CNS

Cerebrum, Diencephalon, Brainstem, Cerebellum

What are the 4 main regions of the brain

Ridges on outer surface of brain

What are gyri

Depressions between ridges of outer brain

What are sulci

Deep sulci

What are fissures

Rostral: caudal

Anterior portion of brain; posterior portion

Grey and white

Brain and spinal cord are composed of what 2 types of tissue

Grey matter

Made of neuron cells bodies, dendrites, and unmyelinated axons

Cerebral cortex

Grey matter surface of cerebrum

Cerebral nuclei

Regions of grey matter (clusters of cell bodies) found deep in the cerebrum

White matter

Consists of myelinated axons

Cranial meninges

3 connective tissue layers Pia matter, Arachnoid matter, Dura matter), separate and support soft tissue in brain, enclose and protect blood vessels supplying the brain, help contain and circulate cerebrospinal fluid

Pia matter

Innermost (deepest) of the meninges, adheres to brain surface; thin layer of areolar CT

Arachnoid matter

Made of a web of collagen and elastic fibers; Lies deep to dura matter, superficial to Pia matter; subdural space is a potential space that can fill with blood if a vein is ruptured

Dura matter

Tough, outer membrane (most superficial); made of dense irregular CT in 2 layers (meningeal layer and periosteal layer) which form the periosteum on on internal surface of cranial bones

Dural venous sinuses

Layers are usually fused, but in some areas, they separate and for this; drains blood from the brain

Epidural space

A potential space between dura and skull that contains arteries and veins

Epidural hematoma

Pool of blood in epidural space of brain usually due to severe blow to the head; adjacent brain tissue distorted and compressed; can lead to severe neurological injury or death unless bleeding stopped and blood removed

Subdural hematoma

Hemorrhage ism subdural space typically from ruptured veins from fast rotational head movement; compression of brain tissue, occurs more slowly than epidural hematoma

Meningitis

Inflammation of the meninges typically caused by contagious viral or bacterial infections; may result in brain damage and death if untreated; symptoms include fever, headache, vomiting, stiff neck

Ventricles

Cavities within the brain, lined with ependymal cells, contains cerebrospinal fluid, connect with each other and with spinal cords central canal

cerebrospinal fluid (CSF)

Clear, colorless liquid surrounding CNS; circulates in ventricles and subarachnoid space; provides buoyancy, reduced brains apparent weight by 95%; protects CNS by providing liquid cushion; keeps CNS environment stable (helps transport nutrients and wastes, protects against chemical fluctuations)

functions of blood-brain barrier (BBB)

Regulates which substances enter brans interstitial fluid; helps prevent neuron exposure to harmful substances (drugs, wastes, abnormal solute concentrations)

Specialized capillaries in BBB

Endothelial cells are connected by many tight junctions; walls have a thick basement membrane; wrapped in perivascular feet (astrocyte extensions)

Choroid plexus needs to produce CSF; hypothalamus and pineal gland need to secrete hormones

Why is BBB reduced in certain locations for functional reasons

Cerebrum

Origin of all complex intellectual functions; two large hemispheres on superior aspect of brain; center of intelligence and reasoning, thought, memory, and judgement, and voluntary motor, visual, and auditory activities

Longitudinal fissure

Deep cleft separating left and right hemisphere of cerebrum

Corpus callosum

Latest tract providing connection between the hemispheres of cerebrum

The right side ; connections with he body are generally crossed

Left hemisphere receives signals from which side of the body and sends motor signals to which side of the body

Lateralization

Higher order functions exhibit what (primarily controlled by one side of the brain) ; speech is frequently located on the left hemisphere

Frontal, Parietal, Temporal, Occipital, Insula

First 4 are named for overlying cranial bones

Insula is not visible at surface

What are the 5 lobes in each hemisphere

Frontal lobe

Anterior part of cerebrum; posterior border is central sulcus; functions like motor control, concentration, verbal communication, decision making, planning, personality

Lateral sulcus

Separates inferior frontal lobe from temporal lobe

Parietal lobe (Superposterior part of cerebrum)

Anterior border is central sulcus; posterior border is perieto-occipital sulcus; lateral border us lateral sulcus; serves general functions like evaluating shape and texture of objects

Temporal lobe

Located inferior to lateral sulcus; internal to temporal bone; functions include hearing and smell

Occipital lobe

Posterior pat of cerebrum; functions in vision and visual memories

Insula

Deep to lateral sulcus; small lobe that can be observed by pulling away temporal lobe; functions in memory and sense of taste

Within frontal lobes

Where are motor areas housed

Primary cortex

Located in precentral gyrus; also called somatic motor area; controls skeletal muscle activity on opposite side of body; the controlled body regions map as a motor homunculus

Motor homunculus

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

Motor speech area (Broca area)

Located in inferolateral portion of left frontal lobe (in most people); controls movements for vocalization

Frontal eye field

On superior surface of middle frontal gyrus; regulates eye movements needed for reading and binocular vision

Premotor cortex (somatic motor association area)

Located anterior to primary motor cortex; coordinates learned, skilled activities

Primary somatosensory cortex

Located in post central gyrus of parietal lobes; receives somatic sensory info from proprioceptors, touch, pressure, pain, temperature receptors; areas of the body sending input can be mapped as a sensory homunculus

Somatosensory association area

Immediately posterior to post central gyrus in parietal lobes; integrates touch info allowing us to identify objects by feel

Primary visual cortex

Located within occipital lobe

Visual association area

Surrounds primary visual cortex; integrates color, form, memory to allow us to identify things we see

Primary auditory cortex

Located within temporal lobe

Auditory association area

Located in temporal lobe; interprets sounds, stores and retrieves memories of sounds

Primary olfactory cortex

Located within temporal lobe; provides conscious awareness of smells

Primary gustatory cortex

Located within Insula; involved in processing taste info

Frontal brain regions (prefrontal cortex, wernicke area, gnostic area)

Integrate info from multiple association areas

Prefrontal cortex

Located rostral to premotor cortex in frontal lobe; complex thought, judgement, personality, planning, deciding; still developing in adolescence

Wernicke area

Typically located in left hemisphere; involved in language comprehension

Gnostic area (common integrative area)

Integrates info from variety for sensory association areas; sights, smells, sounds converge and brain becomes aware of situation

Petalias

Protrusion of a lobe on one side compared to the other side

Hemisphere specialization or cerebral lateralization (categorical hemisphere and representational hemisphere)

Two sides of cerebrum exhibit differences in higher order functions; the two hemispheres communicate though the corpus callosum and other comissures

Categorical hemisphere

Usually the left hemisphere; specialized for language abilities, functions in categorization and an analysis; contains wernicke area and motor speech area

Representational hemisphere

Usually the right hemisphere; concerned with visuospatial relationships, imagination, comparison of senses

cerebral lateralization

Develops in early childhood (seen prior to 5-6 yrs of age); correlated with handedness ( in right handers, left hemisphere is almost always categorical, speech dominant; left handers may have either hemisphere be categorical)

Diencephalon

Includes the epithalamus, thalamus, and hypothalamus; provides relays and switching centers for sensory, motor, visceral pathways

Pineal gland

Located in epithalamus; Endocrine gland secreting melatonin; helps regulate day-night cycles, circadian rhythm

habenular nuclei

Located in epithalamus; help relay signals from limbic system to midbrain; involved in visceral and emotional responses to odors

Thalamus

Receives signals from all conscious senses expect olfaction; relays some signals to appropriate part of cortex and filters out other signals distracting from subject of attention

Infundibulum

Stalk of pituitary that extends from hypothalamus

Functions of hypothalamus

Control of autonomic nervous system; control of endocrine system; regulation of body temperature; emotional behavior; food intake; water intake; sleep-wake rhythms

Brainstem

Connects cerebrum, Diencephalon, and cerebellum to spinal cord; contains ascending and descending tracts; contains autonomic nuclei, nuclei of cranial nerves, and reflex centers; consists of midbrain, pons, medulla oblongata

Components of midbrain

Cerebral peduncles, superior cerebellar peduncles, medial lemniscus, substantia nigra

Cerebral peduncles

Motor tracts (pyramidal system) on anterolateral surface of midbrain; carry voluntary motor commands from primary motor cortex

Superior cerebellar peduncles

Connects cerebellum to midbrain

Medial lemniscus

Bands of ascending, myelinated axons running through brainstem

Substantia nigra

Cluster of cells with black appearance due to melanin; houses neurons producing dopamine; its degeneration causes Parkinson disease

Pons

Bulging region on anterior brainstem; includes sensory and motor tracts connecting brain to spinal cord

Middle cerebellar peduncles; pontine respiratory center; superior olivary nuclei; cranial nerve nuclei

Parts of pons

Middle cerebellar peduncles

Transverse axons connecting pons to cerebellum

Pontine respiratory canter

Helps regulate skeletal muscles of breathing

Superior olivary nuclei

Help with sound localization

Cranial nerve nuclei (sensory and motor)

Nuclei for CN V to CN VIII; trigeminal, abucens, facial, and vestibulocochlear nerves

Medulla

Caudal portion of brainstem; continuous with spinal cord inferiorly; includes sensory and motor tracts connecting brain to spinal cord

Pyramids

Pair of ridges on anterior surface of medulla; house corticospinal tracts for motor control; most tract axons cross at the decussation of the pyramids, so each side of cortex controls movement on opposite body side

Olives

Bulges lateral to each pyramid of medulla; contains inferior olivary nucleus; relay proprioceptive info to cerebellum

Inferior cerebellar peduncles

Tracts connecting medulla to cerebellum

Autonomic nuclei of medulla

Cardiac center, vasometer center, medullary respiratory center; other nuclei for various functions like coughing, sneezing, vomiting, salivating, swallowing

Cardiac center

Regulates hearts output

Vasometer center

Regulates blood vessel diameter; strong influence on blood pressure (vessel constriction increases pressure)

Medullary respiratory center

Controls breathing rate; contains dorsal and ventral respiratory groups; communicates with pontine respiratory center

Cerebellum

2nd largest brain area (after cerebrum) ; cerebellar cortex; left and right cerebellar hemispheres; each hemisphere has an anterior and posterior lobe separated by primary fissure

Cerebellar cortex

Convoluted surface with folia (folds)

Cerebellum

Coordinates and fine tunes movements

Limbic system

The emotional brain; composed of multiple cerebral and diencephalic structures that process and experience emotions

Interconnected components of the limbic system

Cingulate gyrus, parahippocampal gyrus, hippocampus, amygdaloid body, olfactory bulbs, olfactory tracts, olfactory cortex, fornix, nuclei that interconnect other parts of limbic system

Cingulate gyrus

In sagittal plane, above corpus callosum

Parahippocampal gyrus

Associated with hippocampus; cortical tissue in temporal lobe

Hippocampus

Superior to parahippocampal gyrus (temporal lobe); helps form long-term memories

Amygdaloid body

Involved in many aspects of emotion and emotional memory, especially fear

Olfactory bulbs, olfactory tracts, olfactory cortex

Process odors that can provoke emotions

Fornix

Thin white rafts connecting hippocampus with other limbic structures

Nuclei that interconnect to other parts of limbic system

Anterior thalamic nuclei, habenular nuclei, septal nuclei, mammillary bodies

Reticular formation

Loosely organized grey matter of brainstem; motor component an sensory component

Motor component of reticular formation

Regulates muscle tone via spinal cord connections; assists in autonomic functions through brainstem connections

Sensory component

Reticular activating system (RAS); processes sensory information, sends signals to cortex to bring about alertness; alertness helps bring about awareness, which is necessary for highest states of consciousness