Ch 14 A&P Brain And Cranial Nerves

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Ch 14 A&P Brain And Cranial Nerves

Chapter 14 A&P Brain And Cranial Nerves

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Where is 98% of the body's neural tissue?
The brain.
the anterior and largest part of the brain, consisting of two halves or hemispheres
What do the paired cerebral hemispheres control?
Conscious thoughts, sensations, intellect, memory, and complex movement all originate in the cerebrum
What are some landmarks of the cerebral cortex?
gyri, sulci, fissures
a convolution
a groove or fissure, esp. a fissure between two convolutions of the brain, shallower than fissure
a natural division or groove in an organ, as in the brain.
a large portion of the brain, in back of and below the cerebrum and consisting of two lateral lobes and a central lobe - btwn occ lobe and brain stem
What does the cerebellum do?
coordinate voluntary movements, posture, and balance
thalamus (right & left) and hypothalamus, the posterior section of the forebrain
What does the diencephalon contain?
relay and processing centers
between the thalamus and midbrain
What does the hypothalamus do?
Controls emotions, autonomic function, hormone production, apetite, body temperature
What does the brain stem include?
Midbrain, pons (bridge), medulla oblongata
Has nuclei that process visual and auditory information and control reflexes triggered by these stimuli
pons (bridge)
nuclei involved with somatic and visceral motor control
medulla oblongata
sensory information to the thalamus and other places, contains major centers that regulate autonomic functs (
What is the transitional area betweent he diencephalon and the spinal cord?
Conscious thought processes, intellectual functions, memory storage and processing, conscious and subcon. regulation of skeletal muscle contractions
relay and precessing centers for sensory information
Centers controlling emotions, autonomic functions, and hormone production
*Mesencephalon (middbrain)
processing of visual and auditory data, gerneration of reflexive somatic motor responses, maintenance of consciousness
relays sensory information to cerebellum and thalamus, subconscious somatic and visceral motor centers
*Medulla oblongata
relays sensory information to thalamus and to other portions of the brain stem, autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)
coordinates complex somatic motor patterns, adjusts output of other somatic motor centers in brain and spinal cord
What are the ventricles of the brain?
Large lateral ventricle (1&2), diencephalon ventricle (3), and pons and cerebellum ventricle (4)
Central canal
center of the spinal cord, a continuation of the large ventricle
What are 1 & 2?
Large lateral ventricle - cerebrohemisphere ventricles full of CSF, runs into 3
What provides protection and support for the brain?
The cranial meninges
Cranial meninges
continuous with spinal meninges - cranial dura mater, arachnoid mater, pira mater
Cranial pia mater
contains blood vessles, brain tissue itself doesn't have blood
Functions of the cranial meninges 1:
Tough fibrous extensions of the dura mater celled dura folds act like safety belts that hold the brain in position.
Functions of the cranial meninges 2:
The cerebrospinal fluid in the subarachnoid space acts like an airbag that cusions against sudden jolts and shocks
Cerebrospinal Fluid & function
Surrounds and bathes the exposed surfaces of the CNS - Fuctions: Cushioning, supporting, transport nutrients, chem. messenger, waste products
What kind of chemicals does the CSF transport?
neurotransmitters and hormones
Circulation of CSF
Choroid plexus > ventricles > central canal of spinal cord > subarachnoid space surrounding the spinal cord
Some areas of the CSF and blood supply are together so they can...?
exchange nutrients and wastes
How does the brain get its blood supply?
Major arteries (internal carotid arteries and the vertebral arteries) and internal jugular veins (main vein, drains brain)
Why is blood not in the TISSUE of the brain?
Blood brain barrier
blood brain barrier
neural tissure in the CNS is isolated due to astrocytes (support), tight juntions, only lipid-soluble compounds can diffuse
Why is transport across the BBB selective and directional?
neurotransmitter entry from the bloodstream could result in the uncontrolled stimulation of neurons throughout the brain
WBC aren't in the brain to act protect it so what does?
*Exception to BBB 1:
Portions of the hypothalamus – monitors temperature of blood
*Exception to BBB 2:
Posterior lobe of the pituitary gland – secrete hormones into the blood
*Exception to BBB 3:
Capillaries in the pineal gland – secrete melatonin
*Exception to BBB 4:
Capillaries at the choroid plexus – CFS gets rid of waste here
medulla oblongata
continuous with the spinal cord, communication center, coordinates autonomic reflexes, control visceral functions
The pons (bridge)
Links and controls 4 groups of components
1st component controlled by pons
sensory and motor nuclei of cranial nerves
2nd component controlled by pons
nuclei involved with the control of respiration - triggered by the level of CO2 (carbon dioxide) in blood
3rd component controlled by pons
nuclei and tracts that process and relay information and heading to of from the cerebellum - pons right in front of cerebellum, motor information sent from cerebellum to pons to muscles
automatic processing center
2 primary functions of cerebellum
1) adjusting the postural muscles of the body, muscle tone 2) programming and fine-tuning movements, atheletes build up nerve pathways
midbrain, contains corpora quadrigemina - nuclei process visual and auditory sensations - ties them together and reflexes are involved
thal & hypo, conscious and unconscious sensory information and motor commands
Pineal gland (pineal body, epiphysis)
makes melatonin, biological clock
final relay point for ascending sensory information, acts as a filter (tons of information, don't need to be conscious of of everything)
functions of hypothalamus
subconscious control of skeletal muscle contractions, control autonomic function, production of emotions and behavioral drives, regulation of body temperature
Where does the fissure end?
at the top of the corpus collosum
corpus callosum
made of fibers (nervous tissue) two cerebrohemispheres communicate through here
What is the entire part of the brain with the gyri?
cerebrum, ends at corpus callosum = gray matter, diencephalon = white matter
Functions of limbic system
establish emotional states, links conscious with unconscious, facilitates memory storage and retrieval
amygdaloid body
interface btwn limbic system, cerebrum, and various sensory systems - ties in different systems
important in learning, especially in the sotrage and retrieval of new long term memories
What's the largest region of the brain?
cerebrum, contains gray and white matter
cerebral cortex
a blanket of neural cortex - most superficial, gyri, longitudinal fissure, corupus callosum, central sulcus
longitudinal fissure
seperates 2 hemispheres
central sulcus
divides the pregyrus and postgyrus
cerebral lobes
each cerebral hemisphere receives sensory information, the 2 hemispheres have different functions, the assignment of a specific function to a specific region of the cerbral cortex is not exact
integrative centers
direct extremely complex motor activities, complex analytical functions, general interpretive area and the speech center
general interpretive area
receives information from all the sensory association areas, personality may be related to how you interpret those senses, left hemisphere
the speech center
lies along the edge of the premotor cortex, regulates the patterns of breathing and vocalization
hemispheric lateralization
functions that are not ordinarily performed by the opposite hemisphere, left hemisphere, right hemisphere, left/right brained
cranial nerves
PNS components, twelves pairs, number corresponds to position
Types of cranial nerves
sensory, special sensory, motor, mixed
olfactory nerves
I special sensory, sense of smell
optic nerves
II special sensory, eyes
oculomotor nerves
III motor nerves, innervates four of the six extra-ocular muscles
trochlear nerves
IV motor nerves, helps in looking down
abducens nerves
VI motor nerves, makes the eye look side to side
trigeminal nerves
V mixes, provides somatic sensory info from the head and face, has 3 branches: ophthalmic branch, maxillary branch, mandibular branch
facial nerves
VII mixed, provides deep pressure sensations, control the superficial muscles of the scalp and face, bells palsy effects cranial nerve VII
vestibulocochlear nerves
VIII special sensory, balance from inner ear and equilibrium, hearing from cochlea, provides sense of hearing
glossopharyngeal nerves
IX mixed to head and neck, innervate the tongue (speech) and pharynx (swallowing), provide taste sensations (sensory) muscles involved with swallowing
vagus nerves
X mixed, provide somatic sensory information about 6 things, controls breathing and heart rate
Vagus nerves provide somatic sensory info about:
external acoustic canal, diaphragm, pharyngeal taste receptors, esophagus, repiratory tract, abdominal viscera
accessory (spinal) nerves
XI motor to muscles of the neck and upper back, voluntary swallowing muscles, SCM and trapexius muscles
hypoglossal nerves
XII motor, tongue movements