M4 Cerebrum and Diencephalon Flashcards
is the largest part of the brain
cerebrum
Can be divided into two parts:
- Diencephalon (Central Core)
- Telencephalon (Cerebral Hemispheres)
Cerebrum
Superior surface is concealed by the fornix and is formed by the roof of the third ventricle. This layer consists of an ependymal layer.
Diencephalon
- Lateral surface is bounded by the internal capsule of white matter.
- It consists of nerve fiber that connect the cerebral cortex with the other parts of the brain stem and spinal cord
Diencephalon
- Medial surface is formed in its superior part by the medial surface of the thalamus and its inferior part by the hypothalamus.
- They are separated by hypothalamic sulcus
Diencephalon
4 parts of Diencephalon
- Thalamus
- Subthalamus
- Epithalamus
- Hypothalamus
- The largest part of the diencephalon
- A.K.A “Sensory relay”
- influences mood and registers an unlocalized, uncomfortable perception of pain.
- Ovoid in shape
Thalamus
5 thalamic nuclei
- Anterior Nuclei Group
- Nuclei of the midline
- Medial Nuclei
- Lateral Nuclear Mass
- Posterior Nuclei
- Forms the anterior tubercle of the thalamus
- Bordered by the limbs of the internal lamina
- Receives fibers from mamillary bodies
Anterior Nuclei Group
- Found just beneath the lining of the Third Ventricle and in interthalamic adhesions
- They connect hypothalamus and central periaqueductal gray matter
- The centromedian nucleus connects with the cerebellum and corpus striatum
Nuclei of the Midline
These include most of the gray substance medial to internal medullary lamina; the intralaminar nuclei as well as the dorsomedial nucleus, which projects to the frontal cortex.
Medial Nuclei
- Ventral Anterior Nucleus: connects corpus striatum
- Ventral Lateral Nucleus: projects cerebral motor complex
- Dorsolateral Nucleus: projects to parietal cortex
- Ventroposterolateral Nucleus: relays sensory input from the body
- Ventroposteromedial Nucleus: relays sensory input from face
Lateral Nucleus Mass
- Pulvinar Nucleus: it connects to parietal and temporal cortices
- Medial Geniculate Nucleus: receives acoustic fibers from the lateral lemniscus and inferior colliculus.
- Lateral Geniculate Nucleus: major nucleus for vision.
Posterior Nucleus
- Sensory Nuclei
- Motor Nuclei
- Limbic Nuclei
- Multimodal Nuclei
- Nonspecific Nuclei
5 Functional Nuclear Groups
Includes:
- Ventral posterior group (VPL and VPM)
- Lateral and medial geniculate bodies
- Modifies signals from body, face, retina, cochlea and taste receptors (except OLFACTION)
Sensory Nuclei
Includes:
- Ventral anterior and lateral
- convey motor information from the cerebellum and globus pallidus to the precentral motor cortex.
- Sensory nuclei is also called motor relay nuclei
Motor Nuclei
- Interposed between the mammillary nuclei of the hypothalamus and the cingulate gyrus of the cerebral cortex
- The dorsomedial nucleus receives input from the olfactory cortex and amygdala regions
Limbic Nuclei
Includes:
- pulvinar, posterolateral, and dorsolateral
- have connections with the association areas in the parietal lobe (Sensory)
Multimodal Nuclei
Includes:
- Intralaminar, reticular nuclei and centrum medianum
- No known details
- Some say it relates to cortical motor areas, the caudate nucleus, the putamen, and the cerebellum
Non-specific Nuclei
- Is the most inferior part of the diencephalon
- Plays a central role in the control of body temperature, hunger, and thirst.
- Holds the pituitary gland via the infundibulum
Hypothalamus
- Optic chiasm
- Tuber cinereum
- Mammillary bodies
- Infundibulum
- Medial Hypothalamic area
- Lateral hypothalamic area
Hypothalamus
- Eating
- Autonomic Function
- Body Temperature
- Water Balance
- Anterior Pituitary Function
- Circadian Rhythm
- Expression of Emotion
7 parts of Hypothalamus
- Lateral hypothalamus: evoked eating behavior
- Ventromedial Nucleus: stops hunger and inhibits the feeding center when a high blood glucose level is reached after food intake.
- Damage to feeding center of Ventromedial nucleus may lead to anorexia (loss of appetite)
Eating
evoked eating behavior
Lateral hypothalamus
stops hunger and inhibits the feeding center when a high blood
glucose level is reached after food intake
Ventromedial Nucleus
- Posterolateral and Dorsomedial areas: function as a sympathetic activating region
- Anterior area: parasympathetic activating region.
Autonomic Nervous System
- Related to autonomic response
- A fall in body temperature, for example, causes vasoconstriction.
- A rise in body temperature results in sweating and cutaneous vasodilation.
- hypothalamic set point: <37C
Body Temperature
Osmoreceptors in hypothalamus influence vasopressin secretion within the posterior pituitary
- Stimulated by blood osmolarity
- Thirst Center: located near the supraoptic nucleus.
Water Balance
in hypothalamus influence vasopressin secretion within the posterior pituitary
Osmoreceptors
Failure of Osmoreceptors or damage to posterior pituitary (vasopressin) leads to Diabetes Insipidus where there is polyuria and polydipsia
Water Balance
The functions of the body such as temperature, corticosteroid levels, oxygen consumption are influenced by light intensity changes that have a circadian (day-to-day) rhythm
Circadian Rythm
It is involved in the expression of rage, fear, aversion, sexual behavior, and pleasure.
Expression of emotion
Landmarks:
- Subthalamic Nucleus
- Body of Luys
Subthalamus
- Is a small area superior and posterior to the thalamus
- Houses the pineal gland
Epithalamus
- Influences the onset of puberty
- play a role in controlling some long-term cycles that are influenced by the light-dark cycle via Melatonin.
- Melatonin:rises in darkness and falls during the day.
- Plays an important role in the regulation of reproductive function
Pineal Gland
rises in darkness and falls during the day
Melatonin
- is the largest part of the brain
Cerebrum
2 parts of the Cerebrum
Diencephalon and Telencephalon
the crests of the cortical folds
gyrus
furrows of the brain
sulcus
just like sulci but only deeper
fissures
why is the presence of gyri and sulci in a pattern that is relatively constant from brain to brain?
Easy to identify cortical areas that fulfills specific functions
- aka sylvian fissure
- separates the frontal and parietal lobe
Lateral Cerebral fissure
- aka circuminsular fissure
- separates the insula and separates it from the adjacent frontal, parietal, and temporal lobes
Circular Sulcus
separates the left and right hemispheres
Longitudinal Cerebral Fissure
- fissure of rolando
- separates the frontal lobe from the parietal lobe
Central Sulcus
Separates the parietal lobe from the occipital lobe.
Parieto-occipital fissure
Begins on the medial surface of the hemisphere near the occipital pole and extends forward to an area slightly below the splenium of the corpus callosum
Calcarine fissure
Is a large bundle of myelinated and unmyelinated fibers
Corpus Callosum
Serves to integrate the activity of the two
hemispheres and permits them to communicate with each other
Corpus Callosum
Found below the cingulate gyrus
Corpus Callosum
is the largest of the interhemispheric
commissures and is largely responsible for coordinating the activities of the two
cerebral hemispheres.
Corpus Callosum
Anterior part of Corpus C.
Genu
Posterior part of Corpus C.
Splenium
Involved in:
- Motor ,Initiative judgment, abstract
reasoning, creativity, and socially appropriate behavior (inhibition of
socially inappropriate behavior)
Frontal lobe
are phylogenetically newest and
the most uniquely “human”.
Initiative judgment, abstract
reasoning, creativity, and socially appropriate behavior
Lies anterior to the precentral gyrus
Precentral sulcus
Anterior of central sulcus
precentral gyrus
is the crescent-shaped, or arched, convolution on the medial surface between the cingulate sulcus and the
corpus callosum
Cingulate Gyrus
extend forward and downward from the
precentral sulcus, dividing the lateral surface of the frontal lobe into three
parallel gyri
Superior, Middle, and Inferior frontal gyri
includes higher order association cortex involved in judgment, reasoning, initiative, higher order social behavior, and similar functions.
Pre frontal cortex
is located anterior to the primary motor cortex within the precentral gyrus and
the adjacent premotor cortex.
prefrontal cortex
- extends from the central sulcus to the parieto-occipital fissure
- laterally, it extends to the level of the lateral cerebral fissure
Parietal lobe
Posterior to postcentral gyrus
poscentral sulcus
lies behind the central sulcus.
postcentral gyrus
is the portion of the inferior parietal lobule that arches above the ascending end of the posterior ramus of the
lateral cerebral fissure.
supramarginal gyrus
arches above the end of the superior temporal sulcus and becomes
continuous with the middle temporal gyrus.
Angular gyrus
Is the posterior portion of the medial surface between the parieto-occipital fissure and the ascending end of
the cingulate sulcus.
precuneus
- Which most notably houses the primary visual cortex
- Situated behind the parieto-occipital fissure
occipital lobe
Divides the medial surface of the occipital lobe into the cuneus and the lingual
gyrus.
calcarine fissure
- it contains a light band of myelinated fibers in layer IV
- is the site of termination of visual afferents from the lateral geniculate body
Striate Cortex
this region of cortex thus functions as the primary visual cortex.
cuneus
- AKA lateral occipitotemporal
- is between the calcarine fissure and the posterior part of the collateral fissure.
ligual gyrus
- AKA medial occipitotemporal
- is on the basal surface of the occipital lobe.
fusiform gyrus
Lies below the lateral cerebral fissure and extends back to the level of the
parieto-occipital fissure on the medial surface of the hemisphere
temporal lobe
The lateral surface of the temporal lobe is divided into the parallel what?
superior, middle, and inferior temporal gyri
Superior and Middle gyri are
separated by?
superior temporal sulcus
Middle and inferior temporal
gyri are separated by?
middle temporal sulcus
lies between the hippocampal fissure and the anterior part of the collateral fissure
parahippocampal gyrus
- the most medial portion of the temporal lobe
- Curves in the form of a hook
Uncus
- is a sunken portion of the cerebral cortex
- can be exposed by separating the upper and lower lips (opercula) of the lateral
fissure.
Insula
- include the cingulate, parahippocampal, and subcallosal gyri as well as the hippocampal formation
- can be exposed by separating the upper and lower lips (opercula) of the lateral
fissure.
Limbis System
- Several poorly defined cell islands
- located beneath the basal ganglia deep in the hemisphere
Basal Forebrain Nuclei and Septal Area
- These cell islands include the basal forebrain nuclei (also known as the nuclei of Meynert or substantia innominata), which send widespread cholinergic
projections throughout the cerebral cortex.
Basal Forebrain Nuclei and Septal Area
Located just laterally
septal nuclei
Which receive afferent fibers from the hippocampal formation and reticular system and send axons to the hippocampus, hypothalamus, and midbrain.
septal nuclei
The adult cerebral hemisphere contains myelinated nerve fibers of many sizes as well as neuroglia
White Matter
The white center of the cerebral
hemisphere that contains myelinated transverse fibers, projection fibers, and
association fibers.
Centrum semiovale
essentially connect corresponding regions of the two hemispheres.
Commissure fibers
They are as follows: the corpus callosum, the anterior commissure, the posterior
commissure, the fornix, and the habenular commissure
Transverse Fibers
Are nerve fibers that essentially connect various cortical regions within the same hemisphere and may be divided into short and long groups
Association fibers
Afferent and efferent nerve fibers passing to and from the brainstem to the entire cerebral cortex must travel between large nuclear masses of gray
matter within the cerebral hemisphere.
Projection Fibers
Once the nerve fibers have emerged superiorly from between the nuclear masses, they radiate in all directions
to the cerebral cortex.
Corona Radiata
which is flanked medially by the caudate nucleus and the thalamus and laterally
by the lentiform nucleus
Internal Capsule
is bent to form an anterior limb and a
posterior limb, which are continuous with each other at the genu
internal capsule
shaped like a tepee, with an apical dendrite reaching from the upper end toward the cortical surface, and basilar dendrites extending horizontally from the cell body
pyramidal cells
Star shaped, with dendrites extending in all directions
stellate neurons
found in deeper layers, with a large dendrite that ascends toward the surface
of the cortex
fusiform neurons
layer I of the Cerebral cortex
Molecular layer
layer II of the Cerebral cortex
External Granular Layer
layer III of the Cerebral cortex
External pyramidal layer
layer IV of the cerebral cortex
Internal granular layer : stellate cells
layer V of the cerebral cortex
internal pyramidal layer: dominant pyramid, stellate and other interneurons
layer VI of the cerebral cortex
multiform layer: fusiform cells
uses numbers to label individual
areas of the cortex
Brodmann’s area
These anatomically defined areas have been used as a reference base for the
localization of physiologic and pathologic processes.
brodmann’s area
Primary Motor Area
Area 4
- The premotor area
- Medial Aspect of the Hemisphere
- Use for motor planning
Area 6
- The Frontal Eye Field
- Medial Aspect of the Hemisphere
- Eye movements
Area 8
- Prefrontal Cortex
- serves a set of “ executive” functions, planning and initiating adaptive actions
and inhibiting maladaptive ones; prioritizing and sequencing actions.
Area 9
Weaving elementary motor and sensory functions into a coherent, goal-directed
stream of behavior.
Area 9
- motor planning, judgement, reasoning, initiative, higher order social behavior, working memory, and similar functions
- Ant. to the primary motor cortex within the precentral gyrus and the adjacent
premotor cortex
Frontal lobe
- Broca’s Area
- Are located anterior to the motor cortex
- Controlling the lips and tongue. Broca’s area is an important area for speech.
Area 44 and 45
Damage to this area 44 and 45 would
cause speech that is slow and hesitant with limited vocabulary and impaired
syntax is indicative of ?
non fluent aphasia
- Primary Sensory Area
- Found in the postcentral gyrus
- Receives input from Ventral Posterolateral and Ventral Posteromedial Nuclei
Area 3,1,2
Receive contralateral stimuli such as proprioception and touch.
Parietal lobe
Perception of the processing of language
Area 40
Primary Auditory Cortex
Area 41
Associative (Secondary) cortex
Area 42
- Together, area 41 and 42 are called?
- Involved in language and music
Heschl’s gyrus
- Wernicke’s area
- which plays an important role in the comprehension of language
Area 22
Damage to unilateral lesion and bilateral lesion results to?
mild hearing loss and wernicke’s aphasia
The Primary Visual
Area 17
- Visual Association Areas
- Each of these maps represents the entire visual world, but extracts
information about a particular aspect of it
Area 18 and 19
The visual cortex in the right
occipital lobe receives
impulses from the right half
of each retina while the
opposite for the left occipital
lobe
occipital lobe
Refers to masses of gray matter
deep within the cerebral
hemispheres
basal ganglia
Play an essential functional role in
motor control
basal ganglia
include the caudate nucleus, the
putamen, and the globus
pallidus.
basal ganglia
includes:
- Caudate nucleus
- Putamen
- Globus pallidus
Corpus striatum
includes:
- Caudate nucleus
- Putamen
striatum
Functionally, the basal ganglia
and their interconnections and
neurotransmitters form the ……. which includes midbrain nuclei such as the substantia nigra, and the subthalamic nuclei
extrapyramidal system
An elongated gray mass whose
pear shaped head is continuous
with the putamen
caudate nucleus
Is situated between the insula and
the internal capsule.
lenticular nucleus
The external medullary lamina
divides the nucleus into two parts:
putamen, globus pallidus
is the larger, convex
gray mass lying lateral to and just
beneath the insular cortex.
putamen
is the smaller, triangular median zone
whose numerous myelinated fibers
make it appear lighter in color.
globus pallidus
it sends many fibers to the putamen,
which in turn sends short
fibers to the globus
pallidus.
caudate nucleus
The putamen and globus
pallidus receive some fibers
from the ?
sunstanstia nigra
sends fibers to the caudate nucleus
thalamus
Is a small but crucial band of
myelinated fibers that separates
the lentiform nucleus from the
medial caudate nucleus and
thalamus.
internal capsule
Contains critically important
pathways such as the corticobulbar
and corticospinal tracts. Thus, small
lesions within the internal capsule
(which can occur, eg, as a result of
small strokes called lacunar strokes)
can produce devastating clinical
deficits.
internal capsule
