A/P 102: Chapter 14
Substantia Nigra
- A nuclear mass between the Tegmentum and Cerebral Peduncles, - Has interconnections with other Basal Ganglia Nuclei of the Cerebrum and is involved in coordinating movement and muscle tone. - Is a pigmented region of the midbrain with cytoplasmic melanin granules that give it a dark gray-to-black color.
Midbrain or Mesencephalon
- A short segment of brainstem that connects the hindbrain and forebrain. - Is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation
Cerebrum
- About 83% of the brain's volume and consists of a pair of half globes called the *Cerebral Hemispheres* - The embryonic Telencephalon becomes the _____, the largest and most conspicuous part of the human brain.
Taste and Smell
- Gustatory (taste) signals are received by the *primary gustatory cortex* in the inferior end of the postcentral gyrus of the parietal lobe. - Olfactory (smell) signals are recieved by the *primary olfactory cortex* in the medial surface of the temporal lobe and inferior surface of the frontal lobe.
Tegmentum (Cover)
- Main mass of the midbrain - Located between the cerebral peduncles and the cerebral aqueduct - Contains Red Nucleus- aid in the unconscious regulation and coordination of motor activities
Hypothalamus Control Center
- Major control center of the endocrine and autonomic nervous systems. - Plays an essential role in the homeostatic regulation of nearly all organs of the body.
Pons
- Right below the midbrain. - It is involved in the control of breathing, communication between different parts of the brain, and sensations such as hearing, taste, and balance
Functions of Reticular Formation Networks
- Somatic Motor Control - Cardiovascular Control - Pain Modulation - Sleep and consciousness - Habituation
How much CSF is produced by the brain a day?
- The brain produces about 500ml of CSF per day, but the fluid is constantly reabsorbed at the fame rate and only 100 to 160 mL is normally present at one time.
Motor Association (premotor) Area
- The intention to contract a skeletal muscle begins in the _____ of the frontal lobes - This is where we plan our behavior- where neurons compile a program for the degree and sequence of muscle contractions required for an action such as dancing, typing, or speaking.
Commissural Tracts
- _____ enable the two sides of the cerebrum to communicate with each other. - Cross from one cerebral hemisphere to the other through bridges called *commissures*.
Where in the brain is CSF formed?
40% - Subarachnoid space external to the brain 30% - by the general ependymal lining of the brain ventricles 30% - by the choroid Plexuses
Cerebral Crus
A bundle of nerve fibers that connect the cerebrum to the pons and carry the corticospinal nerve tracts. (#2 on Pic: Cross sections of Medulla Oblongata)
Cerebral Aqueduct
A canal called the _____ passes down the core of the midbrain and leads to the fourth ventricle.
Cerebrospinal Fluid
A clear, colorless liquid that fills the ventricles and canals of the CNS and bathes its external surface.
Nuclei
A cluster of cell bodies of neurons in the central nervous system
Cerebrum: *Temporal Lobe* Anatomy
A lateral, horizontal lobe deep to the temporal bone, separated from the parietal lobe above it by a deep *lateral sulcus*
Cerebral Cortex
A layer covering the surface of the hemispheres.
Reticular Formation
A loosew eb of gray matter that runs vertically through all levels of the brainstem
Inferior Olivary Nucleus
A major relay center for signals going from many levels of the brain and spinal cord to the cerebellum.
Third Ventricle
A narrow median space inferior to the corpus callosum.
Corpus Callosum
A prominent landmark for anatomical description with a distinctive 'C' shape in Sagittal section. This connects the two hemispheres at the bottom of the *longitudinal fissure*.
Cerebrum: *Insula* Anatomy
A small mass of cortex deep to the lateral sulcus, made visible only by retracting or cutting away some of the overlying cerebrum.
Fourth Ventricle
A small triangular chamber between the pons and cerebellum.
Longitudinal Fissure
A very deep median groove, the _____, separates the right and left hemispheres from each other.
Epithalamus
A very small mass of tissue composed mainly of the *pineal gland*, the *habenula*, and a thin roof over the third ventricle. - Pineal Gland and endocrine gland. - Habenula: Relay from the limbic system to the midbrain.
Cerebral Cortex: Neocortex
About 90% of the human cerebral cortex is a six-layered tissue called _____ because of its relatively recent evolutionary origin.
Rapid Eye Movement Sleep (REM)
About five times a night, a sleeper backtracks from stages 3 or 4 to stage 2 and exhibits bouts of _____.
Brainstem
All of the brain except the Cerebrum. Main parts from rostral to caudal, are the Diencephalon, midbrain, pons, and medulla oblongata.
Limbic System
An important center of emotion and learning. It is a ring of structures on the medial side of the cerebral hemisphere, encercling the corpus callosum and thalamus.
Cerebral Peduncles
Anterior to the cerebral aqueduct, the midbrain consists mainly of the _____, two stalks that anchor the cerebrum to the brainstem.
Aphasia
Any language deficit resulting from lesions in the hemisphere (usually the left) containing the *Wernicke* and *Broca Areas*.
Limbic System: Cingulate Gyrus
Arches over the top of the corpus callosum in the frontal and parietal lobes
Neural Crest
As the neural tube develops, some ectodermal cells that originally lay along the margin of the groove separate from the rest and form a longitudinal column on each side called the _____
Blood-CSF Barrier
At the choroid plexuses, the brain is protected by a similar _____ formed by tight junctions between the ependymal cells.
Cerebrum: *Occipital Lobe* Anatomy
At the rear of the head Caudal to the *parieto-occipital* sulcus and underlying the occipital bone.
Two potential points of entry that the Blood-brain Barrier guards
Blood Capillaries throughout the brain tissue and the capillaries of the choroid plexuses.
Anterograde Amnesia
Brain-injured people are either unable to store new information
Retrograde Amnesia
Brain-injured people are unable to recall things they knew before the injury.
One of three Purposes of Cerebrolspinal fluid
Buoyancy, Protection, Chemical Stability
Telencephalon & Diencephalon
By the 5th week the forebrain divides into two vesicles called ____ and _____
Metencephalon & myelencephalon
By the 5th week the hind brain divides into two vesicles called _____ and _____
Arachnoid Granulations
CSF is reabsorbed by _____, extentions of the arachnoid meninx shaped like little springs of cauliflower, protruding through the dura mater into the superior sagittal sinus.
Three major portions of the brain
Cerebrum, Cerebellum, and Brainstem.
Associations Areas
Cognition functions are widely distributed over regions of cerebral cortex called _____, which constitute about 75% of all brain tissue.
Cerebrum: *Temporal Lobe* Function
Concerned with hearing, smell, learning, memory, and some aspects of vision and emotion.
Association Tracts
Connect different regions within the same cerebral hemisphere.
Blood-Brain Barrier (or BBB)
Consists of tight junctions between the endothelial cells that form the capillary walls.
Sleep: Stages 4
Deepest sleep - EEG is dominated by low-frequency, high-amplitude delta waves
Granule Cells
Densely spaced _____ are the most abundant type of neuron in the entire brain.
Sleep: Stages 1
Drowsy - EEG is dominated by alpha waves
Folia
Each Hemisphere of the Cerebellum exhibits slender, transverse, parallel folds called _____ separated by shallow *Sulci* (shallow groove).
Deep Nuclei of the Cerebellum
Each hemisphere has four masses of gray matter called _____ embedded in the white matter
Thalamus
Each side of the brain has a _____, an ovoid mass perched at the superior end of the brainstem beneath the cerebral hemisphere.
Circumventricular Organs (CVOs) Function
Enables the brain to monitor and respond to fluctuations in blood glucose, pH, osmolarity, and other variables.
Projection Tracts
Extend vertically between higher and lower brain and spinal cord centers, and carry information between the cerebrum and the rest of the body.
Hypothalamus Origin
Forms the floor and part of the walls of the third ventricle.
Cortex
Forms the surface layer of *Gray Matter* called _____ over the cerebrum and cerebellum.
Cerebrum: *Parietal Lobe* Anatomy
Forms the uppermost part of the brain and underlies the parietal bone.
Corpora Quadrigemina of the tectum
Four bulges of the *Tectum*
Beta Waves
Frequency of 14 to 30 Hz. - Occurs in the frontal to parietal region - Seen during mental activity and sensory stimulation.
Theta Waves
Frequency of 4 to 7 Hz. - Normal in children and in drowsy or sleeping adults.
Alpha Waves
Frequency of 8 to 13 Hz. - Occur in the Pareto-occipital area. - Seen when the person is awake and resting, with the eyes closed and the mind wandering.
Delta Waves
Frequency of less than 3.5 Hz - High-amplitude "slow waves" that infants exhibit when awake, and adults when in deep sleep.
Superior Colliculi
Functions in visual attention, visually tracking moving objects, and such reflexes as blinking, focusing, pupillary dilation and constriction, and turning the eyes and head in responses to visual stimulus.
Medulla oblongata
Helps regulate breathing, heart and blood vessel function, digestion, sneezing, and swallowing. This part of the brain is a center for respiration and circulation.
Sensory Cranial Nerve Classification
I, II, and VIII
Motor Cranial Nerve Classification
III, IV, VI, XI, and XII
Limbic System: Amygdala
Immediately rostral to the Hippocampus, also in the temporal lobe.
Arbor Vitae
In a sagittal section, the white matter exhibits a branching, fern like pattern called the _____
Lower Motor Neurons
In the brainstem or spinal cord, the fibers from the upper motor neurons synapse with _____ whose axons innervate the skeletal muscles.
Limbic System: Hippocampus
In the medial temporal lobe
Tracts
In the spinal cord white matter is composed of _____, or bundles of axons, which here connect one part of the brain to another and to the spinal cord.
Circumventricular Organs (CVOs)
In the third and fourth ventricles where the barrier is absent and the blood has direct access to brain neurons
Prefrontal Cortex (frontal association area)
Integrates information from sensory and motor regions of the cortex and from other association areas. - Gives us a sense of our relationship to the rest of the world. - Enabling us to think about it and to plan and execute appropriate behavior. - Giving appropriate expression to our emotions.
Association Areas of the Cerebral Cortex
Interpret sensory information.
Cerebrum: *Frontal Lobe* Function
It is chiefly concerned with voluntary motor functions, motivation, foresight, planning, memory, mood, emotion, social judgment, and aggression.
Brain Waves
It is common to monitor electrical activity called _____. Recorded with electrodes on the scalp, these are rhythmic voltage changes resulting predominantly from synchronized postsynaptic potentials in the superficial layers of the cerebral cortex.
Olive of the Medullary Pyramids
Lateral to each pyramid is the prominent bulge called the _____
Cerebrum: *Frontal Lobe* Anatomy
Lies immediately behind the frontal bone, superior to the eyes. From the forehead, itextends caudally to the wavy vertical groove, the *Central Sulcus*.
Sleep: Stages 2
Light sleep - EEG declines in frequency
Special Senses
Limited to the head, and some employ relatively complex sense organs. -Vision, hearing, equilibrium, taste, and smell.
Hearing & Auditory Association
Medial and Inferior Temporal Lobe - Remembers the names of a piece of music or identify a person by his voice
Sleep: Stages 3
Moderate to deep sleep - EEG begins to show theta and delta waves
Purkinje Cells
Most distinctive neurons in the *Cerebellum* are the unusually large, globose _____. They have a tremendous profusion of dendrites compressed into a single plane like a flat tree.
Cranial Nerve
Most of the brains input and output travels by way of the spinal cord, but it also communicates by way of 12 pairs of _____
Cerebral Lateralization
Neither hemisphere's of the *Cerebral Cortex* is "dominant", but each is specialized for certain tasks. This difference in function is called _____.
Vision & Visual Association Area
Occipital Lobe - Identify the things we see - faces are recognized in the temporal lobe
Cerebellum
Occupies the posterior cranial fossa inferior to the cerebrum, separated from it by the *transverse cerebral fissure*
Choroid Plexus
On the floor or wall of each ventricle is a spongy mass of blood capillaries called a _____, named for its histological resemblance to a fetal membrane called the chorion.
Memory
One of the cognitive functions,
Suprachiasmatic Nucleus (SCN)
One of the control centers of sleep is _____, acts as biological clock to set our circadian rhythm of sleep and waking
Superior Sagittal Sinus
One of two major *dural sinuses* found just under the cranium along the median line.
Transverses Sinus
One of two major *dural sinuses* which runs horizontally from the rear of the head toward each ear.
Cerebral Cortex: Pyramidal Cells
One of two principal types of neurons of the Cerebral Cortex. - _____ are tall and conical. - Pyramidal cells include the output neurons of the cerebrum-the only cerebral neurons whose fibers leave the cortex and connect with other parts of the CNS. -Pyramidal cell axons have collateral's that synapse with other neurons in the cortex or in deeper regions of the brain.
Cerebral Cortex: Stellate Cells
One of two principal types of neurons of the Cerebral Cortex. - _____ have spheroid somas with dendrites projecting for short distances in all directions. - They are concerned largely with receiving sensory input and processing information on the local level.
Cerebrum: *Insula* Function
Plays roles in understanding spoken language, in taste, and in integrating information from visceral receptors.
Gracile & Cuneate Fasciculi of the Medulla Oblongata
Posteriorly, the _____ & _____ of the spinal cord continue as two pairs of ridges on the medulla.
Neural Tube
Present by the 26th day of Embryonic development.
Motor Homunculus
Proportional to number of muscle motor units in a region (fine control)
Inferior Calliculi
Receives signals from the inner ear and relays them to other parts of the brain, especially the thalamus.
Wernicke (WUR-ni-keh) area
Responsible for the recognition of spoken and written language
Equilibrium
Signals from the inner ear for _____ project mainly to the cerebellum and several brainstem nuclei
General Senses
Somatosensory, Somesthetic, and Somatic
Dural Sinuses
Spaces that collect blood that has circulated through the brain.
Brain Barrier System
Strictly regulates what can get from the bloodstream into the tissue fluid of the brain.
Sleep
Temporary state of unconsciousness from which one can awaken when stimulated.
Central canal
The *fourth ventricle* narrows and forms a _____ that extends through the medulla oblongata into the spinal cord
Circadian Rhythms
The 24-hour biological cycles found in humans and many other species.
Gyri & Sulci
The Cerebral Hemispheres of the Cerebrum is marked by thick folds called _____ separated by shallow grooves called _____.
Categorical Hemisphere
The Left hemisphere of the Cerebral Cortex - Specialized for spoken and written language and for the sequential and analytical reasoning such as science and mathematics.
Representational Hemisphere
The Right hemisphere of the Cerebral Cortex - It perceives information in more integrated, holistic way. It is the seat of imagination and insight, musical and artistic skill, perception of patterns and spatial relationships and comparison of sight, sound, smell, and tastes.
Medullary Pyramids
The _____ are paired white matter structures of the brainstem's medulla oblongata that contain motor fibers of the corticospinal and corticobulbar tracts - known together as the pyramidal tracts. The lower limit of the pyramids is marked when the fibers cross (decussate).
The Forebrain
The _____ consists of the *diencephalon* and *telencephalon*. The diencephalon encloses the third ventricle and is the most rostral part of the brianstem. The telencephalon develops chiefly into the cerebrum.
Ventricles
The brain has four internal chambers called _____
Cerebellar *Peduncles*
The cerebellum is connected to the brainstem by three pairs of stalks called _____ a pair of inferior _____ connected to the medulla oblongata, a pair of middle _____ to the pons, anda pair of superior _____ to the midbrain.
Central (periaqueductal) Gray Matter
The cerebral aqueduct is encircled by the _____. This is involved with the reticulospinal tracts in controlling awareness of pain.
Mammillary Bodies Origin
The hypothalamus extends anteriorly to the optic chiasm, where the optic nerves meet, and posteriorly to the pair of humps called the _____.
Lateral Ventricles
The largest and most rostral ones are the two _____, which form an arc in each cerebral hemisphere.
Cerebellum
The largest part of the Hindbrain and second-largest part of the brain as a whole.
Cerebellar Hemispheres & Vermis
The left and right side of the Cerebellum is connected together by the *Vermis*
Hippocampus
The limbic system is an important memory-forming center. - It does not sore memories, but organizes sensory and cognitive experiences into a unified long-term memory. - The _____ learns from sensory input while an experience is happening, but it has a short memory.
Fourth Week of Embryonic Development
The neural tube exhibits three anterior dilation, or primary vesicles, called : Forebrain - Prosencephalon Midbrain - mesencephalon Hindbrain - rhombencephalon
Tectum (roof, cover)
The part of the midbrain posterior to the cerebral aqueduct is a roof-like _____.
Precentral gyrus (primary motor area)
The planned behavior of the *Motor Association (premotor) Area* program is then transmitted to neurons of the _____, which is the most posterior gyrus of the frontal lobe, immediately anterior to the central sulcus
Cerebrum: *Parietal Lobe* Function
The primary site for receiving and interpreting signals of the general senses for taste and some visual processing.
Cerebrum: *Occipital Lobe* Function
The principal visual center of the brain.
Memory Consolidation
The process of "teaching the cerebral cortex" until a long-term memory is established is called _____.
Upper Motor Neurons
The pyramidal cells of the precentral gyrus are called _____. - Forms the corticospinal tract.
Cognition
The range of mental processes by which we acquire and use knowledge-sensory perception, thought, reasoning, judgment, memory, imagination, and intuition.
Primary Sensory Cortex
The sites where sensory input is first received and one becomes conscious of a stimulus.
Corpus Striatum
The three Basal Nuclei: Caudate Nucleus, Putamen, and Globus Pallidus.
Mammillary Bodies Function
Their primary function is to relay signals from the limbic system to the thalamus.
Embryonic Diencephalon
Three structures arise from the embryonic _____: The Thalamus, Hypothalamus, and Epithalamus.
Interventricular Foramen
Through a tiny pore called the _____, each lateral ventricle is connected to the *third ventricle*.
Rostal
Towards the Forehead
Caudal
Towards the Spinal Cord.
Mixed Cranial Nerve Classification
V, VII, IX, and X
Parieta-occipital sulcus
Visible on the medial surface of each hemesphere.
Broca Area
When we entend to speak, the Wernicke area formulates phrases according to learned rules of grammar and transmits a plan of speech to the _____, located in the inferior prefrontal cortex of the same hemisphere.
Hypothalamus Nuclei
Wide variety of visceral functions: - Hormone Secretion - Autonomic Effects - Thermoregulation - Food and water intake - Sleep and circadian Rhythms - Memory - Emotional behavior and Sexual Response