Brain Flashcards
Prosencephalon, mesencephalon and phombencephalin all go on to form which portions of the brain?
Prosencephalon is the future forebrain
Mesencephalon is the future midbrain
Rhombencephalon is the future hindbrain
What are the major envaginations from the prosencephalon?
Unlike the rest of the neural tube the prosencephalon is not divided into alar and basal plates.
The envaginations form
- telencephalon vesicles: cerebral hemipheres
- optic vesicles: retinas and association with diencephalon
Myelencephalon
The medulla oblongata
Continuous with the spinal cord
In agnathans: it is the most developed part of the brain
Teleosts: vagal lobes w/ sensory nucleus - cause bulge.
Amphibians - vagal lobes disappeared
Mammals - well developed myelencephalon
Vagal lobes are associated with the ssense of taste
Metencephalon
Rhombencephalon derivative
Cerebellum
Agnathans: cell bodies on surface, doesnt bugle (no cortex)
Chondrichthyes: well-developed with restiform bodies: equilibrium
Teleosts: better developed in more active fish. Larger than what is found in amphibians (cerebellum is poorly developed)
Reptiles: poorly developed but better developed in swimmers. Floccular lobes (sim to restiform bodies)
Birds: large cerebellum, associated with flight. Well-developed floccular lobes
Mammals: well developed, controlled by motor cortex in cerebral hemispheres. Connected to brainstem by 3 pairs of fiber tracts: peduncles
- superior to midbrain - middle to pons - inferior to medulla
Mesencephalon
Roof is the tectum- pair of optic lobes in all craniates
-masses of gray matter
-reflex and relay centers for
mpulses from retinue
-especially in large birds
Chondrichthyes - well-dev optic lobes and tracts.
Amphibians - two pairs of dorsal lobes:
-optic lobes - superior colliculi
-auditory lobes - inferior coliculi
(Corpora quarigemina)
Floor- basal plate: tegmentum
- large fibertracts
- red nuclei in mammals
Diencephalon
Made of:
-Epithalamus
-pineal body
-parapineal body
-choroid plexus
-habenulae
-thalamus
-hypothalamus
-optic chiasma is the cephalopod
boundary
-infundibular recess and stalk
-posterior pituitary (pars nervosa)Epithalamus
Agnathans: pineal (posterior) and parietal body (anterior). Absent in hagfishes, a photoreceptor in lampreys
Gnathostomes: pineal body is endocrine, stim by light.
Absent in: crocodiles and permanently aquatic animals
Larger in primates and sheep.
Median eye: parapineal derivitive, photosensitive. Parietal. Produces melatonin. Do not form a retinal image but monitor photoperiods.
Habenulae
Elevations of habenular neclei
- associated witholfaction
- associated with reflex responces associated with odors
Largest in sharks and bloodhounds
Inconspicuous in birds
Poorly developed in aquatic animals
Thalamus
-anatomy
Paired masses of nuclei in lateral walls of the third ventricle
-relay nuclei for motor and sensory pathways, association nuclei.
Seperated from the hypothalamus by the hypothalamic sulcus
Thalamus
-Function
Relays all sensory information except smell to the cerebral cortex.
“Crude awareness”
Intial response to intense pain, shock
Interpretation center for crude pain, temp, light touch and pressure. Arousal and alerting, and a role in complex reflex movements.
Hypothalamus
Complex of nuclei that form the floor and ventrolateral walls of the third ventricle
Functions:
- controls ANS
- regulates gonads and pituitary gland through neurohormones
- monitors NaCl and glucose blood content
- regulates appetite
- associated with temperature regulatation in endothermic
Homeostasis
Connected to thalamus, basal nuclei.
Connections to limbic system for emotional responces, to hippocampus which is the ancient olfactory cortex.
Produces ADH and oxytocin, biorhythm oscillator
Telencephalon
Composed of:
Cerebrum: left and right hemispheres
Connects to brainstem via internal capsule
Olfactory tract and bulbs: anterior extensions from the floor
Striatum: floor of telencephalon - basal ganglia
Lamina terminalis: original boundary of the neural tube, seperates the two lateral ventricles
Cerebrum
-development of
Paired right and left hemispheres each with a ventricle
-not divided in ray-finned fish
Primitive roof - pallium: no true cortex
-agnathans, fish, amphibians
Reptiles: ridge-like structure from the floor of each ventricle: dorsal ventricular ridge
-visual, auditory. And somatic sensory stimuli from thalamus directs to striatum
Croc - pallium forms first ‘cortex’
Birds - layer on top of the dorsa ventricular ridge: avian ridge
-sensory information from optic nerves, homing or nest building
Mammals: add neocortex
-80% brain mass. Layers of grey matter
Sits on top of the pallium
SA increased by sulci and gyri - not in monotremes or marsupials
Lobes: Frontal, parietal, temporal, insula, occipital
Occipital lobe
Integrates Eye focusing movement
Associates visual images with visual memory
Conscious perception
Gets info from thalamus
Sept from parietal lobe by parietoccipital sulcus
Parietal lobe
Somatesthetic interpretation - postcentral gyrus
-touch presssure pain
Wenicke’s area - language comprehension
Formulating words to express thoughts and emotions
