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223 Cards in this Set
- Front
- Back
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Describe a Unipolar Nueron
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a single process extends from the soma
Not found in fully developed humans |
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Describe a Psuedo-unipolar Nueron
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a single process extends from the soma and immediately divides into two
sensory nueron of spinal nerves and all cranial nerves except I, II and VIII perpherial axon typically connects to sensory receptors |
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What type of neuron is the dorsal root ganglion composed of?
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Psuedo-unipolar nuerons
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Describe a Bipolar Nueron
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2 process emerge from the soma
found only in the peripheral nervous system associated with CN I, II, and VIII |
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Where is the location of the cell bodies for smell located (CNI)?
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Olfactory mucosa
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Where are the cell bodies of vision located (CNII)?
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Retina
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Where are the cell bodies of hearing located (CN VIII)?
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Spiral ganglion
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Where are the cell bodies of balance located (CN VIII)?
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Vestibular ganglion
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Describe a Multipolar Nueron
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> 2 processes emerge from the soma
majority of all nuerons functions in sensory, motor and autonomic systems Ex. Purkinje Fibers and Pyramidal nuerons |
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Brain Stem
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Medulla, Pons, Midbrain
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Forebrain
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Porsencephalon
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Midbrain
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Mesencephalon
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Hindbrain
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Rhombencephalon
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Cerebellum & Pons
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Metachephalon
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Medulla
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Myelencephalon
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Describe the axis orientation of the forebrain
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Dorsal = Superior
Caudal = Posterior Ventral = Inferior Rostral = Anterior |
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Describe the axis orientation inferior to the Midbrain, Diencephalic junction
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Rostral = Superior
Dorsal = Posterior Caudal = Inferior Ventral = Anterior |
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Describe the Longitudinal Fissure
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Midsagittal Section (splits the brain into halves)
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What separates the Frontal Lobe from the Parietal Lobe
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Central Sulcus
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What separates the Frontal and Parietal Lobes from the Temporal Lobe
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Sylvian Fissure (lateral Sulcus)
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What does the Precentral Gyrus control and in what lobe is it located?
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Motor and the Frontal Lobe
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What does the Postcentral Gyrus control and in what lobe is it located?
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Somato-sensory and the Parietal Lobe
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In what lobe does the Calcarine Sulcus run?
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Occipital Lobe
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Decussation
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Cross the midline
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Collections of Cell bodies in the CNS
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Gray matter, nucleus/nuclei, body, locus, substantia
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What does the corpus callosum connect?
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connects the R and L cerebral hemispheres
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What does the Cerebral Aqueduct pass through to reach __________?
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The midbrain (tectum and tegmentum) to reach the 4th ventrical.
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Term for collection of cell bodies in the PNS
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Ganglion/ganglia
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Terms for bundle of axons in the CNS
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White matter, capsule, brachium, peduncle, tract, commisure
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Term for bundle of axons in the PNS
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NERVE! (the only term)
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What are the 4 types of supportive tissue of the CNS?
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1. astrocytes
2. oligodendrocytes 3. microglia 4. Ependymal cells |
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Describe astrocytes
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only in the CNS
functions: physical support, scar tissue, removes excess waste and ions (K+), remove neurotransmitter from synapse, blood brain barrier |
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Describe oligodendrocytes
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only in the CNS mainly in white matter
functions: produce myelin around axons 1 oligodendrocyte can provide myelin segments to over 50 axons |
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The main constituents of myelin
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70% lipids (cholesterol and cerebroside) and Protiens (mainly mylein basic protein)
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Describe Microglia
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function: macrophage (remove damaged tissue by phagocytosis)
Always present in the CNS |
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Describe Ependymal cells
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line cavities of the brain and spinal cord
circulate cerebrospinal fluid |
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Types of support cells of the PNS
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1. Schwann Cells
2. Satellite Cells |
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Describe Schwann Cells
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only in the PNS
functions: support, macrophage, protects axon, myelination 1 Schwann cell can provide only 1 myelin segment |
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What is the difference between a myelinated axon and an unmyelinated axon with regard to Schwann cells?
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a schwann cell is able to myelinate one segement of one axon or engulf several axons
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Describe a satellite cell
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protects neuronal cell bodies (bascially covers the soma) in the PNS
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Describe the location of the Diencephalon
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rostral to the brainstem
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Major subdivisions of the diencephalon
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Epithalamus
Subthalamus Hypothalamus Thalamus Third Ventrical |
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Anterior border of the diencephalon
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Lamina Terminalis
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Roof of the diencephalon
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Body of the fornix
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Structure that connects the R and L thalamus
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Massa Intermedia
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What separates the thalamus from the hypothalamus
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hypothalamic sulcus
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What 2 structures are located in the midbrain tectum
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Superior and Inferior Colliculus
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The dienephalon is bound laterally by...
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posterior limb of the internal capsule
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What separates the diencephalon into 2 symmetrical halves
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third ventrical
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What structure is found in the epithalamus?
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Pineal Gland
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Describe the location of the pineal gland
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attached to the roof of the third ventricle near the posterior commissure
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Pinealocytes
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glia cells found in the epiphysis
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Functions of the epiphysis
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circadian rhythmicity, spontaneous locomotor activity, feeding and drinking patterns, initiation of puberity
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What do pinealocytes secrete
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hormone, melatonin
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Percocious puberity
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caused by tumors of the pineal gland
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Brain Sand
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calcification of the epiphysis
(ID midline in a radiograph) |
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Describe the Subthalamus
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located rostral to the midbrain
contains the subthalamic nucleus (crucial relay of the basal ganglia, organize movement) |
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What separates the thalami
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Third ventrical
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Thalamic Radiations
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afferent fibers to the cortex from the thalamus
(specifically from lateral thalamus to the internal capsule then to the cortex) |
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Thalamus is a relay center to...
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cortex, cerebellum, and basal ganglia
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Internal Medullary Lamina
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Y shaped structure within the thalamus
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Name the 3 groups created by the internal medullary lamina
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1. anterior nuclear group
2. medial nuclear group 3. lateral nuclear group |
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Where is the centromedian nucleus nuclei of the thalamus located?
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within the internal medullary lamina
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What 3 structures does the posterior region of the thalamus contain
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1. pulvinar
2. lateral geniculate body 3. medial geniculate body |
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Reticular Thalamic Nucleus
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surrounds the lateral portion of the thalamus and contains inhibitory nuerons
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What is unique about the Reticular Thalamic Nucleus
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1. all of its projections terminate in the thalamic nuclei
2. purely GABAergic (inhibitory) |
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Thalamocortical Circuit
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nearby points in the thalamus project to nearby points in the cortex (topological)
excitatory (glutamatergic) reciprocated by a topological and excitatory corticothalamic projection |
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Function of the Reticular Thalamic Nucleus
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prevent recprical feedback between the thalamus and cortex)
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Name some of the functions of the thalamus
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maintenance and regulation of consciousness, alertness and attention
conscious perception and interpretation of pain synaptic input for all sensory impulses (except olfaction signals) |
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Name the structures ovserved in the area of the hypothalamus
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mammillary bodies, tuber cincereum, infundibulum, neurohypophysis, optic chiasm
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Bounderies of the hypothalamus
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anterior = lamina terminalis
superior = hypothalamic sulcus Inferior = optic chiasm and tracts posterior = posterior edge of mammillary bodies |
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Tuber Cinereum
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imaginary area on the inferior border of the hypothalamus between the optic chiasm and mammillary bodies.
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General functions of the hypothalamus
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regulates: heart rate, blood pressure, water metabolism, general metabolism, sexual behavior, temperature, GI activity
elaboration of emotional responses modulates autonomic responses |
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2 Afferent inputs to the hypothalamus
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1. forebrain (limbic system, retina and others)
2. brain stem/spinal cord (sensory input via dorsal longitudinal fasciculus (DLF)) |
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Associated pathways of forebrain afferent input to the hypothalamus
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hippocampus to hypothalamus via fornix
amygdala to hypothalamus via stria terminalis |
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Hypothalamic efferents
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sends out to same areas from which recieved input
(exception: mammillary bodies to thalamus via mammillothalamic tract) |
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Hypophysis
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connection between the hypothalamus with the pituitary gland
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Neurohypophysis
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porterior portion of the pituitary gland
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Adenohypophysis
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anterior portion of the pituitary gland
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Hypothalamic Areas
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Lateral
Medial Periventricular (most medial surrounding the third ventricle) |
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Hypophyseal portal vessels
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blood vessels that connect the hypothalamus to the adenohypophysis
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2 Nuclei connecting with the posterior pituitary (neurophypophysis)
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1. Supraoptic nucleus (SON)
2. Paraventricular nucleus (PVN) both release neuroendocrine products into the general circulation via the nuerohypophysis |
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Infindibulum & Pars Nervosa
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axons and axon terminals of the neurohypophysis, respectively
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3 parts of the adenohypophysis
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1. pars tuberalis
2. pars distalis 3. pars intermedia |
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Median eminence
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ventral portion of the hypothalamus, where hypothalamic axons converge to secrete releasing/inhibiting hormones with act on cells in pars distals as signals to release/store hormones
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Function of Anterior Hypothalamus
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Detects an increase in blood temperature
Activated cutaneous vasodilation and sweating (lesion results in hyperthermia) |
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Function of Posterior Hypothalamus
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Detects decrease in blood temperature
Activiates cutaneous vasoconstriction and shivering to raise temperature (lesion results in hypothermia) |
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Function of Lateral Hypothalamus
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feeding center
(lesion: anorexia) |
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Function of the Ventromedial Hypothalamus
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satiety center
(lesion: overeating and rage) |
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CN I
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Olfactory nerve
(olfaction) |
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CN II
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Optic nerve
(vision) |
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CN III
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Oculomotor nerve
(eye movement, pupil constriction) |
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CN IV
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Trochlear nerve
(eye movement) |
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CN V
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Trigeminal nerve
(facial sensation, muscles of mastication) |
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CN VI
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Abducens nerve
(eye movement) |
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CN VII
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Facial nerve
(muscles of facial expression, taste, lacrimation, salivation) |
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CN VIII
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Vestibulocochlear nerve
(hearing, equilibrium sense) |
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CN IX
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Glossopharyngeal nerve
(pharyngeal muscles, carotid body reflex, salivation) |
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CN X
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Vagus nerve
(parasympathetic to most organs, laryngeal muscles, pharyngeal muscles, aortic arch reflexes) |
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CN XI
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Spinal Accessory nerve
(head turning) |
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CN XII
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Hypoglossal nerve
(tongue movement) |
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Dysnosmias: Anosmia & Hyposmia
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Anosmia = no smell
Hyposmia = decreased function |
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Cacosmia
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hallucination of unpleasant smells
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Olfactory pathway
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1. odorants must dissolve in mucosa
2, olfactory receptors (metabotropic chemoreceptors) on dendrites of first order nuerons are activated 3. axons collect and penetrate the cribiform plate of ethmoid bone 4. first synapse occurs in teh olfactory bulb between first order bipolar neurons synapse with second order mitral cells |
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Lateral Olfactory Stria
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one olfactory tract
projects to the pyriform and entorhinal regions of the cerebral cortex, and amygdala |
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Medial Olfactory Stria
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one olfactory tract
projects to the contralateral olfactory bulb via the anterior commissure |
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Is the thalamus involved with the olfaction
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NO
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The layers of the eye from innermost to outermost
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Retina (Nueral)
Choriod (vascular) Sclera (fiberous) |
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Of the 10 layers of the retina is 1 the innermost or outermost?
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1 is the outermost and layer 10 is the innermost
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What are the 5 types of nuerons in the retina and which are involved in the visual pathway?
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Receptor, Bipolar, Ganglion -> involved with the visual pathway
horizontal and amacrine -> not involved |
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2 types of receptor neurons of the retina
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Rods (night vision)
Cone (color) |
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Describe the Rod receptor nueron
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-low intensity of illumination and subserve twilight and night vision
-when only rods activated, we cannot see color -contain more visual pigment and are more sensitive than cones -total loss of rods = night blindness |
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Describe the Cone receptor nueron
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-higher threshold of excitability (stimulated by light of relatively high intensity)
-sharp vision -color discrimination -day vision -3 types of cones (encompass the visual spectrum) |
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Layer 1 of the retina
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pigment epithelium, absorbs light not captured by retina
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Layer 2 of the retina
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contains the receptor portion of rods and cones
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Layer 6 of the retina
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contains cell bodies of horizontal, bipolar, and amacrine neurons
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Layer 8 of the retina
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contains cell bodies of the ganglion cells
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Layer 9 of the retina
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next to innermost layer
contains axons of the ganglion cells, these axons become the optic nerve |
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Ganglion nuerons of the retina
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axons project to become the optic nerve
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Bipolar nuerons of the retina
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neuronal "link" between the receptor nuerons and ganglion neurons
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Amacrine and Horizontal nuerons of the retina
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internuerons in the retina that make synapses on other neurons
Involved with visual processing |
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Optic disc
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one area of specialization of the retina
axons of the ganglion nerves converge here to form the optic nerve |
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Fovea Centralis
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area of the retina containing only cones
inner layers are shifted to the side so light may hit the photoreceptors without any distortions [sharpest vision and most acute color discrimination] |
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Central visual pathway -
Pupillary pathways - Visual association pathway - Reticular pathway - Hypothalamic pathway - |
Central visual pathway - produces vision
Pupillary pathways - one to iris (constricts pupil), one to ciliary body (lens accommodation) Visual association pathway - via super colliculus Reticular pathway - produces alertness Hypothalamic pathway - circadian rhythm |
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The path from light to optic nerve
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light -> photoreceptor -> bipolar neuron -> ganglion nueron -> optic nerve
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Which neurons are 1st and 2nd order in the visual pathway
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1st order = bipolar neuron
2nd order = ganglion nueron |
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What is the difference between Optic Nerve and Optic Tract
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Optic nerve is before the optic chiasm and optic tract is after
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What information does the Right optic tract contain
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contralateral visual field
aka. Left visual field |
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Central Visual Pathway
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80% of optic tract -> lateral geniculate body -> primary visual cortex in occipital lobe
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Does that lateral geniculate body receive information from both eyes?
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Yes, but from the contralateral visual field
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How many cellular layers does the lateral geniculate body have, and how are they arranged?
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6 layers
3 devoted to contralateral axons 3 devoted to ipsilateral axons |
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What order are the neurons in the lateral geniculate body?
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3rd order
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Where does information from the fovea project to on the occipital lobe?
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occipital pole (most posterior portion)
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Where does the superior half of the visual field project to?
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area inferior to the calcarine fissure
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Where does the inferior half of the visual field project to?
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area superior to the calcarine fissure
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Meyer's Loop
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optic radiations conveying info to the inferior occipital lobe
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Will a person be able to see if there is a lesion to V1 in the central visual pathway
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No
V1 = visual awareness A person would be aware enough to move out of the way if a ball was thrown at them |
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Agnosia
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inability to recognize objects
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Prosopagnosia
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inability to recognize faces
(right occipitoparietal cortex, grandmother cells) |
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Refraction
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bending of light at an angled surface
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What does a Convex lens do to light?
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causes light rays to converge to a focal point
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What does a Concave lens do to light?
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causes light rays to diverge
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Does a green car absorb the green light or reflect it?
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The green car will absorb all the colors of white light except green, which it reflects
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Spectrum
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ROYGBIV
Red (longest wavelenght, less energy) Orange Yellow Green Blue Indigo Violet (short wavelength, more energy) |
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Photopic Vision
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daytime vision
[Cones] |
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Purpose and contents of photopigment
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transduce light into receptor potential
contains: retinal and Opsin |
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Retinal + Scotopsin =
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Rhodopsin
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Retinal + Blue Opsin =
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Blue photopigment
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Retinal + Green Opsin =
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Green photogpigment
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Retinal + Red Opsin =
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Red photopigment
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In the dark (at rest) the photoreceptor is _____________
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depolarized
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In the presence of light, the photoreceptor _______________
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hyperpolarizes
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Are the Na+ channels in the photoreceptor OPEN or CLOSED in the presence of cGMP?
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OPEN
cAMP is present at rest (in the dark) keeping the photoreceptor depolarized at rest |
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Does light INCREASE or DECREASE the intracellular concentration of cGMP
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Decrease
causing a closure of Na+ channels |
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Light __________ the photoreceptor
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hyperpolarizes
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Sequence of events leading to degradation of cGMP
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1. light detected by a photopigment
2. conformational change in retinal 3. change in opsin structure 4. activate G-protein (tranducin) 5. transducin activated phosphodiesterase (eat up cGMP) |
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Does hyperpolarization lead to an increase or decrease of glutamate release?
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decrease onto the bipolar nueron
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1 Rhodopsin molecule absorbs ____ photon
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One -> leading to an amplification of response
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What does glutamate do to bipolar cells?
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inhibits them
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Reduction of glutamate levels leads to DEPOLARIZATION or HYPERPOLARIZATION of the bipolar cell, which leads to _________ of the ganglion cell.
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Depolarization
Activation |
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What do nuclei of CN III, IV and VI have in common
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nuclei of ocular motion
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What are the 2 nuclei associated with CN III
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1. Oculomotor Nucleus
2. Edinger-Westphal Nucleus (both in the midline in the midbrain) |
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CN IV nucleus
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Troclear Nucleus
(midline in midbrain) |
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CN VI nucleus
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Abducens Nucleus
(midline in caudal pons) |
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Direct pupillary light reflex
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constriction in the eye stimulated
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Consensual light reflex
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constriction in the opposite eye
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Neurons in the Pupillary Pathway from the bipolar neuron to the pupillae muscle
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1. bipolar n.
2. ganglion n. 3. neurons in the pretectal area 4. Edinger - Westphal nucleus 5. ciliary ganglion 6. pupillae muscle |
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What causes the consensual light reflex in pupillary pathway?
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The pretectal area sends two axons out, one to each Edinger-Westphal nucleus
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Is pupil constriction a sympathetic or parasympathetic response?
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parasympathetic
Parasympathetic CN (3,7,9,10) |
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Where does pupillary dilation initiate from and what path does it follow?
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Initiates in the hypothalamus then travels down the spinal cord. It passes through the white rami communicantes to the superior cervical ganglion onto the carotid plexus and lastly to the pupillary dilator muscle.
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Pupillary Pathway for lens accommodation and convergence
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visual info -> visual cortex -> axons to pretectal area -> axons to oculomotor nucleus and Edinger-Westphal nucleus
oculomotor nuclues -> contraction of the medial recti muscle (convergence) Edinger-Westphal -> ciliary ganglion -> contraction of ciliary muscle -> adjust tension in lens |
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Accommodation
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[change in refractive power of lens]
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At rest is the lens thin or thick?
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thin
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What happens upon contraction of the ciliary muscle?
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tension is relieved from the zonule fibers and the lens thickens
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Where is the oculomotor nuclei located?
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Midbrain - level of superior colliculus
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Where is the Trochlear nucleus located?
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Midbrain - level of inferior colliculus
Note: CN leaves dorsally and projects contralaterally |
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Where is the Abducens nucleus located?
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Pons - dorsal in the brainstem
exits ipislaterally at the pons-medullary junction |
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Is CN VII a mixed nerve?
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Yes
4 Nuclei -2 efferent (motor) components -2 afferent (sensory) components |
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Facial motor nucleus
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(1 of 2) efferent nucleus of CN VII
-> innervates the facial muscles |
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Superior Salivatory Nucleus
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1 efferent nucleus of CN VII
parasympathetic innervation to mediate lacrimation and salvation |
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Describe the location of the facial motor nucleus and it's exiting axons
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nucleus - caudal pons
axons travel inward and wrap around the abducens nucleus then travel ventrally |
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What input does the upper 1/2 of the facial motor nucleus receive?
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bilateral input from the cerebral cortex
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What input does the lower 1/2 of the facial motor nucleus receive?
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only contralateral input from the cerebral cortex
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Lesion to the facial motor nucleus
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ipsilateral paresis of the entire half of face
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Lesion to the corticobulbar tract
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contralateral lower face paralysis
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Through what tract does the facial motor nucleus receive input from?
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cortex -> Corticobulbar tract -> facial motor nucleus
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Bell's Palsy
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Lesion facial nerve
paralysis to half of face on ipsilateral side of lesion |
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the facial nerve contains ___________ preganglionic axons that arise from the superior ________ nucleus.
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Parasympathetic
Salivatory |
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Pterygopalatine Ganglion
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receive axons from the superior salivatory nucleus via the facial nerves
leads to lacrimination via the lacrimal glands |
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Submandibular Ganglion
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receive axons from the superior salivatory nucleus via the facial nerves
leads to salivation via the sublingual and submandibular glands |
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What carries gustatory (sensory) info from the anterior 2/3 of the tongue
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CN VII
cell bodies in the geniculate ganglion, and synapse in the solitary nucleus |
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What carries somatic sensations from the small area within the pinna (external ear)
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CN VII
cell bodies in the geniculate ganglion, and synapse in the spinal trigeminal nucleus |
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What is the spinal cord continuous with?
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medulla
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Term for the end of the spinal cord
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conus medullaris
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segments of the spinal nerves
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8 cervical
12 thoracic 5 lumbar 5 sacral 1 coccygeal |
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Where does the spinal nerve C8 emerge from?
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between the seventh cervical vertebrae and the first thoracic vertebrae
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Arrangement of the 10 layers within the gray matter
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Lamina (layer) I is dorsal
Lamina IX is ventral Lamina X surrounds the central canal |
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3 paired funiculi of White Matter in the spinal cord
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Posterior funiculus
Lateral funiculus Anterior funiculus |
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Anterior median fissure
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midline on the spinal cord on anterior surface
contains anterior spinal artery |
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Posterior median sulcus
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posterior midline in the spinal cord
contains posterior spinal vein |
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Posterior Intermediate sulcus
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divides the posterior funiculus into 2 on the spinal cord
only present T7 and above |
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Does the sacral spinal cord contain more gray or white matter?
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large amounts of gray and small amounts of white matter
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Why does the amount of white matter increase as you move up the spinal cord?
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gain more sensory axons
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Where is the dorsal nucleus of Clarke located?
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Thoracic spinal cord - within the posterior horn
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What separates the fasiculus gracilis and fasiculus cuneatus?
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posterior intermediate septum (sulcus)
above T7 |
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Alpha peripheral neuron
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proprioception, somatic motor
largest is diameter and conduction velocity (myelinated) |
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Beta peripheral neuron
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touch, pressure
(myelinated) |
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Gamma peripheral neuron
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Motor to muscle spindles
(myelinated) |
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Delta peripheral neuron
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pain, temperature, touch
(myelinated) |
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B peripheral neuron
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preganglionic autonomic
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C peripheral neuron
-dorsal root -sympathetic |
dorsal root - pain, reflex response
sympathetic - postganglionic sympathetis (unmyelinated) |
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Relative fiber diameter and conduction velocity of fibers of type A
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Diameter and conduction velocity:
alpha > beta > gamma > delta (all myelinated) |
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Ascending Spinal Pathways
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somatosensory pathways for the entire body except orofacial complex
1. Dorsal column/ medial lemniscus pathway 2. Anterior Lateral System (ALS) |
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Where do the central process of the DRG go in the Dorsal Column/ medial lemniscus pathway?
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enter into the spinal cord in the posterior horn
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What is the organization of the posterior funiculus?
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sacral fibers are most medial
cervical fibers are most lateral |
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Fasciculus Gracilis: where and what it carries
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present in all spinal levels
ascending fibers from sacral, lumbar and lower 6 thoracic dorsal roots |
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Fasciculus Cuneatus: where and what it carries
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appear around T7
ascending fibers from upper 6 thoracic and all cervical dorsal roots |
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Where do the internal arcuate fibers cross the midline is the Dorsal column pathway?
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in the medulla
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What sensory information does the dorsal column/medial lemniscus pathway carry?
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fine touch, proprioception, vibration
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What sensory information does the anterior lateral system carry?
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pain, temperature, crude touch
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What are the 3 neurons in the Anterior Lateral System?
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1. DRG neurons (A-delta and C fibers)
2. neuron in dorsal horn to VPL 3. VPL to somatosensory cortex |
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Where do the neurons of the lissauer's tract synapse in the dorsal horn?
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Laminae I, II, and V
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Where does the Anterior Lateral system cross the midline?
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upon entry into the spinal cord via the ventral white commissure
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