Brain and Cranial Nerves Flashcards
Full growth and weight of the brain?
3LBS and 20 YRS
limited storage capacity for _____ and must be continually supplied; deficiency may cause:
glucose; confusion, dizziness, convulsions, unconsciousness
major parts of brain
brain stem, diencephalon, cerebrum, cerebellum
three extensions of the meningeal layer of the dura mater separate parts of the brain
falx cerebri, falx cerebelli, tentorium cerebelli
Role of falx cerebri:
separate right from left cerebral hemisphere
Role of falx cerebelli
found between right and left halves of cerebellum
Role of tentorium cerebelli -
separate cerebellum from occipital lobe
Formation of CSF occurs where?
four place, ventricles
Principal site of CSF production
Lateral ventricle, 1 and 2
Drains lateral ventricles
3rd ventricle
Drains 3rd ventricle
4th ventricle
How is CSF formed
filtration of blood water through a network of capillaries produced at the rate of about 1 liter per day and ependymal cells called the choroid plexus
Trace pathway of CSF flow
lateral ventricles – foramen of Monro –third ventricle – 4th ventricle – aqueduct of Sylvius (cerebral aqueduct) – central canal of spinal cord
what is the CSF reabsorbed by
the arachnoid villi of the superior sagittal blood sinus
Cause of hydrocephalus
is CSF cant circulate or drain properly due to an obstruction in the ventricles or subarachnoid space, a buildup will occur causing increased pressure on the brain - headache, nauseous, coma
autonomic reflex centers
respiratory (breathing rhythm) cardiac control (force/rate of heart beat) vasomotor (vessel vasoconstriction) coughing, vomiting, sneezing, swallowing, hiccupping :: receive visceral, afferent fibers from spinal/cranial nerves and synapse in reflex centers - efferent fibers leave by way of spinal/cranial nerves
pons white matter
interconnects different levels of the brain by way of tracts and relays nerve impulses related to voluntary skeletal movements from the cerebral cortex to the cerebellum
pons gray matter
nuclei for origin of CN 5,6,7,8 and the pneumotaxic and apneustic centers - regulate rate and rhythm of breathing along with medulla
midbrain connects what to what?
pons to diencephalon
Role of cerebral aqueduct?
transports CSF
White matter organized into?
tracts organized into cerebral peduncles that convey motor and sensory impulses
Gray matter organized
nuclei for origin for CN 3,4 and the corpora quadrigemina (two pairs of rounded nuclei) on roof of midbrain
superior colliculi vs inferior colliculi
superior-visual reflex
inferior-auditory
ascending sensory pathways are relayed to
the thalamus and then the cerebral cortex
reticular activating system; 3 functions
- regulation of muscle tone 2. arousal from sleep with stimulation from eyes ears skin 3. maintains consciousness and alertness
Vermis connects
two cerebellar hypothesis
Cerebellum: % of brain volume and % of neurons in CNS
10 % brain
50% nuerons
White matter organized into?
three cerebellar tracts: superior, middle, inferior cerebellar peduncles
Superior Tract
afferent or efferent?
carry impulses from ___ to ___?
efferent fibers that carry impulses from cerebellum to midbrain, thalamus, and cortex
Middle tract carries fibers from?
Cortex
Inferior cerebellar peduncle
Ascending or descending to ?
ascending afferent fibers from cord and medulla
cerebellum functions
- error control in body movements (executes the movement intended by cerebral cortex and makes adjustments in muscle contraction) 2. predictive function (detects speed and progress of body movements and will slow down and even stop them in order to smoothly accomplish a movement) 3. efficient body movement (influences antagonistic muscles for most efficient body movement) 4. maintains muscle tone (to maintain posture and equilibrium
injury to cerebellum results in
cerebellar ataxia-uncoordinated walking
Diencephalon develops from?
forebrain
Thalamus relay station for?
principal relay station for sensory pathways to the cerebral cortex; receives all sensory nerve impulses except smell from the spinal cord, brain stem, cerebellum, and cerebrum; registers conscious recognition of pain, temp, and awareness of light touch and pressure
Hypothalamus
; receives sensory impulses from sound, taste, smell, and somatic and visceral receptors, 3 major regions possessing important nuclei ( mammillary, tuberal, supraoptic)
Mamillary bodies are a relay station for ?
Smell
Tuberal contains? Connects ?
infundibulum- connects hypothalamus to pituitary gland
2 hormones produced by supraoptic
ADH & Oxytocin
Homeostatic functions of hypothalamus
controls and integrates the ANS, connects with reflex center in the medulla, integrates the activity of the nervous system with the endocrine system (produces hormones), regulates emotional and behavioral patterns, regulates eating and drinking through the feeding, satiety, and thirst centers, regulates body temp
Feeding vs satiety center
When damaged?
feeding-hunger and desire for food if damaged leads to anorexia
Satiety-inhibits appetite damaged-obesity
pineal gland
epithalamus that secretes the hormone melatonin that helps regulate the body’s natural cycle of sleeping and waking hours (circadian rhythm)
Insula aka
island of Reil
Association fibers
connect one part of cortex to another part of the same hemispehre
Commissural fibers
corpus callosum- largest white matter tract
Projection fibers
conect cortex to lower parts of CNS
Basal Ganglion
paired masses of gray matter deep within each cerebral hemisphere; serve as relay station for control of skeletal muscle movements that originate in cerebral cortex. Also serve as extensive interconnections between cerebral cortex , thalamus, hypothalamus, and some fibers descend into cord
Parkinson’s disease
neurons from the corpus striatum that produce dopamine degenerate ( excessive muscle tone leads to rigidity
Limbic systems are located where 2-places
located in the cerebral hemispheres and diencephalon
2 functions of limb systems
one is memory, behavioral and emotional responses. Ie. Rage, aggression, anger, fear, sorrow, pleasure, docile behavior.
Cerebral cortex processes what?
sensory, motor and integrative signals are processed
primary somatosensory cortex (areas 1,2,3)
parietal lobe immediately posterior to the central sulcus (post central gyrus) receives sensory impulses from cutaneous muscle and visceral receptors. (extends from longitudinal fissure to lateral fissure) – each area on the body is represented by a specific area on the gyrus - sensory body image
somatosensory association cortex (areas 5,7)
receives sensory impulses directly from the thalamus; primary and association sensory areas permit aspects of sensory perception - 1. memory of sensory experiences 2. pain, temp, touch 3. allows you to distinguish one sense from another as well as shape and texture
primary visual cortex (area 17) Located where?
occipital lobe
Which areas have the most sensory receptors
face, hands and lips
visual association cortex (areas 18,19)
visual memory - recognition, evaluation, visual memory
optic nerves meet and cross at the
optic chiasma - later vision doesn’t cross, medial does
primary auditory cortex (areas 41,42)
temporal lobe, recognized pitch and rhythm
auditory association cortex (area 22/Wernicke’s)
permits 3 aspects of hearing - auditory memory, recognition of meaning of speech, distinguish between speech noise and music
primary gustatory cortex (area 43)
base of the post central gyrus, interprets sensations related to the sense of taste
motor areas
are regions in the frontal lobe that manage muscular movement
Broca’s motor speech cortex (area 44)
located in frontal cortex - translates thought into speech and coordinates voluntary muscle activity
aphasia
result of injury to the association or motor speech areas - inability to use/comprehend words; can make sound, but not articulate speech
motor association cortex (area 6)
immediately anterior to the pre-central gyrus - learned complex and sequential nature motor skills - generates nerve impulses that causes muscles to contract in a specific sequences that has been practiced and learned (muscle memory)
asymmetry (unevenness) of the cerebral hemisphere
more pronounced in men; women have larger connections between the two hemispheres
twelve pairs of cranial nerves
originate from the brain; named on the basis of distribution and are numbered by order of attachment from anterior to posterior
sensory cranial nerves-which contain only sensory nerves?
1,2,8
