total volume is 150 mL and the entire volume is replaced every 8 hours.

Primary fissure

The anterior and posterior lobes of the cerebellum are separated by this.

Dura Mater (Cranial)

The outermost layer of the cranial meninges. Consists of outer and inner fibrous layers. The outer layer is fused to the periosteum of the cranial bones, so there is no epidural space. The outer (periosteal) and inner (meningeal) layers are typically fused together. Where separated, they contain tissue fluids and blood vessels, including several including several large dural venous sinuses. The dural venous sinuses collect blood from the veins of the brain.

Auditory Cortex

The primary auditory cortex is responsible for monitoring auditory information. The auditory association area monitors sensory activity in the auditory cortex and recognizes sounds, such as spoken words.

Visual Cortex

The primary visual cortex receives information from the lateral geniculate bodies (nuclei). The visual association area monitors the patterns of activity in the visual cortex and interprets the results. Ex: When you see "c" "a" "r" together it is the word "car".

Corpora Quadrigemina

Two pairs of sensory nuclei located in the roof of the midbrain. (Inferior and superior colliculi)

Arbor Vitae

White matter of the cerebellum. Connects the cerebellar cortex and nuclei with tracts of white matter that form the cerebellar peduncles.