forebrain anatomy Flashcards
parts of the forebrain
telencephalon: cerebral hemispheres
Diencephalon: thalamus, hypothalamus, epithalamus, subthalamus
Internal Capsule
Limbic system: hypothalamus, Hippocampus, Amygdala
parts of the deincephalon
Epithalamus (pineal gland, Habenula)
Thalamus
Hypothalamus
Subthalamus
where do most pathways in the brain relay
Thalamus
what all relays in the thalams
All sensory (other than olfactory) pathways
Limbic systems
Basal ganglia projections
Cerebellum projections
how to pathways that relay in the thalamus use the thalamus
use different parts (with some overlap) giving the thalamus distinct nuclei
what nuclei are found in the anterior division of the thalamus
anterior nucleus
what nuclei are found in the medial division of the thalamus
dorsomedial nucleus (medial dorsal)
what nuclei are found in the dorsal tier of the lateral division of the thalamus
Lateral dorsal, lateral posterior, and pulvinar
what nuclei are found in the ventral tier of the lateral division of the thalamas
ventral anterior ventral lateral ventral posterior lateral medial medial geniculate lateral geniculate
what nuclei are found in the intralaminar area of the thalamus
centromedian, parafascicular etc
what nuclei are found in their own subdivisions of the thalamus
midline nuclei
reticular nucleus
what defines the subdivions of the thalamus
Internal Medullar Lamina
where does the anterior subdivision of the thalamus sit
sits in a split in the Internal Medullary Lamina
what subdivion of the thalamus is the largest
lateral subdivision
where is the reticular nucleus located along the thalamus
discontinuously along the lateral aspect
what are the themes of all thalamic nuclei asside from reticular nuclei
consist of projection neurons to provide output from thalamus as excititory and interneurons that are small and inhibitior
(proportions vary from nucleus- to-nucleus
specific thalamic inputs come from where and travel to where
specific subcortical site to convey info to a thalamic nuclei that in turn passes onto the cortex
regulatory inputs to the thalamus come from where
areas of the cortex to a thalamic nucleus which also contibutes info before passing it on to the cortex
the 3 categories of thalamic nuclei
relay nuclei
association nuclei
intralaminar and midline nuclei
what do Relay Nuclei receive
well defined specific input from a subcortical source
what do relay nuclei project to
sends information to a well-defined area of the cortex
what regulates the action of relay nuclei
activity is regulated by regulatory input both direct and indirect
input and output to anterior Relay nuclei
Mammillothalamic tract, hippocampus
Cingulate Gyrus
Input and output to Lateral dorsal Relay nuclei
Hippocampus
Cingulate Gyrus
input and output to VA/VL Relay Nuclei
Basal ganglia (VA), cerebellum (VL) Motor Areas
Input and output to VPL relay nuclei
Medial Lemniscus, spinothalamic Tract (ALP
Somatosensory cortex
input and output to VPM relay nuclei
Trigeminal system, central tegmental tract
Somatosensory cortex, insula
input and output to MGN relay nuclei
Brachium of inferior colliculus
Auditory cortex
input and output to LGN relay nuclei
Optic tract
Visual Cortex
Association nuclei receive input from and project out to
specific input from and project out to association cortex( the prefrontal cortex)
the 2 huge areas of association fortex
Dorsal Medial Nuclei
Pulvinar-Lateral Posterior Nuclei
location of the Dorsal Medial nuclei
Prefrontal
roll of Dorsal Medial nuclei
Foresight, organization
location of the Pulvinar-Lateral Posterior Nuclei
Parietal-occipital-temporal
function of the Pulvinar- Lateral Posterior Nuclei
unknown: maybe in visual perception or attention
Intralaminar and midline nuclei receive inputs from and project where
receive a distinct set of specific inputs (basal ganglia and limbic strcutures)
Project to cortex, basal ganaglia, and limbic structures
Roll of Reticular Nucleus
Source of regulatory input to the thalamus
what does the Reticular Nucleus look like
sheet of neurons, covering th thalamus
travel of axons of the Reticular Nucleus
traverse nucleus to enter/leave thalamus and send collaterals to it
what are the inputs and the outputs of the Reticular Nucleus
input from the Cortex and the Thalamus and output are inhibitory axons to the thalamus (no projections to the cortex)
how fibers project out to the cortex
internal capsule
what passes through the internal capsule
thalamocortical and corticothalamic fibers
almost all fibers going to and from the cortex
the collection of fibers in the internal capsule form what
the cerebral peduncle
what does the cerebreal peduncle do
Corticospinal, sorticobulbar, and corticopontine fibers descend down it
Internal Capsule Divisions
Anterior Limb Genu (G) Posterior Limb Retrolenticular Limb sublenticular parts
how is the internal capsule devided
based on relationship to lenticular nuclues (plobus pallidus + putamen)
where is the Anterior Limb of the Internal Capsule
between the lenticular nucleus and caudate
where is the Genu of the Internal Capsule
Between the anterior and posterior limbs
where is the posterior limb of the Internal Capsule
between the lenticular nucleus and the thalamus
where is the retrolenticular limb of the Internal Capsule
Behind the lenticular nucleus
where is the sublenticular part of the Internal Capsule
beneath the lenticular nucleus
what projects through the anterior limb of the internal capsule
the anterior nucleus to the cingular gyrus
the DM to the prefrontal cortex
what projects through the posterior limb of the internal capsule
VA/VL to motor areas
motor areas to the brainstem and spinal cord
VPL/VPM to the seomatosensory cortex
what projects through the sublenticular limb of the internal capsul
MGN to the auditory cortex
LGN to visual cortex, the superior visual field
what projects through the retrolenticular limb of the internal capsule
Pulvinar/LP to the parietal-occipital-temporal cortex
LGN to Visual cortex, the inferior visual field
Roll of the Hypothalamus
Autonomic, endocrine, emotional, and somatic function
Maintains homeostasis
control pituitary
also can talk to cortex to aid in fight and flight
borders of the Hypothalamus
Superior border: hypothalamic sulcus Anterior border: lamina terminalis Posterior border: midbrain tegmentum Medial border: 3rd ventricle Lateral Border: internal Capsule Inferior border: optic chiasm, tuber cinereum, median Eminence, Mammillary bodies
Longitudianl organization of the hypothalamus
Anterior: lamina terminalis to infundibulum
Tuberal: Infundibulum to mammilary bodies
Posterior: mammilary bodies to tegmentum
the most anterior portion of the hypothalamus
lamina terminalis(the most rostral extent of the neural tube closure)
What is included in the tuberal region of the hypothalamus
Median eminence, Tuber cinereum
medial-lateral organization of the hypothalamus
Lateral
medial
Periventricular
the rostral continuation of the reticular formation
lateral hypothalamus
what is contained in the lateral hypothalamus
variety of nuclei and tracts (medial forebrain bundle)
the hypothalamic subnuclei
Medial hyopthalamus
the rostral continuation of periaqueductal gray from midbrain
Periventricular hypothalamus
what is found in the Periventricular Hypothalamus
Contains nuclei and tracts (dorsal longitudinal fasciculus)
the superior hypophyseal artery branches from
internal carotid artery
what does the superior hypophyseal artery supply
capillary bed in infundibulum
the capillary bed in the infundibulum drains into
portal vessels in adenohypophysis (aka anterior pituitary)
portal vessels drain to
second capillary bed around endocrine cells of adenohypophysis (anterior pituitary)
where do neurons of the hypothalamus secrete their hormones
into the superior hypophyseal artery
what do the endocrine cells of adenohypophysis (anterior pituitary) release thier hormones
in the second cappiliary bed to the cavernous sinus
The inferior hypophyseal artery branches from what
internal carotid
what does the inferior hypophyseal artery supply
neurohyposphysis (posterior pituitary)
where do cappliaries of the hypothalamus drain to delive both anterior and psoterior pituitary hormones to systemic circulation
into cavernous sinus
what controls pituitary secretions
neuroendocrine cells
where do neuroendocrine cells synapse
on walls of capillaries
are neuroendocrine cells true endocrine cells
yes, because they release secretions into capillaries
where are the somas of neuroendocrine cells
hypophysiotrophic area in the lower half od preoptic and tuberal regions
the types of neuroendocrine cells
parvocellular
Magnocellular
neuroendocrine cells that end in the median eminence
parvocellular
neuroendocrine cells that end in the posterior lobe
magnocellular
nucleus of the parvocellular neucroendocrine cells
preoptic
ventromedial
arcuate
nucleus of the magnocellular neuroendocrine cells
supraoptic
paraventricular
what do parvocellular neurons give rise to as a tract
tuberoinfundibular tract
what kind of hormoes are carried by the parvocellular neurons
releasing or inhibiting hormes
all peptide but prolactin IH
ant or post pituiary for parvocellular neurons
anterior
the two hormes released by posterior pituitary neurons
Antidiuretic horme (Vasopressin) oxytocin
roll of antidiuretic hormone
increase water uptake by kidney, decrease urine output
loss of Antidiuretic hormone leads to
diabetes insipidis
what causes a release of antidiuretic hormone
Hypothalamus senses blood osmotic pressure
input from subfornical circumventricular organ
oxytocin leads to
contraction of uterine and other smooth muscles
oxytocin is released when
Breastfeeding
Infant suckling
infant suckling reflex
in mom from nipple and spinoreticular tract and spinohypothalamic tract
what does stimulation of the anterior hypothalamus lead to
parasympathetic effect: Slow HR, Constrict Pupil, Peristalsis, Salivation
stimulation of the Posterior hypothalamus leads to
sympathetic effects: increase HR, BP, dilate pupils, intestinal stasis
axons from hypothalamus project down
brainsteam and spinal cord in dorsal longitudinal fasciculus
Eating
baseline calorid/nutrient intake
Eating is sesnitive to
blood glucose
what is involved in creating appestat(appetite set point)
interplay of lateral and ventromedial nuclei
also serotonin
high levels of serotonin effect on appetite
Anorexia
low levels of serotonin effect on appetitte
bulimics
Lateral nucleus of hypothalamus effect on eating
stimulates eating
Ventromeidal nucleus of hypothalamus effect on eating
refuse food
Ventromedial lession leads to
overweight
anger/agressions
release of ACTH in males from the anterior pituitary leads to
fight or flight
increase in cortisol from adrenal gland
activation of the fight or flight response in males shows activation where else
lateral prefrontal cortex
what is the female reponse for fight of flight due to hypothalamic function
tend and befriend - protect offspring; affiliate with social groups
effect of oxytocin released in capillary bed of neurohypophysis and estrogen
counteract sympathetic over activity due to stress
activation of the female tend and befriend response shows activation where in the brain
cingulate gyrus (cortical emotional control center)
nucleus that gives hypothalmic control of sleep wake cycle
suprachiasmatic nucleus
where does the suprachiasmatic nucleus get input
direct input from retina
how does the body set the sleep wake cycle
due to the suprachiasmatic nucleus with the pineal gland
lesion of posterior hypothalamus leads to
hypersomnolence (increased sleep) or coma
what does the tuberomammillary nucleus contain
histminergic neurons with wide projections
roll of histiminergic neurons
arousal function
what plays a roll in arousal
histiminergic neurons also orexin (PR hormone)
where is orexin relased
lateral nucleus
what nuerons are in control of sexual arousal
subset of neurons in the medial aspect of the preoptic nucleus (contains androgen receptors)
size of sex neurons in males and females
2x as large in males
what receptors are found in the ventromedial nuclues for female sexual arousal
estrogen rich receptors
where do mammillary bodies send info
send infro to anterior nucleus of thalamus(limbic relay)
what is invovled in memory in the hypothalamus
memory
mammmillary bodies are invovled in what circuit from the hippocampus
Papez circuit
what are the 2 main hypothalamic inputs
Parts of forebrain, especially limbic system
brainstem and spinal cord
what info is conveyed from the forebrain, limbic system to the hypothalmus
infro needed for th hypothalamus to mediate autonomic/somatic aspects of emotional states
what info is conveyed from the brainstem and spinal cord to the hypothalamus
convey visceral and sensory info
how do septal nuclei reach the hypothalamus
via MFB
how do ventral striatum reach the hypothalamus
via MFB
how do insula and orbitofrontal cortex reach the hypothalamus
via MFB
how does the hippocampus reach the hypothalamus
via fornix
how does the amygdala reach the hypothalamus
via stria terminalis, ventral amygdalofugal pathways
how does the brainstem and the spinal cord reach the hypothalamus
via DLF and MFB
pathways of hypothalmic outputs
mirror the inputs
