Neuroanatomy: cortical anatomy, thalamus, basal ganglia, hypothalamus, hippocampus

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Anterior nucleus of thalamus

Central sulcus

Corpus callosum

Dorsomedial nucleus

Fornix

Frontal pole

Longitudinal fissure (interhemispheric fissure)

Paraventricular nucleus

Cuneus

Dentate gyrus of the hippocampus

Globus pallidus

Olfactory bulb

Optic chiasm

Parietooccipital sulcus

Superior colliculus

Calcarine fissure

Olfactory tract

Pulvinar

Stria terminalis

Supraoptic nucleus

Thalamus

Transverse occipital sulcus

Anterior ramus (of the Sylvian fissure)* *The anterior ramus of the lateral sulcus, is located at the very anterior end of the lateral sulcus (sylvian fissure), just anterior to the ascending ramus, and passes superiorly into the inferior frontal gyrus separating the pars orbitalis form the pars triangularis of the frontal operculum.

Habenula

Mammillary body

Occipital pole

Subthalamic nucleus

Ventromedial nucleus

Amygdala

Ascending ramus (of the Sylvian fissure)

Mamillary body

Preoptic neucleus

Superior parietal lobule

Taenia choroidea

Corpus callosum 13) rostrum of CC 14) genu of CC 15) body of CC 16) splenium of CC

13-16

Amygdala

Dorsomedial nucleus

Inferior parietal lobule

Lamina affixa

Parahippocampal gyrus

Posterior ramus (of the Sylvian fissure) (this is essentially most of the Sylvian fissure)

Diagonal band of Broca

Fornix

Frontal operculum

Optic tract

Postcentral gyrus

Frontoparietal operculum

Olfactory tubercle

Paracentral lobule The central sulcus extends into the posterosuperior aspect of the paracentral lobule in most cases. Hence, the portion lying anterior to the sulcus is frontal lobe, while the portion lying posterior is parietal lobe

Septum pellucidum

Third ventricle and choroid plexus

Body of the fornix

Lamina terminalis

Lateral ventricle

Olfactory bulb

Precentral gyrus

Superior temporal gyrus

Anterior commisure

Inferior frontal gyrus

Lateral ventricle and choroid plexus

Middle temporal gyrus

Septal nucleus

Cortex of the insula

Middle frontal gyrus

Septum pellucidum

Subcallosal area

Superior temporal sulcus

Area dorsalis

Area lateralis (lateral hypothalamic area)

Caudate

Cingulate sulcus

Fornix

Mammillothalamic tract

Medial frontal gyrus

Precentral gyrus

Superior margin of cerebrum

Anterior commissure

Fornix

Inferior temporal sulcus

Superior frontal gyrus

Inferior temporal gyrus

Medial forebrain bundle

Tela choroidea of the third ventricle

Choroid plexus of the third ventricle

Preocciptial notch

Occipital pole

Transverse cerebral fissure

Thalamus

Transverse occipital sulcus

Inferior parietal lobules

Interthalamic adhesion

Interventricular foramen of Monro

Intraparietal sulcus

Hypothalamus

Superior parietal lobule

Postcentral sulcus

Suprapineal recess and pineal body

Postcentral gyrus

Vermis of cerebellum

Area lateralis

Area medialis

Cingulate gyrus

Cingulate sucus

Frontal pole

Hypothalamic sulcus

Precentral sulcus

Stria medullaris

Thalamostriate vein

Cerebellar hemisphere

Supramarginal gyrus The supramarginal gyrus is horseshoe-shaped and caps the posterior ascending ramus of the lateral sulcus

Angular gyrus It lies as a horseshoe shaped gyrus capping the angular sulcus, a continuation of the upswing of the superior temporal sulcus. It is bound by the intraparietal sulcus superiorly, parieto-occipital sulcus caudally and supramarginal gyrus rostrally.

Choroid plexus of the 4th ventricle

Medulla

Pons

4th ventricle

Pyramid (medulla)

Olive* *The olive consists of two parts: The superior olivary nucleus, considered part of the pons and part of the auditory system, aiding the perception of sound. The inferior olivary nucleus (or 'complex'), which is a part of the olivo-cerebellar system and is mainly involved in cerebellar motor-learning and function.

Pons

Flocculus

Tectum and mesencephalic aqueduct of Sylvius

Cerebellar hemisphere

Mamillary body

Oculomotor nerve

Infundibular recess

Temporal lobe / lateral occipitotemporal gyrus

Habenular nucleus

Interthalamic adhesion

Posterior nucleus

Sulcus of the corpus callosum

Superior frontal gyrus

Superior frontal sulcus

Third ventricle

Tuberal nuclei

Rhinal fissure

Pituitary (hypophysis) with adenohypophysis (anterior lobe) and neurohypophysis (posterior lobe)

Optic chiasm

Optic nerve

Olfactory bulb and tract

Cingulate gyrus

Corpus callosum

Indusium griseum

Inferior frontal sulcus

Mamillary body

Optic chiasm

Superior frontal sulcus

Third ventricle

Fasciolar gyrus

Lateral sulcus (Sylvian fissure)

Middle frontal gyrus

Paracentral lobule

Precentral sulcus

Supraoptic nucleus

Thalamus

Tuberal nuclei

Ventromedial nucleus

Central sulcus

Claustrum

Fornix

Inferior frontal sulcus

Optic tract

Paraventricular nucleus

Pineal

Posterior lobe of pituitary gland

Precuneus

Anterior lobe of pituitary gland

Caudate nucleus

Fibria (of the hippocampus)

Fornix

Frontal pole

Inferior colliculus

Postcentral sulcus

Subparietal sulcus

Hippocampal formation

Infundibular nucleus

Intraparietal sulcus (separates the superior and inferior parietal lobules)

Orbitofrontal gyrus

Parietooccipital sulcus

Putamen

Quadrigeminal plate

1) Parasympathetic - anterior and medial (ventromedial) hypothalamic nuclei 2) Sympathetic - posterior and lateral hypothalamic nuclei 3) Decreasing body temp - anterior hypothalamic nucleus 4) Increasing body temp - posterior hypothalamic nucleus 5) Satiety center - medial hypothalamic nucleus 6) Feeding center - lateral hypothalamic nucleus 7) Arousal center - posterior hypothalamic nucleus In general: -anterior/medial: parasympathetic, cooling, satiety -posterior/lateral: sympathetic, heating, feeding, arousal

Describe the 7 levers of the hypothalamus (i.e. 7 aspects of hypothalamic control) and where they are located within the hypothalamus

Medial lemniscus/spinothalamic tract/trigeminothalamic tract --> VPLc/VPM (face) --> S1

Describe the basic pathway to the primary somatosensory area (S1)

Striatum = caudate + putamen Corticostriate fibers 1) Primary motor (area 4) >>> bilateral putamen 2) Premotor cortex >>> ipsilateral caudate and putamen 3) Prefrontal cortex >>> caudate

Describe the cortical input to the striatum

Paraventricular nuclei, lateral hypothalamus, and posterior hypothalamus >>> dorsal motor nucleus of X, nucleus solitarious, nucleus ambiguous, medulla, and spinal intermediolateral cell column

Describe the descending autonomic projections from the hypothalamus

Layer III (3rd from the top) The external pyramidal layer of cortex contains commissural fibers that connect the two hemispheres as well as ipsilateral cortico-cortico association fibers

Describe the fibers/projections and role of the external pyramidal layer of cortex

Layer IV (4th from the top) This is the main area of sensory input >>> enlarged in sensory cortex

Describe the fibers/projections and role of the internal granular layer of cortex

Internal pyramidal layer = layer V Main source of efferents to the brain stem and spinal cord >>> enlarged in motor cortex

Describe the fibers/projections and role of the internal pyramidal layer of cortex

Molecular = layer I (most superficial) Receives diffuse afferent fibers from the lower brain to control the excitability of the region

Describe the fibers/projections and role of the molecular layer of cortex

Multiform layer = VI (farthest from surface) Sends efferent fibers to the thalamus

Describe the fibers/projections and role of the multiform layer of cortex

Primary visual cortex Banks of the calcarine fissure Vision

Describe the functional area, location, and function of Brodmann's area 17

Secondary visual cortex Medial and lateral occipital gyri Vision, depth

Describe the functional area, location, and function of Brodmann's area 18

Tertiary visual cortex and middle temporal visual area Medial and lateral occipital gyri Vision, color, motion

Describe the functional area, location, and function of Brodmann's area 19

Visual inferotemporal area Interior temportal gyrus Form vision

Describe the functional area, location, and function of Brodmann's area 20

Visual inferotemporal gyrus Middle temporal gyrus Form vision

Describe the functional area, location, and function of Brodmann's area 21

Higher order auditory cortex (?Wernicke's versus BA 40) Superior temporal gyrus Hearing, speech

Describe the functional area, location, and function of Brodmann's area 22

Primary olfactory cortex, limbic association cortex Parahippocampal gyrus Smell, emotions

Describe the functional area, location, and function of Brodmann's area 28

Limbic association cortex Cingulate gyrus and limbic association cortex Emotions

Describe the functional area, location, and function of Brodmann's area 29, 30, 31, 32, 33

Primary olfactory cortex, limbic association cortex Parahippocampal gyrus Smell, emotions

Describe the functional area, location, and function of Brodmann's area 34, 35, 36

Parietal-temporal-occipital association cortex, middle temporal visual area Middle and inferior temporal gyri at themporo-occipital junction Perceptions, vision, reading, speech

Describe the functional area, location, and function of Brodmann's area 37

Primary olfactory cortex, limbic association cortex Temporal pole Smell, emotions

Describe the functional area, location, and function of Brodmann's area 38

Parietal-temporal-occipital association cortex Inferior parietal lobule (angular gyrus) Perception, vision, reading, speech

Describe the functional area, location, and function of Brodmann's area 39

Primary motor cortex Precentral gyrus Voluntary motor control

Describe the functional area, location, and function of Brodmann's area 4

Parietal-temporal-occipital association cortex (?Wernicke's versus BA 22) Inferior parietal lobule (supramarginal gyrus) Perception, vision, reading, speech

Describe the functional area, location, and function of Brodmann's area 40

Primary auditory cortex Heschl's gyrus and superior temporal gyrus Hearing

Describe the functional area, location, and function of Brodmann's area 41

Secondary auditory cortex Heschl's gyrus and superior temporal gyrus Hearing

Describe the functional area, location, and function of Brodmann's area 42

Gustatory cortex Insular cortex, fronto parietal operculum Taste

Describe the functional area, location, and function of Brodmann's area 43

Broca's area, lateral premotor cortex Inferior frontal gyrus (frontal operculum) Speech, movement planning

Describe the functional area, location, and function of Brodmann's area 44

Prefrontal association cortex Inferior frontal gyrus (frontal operculum) Thought, cognition, planning behavior

Describe the functional area, location, and function of Brodmann's area 45

Prefrontal association cortex (dorsolateral prefrontal cortex) Middle frontal gyrus Thought, cognition, planning behavior, eye movement

Describe the functional area, location, and function of Brodmann's area 46

Prefrontal association cortex Inferior frontal gyrus (frontal operculum) Thought, cognition, planning behavior

Describe the functional area, location, and function of Brodmann's area 47

Tertiary somatosensory cortex, posterior parietal association Superior parietal lobule Sterognosis

Describe the functional area, location, and function of Brodmann's area 5

Supplementary motor control, supplementary eye field, premotor adjacent cortex Precentral gyrus and rostral adjacent cortex Limb and eye movement planning

Describe the functional area, location, and function of Brodmann's area 6

Posterior parietal association Superior parietal lobule Visuomotor control, perception

Describe the functional area, location, and function of Brodmann's area 7

Frontal eye fields Superior and middle frontal gyri, medial frontal lobe Saccadic eye movements

Describe the functional area, location, and function of Brodmann's area 8

Primary somatosensory cortex Postcentral gyrus Touch

Describe the functional area, location, and function of Brodmann's areas 1, 2, and 3

Insular cortex Insula Involved with pain perception and speech production, processing of social emotions, autonomic function.

Describe the functional area, location, and function of Brodmann's areas 13, 14, 15, 16

Limbic association cortex Cingulate gyrus, subcallosal area, retrosplenial area, parahippocampus gyrus Emotions

Describe the functional area, location, and function of Brodmann's areas 23, 24, 25, 26, 27

Prefrontal association cortex Superior and medial frontal lobe Thought, cognition Area near frontal eye fields (medial frontal lobe) also involved in motor planning

Describe the functional area, location, and function of Brodmann's areas 9, 10, 11, 12

Amygdalostriate fibers: Amygdala to caudate + putamen

Describe the input from the amygdala to the striatum

Striatum = caudate + putamen Raphe nucleus sends inhibitory fibers (serotonin)

Describe the input from the midbrain dorsal raphe nucleus to the striatum

Striatum = caudate + putamen Nigrostriatal fibers: SN >>> caudate + putamen (?inhibitory dopamine)

Describe the input from the substantia nigra to the striatum

Striatum = caudate + putamen Thalamostriate fibers: 1) Intralaminar CM (centromedial) nucleus (largest intralaminar nucleus) >>> putamen 2) Parafascicular nucleus >>> caudate

Describe the input from the thalamus to the striatum

NSol rostral segment >>> medial hypothalamus (taste) NSol caudal segment >>> lateral hypothalamus (visceral sensation)

Describe the nucleus solitarius' (NSol) connections with the hypothalamus

1) Some fibers cross in the anterior commissure to contralateral anterior olfactory nucleus and olfactory bulb 2) Olfactory tubercle (olfactory cortex) 3) Amgydala 4a) Pyriform cortex >>> entorhinal cornex >>> hippocampus, insula, and frontal lobe via uncinate fasciculus 4b) Pyriform cortex >>> amygdala, lateral preoptic hypothalamus 4c) Pyriform cortex >>> MD thalamus >>> orbitofrontal cortex

Describe the outputs from the lateral olfactory stria (4 main -- broad strokes)

Subcallosal area Septal area (paraterminal gyrus)

Describe the outputs from the medial olfactory stria (2)

Right-handed individuals are nearly always left-brain language dominant Left-handed individuals are usually still left-brain dominant (85% of them are left dominant, 15% bilaterally dominant, rare right dominant)

Discuss handed-ness and hemispheric dominance

Nope

Do dentate fibers leave the hippocampus?

-Direct pathway neurons have excitatory D1 receptors; dopamine thus activates the direct pathway, facilitating movement -Indirect pathway neurons have inhibitory D2 receptors; dopamine thus inactivates the indirect pathway, facilitating movement

How does dopamine have its effect on the striatum?

Hippocampus >>> mamillary bodies

In broad strokes, what two man structures does the fornix connect?

1) primary olfactory cortex (pyriform cortex + periamygdaloid cortex) 2) secondary olfactory cortex (entorhinal area of anterior parahippocampus - area 28)

Name the 2 components of olfactory cortex

Lateral medullary lamina - between putamen and GP Medial medullary lamina - divides GPe and GPi Accessory medullary lamina - divides GPi itself into inner and outer segments

Name the 3 medullary laminae What do they separate?

Outputs: 1) Stria terminalis: amygdala >>> stria terminalis >>> nucleus of the stria terminalis (at caudate/thalamus junction) >> hypothalamus ("the fornix of hte amygdala") 2) ventral amygdalofugal tract: amygdala/pyriform area >> lateral preoptic area/septal area/nucleus of the diagonal band/substantia innominata/hippocampus/brainstem nucleu to regulate autonomic function (fear and stress) 3) amygdalocortical output 4) amygdalostriate (amygdala >> nucleus accumbens) ***** Inputs: literally from everything (lateral olfactory cortex, pyriform cortex, hypothalamus, paraventricular thalamus, nucleus of the solitary tract, lateral parabrachial nuclues, locus ceruleus (noradrenalin), SN and ventral tegmentum (DA), substantia innominata and lateral olfactory area (AcCh), raphe nucleus (serotonin)

Name the 4 main outputs of the amygdala Why haven't I asked about inputs to the amygdala?

1) Presubiculum 2) Subiculum 3) Prosubiculum 4) Hippocampus 5) Dentate gyrus

Name the 5 parts of the hippocampal formation

1) Parahippocampus gyrus 2) Hippocampal formation 3) Dentate gyrus 4) Cingulate gyrus 5) Insula 6) Orbitofrontal cortex

Name the 6 parts of the the limbic cortex

1) Amygdala 2) Hypothalamus 3) Septal nuclei 4) Habenular nuclei 5) Anterior and dorsomedial thalamic nuclei 6) Indusium griseum

Name the 6 subcortical limbic structures

1) Ansa lenticularis (main output tract) - from GPi AROUND the IC >>> Forel's field H1 (FFH1), the prerubral field 2) Lenticular fasciculus (FFH2 fibers) - from GPi THROUGH IC to join ansa lenticularis in Forel's field, forming the thalamic fasciculus 3) Thalamic fasciculus (FFH1 fibers) - composed of the joined ansa lenticular, lenticular fasciculus, nad cerebellothalamic tract (fibers from contralateral deep cerebelar nuclei) >>> thalamic VL and VA 4) Pallidosubthalamic fibers a) GPe >>> subthalamic nucleus (STN) b) GPi >>> stria medullaris >>> lateral habenulum

Name the four output bundles from the globus pallidus

1) Mammillothalamic tract 2) Fornix 3) Stria medullaris (thalami) 4) Stria terminalis

Name the key fiber tracts of the limbic system

From 2 oldest cortical areas 1) Pyriform cortex >>> amgydala >>> stria terminalis >>> hypothalamus and hippocampus >>> fornix >>> septum 2) Closed loop from the cingulate gyrus >>> entorhinal cortex >>> hippocampus >>> hypothalamus >>> anterior thalamic nucleus >>> cingulate gyrus

Two main inputs to the hypothalamus

1) olfactory receptors (epithelium w/ primary bipolar cells with kinocilium >>> 2) olfactory nerve (unmyelinated fibers) >>> 3) synapses on mitral cells (second neurons) in olfactory bulb (glutamate and aspartate mediated) 4) >>> olfactory tract (lateral olfactory stria** and gyrus and medial olfactory stria and gyrus) 5) >>> complex cortical connections (see other cards) **axons of the mitral and tufted cells

Walk through the olfactory pathway

3) Pars orbitalis 2) Pars triangularis 1) Pars opercularis ++ ) anterior ramus of Sylvian fissure +) ascending ramus of Sylvian fissure Broca's area considered to be formed by the pars triangularis and pars opercularis (2 and 1)

What are 1, 2, and 3? What are + and ++? What part marks up Broca's area?

Fibriae >> crura >> body >> columns

What are the 4 main components of the fornix?

I Molecular layer II External granular layer III External pyramidal layer IV Internal granular layer V Internal pyramidal layer VI Multiform layer

What are the layers of neocortex?

Caudate and putamen (striatum) They receive input from cortex (most importantly)

What are the main input nuclei of the basal ganglia? Where do they receive their most important input?

Globus pallidus and substantia nigra

What are the main output nuclei of the basal ganglia?

1) Fornix 2) Subiculum (the most inferior component of the hippocampal formation) that projects to cortex** ** subiculum is the sole direct cortical projector, may project to medial frontal cortex / cingulate / parahippocampal gyrus; may also project to cortex throguh postcommissural fornix and anterior nucleus of thalamus

What are the main outputs from the hippocampus (2)?

The fields of Forel are areas in the diencephalon. They are below the thalamus and consist of three defined, white matter areas of the subthalamus. These three regions are also named "H fields": Field H1, is the thalamic fasciculus, a horizontal white matter tract composed of the ansa lenticularis, lenticular fasciculus, and cerebellothalamic tracts between the subthalamus and the thalamus. These fibers are projections to the ventral anterior and ventral lateral thalamus from the basal ganglia (globus pallidus) and the cerebellum. H1 is separated from H2 by the zona incerta. Field H2 (synonymous with lenticular fasciculus) is also made up of projections from the pallidum to the thalamus, but these course the subthalamic nucleus (dorsal). Field H (sometimes called field H3) is a large zone of mixed grey and white matter from the pallidothalamic tracts of the lenticular fasciculus and the ansa lenticularis which combine in an area just in front of the red nucleus. The grey matter from this field is said to form a prerubral nucleus.

What are the three fields of Forel?

1) Entorhinal cortex (28) >>> hippocampus and dentate gyrus 2) Medial septal nucleus >>> fibria of hippocampus 3) Cingulate gyrus >>> cingulum >>> presubiculum/entorhinal cortex >>> hippocampus

What are the three main inputs into the hippocampus?

1) Pars tuberalis -portion of the infundibular stalk -median eminence of hypothalamus 2) Pars intermedia 3) Pars distalis (majority of the gland, has no direct blood supply >>> vulnerable)

What are the three parts of the adenohypophysis?

The three parts of the frontal operculum are the pars orbitalis, pars triangularis, and pars opercularis. (O-T-O with orbitalis in front) They result in the inferior frontal gyrus having a characteristic "M" configuration sometimes referred to as the M sign. The Sylvian fissure gives off two branches that subdivide the inferior frontal gyrus into three parts. From anterior to posterior: the anterior ramus (a.k.a. anterior horizontal ramus) separates the pars orbitalis from the pars triangularis, and the ascending ramus (aka anterior ascending ramus) separates the pars triangularis form the pars opercularis. Broca's area considered to be formed by the pars triangularis and pars opercularis.

What are the three parts of the inferior frontal gyrus? What is the relation between this region and Broca's area?

1) Pars nervosa (posterior lobe) 2) Infundibulum 3) Nuclei (supraoptic and paraventricular)

What are the three parts of the neurohypophysis?

Supplemental motor cortex (SMA, M2, area 6) There is a somatotopic organization of neurons Input is bilateral Input from S1 and input from globus pallidus (medial GP >>> ipsilateral thalamic ventroaterior pars compacta (VApc), ventrolateral pars oralis (VLo), centromedial (CM) >>> M2 and premotor (not M1)) Output to ipsilateral M1 (area 4) and parietal association cortex (areas 5 and 7); contralateral M2; bilateral spinal cord, caudate, putamen, and thalamus Lesion>>>hemiparesis/plegia, deminished spontaneous speech, may retain volitional movement with effort

What area manages programming, planning, and initiation of motor movements? Is there a somatotopic organization of neurons? Is the input unilateral or bilateral? What is the output? What does a lesion cause?

Premotor cortex (area 6) Input from cortex (M2, S1) as well as VL and VA of thalamus Also receives input from globus pallidus (medial GP >>> ipsilateral thalamic ventroaterior pars compacta (VApc), ventrolateral pars oralis (VLo), centromedial (CM) >>> M2 and premotor (not M1) Bilateral input >>> unilateral lesion causes no deficit

What area of the brain manages voluntary control for responses dependent on sensory input? What is the input from? unilateral or bilateral?

Amygdala

What defines archistriatum?

Neostriatum + paleostriatum >>> caudate, putamen, and GP

What defines corpus striatum?

Paleostriatum (GP) + subthalamic nucleus

What defines diencephalic nucleus?

Putamen and GP

What defines lentiform nuclei?

caudate and putamen

What defines neostriatum (or striatum)?

What defines paleostriatum?

Gerstmann's syndrome 1) Agraphia 2) Acalculia 3) Finger agnosia 4) Right/left dissociation (inability to distinguish between the right and left sides of one's body)

What does a lesion in the dominant angular and supramarginal gyrus cause?

Neglect Anosognosia

What does a lesion in the non-dominant inferior parietal lobule cause (angular and supramarginal gyri)?

1) Anterior portion of AC connects 2 olfactory bulbs 2) Posterior portion of AC connects the two GPs, putamens, external capsules, claustrums, and inferior and middle frontal gyri

What does the anterior commissure connect (2 parts of AC)?

Cortical association areas >>> caudate >>> GP >>> thalamus >>> cortex (SMA/prefrontal cortex)

What does the cognitive basal ganglia circuit involve?

Lateral hypothalamic nucleus

What does the lateral hypothalamic area contain?

Mamillary bodies >>> midbrain ventral and dorsal tegmentum

What does the mamillotegmental tract connect?

Mamillary bodies >>> anterior thalamic nucleus

What does the mamillothalamic tract connect?

Motor/somatosensory cortex >>> putamen >>> GP >>> thalamus >>> supplementary motor area

What does the motor basal ganglia circuit involve?

Retinal ganglion cells >>> suprachiasmatic nuclei (circadian rhythms)

What does the retinohypothalamic tract connect? What does it help mediate?

Neurological circuit of historical interest Suggested involvement with emotion, combining subjective/autonomic/somatic elements Involves bidirectional connections from the subiculum <> mammillary bodies <> mammillothalamic tract <> anterior thalamic nucleus <> entorhinal cortex <> subiculum

What is Papez's Circuit?

The superior hypophyseal artery (off the supraclinoid ICA) and the inferior hypophyseal artery (branch of cavernous ICA meningohypohyseal trunk. These arteries join >>> sinusoids >>> infundibulum and anterior pituitary gland via portal system. The inferior hypophyseal artery is primary responsible for blood supply to the posterior pituitary lobe.

What is the blood supply to the pituitary?

The direct or excitatory pathway involves the disinhibition of the thalamus through the inhibition of the tonically inhibitory GPi/SNr. Overall effect of direct pathway is MORE MOVEMENT 1) Motor cortex excites (via glutamate) inhibitory neurons in the striatum 2) Inhibitory neurons in the striatum inhibit (via GABA) an inhibitory neuron in the GPi 3) Tonically inhibitory (GABAergic) neurons in GPi now no longer inhibiting thalamus 4) Thalamus now able to excite cortex and allow for movement

What is the direct pathway (components, neurotransmitters, overall effect)? Describe the direct pathway in 4 steps.

White matter tract that connects midbrain's central gray area (dorsal periaqueductal gray matter) <<<>>> periventricular hypothalamus (reciprocal)

What is the dorsal longitudinal fasciculus?

Facilitates movement

What is the effect of dopamine on the striatum?

Recent memory (not remote memory) and consolidation of short-term memory into long-term memory

What is the function of the hippocampal formation?

Controls behavior and emotion

What is the function of the limbic system?

The INHIBITORY indirect pathway allows for increased inhibition of the thalamus by the GPi thus inhibiting movement. It does so via inhibition of GPe, allowing for the disinhibition of GPi. 1) Motor cortex excites (via glutamate) inhibitory neurons in the striatum. 2) These inhibitory striatal neurons ramp up inhibition of GPe (via GABA) 3) At baseline, GPe inhibits both GPi and STN via GABA a) When GPe is inhibited per step 2, this turns down tonic GABA inhibition of GPi by GPe, thus allowing GPi to inhibit thalamus. b) When GPe is inhibited per step 2, this turns down tonic GABA inhibition of STN by GPe, thus increasing the excitatory activity of STN. 4) With increased excitatory activity of STN, STN is able to excite (the tonically inhibitory) GPi. 5) With increased activity of GPi, tonically inhibitory GPi is able to inhibit the thalamus. 6) The final result of both limbs of the indirect pathway is LESS MOVEMENT.

What is the indirect pathway (components, neurotransmitters, overall effect)? Describe the indirect pathway in 3-6 steps

Composed of supracallosal gyrus and medial and lateral longitudinal striae These are remnants of the hippocampus that course over the dorsal surface of the CC Connects the septal area with the hippocampus

What is the indusium griseum? What does it connect?

Primary related to limbic loops Input: 1) fornix 2) mamillary peduncle Output: 1) stria medularis >>> medial habenular nucleus 2) medial forebrain bundle >>> lateral hypothalamus, midbrain, and tegmentum 3) fornix >>> hippocampus

What is the input to the septal nuclei (2)? What is the output from the septal nuclei (3)?

An axon tract carrying secondary sensory information from the tegmentum of the midbrain to the mammillary body. Connects brainstem reticular formation >>> lateral mamillary nucleus

What is the mamillary peduncle?

Mamillary region = posterior portion of the medial hypothalamus It contains the mamillary bodies and the posterior hypothalamic nuclei

What is the mamillary region of the hypothalamus? What does it contain?

Runs from the basal olfactory areas, septal nuclei, periamygdala and subiculum >>> lateral preoptic and lateral hypothalamic areas >>>> hippocampus (pathway that conveys information related to basic emotional drives and smell)

What is the medial forebrain bundle?

Region of the hypothalamus where the CNS interacts with the pituitary (represents a funnel-like extension of the tuber cinereum)

What is the median eminence of the hypothalamus? What happens there?

Also called substantia innominata Located on basal forebrain (lies below the anterior part of the thalamus and lentiform nucleus) extends from olfactory tubercle to the hypothalamus (of note, the ansa lenticularis passes through this region en route from GPi to thalamus) Contains a high concentration of cholinergic neurons (it is the single major source of cholinergic fibers to the cortex) Input from amygdala, temporal lobe, pyriform cortex, and entorhinal cortex Diffuse cortical output

What is the nucleus basalis of Meynert? Where is it? What does it contain a lot of? Where does it extend? What is its input? Output?

Face is in the genu Then posterior limb contains body (organized rostral to caudal (cervical in front >>> sacral in back)

What is the orientation of motor fibers within the internal capsule?

adenohypophysis = ectodermal origin from roof of the stomodeum neurohypophysis = diencephalic origin

What is the origin of adenohypophysis? neurohypophysis

Substantia nigra pars compacta (SNpc) >>> striatum Substantia nigra pars reticulata (SNpr) >>> thalamus

What is the output (2) from the substantia nigra?

The pars marginalis (marginal sulcus) is the extension of the cingulate sulcus posterosuperiorly, separating the paracentral lobule from the precuneus of the parietal lobe on the medial surface of the cerebral hemispheres. On axial images it appears as a short sulcus, reaching the apex but not extending laterally. It is an excellent landmark to help confirm the location of the central sulcus, which is located ONE SULCUS ANTERIOR to the marginal sulcus, on the other side of the postcentral gyrus.

What is the pars marginalis? How is it useful radiographically?

Fornix divides anterior/posterior near the AC The posterior fibers (postcommissural fornix, majority of fornix fibers) pass caudal to the AC through the hypothalamus to the mammillary bodies; then to the anterior nuclei of thalamus, which project to the cingulate cortex. Pathway: Hippocampus >>> postcommissural fornix >>> mammillary bodies >>> anterior nuclei of thalamus >>> cingulate cortex (possibly to cingulum >>> presubiculum/entorhinal cortex >>> hippocampus)

What is the postcommissural fornix? Describe the pathway in which it is involved

Fornix divides anterior/posterior near the AC The anterior fibers (precommissural fornix, minority of fornix fibers) head anteriorly towards the septal nuclei and nucleus accumbens of each half of the brain. Pathway: Hippocampus >>> precommissural fornix >>> caudal septal nucleus

What is the precommisural fornix? Describe the pathway in which it is involved

Periventricular nucleus / periventricular gray of the most rostral third ventricle portion Contains medial and lateral preoptic nulcei

What is the preoptic area of the hypothalamus? What does it contain?

Part of the epithalamus. It is a fiber bundle containing afferent fibers from the septal nuclei, lateral preoptico-hypothalamic region, and anterior thalamic nuclei to the habenula. It forms a horizontal ridge on the medial surface of the thalamus, and is found on the border between dorsal and medial surfaces of thalamus. It projects to the habenular nuclei, from anterior perforated substance and hypothalamus, to habenular trigone, to habenular commissure, to habenular nucleus.

What is the stria medullaris?

Striatum = caudate + putamen Input: 1) cortex via corticostriate fibers (most important) 2) thalamic CM and parafascicular nuclei via thalmostriate fibers 3) substantia nigra via nigrostriatal fibers 4) midbrain dorsal raphe nucleus 5) lateral amygdala via amygdalostriate fibers Output (take with grain of salt) 1) striatonigral fibers: head of caudate >>> substantia nigra pars reticulata (SNpr) 2) striatopallidal fibers: caudate/putamen >>> GPi (inhibitory via gaba) 3) nigrothalamic fibers: terminate in VA, VLm, MD (inhibitory via gaba)

What is the striatum? What is its input (5)? What is its output (3)?

Supraoptic and paraventricular nuclei >>> posterior pituitary gland (releates oxytocin, vasopressin, cholecystokinin, enkephalins, glucagon, dynorphin, and angiotensin)

What is the supraoptichypophyseal tract?

The tuberal region is the middle part of the medial hypothalamus This is the region where the fornix separates the hypothalamus into medial and lateral regions

What is the tuberal region of the hypothalamus? What key division happens there?

Arcuate nucleus of the tuber region >>> median eminence and the infundibular stem (Releasing hormones are secreted into fenestrated capillaries that form the hypophyseal portal system >>> anterior pituitary gland)

What is the tuberohypophyseal tract?

Anterior thalamic nuclei (ATN) / anterior nuclear group Input from the mammillothalamic tract and fornix Output to cingulate gyrus via anterior limb of IC It is involved with the regulation of memory, emotion, visceral function (part of limbic system)