Introduction Flashcards
Telencephalon
Cerebral hemispheres
Lateral ventricles
Diencephalon
Thalamus and hypothalamus
Ventricular lumen is 3
Mesencephalon
Midbrain
Mesencephalic aquaduct
Metencephalon
Pons and cerebellum
Fourth ventricle
Myelencephalon
Medulla
Fourth ventricle
Spinal cord
Spinal cord
Central canal
Ventricular system
Lumen of neural tube, this and meninges spaces are continuous
Fluid transport within the brain
Nutritive and protective function for brain, contain CSF for nutrition and ionic substance for brain so can properly function
Choroid plexus
Origination of CSF
Meninges
Three connective tissue membranes
Protection and support for the brain and spinal cord and substrate for vasculature
Dura, arachnoid, Pia
Arachnoid
Under lain by subarachnoid space where CSF and vessels travel
Delicate trabeculated middle layer
Spinal cord matter
White matter outside gray matter inside
Cerebral cortex matter
Gray matter outside and white inside
White matter
Composed of axons
White because lipoprotein myelin and reflects light
Tract
Bundle of functionally related axons in the CNS
When travel together = fasciculus or peduncle
Ex: corpus collosum
Commissure
Some facts cross to the contralateral side of brain
Any fiber bundle that crosses midline
5 commissures interconnecting telencephalon and diencephalon
corpus callosum, hippocampal commissure, rostral commissure, caudal commissure and habenular commissure
Afferent
Axons inputs that terminate as synapses
Efferent
Outputs, axons that leave that region and make synaptic terminations in another
Also called projection
Gray matter
Contains neuron cell bodies, dendrites and the fine branches of axons from sources along with synapses
Nuclei
Specific regions of gray matter contain these specific groups of neuron cell bodies
Only when found in subcortical locations, areas when in cerebral cortex and cerebellar cortex
Neurophil
Background between groups of neurons
Where dendrites, axons and synapses are most dense
Analogies of white and gray matter
White matter= large highways Gray matter= local neighborhoods Neuron cell bodies= houses Axons branches= streets Neurophils= lawns Dendrites= driveway
Cars are the action potential
Central nervous system
Brain and spinal cord and communicates with rest of the body via sensory and motor nerves
Peripheral nervous system
Sensory and motor nerves
Nerve
Bundle of axons in the PNS
Tract definition
Bundle of axons in the CNS
Fascicles
Small tract
Nucleus vs. ganglion
Nucleus is a collection of nerve bodies in CNS
Ganglion is a collection of nerve cell bodies in PNS
Motor output
Neuromuscular junctions are dark and what communicates with muscle
Sensory input and motor output
Located in periphery but communicate with CNS
Input is afferent signals to the Brain and then sends out efferent signals
Interneurons
Process information that sensory afferent bringing in
Talking to different layers, lots of dendrites
Dendritic spines can receive lots of information and create synapses
Synapses have a thickening which is the active zone where axons communicate
Spinal cord
Segmented because receive lots of information from different parts of the brain
Axons entering dorsal roots of a segment convey sensory info
Axons exiting ventral roots of that segment terminate on muscles in the same area
Central canal
Remnant of lumen in neural tube
Spinal cord gray matter
Organized into dorsal horn containing interneurons that process incoming sensory info and enters via dorsal roots
Ventral horn contains motor neurons whose axons exit the ventral roots
Interneurons
All neurons in dorsal horn and most in ventral horn
Gray matter because
Mostly nuclei but speckled because contain some neurons
Descending tracts to the spinal cord
Any region of the spinal cord has these from cerebral cortex, midbrain and brainstem- travel in spinal cord white matter
Spinal cord white matter
Also contains ascending tracts conveying sensory info to the rostral brain
Brainstem
Medulla and pons also the midbrain and diencephalon
Cerebellum not a part
Medulla
Cervical spinal cord to the caudal margin of pontine fibers
Cranial nerves VI-XII originate in medulla
Ventral medulla
Pyramids, trapezoid bodies and caudal olive
Fourth ventricle
On dorsal medulla and pons
Opens from central canal at obex which is the caudal margin of medulla
Open forms rhomboid fossa
Medulla development
Roof plate of medulla and pons expands during development
Because of this fourth ventricle has thin roof of Pia and ependyma
Sulcus limitans
Dorsal medulla
Dorsolateral= sensory and ventromedial= motor
Caudal olive
Relay to cerebellum and pyramids
Trapezoid body
Band of axons that crosses the midline
Conveys auditory information to brainstem
Nerve functions
SSMMBMBSBBMM
Alar plate of medulla
Sensory
Basal plate of medulla
Motor
Sensory medulla
Gracile and cuneate nuclei
Cochlear and vestibular nuclei
Solitary nucleus
Gracile and cuneate nuclei
Spinal nucleus V
Somatic sensation
Cochlear and vestibular nuclei
Of VIII
hearing and balance
Solitary nucleus
Visceral sensation
Main motor structures of medulla
Hypoglossal, dorsal motor of X, ambiguous nucleus, salivatory nuclei, facial motor nucleus and abducens nuclei
Hypoglossal Nerve
CN XII
Tongue movement
Ambiguous nucleus
IX, X, XI
smooth muscle of pharynx and larynx
Salivatory nuclei
IX, X
Gland secretion
Reticular formation
Middle portion of medulla
Medulla to midbrain
Receiving sensory input and generating motor output and refinement
Pons
Pontine nuclei- cortical axons
Associated with fourth ventricle
Reticular formation
Middle cerebellar peduncles
Pontine neurons then project axons to cerebellum on opposite side via large white matter band that becomes this middle cerebellar peduncles
Fine movement modulation
CN V
Originates in the pons
Pontine decussation
Large axonal bundle bringing info from cortex communicating with spinal cord
Cerebellar nuclei
Source of outputs from the cerebellum
Cerebellar cortex
Receives wide array of input from sensory systems and generates fine motor responses
Peduncles
There are three that connect cerebellum to brain stem
Caudal cerebellar peduncles
Afferent from spinal cord and medulla
Middle cerebellar peduncle
Afferent from pontine nuclei
Rostral cerebellar peduncle
Supplies efferents from the deep cerebellar nuclei to the brainstem, midbrain and diencephalon
Midbrain
Thalamus from pons
Demarcated by caudal commissure
Mesencephalon
CN 3 and 4= oculomotor and trochlear
Ventricular lumen is the mesencephalic aquaduct
Periaqueductal gray
Surrounds the aquaduct
Coordinating defensive and attack behaviors
Reticular formation
Rostral and caudal colliculi
On midbrain roof, form dorsal bumps
Visual and auditory processing
Crus cerebri
Cerebral peduncles
Tracts that contain acorns that descend from cerebral cortex to the brainstem and spinal cord
Red nucleus and substantia nigra
Important motor nuclei in ventromedial tegmentum
Diencephalon
Thalamus dorsal and hypothalamus ventrally
Third ventricle
CN II- optic nerve
Forms part of pituitary gland
Pituitary gland formation
Pineal gland and infundibulum
Internal capsule
Forms massive neural highway of communication between thalamus and cerebral cortex
Ascending axons convey sensory info from thalamus to cortex, conscious sensation
Descending from cortex provide feedback to thalamus and continue into internal capsule, crus cerebri, pyramids and terminate in brainstem and spinal cord
Corticobulbar projections
Brainstem
Corticospinal projections
Spinal cord
Pineal recess
Outpocketing of 3rd ventricle extends into proximal pineal gland
Infundibular recess
Ventral extension of 3rd ventricle into infundibular recess stalk of pituitary gland
Lateral geniculate
Nucleus of the caudal thalamus is a prominent structure in visually dominant mammals
Receives axons from optic nerve
Midbrain
Medial geniculate
Nucleus related to the auditory system
Large in auditory dominant species and receives input from the caudal colliculus
Telencephalon
Continues after other regions
Cerebral cortex- neocortex, hippocampus and pyriform lobe
Subcortical nuclei of basal ganglia and amygdala
CN I- olfactory nerve
Cortex
Arranged in distinct layers
Rostral commissure
Boundary between diencephalon and subcortical telencephalon
Cerebral hemispheres
Bilateral unlike brainstem
So ventricular lumen is extended into left and right lateral ventricles
Internal capsule telencephalon
Communication for telencephalon
Passes between caudate and putamen nuclei of basal ganglia
Axons leave and supply cortical targets forming corona radiata
Cortical areas
Communicate with other areas in same hemisphere and in opposite
If cross hemispheres form corpus callosum= massive commissure
Gyri development
Grow in thickness as neurons multiply and form dendrites and synaptic connections with incoming axons
If thinner with fewer neurons remain sulci
Smaller mammalian tend to be ungyrated
Gyration increases cortex inside the skull
Neocortex, hippocampus and pyriform lobe
Outer region is gray matter, underlain is white matter
Neocortex
Frontal, parietal,occipital and temporal lobes
Axons in or out travel via internal capsule, major white matter tract and becomes cerebral peduncle on ventral surface of midbrain and pyramids on ventral medulla
Exhibits 6 cellular layers of neurons to optimize info processing capacity
Frontal lobe
Contains motor cortex
Parietal lobe
Processes somatosensory information
Occipital lobe
Visual information
Temporal lobe
Auditory processing
Prefrontal areas
Rostral to motor cortex mediate key aspects of personality including emotional response
Pyramidal cortical neurons
Vertically oriented dendritic trees and axons descend to enter white matter and travel
Excitatory= glutamate as neurotransmitter
Non pyramidial cortical neurons
Local interneurons, immediate vicinity
Inhibitory
GABA neurotransmitter
Hippocampus
Medial wall of telencephalon and lateral ventricle will separate it from the rest of the cortex
Dentate gurus
During development pulled into curbed trajectory
White matter bundle is the fornix, contains axons entering and leaving the hippocampus
Hippocampus commissure
Axons from one hippocampus to the other hemisphere
Fimbria
White matter associated with the cortex of hippocampal formation before being concentrated in the fornix
Fornix targets
Mammillary bodies of diencephalon
Hippocampus and memory
Place cells are neurons that fire only when the animal is in a particular location
Direct input from the entorhinal cortex
Fire at spaced locations- grid cells
Spatial location and reward
Communication between hippocampus and ventral striatum
Short term memory
Represented in hippocampus, long term is cerebral cortex
Memory consolidation during sleep
Pyriform lobe
Rhinal fissure separates neocortex dorsal from pyriform lobe
Devoted to olfactory info from olfactory bulbs via lateral olfactory tract
3 cell layers
Rostral commissure
Functions like the corpus collasum and hippocampal commissure for brain regions below rhinal fissure
Interconnects lobes
Subcortical telencephalon
Basal ganglia is the largest associated
Amygdala
Basal ganglia
Striatum- caudate, putamen and nucleus accumbens
Pallidum- globus pallidus
Bisected by internal capsule
Striatum receives excitatory input from cerebral cortex and modulatory dopaminergic input from substantia nigra to midbrain
Parkinson’s
Disrupts flow from thalamus to cortex, globus pallidus disrupted
Amygdala
Survival reactions
Multimodal cortical areas
Parietal, frontal and temporal
Respond to variety of stimuli
Can either be multi to Unimodal or multi to multi
Working memory
Operates in parietal and frontal areas
Damage to one region results in hypoactivation of other regions due to interconnectivity- diaschisis