Brain and cranial nerves Flashcards
Brain integrations
sensations muscle contraction/coordination language memory emotions thinking learning
major parts of brain
- brain stem = continuation of spinal cord (medulla, pons, midbrain)
- cerebellum = 2nd biggest part of brain
- diencephalon = thalamus, hypothalamus, epithalamus
- cerebrum = biggest part of brain
meninges
dura mater: periosteal and meningeal layers, b/t which is the venous sinus where CSF drains
arachnoid mater
-sub arachnoid space where CSF circulates
-arachnoid granulations
pia mater
extensions of dura mater
falx cerebri = separates 2 cerebral hemispheres
tentorium cerebelli = separates cerebellum from cerebrum
falx cerebelli = separates 2 cerebellum hemispheres
Blood flow to/from brain
- gets 20% of blood supply
- internal carotid and vertebral arteries bring blood
- internal jugular veins take blood
CSF
- clear fluid
- circulates thru cavities in brain (ventricles), spinal cord (central canal), and subarachnoid space
- absorbs shock and protects brain/spinal cord
- transports nutrients and waste bt brain and blood
ventricles
- csf filled cavities w/in brain
- lateral ventricles = cerebral hemispheres
- third ventricle = diencephalon
- cerebral aqueduct = midbrain
- fourth ventricle = brain stem and cerebellum
formation of CSF
choroid plexuses = capillaries in ventricle walls
-ependmal cells lining ventricles draw plasma from choroid plexuses through ependymal cells into ventricles
Circulation of CSF
- lateral ventricles –> interventricular foramina –> 3rd ventricle –> cerebral aqueduct –> 4th ventricle –> subarachnoid space or cenral canal
- reabsorbed into blood by arachnoid villi
medulla oblongata
- Pyramids = bulges on anterior formed by corticospinal trancts from cerebrum to spinal cord
- common site for decussation of ascending/descending tracts
- Vital centers : cardiovascular and respiratory
- centers for vomiting, swallowing, sneezing, coughing, and hiccupping
- cranial nerves VIII-XII
- part of 4th ventricel
pons
- nuclei relay motor input from cerebral cortex to cerebellum
- vestibular nuclei
- peneumotaxic and apneustic area
- nuclei for cranial nerves V-VIII
Midbrain or Mesencephalon
- pons to diencephalon
- cerebral aquaduct flows through
- cerebral peduncles on front
- tectum/corpora quadrigemina w/ superior and inferior colliculi
- substantia nigra, red nucleus, cranial nerves 3-4
Substantia Nigra and Red Nucleus
- both in midbrain
- substantia nigra = associated with dopaminergic neurons–> control subconscious muscle activities –> loss of neurons = parkinson –> excess neurons = shizophrenia –> communicate with basal nuclei
Red nucleus = helps control voluntary movement of limbs
Reticular formation
- upper part of spinal cord, through brain stem, into lower diencephalon
- Reticular Activating System (RAS) = sensory axons that go from reticular formation through thalamus to cerebral cortex–> help maintain consciousness + sleep/waking –> doesn’t include smell
Cerebellum
- 2nd biggest part of brain
- vermis
- anterior and posterior lobes control subconscious skeletal movements
- inferior flocculonodular lobe contributes to equilibrium/balance
- coordinates movements and regulates posture/balance
- smoothes movements during skilled stuff
- musce memory
cerebral cortex
arbor vitae
cerebellar peduncles
- gray matter in form of parallel folds called folia
- tracts of white matter
- 3 pairs, superior, middle, and inferior –> attach cerebellum to brainstem
thalamus
major relay station for most sensory impulses
hypothalamus
consists of mammilary body, median eminence, infundibulum, and nuclei
-controls ANS, produces hormones, regulates emotional/behavioral patterns, eating/drinking, body temp, and circadia rhythms
epithalamus
-consists of pineal gland which secretes melatoin –> sleep inducer
Cerebrum: lobes sulci and gyri
- frontal, parietal, temporal, occipital, and insula
- Central sulcus separates frontal and parietal lobes
- precentral gyrus = primary motor area
- postcentral gyrus = primary somatosensory area
Cerebral white matter
- Association fibers = horizontal and connect different parts of the same hemisphere
- commissural fibers = horizontal and connect gray matter of two hemispheres (corpus colosom)
- projectio fibers = vertical and connect hemispheres with lower brain or spinal cord (corona radiata and internal capsule)
Basal nuclei
- 3 within each cerebral hemisphere
- globus pallidus, putamen, and caudate nucleus
- initiate and terminate movements, supress unwanted movements and regulate muscle tone
Limbic System
- ring of structures on inner border of cerebrum and floor of diencephalon
- cingulate gyrus, hippocampus, dentate gyrus, amygdala, mammillary bodies, thalamus, and olfactory bulb
- “emotional brain”–> behavior
- olfaction + memory
Amygdala
center of rage
-helps us control rage
hippocampus
memory
- destruction takes away ability to form short term memories
- maybe cotributes to alzheimers
Primary somatosensory area Primary visual area Primary auditory area Primary gustatory area Primary olfactory area Primary motor area
- postcentral gyrus
- occipital lobe
- temporal lobe
- base of postcentral gyrus
- temporal lobe
- precentral gyrus
- Somatosensory association area
- visual associaion area
- auditory association area
- posterior to primary somatosensory area
- occipital lobe
- temporal lobe
Broca’s speach area LvR
Wernicke’s area LvR
Broca’s L for anunciation/forming words and R for putting emotion into words
Wernickes L for understanding words and R for understanding the emotion behind words
Prefrontal cortex
mostly inhibits behaviors/impulses
mapping somatosensory area
-size of region depends on sensory impulses received from that part –> greater density of receptors = greater cortical representation
Mapping motor area
- more area is devoted to those muscles involved in skilled, complex, or delicate movements
- more motor units = more cortex area
-includes Broca’s speach area
Hemispheric Lateralization
Left
- receives sensory signals from and controls muscles of right side
- resoning, numbers, science, sign language, written/spoen language
Right
- senses and motorizes left side
- music, art, space/pattern perception, recognizing faces/emotion, mental images, smells
-females use both while men use one or the other
Brain Waves
Electroencephalogram = records electric activity w/in brain
Alpha = awake and resting with eyes closed Beta = nervous system is active Theta = times of stress Delta = sleeping adults and all the time infants
