Brain Structures Flashcards
Embryonic subdivisions of the Brain
Forebrain (Proencephalon), Midbrain (mesencephalon), Hindbrain (Rhombencephalon)
Telencephalon
dorsal part of prosencephalon; composed of cerebral hemispheres
Diencephalon
ventral part of prosencephalon; thalamus and hypothalamus
Cerebrum
convoluted cortex of gray matter covering a central mass of white matter (Medulla_
Five subdivisions of the Cerebrum
Frontal, occipital, parietal, temporal, olfactory lobes
Frontal lobe
part of cerebrum; motor functionsl higher functions (reasonings)
Parietal Lobe
pain, temperature, touch, taste
Temporal Lobe
hearing
Occipital lobe
vision
olfactory lobe
smell
Outer cerebral Cortex of cerebrum
Neurons, neuron cell processes, CNS glial cells
Inner medulla of Cerebrum
Axons, CNS glial cells, blood vessels
Stratification of cerebrum
MOOIIM (Molecular layer, outer granular layer, outer pyramidal cell layer, inner granular layer, inner pyramidal cell layer, multiform (fusiform) Cell layer.
Diencephalon components
Thalamus, hypothalamus, optic chiasm
Thalamus
Primary relay station for sensory information (Excluding olfaction) going to cerebrum; assists cerebral cortex with higher functions (alertness, pattern recognition, emotions, data analysis and assimilation; directing motor activities.
Hypothalamus
intermediary between nervous and endocrine systems; control and integration of ANS; feeding, satiety and thirst centers; maintenance of wake and sleep cycles; regulations of body temperature
Optic chiasm
where fibers of axons of optic nerves cross over
Rhombencephalon divisions
Metencephalon and Myelencephalon
Cerebellum Gross Anatomy
Vermis, sulci, folia
Vermis
midline mass that separates two lateral cerebral hemispheres
folia
narrow ridges that cover cerebellum
Sulci
grooves on cerebellum
Function of the cerebellum
receives information regarding head movements; muscle, tendon, joint, and ligaments stretch stretch from ipsilateral/ Modulates pools of motor neurons in the ipsilateral spinal cord to coordinate posture and movement.
arbor vitae
white matter of cerebellum; looks like a tree
What is the ventricle system?
a number of interconnecting cavities which are remants of the lumen of the embryonic neural tube
CSF composition
blood, and secretions from cells lining interior of ventricle system; low calcium, potassium, glucose, and protein; but more magnesium, sodium and chloride
How is CSF produced?
formed from choroid plexus
where is the majority of CSF produced?
lateral ventricles
How does reabsorption of CSF occur?
Absorption of CSF occurs at arachnoid villi and is controlled by CSF/blood pressure gradients.
Arachnoid villi
evaginations of arachnoid layer into dural sinuses of brain/ acts as pressure-dependent, unidirectional valves.
Hydrocephalus
water on brain; result of accumulating CSF within ventricles from obstruction of ducts (i.e foramen of monro); excessive CSF pressure damages CNS neurons
Head trauma and CSF
Trauma causes bleeding into dural sinuses creates excess pressure which collapses arachnoid villi and shits down CSF absorption damaging CSF neurons. Increased sinus blood pressure can comprress central veins and efferent lymphatics of the optic nerve causing swelling of retinal veins, whcih can damage vision.
What fibers are utilized in the autonomic nervous system?
GVE; General visceral efferent fibers
What kind of neuronal system does the ANS employ?
a 2-neuron system; preganglionic neurons and axons & postganglionic neurons and axons
2 - Neuron System overview
1) pre-ganglionic neurons 2) pre-ganglionic axons 3) postganglionic neurons 4) postganglionic axons
Pre-ganglionic neurons
located in the CNS
pre-ganglionic axons
nerve fibers extending from pre-ganglionic neuron. Synapse on postganglionic neuron
post-ganglionic neuron
located in an autonomic ganglion of PNS
Postganlionic axon
nerve fibers extending from post-ganglionic neuron; synapse with an effector organ
Where do sympathetic nerve impulses originate? Step#1 SNS
1) Sympathetic impulses originate from preganglionc sympathetic neurons located in the intermediolateral cell column of the thoracolumbar spinal cord (T1-L3-4)
Step #2 SNS
Preganglionic sympathetic axons synapse on post ganglionic sympathetic neurons in sympathetic ganglia (i.e Cranial nerve).
Step # 3 SNS
Postganglionc sympathetic axons synapse on structures of effector organs (i.e dilator muscle of eye, smooth muscle in the walls of blood vessels)
Where do parasympathetic nerve impulses originate? Step # 1
Impulses originate from preganglionic parasympathetic neurons in nuclei located in the brainstem or sacral spinal cord
Step # 2 PNS
preganglionic parasympathetic axons exit midbrain and hindbrin with cranial nerves III, VII, IX, & X; synapse on post-ganglionic parasympathetic axons of parasympathetic ganglia
Step #3 PNS
Post-ganglionic parasympathetic axons synapse on structures of effextor organs.
Parasympathetic vs. Sympathetic
Parasympathetic - effects specific, discrete, local vs Sympathetic -effects more widespread
Postganglionic axon of sympathetic vs. parasympathetic
Sympathetic axons are adrenergic (release norepinepphrine); parasympathetic axons cholinergic (release acetylcholine)
Preganglionic axon of sympathetic vs. parasympathetic
both cholinergic (release ACH)
